Power generator protection system with arc flash incident energy reduction

Abstract

One example includes a power generator protection system. The system includes a circuit breaker configured, when triggered, to provide an open circuit in a power line configured to conduct a current between a power grid point-of-interconnect (POI) and a power generator system. The system also includes a programmable controller configured to monitor the current and to generate a dynamic current threshold based on the current. The programmable controller can further be configured to compare the current with the dynamic current threshold and to trigger the circuit breaker based on a difference of the current relative to the dynamic current threshold to set an arc flash incident energy level of the power generator system at or below a predetermined safety level.

Claims

1. A power generator protection system comprising: a circuit breaker configured, when triggered, to provide an open circuit in a power line configured to conduct a current between a power grid point-of-interconnect (POI) and a power generator system; and a programmable controller configured to monitor the current and to generate a dynamic current threshold based on the current, the programmable controller being further configured to compare the current with the dynamic current threshold and to trigger the circuit breaker based on a difference of the current relative to the dynamic current threshold to set an arc flash incident energy level of the power generator system at or below a predetermined safety level.

2. The system of claim 1, wherein the power generator system comprises a plurality of power generator systems configured to collectively provide the current on the power line, wherein the programmable controller is a site programmable controller configured to control the plurality of power generator systems, wherein the circuit breaker is configured, when triggered, to provide the open circuit in the power line configured to conduct the current between the power grid POI and the plurality of power generators.

3. The system of claim 1, wherein the power generator system comprises a plurality of power generator systems configured to collectively provide the current from each of the plurality of power generator systems as a collective current on a main power line, wherein the power generator protection system is arranged as one of a plurality of local power generator protection systems that are associated with the respective plurality of power generator systems.

4. The system of claim 2, wherein the programmable controller associated with each of the plurality of power generator systems is configured to receive a shutdown signal from one of a power relay system or a site programmable controller associated with the plurality of power generator systems in response to a site circuit breaker being triggered to provide an open circuit in the site power between the power grid POI and the plurality of power generator systems, wherein the programmable controller associated with each of the plurality of power generator systems is configured to trigger the circuit breaker associated with the respective one of the power generators in response to receiving the shutdown signal.

5. The system of claim 2, wherein the programmable controller associated with each of the plurality of power generator systems is configured to provide a status signal to a site programmable controller associated with the plurality of power generator systems in response to the current exceeding the dynamic current threshold, wherein the site programmable controller is configured to trigger a site circuit breaker to provide an open circuit in the main power line between the power grid POI and the plurality of power generator systems in response to the status signal.

6. The system of claim 5, wherein the site programmable controller is configured to provide at least one control command to the programmable controller associated with each of the plurality of power generator systems to provide operational control of the respective one of the plurality of power generator systems via the respective programmable controller.

7. The system of claim 1, wherein the programmable controller comprises a current sampler configured to sample the current from a transformer coupled to the power line to generate a plurality of current samples and to generate a cycle current value for each of the plurality of cycles based on the plurality of current samples associated with each respective one of the plurality of cycles, wherein the dynamic current threshold is generated based on the cycle current value, and wherein the programmable controller is configured to compare the cycle current value with the dynamic current threshold and to trigger the circuit breaker based on a difference of the cycle current value relative to the dynamic current threshold.

8. The system of claim 7, wherein the programmable controller comprises an averaging component configured to substantially continuously average the cycle current value associated with a predetermined number of the plurality of cycles of the current to generate the dynamic current threshold.

9. A method for protecting a power generator system: monitoring a current propagating in a power line between a power grid point-of-interconnect (POI) and the power generator system via an analog input to a programmable controller; sampling each cycle of the current to generate a plurality of current samples for each cycle of the current; generating a cycle current value for each cycle of the current based on the plurality of current samples associated with the respective cycle of the current; continuously storing a predetermined number of cycle current values in a time-wise manner; substantially continuously averaging the predetermined number of cycle current values to generate a dynamic current threshold; comparing the cycle current value associated with at least one of the plurality of cycles with the dynamic current threshold; and providing a digital output signal from the programmable controller to trigger a circuit breaker based on an amplitude difference of the cycle current relative to the dynamic current threshold.

10. The method of claim 9, wherein comparing the cycle current value comprises comparing one of a plurality of sequential cycle current values with a previous one of the sequential cycle current values, wherein providing the digital output signal comprises providing the digital output signal to generate the trigger signal in response to the respective one of the sequential cycle current values differing from the previous one of the sequential cycle current values by greater than a programmable threshold current change value relative to the dynamic current threshold.

11. The method of claim 9, wherein comparing the cycle current value comprises comparing a programmable number of sequential cycle current values with the dynamic current threshold, wherein providing the digital output signal comprises providing the digital output signal to generate the trigger signal in response to each of the programmable number of sequential cycle current values differing from a programmable threshold current change value relative to the dynamic current threshold.

12. The method of claim 9, further comprising generating a statistical aggregation of a programmable number of sequential cycle current values, wherein comparing the plurality of sequential cycle current values comprises comparing the statistical aggregation with the dynamic current threshold, wherein providing the digital output signal comprises providing the digital output signal to generate the trigger signal based on the statistical aggregation relative to the dynamic current threshold.

13. The method of claim 9, wherein providing the digital output signal comprises providing the digital output signal to generate the trigger signal in response to the cycle current value decreasing less than a programmable threshold current change value relative to the dynamic current threshold.

14. The method of claim 9, further comprising maintaining the power generator system via personnel, wherein the personnel maintain the power generator system without at least a portion of personal protective equipment (PPE) that is rated for incident energy levels of greater than 10 calories/cm.sup.2 due to an arc flash incident energy level being set to at or below 10 calories/cm.sup.2.

15. The method of claim 14, wherein the maintaining the power generator system via the personnel comprises maintaining the power generator system via the personnel without at least one of a body suit, a helmet, and gloves.

16. The method of claim 9, wherein generating the trigger signal comprises generating the trigger signal to trigger the circuit breaker to set an arc flash incident energy level to at or below 10 calories/cm.sup.2.

17. The method of claim 9, wherein the power generator system is a plurality of power generator systems, the method further comprising: providing a shutdown signal from the programmable controller to each of a plurality of local programmable controllers associated with the respective plurality of power generator systems in response to providing the digital output signal to trigger the circuit breaker; and triggering a plurality of local circuit breakers from the respective plurality of local programmable controllers in response to each of the local programmable controllers receiving the shutdown signal.

18. A power generator protection system for a plurality of power generator systems, the power generator protection system comprising: a local circuit breaker configured, when triggered, to provide an open circuit in a power line configured to conduct a current between a main power line and a respective one of the plurality of power generator systems, the main power line being configured to conduct a collective current associated with the plurality of power generator systems between the plurality of power generator systems and a power grid point-of-interconnect (POI); and a local programmable controller configured to monitor the current and to generate a dynamic current threshold based on the current, the programmable controller being further configured to compare the current with the dynamic current threshold and to trigger the local circuit breaker based on a difference of the current relative to the dynamic current threshold to set an arc flash incident energy level of the respective one of the plurality of power generator systems at or below a predetermined safety level.

19. The system of claim 18, further comprising: a site circuit breaker configured, when triggered, to provide an open circuit in the main power line; and a site programmable controller configured to monitor the collective current and to generate a dynamic current threshold based on the collective current, the site programmable controller being further configured to compare the collective current with the dynamic current threshold and to trigger the circuit breaker based on a difference of the collective current relative to the dynamic current threshold to set an arc flash incident energy level of at least one of the plurality of power generator systems at or below a predetermined safety level.

20. The system of claim 19, wherein the local programmable controller associated with each of the plurality of power generator systems is configured to receive a shutdown signal from the site programmable controller in response to the site circuit breaker being triggered, wherein the local programmable controller associated with each of the plurality of power generator systems is configured to trigger the respective local circuit breaker in response to receiving the shutdown signal.

21. The system of claim 19, wherein the local programmable controller associated with each of the plurality of power generator systems is configured to provide a status signal to the site programmable controller in response to triggering the local circuit breaker, wherein the site programmable controller is configured to trigger the site circuit breaker in response to the status signal.

22. The system of claim 19, wherein the site programmable controller is configured to provide at least one control command to the local programmable controller associated with each of the plurality of power generator systems to provide operational control of the respective one of the plurality of power generator systems via the respective local programmable controller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates an example of a utility power system.

(2) FIG. 2 illustrates an example of a power generator system.

(3) FIG. 3 illustrates an example of a power relay system.

(4) FIG. 4 illustrates an example diagram of a power generator system.

(5) FIG. 5 illustrates another example diagram of a power generator system.

(6) FIG. 6 illustrates another example diagram of a power generator system.

(7) FIG. 7 illustrates another example diagram of a power generator system.

(8) FIG. 8 illustrates an example of a method for protecting a power generator system.

(9) FIG. 9 illustrates another example of a utility power system.

(10) FIG. 10 illustrates another example of a power generator protection system.

(11) FIG. 11 illustrates another example of a power generator protection system.

(12) FIG. 12 illustrates another example of a power generator protection system.

(13) FIG. 13 illustrates another example of a power generator protection system.

(14) FIG. 14 illustrates an example of a method for protecting a power generator system.

DETAILED DESCRIPTION

(15) This disclosure relates generally to the generation, transmission and distribution electric system, and more specifically to a power generator protection system with arc flash incident energy reduction. A power relay system or programmable controller can detect overcurrent conditions, such as associated with faults, in a power generation system. The power relay system or programmable controller is configured to sample a current in a power line between a power generator system (e.g., a solar cell system or a wind-power system) and a point-of-interconnect (POI) that connects the power generator system to a power grid (e.g., the public utility grid). The power relay system or programmable controller determines a cycle current value corresponding to each given cycle (e.g., AC period) of the current. The power relay system or programmable controller can thus calculate an average of the cycle current values over a predetermined number of cycles of the current. The calculated average current value can thus act as a dynamic current threshold for the power relay system or programmable controller that can change with respect to the calculated average current value over time. Moreover, the power relay system or programmable controller can monitor the current on the power line relative to the dynamic current threshold. In response to the power relay system or programmable controller detecting an amplitude of the current that exceeds the dynamic current threshold, the power relay system or programmable controller can send a trip command to an associated circuit breaker to provide an open circuit in the power line, and can thus cease current flow in the power line.

(16) As an example, the power relay system or programmable controller can compare the cycle current values with the dynamic current threshold in a variety of different ways. For example, the power relay system or programmable controller can compare one or more cycle current values with a programmable threshold difference value relative to the dynamic current threshold, such that if the cycle current value(s) are greater than or less than the dynamic current threshold by greater than the programmable threshold difference value, then the circuit breaker trips. As another example, the power relay system or programmable controller can provide statistical analysis of an aggregation of a sequence of the cycle current values, and can compare the aggregate score with the dynamic current threshold, such as with respect to the programmable threshold difference value, to provide the trip command. As yet another example, the power relay system or programmable controller can analyze the amplitude of the cycle current value(s) relative to the dynamic current threshold over a programmable duration of time (e.g., based on the programmable number of sequential cycle current values) to determine whether to initiate the trip command.

(17) The power relay system or programmable controller can be implemented in solar/renewable energy generation, where troubleshooting power equipment is performed on site. Some solar generation facilities perform incident energy calculations, which can render maintenance on energized equipment difficult based on the variable conditions that can falsely appear as an overcurrent condition. Furthermore, when needed to perform maintenance on power equipment, setting relays to reduce incident energy levels at certain work locations can be based on the power generation facilities having high variability in the amount of current flowing through the breakers. Also, the power generation sites may allow power to flow in both directions through the power line, and the site itself can contribute significantly to the available fault current without being seen by the breaker. Moreover, when troubleshooting the power equipment on the solar generation site, multiple components of solar power equipment (such as inverters) have to be set offline, in order to perform simple maintenance work, resulting in a loss in revenue. Furthermore, maintenance performed by personnel for areas of the power generation system that may not be switched off may require heavy and uncomfortable protective equipment worn by maintenance personnel.

(18) The power relay system or programmable controller identifies conditions in which overcurrent conditions and faults can occur in the power generation facility. Once the power relay system or programmable controller has identified that there are conditions that result in an overcurrent, the power relay system or programmable controller can send a trip command to the breaker to prevent an overcurrent, or to reduce the time duration of a potential arc flash. Minimizing the time duration of arc flashes is beneficial when performing maintenance to render maintenance work more manageable since workers do not have to rely on heavy protective gear to perform the maintenance. Moreover, the benefit of not being required to switch offline an entire power generating system when performing maintenance can result in reduced costs.

(19) A power relay system can be implemented in any of a variety of utility power systems, such as demonstrated in the example of FIG. 1. FIG. 1 illustrates an example of a utility power system 10. The utility power system 10 includes at least one power generator system 12 that is configured to provide power, demonstrated in the example of FIG. 1 as POW, to a power transmission system 14, which can correspond to a power bus or one or more points-of-interconnect (POIs) that provide power via a power distribution system 16 (e.g., transformers, substations, and power lines) to consumers, demonstrated generally at 18. In the example of FIG. 1, the power generator system(s) 12 are demonstrated as solar power generator system(s) that include sets of solar panels 20 configured to generate the power POW via the Sun, demonstrated at 22. However, it is understood that the power generator system(s) 12, with the functionality as described herein, can instead be arranged as any of a variety of other types of power generation systems, such as fossil-fuel power, wind power, or battery power.

(20) In the example of FIG. 1, the power generator system(s) 12 includes a power relay system 24 that is configured to monitor current between the power transmission system 14 and the respective power generator system(s) 12. As described in greater detail herein, the power relay system 24 can sample the current and can determine a cycle current value corresponding to each given cycle (e.g., AC period) of the current. The power relay system 24 can thus calculate an average of the cycle current values over a predetermined number of cycles of the current. The calculated average current value can thus act as a dynamic current threshold for the power relay system that can change with respect to the calculated average current value over time. The power relay system 24 can monitor the current on the power line relative to the dynamic current threshold to detect an overcurrent condition or fault condition (e.g., including arc fault conditions) in one of the power generators of the respective power generator system(s) 12. In response to the power relay system 24 detecting an amplitude of the current that exceeds the dynamic current threshold, such as based on one or more programmable characteristics, the power relay system 24 can send a trip command to an associated circuit breaker to provide an open circuit in the power line, and can thus cease current flow in the power line.

(21) FIG. 2 illustrates an example of a power generator system 50. The power generator system 50 can correspond to any of a variety of power generator system types, such as fossil-fuel, solar power, wind power, or any of a variety of other types of power generator systems. The power generator system 50 can correspond to one of the power generator system(s) 12 in the example of FIG. 1. Therefore, reference is to be made to the example of FIG. 1 in the following description of the example of FIG. 2.

(22) The power generator system 50 includes a plurality N of power generators 52, demonstrated as “POWER GENERATOR 1” through “POWER GENERATOR N”, where N is a positive integer. The power generators 52 can each correspond to one or more power generating elements, such as one or more solar panels, one or more wind turbines, or one or more driven turbines (e.g., fossil-fuel or nuclear powered), that are configured to conduct current I.sub.PWR to a power line 54. The current I.sub.PWR can be provided on the power line 54 to a POI 56, such that the current I.sub.PWR can be provided to the public power utility grid as power to be consumed by power customers. As an example, the power generators 52 can each also include additional supporting equipment, such as inverters (e.g., for solar power generators), transformers, and/or other equipment (e.g., enclosures).

(23) In the example of FIG. 2, the power generator system 50 includes a power relay system 58 that is demonstrated as coupled to the power line 54. It is to be understood that the power line 54 can be provided as multiple separate conductors, such that the power relay system 58 can interconnect separate portions of the power line 54. The power relay system 58 can be configured to protect the power generators 52, and thus the power generator system 50 as a whole, from overcurrent conditions and/or from fault conditions (e.g., including arc fault conditions), as described in greater detail herein. The power relay system 58 includes a circuit breaker 60 that is configured to provide an open circuit in the power line 54 in response to being triggered. The power relay system 58 also includes a power controller 62 configured to sample the current I.sub.PWR to generate a cycle current value at each of a plurality of cycles of the current I.sub.PWR. The power controller 62 can thus generate a dynamic current threshold based on the current cycle values, as described in greater detail herein. As an example, the dynamic current threshold can be generated based on continuously averaging the cycle current values from sequential cycles of the current I.sub.PWR. The power controller 62 can further be configured to compare the current I.sub.PWR with the dynamic current threshold, such that the power controller 62 can trigger the circuit breaker 60 based on an amplitude of the current I.sub.PWR relative to the dynamic current threshold.

(24) FIG. 3 illustrates an example of a power relay system 100. The power relay system 100 can correspond to the power relay system 58 in the example of FIG. 2 or the power relay system 24 in the example of FIG. 1. Therefore, reference is to be made to the examples of FIGS. 1 and 2 in the following description of the example of FIG. 3.

(25) The power relay system 100 includes a circuit breaker 102 and a power controller 104. The circuit breaker 102 is demonstrated as interconnecting portions of a power line 106 on which the current I.sub.PWR propagates. As described in greater detail herein, the current I.sub.PWR is demonstrated as bidirectional, such that the power relay system 100 can protect the associated power generator system from overcurrent and/or fault conditions (e.g., including arc fault conditions) based on different directions of the current I.sub.PWR. Thus, in response to being triggered in response to a trigger signal TRG, the circuit breaker 102 can provide an open circuit condition for the power line 106, thus ceasing flow of the current I.sub.PWR in the power line 106.

(26) The power controller 104 can be configured to implement a power protection algorithm to monitor the current I.sub.PWR and to provide the trigger signal TRG in response to an indication of an overcurrent condition or a fault condition (e.g., including arc fault conditions). The power controller 104 includes a current sampler 108 that is coupled to the power line 106. The current sampler 108 is thus configured to sample the current I.sub.PWR at a predetermined sampling rate (e.g., sixteen samples per period of the current I.sub.PWR). The current sampler 108 can thus generate a current cycle value I.sub.CYC corresponding to a current amplitude for the respective cycle of the current I.sub.PWR. The cycle current value I.sub.CYC can correspond to a type of amplitude representation, such as peak, peak-to-peak, or root-mean-square (RMS) current amplitude of the current I.sub.PWR.

(27) The current sampler 108 can provide the cycle current value I.sub.CYC to a current buffer 110 that is configured to store the cycle current value of each of a sequence of cycles of the current I.sub.PWR, and thus a predetermined number of sequential cycle current values I.sub.CYC. As an example, the predetermined number of the sequential cycle current values I.sub.CYC can be programmable based on the specific characteristics of the power generator system 50. The current buffer 110 can store a number of sequential cycle current values I.sub.CYC that can correspond to a variety of operational features of the power relay system 100, as described in greater detail herein. Therefore, the programmable aspect of the predetermined number of the sequential cycle current values I.sub.CYC can be based on a variety of desired operational characteristics of the power relay system 100.

(28) The power controller 104 can also include an averaging component 112 that is configured to generate an average current value I.sub.AVG corresponding to an average of a plurality of cycle current values I.sub.CYC. As an example, the averaging component 112 can substantially continuously generate an average of the plurality of cycle current values I.sub.CYC, such as a subset (e.g., all) of the predetermined number of the sequential cycle current values I.sub.CYC in the current buffer 110. Alternatively, the averaging component 112 can generate an average of each consecutive set of the cycle current values I.sub.CYC in the current buffer over a given interval of time. As yet another example, the averaging component 112 can receive the current samples of the current I.sub.PWR, such that the averaging component 112 can generate the average current value I.sub.AVG based on the digital samples directly. The averaging component 112 can provide the average current value I.sub.AVG to a current comparator 114, such that the current comparator 114 can generate a dynamic current threshold 116 based on the average current value I.sub.AVG. As an example, the dynamic current threshold 116 can correspond directly to the average current value I.sub.AVG, or can correspond to an adjusted version of the average current value I.sub.AVG (e.g., based on an offset value).

(29) In the example of FIG. 3, the current buffer 110 also provides one or more of the cycle current values I.sub.CYC to the current comparator 114. The current comparator 114 can thus analyze the cycle current value(s) I.sub.CYC relative to the dynamic current threshold 116 to determine the occurrence of an overcurrent condition or a fault condition (e.g., including arc fault conditions). In response to detecting the overcurrent condition or the arc fault condition based on the cycle current value(s) I.sub.CYC relative to the dynamic current threshold 116, the current comparator 114 can provide the trigger signal TRG to the circuit breaker 102. As a result, the circuit breaker 102 can provide an open circuit in the power line 106 to cease flow of the current I.sub.PWR in the power line 106.

(30) The current comparator 114 can be configured to provide the trigger signal TRG based on any of a variety of conditions that can be indicative of an overcurrent or a fault condition (e.g., including arc fault conditions). In the example of FIG. 3, the current comparator 114 can be provided one or more programmable thresholds, demonstrated as a signal TH provided to the current comparator 114. As an example, the current comparator 114 can compare a single cycle current value I.sub.CYC with a programmable current difference threshold (e.g., provided via the signal TH) relative to the dynamic current threshold 116. Therefore, in response to single cycle current value I.sub.CYC having an amplitude that is greater than or less than the dynamic current threshold 116 by the programmable current difference threshold, the current comparator 114 can provide the trigger signal TRG. Based on comparing a single cycle current value I.sub.CYC to the dynamic current threshold 116, the current comparator 114 can provide the trigger signal TRG very rapidly (e.g., within 0.02 seconds), such that the circuit breaker 102 can provide the open circuit very rapidly (e.g., within 0.05 seconds) in response to the trigger signal TRG. As a result, as described in greater detail herein, the power relay system 100 can provide for a significantly reduced arc flash incident energy (e.g., less than 10 calories/cm.sup.2) based on the substantially reduced duration of time of current associated with the arc flash event.

(31) As another example, the signal TH can also include a programmable threshold associated with a dynamic baseline current associated with the comparison. For example, the current comparator 114 can be configured to provide the trigger signal TRG in response to a plurality of cycle current values I.sub.CYC being greater than or less than the dynamic current threshold 116, such as by the programmable difference current threshold, for the programmable current threshold. The programmable difference current threshold can, for example, correspond to a predetermined number of sequential cycle current values I.sub.CYC (e.g., cycle current values I.sub.CYC in each of sequential cycles of the current I.sub.PWR), as stored in the current buffer 110, such as all or less than all of the cycle current values I.sub.CYC stored in the buffer 110 at a given time.

(32) As another example, the current comparator 114 can provide a statistical analysis of an aggregation of a subset of the cycle current values I.sub.CYC stored in the current buffer 110. Thus, the current comparator 114 can compare a characteristic of the statistical aggregation of the cycle current values I.sub.CYC with the dynamic current threshold 114, such as including the programmable difference current threshold and/or the programmable dynamic amplitude threshold. As an example, the current comparator 114 can analyze a plurality of the cycle current values I.sub.CYC stored in the current buffer 110 to provide an aggregate amplitude score that is compared with the dynamic current threshold 116. For example, the aggregate amplitude score can be an average of a plurality of cycle current values I.sub.CYC (e.g., less than all of the cycle current values I.sub.CYC stored in the current buffer 110) that can be compared with the dynamic current threshold 116. As another example, the aggregate amplitude score can be a median of the plurality of cycle current values I.sub.CYC, a difference between the first and last cycle current values I.sub.CYC in a given sequential range of cycle current values I.sub.CYC (e.g., relative to the programmable current difference threshold), a difference between high and low values of a given sequential range of cycle current values I.sub.CYC (e.g., such as with one or more extreme values removed), or any of a variety of other statistical manipulations of a set of cycle current values I.sub.CYC. Therefore, the current comparator 114 can provide a number of different ways of statistically analyzing a sequential set of the cycle current values I.sub.CYC with the dynamic current threshold 116 to provide the trigger signal TRG in response to a given comparison condition that is indicative of an overcurrent or a fault condition (e.g., including arc fault conditions).

(33) As yet another example, the current comparator 114 can compare sequential cycle current values I.sub.CYC on an individual basis. For example, the current comparator 114 can compare a given one of the cycle current values I.sub.CYC with a preceding one of the cycle current values I.sub.CYC. In this example, if the current comparator determines that the two sequential cycle current values I.sub.CYC have a difference that is greater than the programmable current difference threshold relative to the dynamic current threshold 116 (e.g., greater than or less than the dynamic current threshold 116), then the current comparator 116 can provide the trigger signal TRG. Therefore, the current comparator 114 can determine the indication of the overcurrent and/or fault condition in a variety of ways.

(34) As yet another example, the power relay system 100 can be configured to detect a sudden current direction reversal, such as can be indicative of an overcurrent or fault condition. For example, a fault condition can result in the current I.sub.PWR through the circuit breaker 102 suddenly reversing direction (e.g., based on an arc fault at one of the power generators 52). However, if the absolute value of the amplitude of the current I.sub.PWR does not appreciably change, a typical power relay system could be unable to identify the change in current direction. Therefore, the power relay system 100 can be configured to identify the change in direction of the current I.sub.PWR and apply the change in direction in the algorithm for generating the dynamic current threshold 116 and/or the comparison of the cycle current value I.sub.CYC with the dynamic current threshold 116.

(35) For example, with respect to the current I.sub.PWR, the power controller 104 (e.g., via the current sampler 108) can be configured to identify the angle of the sequence of the current I.sub.PWR. The power controller 104 can measure the impedance angle, such as for a three-phase voltage/current aspect of the current I.sub.PWR. The sequence angle of the current I.sub.PWR can be observed based on a comparison of the current I.sub.PWR (e.g., a set of samples for a given cycle of the current I.sub.PWR) to a predetermined setpoint. As an example, the power controller 104 can identify that, if the sequence angle has changed by more than the predetermined setpoint (e.g., approximately 30 degrees), then the power controller 104 can identify that the current I.sub.PWR has changed direction. In response to detecting the reversal of direction of the current I.sub.PWR, the current comparator 114 can apply the signed amplitude of the cycle current value I.sub.CYC in generating the dynamic current threshold 116, thus effecting a large change in the amplitude of the dynamic current threshold 116. As another example, the current comparator 116 can apply the comparison of the signed amplitude of the cycle current value I.sub.CYC with the dynamic current threshold 116. Accordingly, the power relay system 100 can identify a reversal in the direction of the current I.sub.PWR to identify a potential fault, even when the absolute amplitude of the current I.sub.PWR is substantially the same before and after reversal.

(36) As described herein, the current comparator 114 can determine the indication of the overcurrent and/or fault condition (e.g., including arc fault conditions) based on implementing a dynamic current threshold 116. As a result, the instantaneous or time duration comparison of the current I.sub.PWR is with respect to a dynamic (potentially fast or slow changing) current threshold, as opposed to a static threshold referenced to zero amps. Accordingly, the current comparator 114 can more accurately identify an overcurrent or fault condition (e.g., including arc fault conditions) to trigger the circuit breaker 102 relative to typical power generator systems that cannot account for changing conditions in the power generator system. As a result, the power relay system 100 can result in a significantly safer environment for performing maintenance on the associated power generator system 50.

(37) For example, and as demonstrated in greater detail in the examples of FIGS. 4-7 herein, a solar power generator system can provide the current I.sub.PWR to the POI 56 during the daytime at a given amplitude. However, at night, the current I.sub.PWR may flow from the POI 56 to the power generators 52 at a significantly lower amplitude. Therefore, a fault condition of one of the power generators 52 can cause the current I.sub.PWR to change in amplitude, but at a lower amplitude than a trip-point of the circuit breaker of a typical power generator system. Thus, a typical power generator system may not detect the fault condition within a short amount of time, or may not be able to rapidly react to the fault condition by tripping the respective circuit breaker. Such a possibility can create a dangerous working environment for maintenance personnel based on an arc flash event occurring over an extended amount of time (e.g., two seconds or more), thus resulting in extremely high incident energy levels (e.g., greater than 60 calories/cm.sup.2) at a high arc flash boundary (e.g., greater than thirty feet). As a result, maintenance personnel may be required to wear bulky and uncomfortable personal protective equipment (PPE), similar to a “bomb-suit”, to provide maintenance to such typical power generator systems. As an example, the PPE worn by maintenance personnel in a typical power generator system maintenance procedure can include a thick material body suit, a fully enclosed helmet, and thick gloves and boots. Wearing such PPE can be uncomfortable, and much more uncomfortable in warm-weather regions, which may greatly limit an amount of time that personnel can service a maintenance issue before taking a break.

(38) However, by implementing the dynamic current threshold 116, and by implementing one or more of the various different ways of comparing the current I.sub.PWR to the dynamic current threshold 116, as described previously, the power relay system 100 can provide for a more rapid and accurate detection of the overcurrent or fault condition (e.g., including arc fault conditions). As a result, the power relay system 100 can provide a more rapid response to the circuit breaker 102 (e.g., less than one-tenth of a second), thus creating a much safer working environment for maintenance personnel. Particularly, by greatly reducing the reaction time to an arc flash event, the incident energy level of the power generator system 50 can be significantly reduced (e.g., to less than ten calories/cm.sup.2). Such a safer working environment can result in a significant reduction in an arc flash boundary (e.g., to approximately eleven feet). Additionally, maintenance personnel can safely avoid wearing significant uncomfortable PPE, thus allowing for a significant improvement in comfort and efficacy of the maintenance personnel, particularly in warm climates. By mitigating the necessity of wearing extreme PPE, maintenance personnel can safely and more comfortably provide service to the power generator system 50 for longer durations of time before needing to take a break. Additionally, the power generator system 100 can be resilient to spurious temporary changes in the amplitude of the current I.sub.PWR, as well as to adiabatic changes to the amplitude of the current I.sub.PWR based on the changing dynamic current threshold 116.

(39) FIG. 4 illustrates an example diagram 150 of a power generator system. The power generator system in the diagram 150 can correspond to a solar power generator system. The power generator system 50 can correspond to one of the power generator system(s) 12 in the example of FIG. 1. Therefore, reference is to be made to the example of FIGS. 1-3 in the following description of the example of FIG. 4.

(40) The power generator system in the diagram 150 includes a plurality N of power generators 152, demonstrated as “POWER GENERATOR 1” through “POWER GENERATOR N”, where N is a positive integer. The power generators 152 can each correspond to a set of one or more solar panels. Thus, in the example of FIG. 4, the power generators 152 operate in the daytime (as indicated by the presence of the Sun at 154) to conduct individual currents I.sub.PWR_1 through I.sub.PWR_N to a power line 156 on which the current I.sub.PWR is provided as a sum of the currents I.sub.PWR_1 through I.sub.PWR_N. The current I.sub.PWR can be provided on the power line 156 to a POI 158, such that the current I.sub.PWR can be provided to the public power utility grid as power to be consumed by power customers. The current I.sub.PWR can have a relatively high amplitude during normal daytime operation of the power generators 152. For example, for N=6, as an example, each of the currents I.sub.PWR_1 through I.sub.PWR_N can have an amplitude of approximately 100 amps, such that the current I.sub.PWR has an amplitude of approximately 600 amps. As an example, the power generators 152 can each also include additional supporting equipment, such as inverters, transformers, and/or other equipment (e.g., enclosures).

(41) In the example of FIG. 4, the power generator system in the diagram 150 includes a power relay system 160 that is demonstrated as coupled to the power line 156. As an example, the power relay system 160 can correspond to the power relay system 100 in the example of FIG. 3. The power relay system 160 can be configured to protect the power generators 152, and thus the power generator system in the diagram 150 as a whole, from overcurrent conditions and/or from fault conditions (e.g., including arc fault conditions). The power relay system 160 includes a circuit breaker 162 that is configured to provide an open circuit in the power line 156 in response to being triggered, similar to as described previously.

(42) FIG. 5 illustrates another example diagram 200 of the power generator system. The power generator system in the diagram 200 can correspond to the solar power generator system in the example of FIG. 4. Therefore, reference is to be made to the example of FIGS. 1-4 in the following description of the example of FIG. 5.

(43) In the example of FIG. 5, a Kth power generator 152 is demonstrated as having experienced an arc fault event, demonstrated at 202. As a result, while the other power generators 152 are demonstrated as providing the currents I.sub.PWR_1 through I.sub.PWR_N to the power line 156, the Kth power generator 152 is drawing current I.sub.PWR_K from the power line 156, such as corresponding to a short-circuit in the Kth power generator 152. As a result, the current I.sub.PWR can have a diminished amplitude relative to the normal operation in the diagram 150 in the example of FIG. 4. For example, for N=6, as an example, each of the currents I.sub.PWR_1 through I.sub.PWR_N can have an amplitude of approximately 100 amps provided to the power line 156 for normal operation, and the current I.sub.PWR_K can have an amplitude of approximately 200 amps provided from the power line 156, such that the current I.sub.PWR has an amplitude of approximately 300 amps.

(44) The amplitude of approximately 300 amps is less than the amplitude of the current I.sub.PWR during normal operation of the power generator system, as demonstrated in the example of FIG. 4. Therefore, a typical power relay system may not be able to identify the fault condition that caused a reduction in the amplitude of the current I.sub.PWR. However, because the difference between the amplitudes of the current I.sub.PWR is significant, the power relay system 160 can rapidly detect such a change in amplitude of the current I.sub.PWR, as described previously, to open the circuit breaker 162 via the trigger signal TRG. Accordingly, the power relay system 160 can rapidly and safely respond to the fault condition that could be undetected by a typical power relay system. As a result, the power relay system 160 can provide for a reduction in incident energy level resulting from arc flash events, along with a reduction in arc flash boundaries. Therefore, the power relay system 160 can allow for minimization of the need for bulky, heavy, and uncomfortable PPE to be worn by maintenance personnel.

(45) FIG. 6 illustrates another example diagram 250 of the power generator system. The power generator system in the diagram 250 can correspond to the solar power generator system in the example of FIG. 4. Therefore, reference is to be made to the example of FIGS. 1-5 in the following description of the example of FIG. 6.

(46) In the example of FIG. 6, the power generators 152 operate at night (as indicated by the presence of the Moon at 252) to conduct the current I.sub.PWR from the power line 156. Particularly, the power generators 152 can consume some small amount of power based on the operation of heaters and other ancillary equipment at night. Therefore, the current I.sub.PWR can be provided on the power line 156 from the POI 158, such that the current I.sub.PWR can be provided to the power generators 152. For example, for N=6, as an example, each of the currents I.sub.PWR_1 through I.sub.PWR_N can have an amplitude of approximately 2 amps provided from the power line 156 for normal operation, such that the current I.sub.PWR has an amplitude of approximately 12 amps.

(47) FIG. 7 illustrates another example diagram 300 of the power generator system. The power generator system in the diagram 300 can correspond to the solar power generator system in the example of FIG. 4. Therefore, reference is to be made to the example of FIGS. 1-6 in the following description of the example of FIG. 7.

(48) In the example of FIG. 7, a Kth power generator 152 is demonstrated as having experienced a fault event, demonstrated at 302. As a result, while the other power generators 152 are drawing the currents I.sub.PWR_1 through I.sub.PWR_N from the power line 156 at a lower relative amplitude, the Kth power generator 152 is drawing current I.sub.PWR_K from the power line 156 at a significantly higher amplitude (e.g., approximately 200 amps), such as corresponding to a short-circuit in the Kth power generator 152. As a result, the current I.sub.PWR can have a diminished amplitude relative to the normal operation in the diagram 150 in the example of FIG. 4, but greater than the nighttime operation in the example of FIG. 6. For example, for N=6, as an example, each of the currents I.sub.PWR_1 through I.sub.PWR_N can have an amplitude of approximately 2 amps provided from the power line 156 for normal operation, and the current I.sub.PWR_K can have an amplitude of approximately 200 amps provided from the power line 156, such that the current I.sub.PWR has an amplitude of approximately 210 amps.

(49) The amplitude of approximately 210 amps is less than the amplitude of the current I.sub.PWR during normal operation of the power generator system during the daytime, as demonstrated in the example of FIG. 4. Therefore, a typical power relay system may not be able to identify the fault condition that caused a reduction in the amplitude of the current I.sub.PWR. However, because the difference between the amplitudes of the current I.sub.PWR is significant, the power relay system 160 can rapidly detect such a change in amplitude of the current I.sub.PWR, as described previously, to open the circuit breaker 162 via the trigger signal TRG. Accordingly, the power relay system 160 can rapidly and safely respond to the fault condition that could be undetected by a typical power relay system. As a result, the power relay system 160 can provide for a reduction in incident energy level resulting from arc flash events, along with a reduction in arc flash boundaries. Therefore, the power relay system 160 can allow for minimization of the need for bulky, heavy, and uncomfortable PPE to be worn by maintenance personnel.

(50) In view of the foregoing structural and functional features described above, methods in accordance with various aspects of the present disclosure will be better appreciated with reference to FIG. 8. While, for purposes of simplicity of explanation, the method of FIG. 8 is shown and described as executing serially, it is to be understood and appreciated that the present disclosure is not limited by the illustrated orders, as some aspects could, in accordance with the present disclosure, occur in different orders and/or concurrently with other aspects from that shown and described herein. Moreover, not all illustrated features may be required to implement method in accordance with an aspect of the present disclosure.

(51) FIG. 8 illustrates a method 350 for protecting a power generator system (e.g., the power generator system 50). At 352, a current (e.g., the current I.sub.PWR) propagating in a power line (e.g., the power line 54) between a power grid POI (e.g., the POI 56) and the power generator system is monitored. At 354, a dynamic current threshold (e.g., the dynamic current threshold 116) is generated based on the current. At 356, the current is compared with the dynamic current threshold. At 358, a trigger signal (e.g., the trigger signal TRG) is provided to trigger a circuit breaker (e.g., the circuit breaker 60) based on the plurality of sequential cycle current values relative to the dynamic current threshold.

(52) As another example, a programmable controller can be implemented in any of a variety of utility power systems, such as demonstrated in the example of FIG. 9. FIG. 9 illustrates an example of a utility power system 400. The utility power system 400 includes at least one power generator system 402, demonstrated in the example of FIG. 9 as “N” power generator systems 402, where N is an integer greater than or equal to one. The power generator system(s) 402 are configured to provide power, demonstrated in the example of FIG. 9 as POW, to a power transmission system 404, which can correspond to a power bus or one or more points-of-interconnect (POIs) that provide power via a power distribution system 406 (e.g., transformers, substations, and power lines) to consumers, demonstrated generally at 408. In the example of FIG. 9, the power generator system(s) 402 are demonstrated as solar power generator system(s) configured to generate the power POW via the Sun, demonstrated at 412. However, it is understood that the power generator system(s) 402, with the functionality as described herein, can instead be arranged as any of a variety of other types of power generation systems, such as fossil-fuel power, wind power, or battery power.

(53) In the example of FIG. 9, the power generator system(s) 402 includes a site programmable controller 414 that is configured to provide operational control of the power generator system(s) 402. As an example, the site programmable controller 414 can be configured as any of a variety of computing devices that can receive analog and/or digital inputs, process the analog and/or digital inputs, and provide analog and/or digital outputs based on the processed inputs. For example, the site programmable controller 414 can be configured as a computer, as a programmable logic controller (PLC), as a microcontroller, as a supervisory control and data acquisition (SCADA) system, or any other of a variety of computing devices. In addition, the site programmable controller 414 is configured to monitor a collective current generated by the power generator system(s) 402 on a main power line 416. In response to the detection of a fault condition based on the amplitude of the collective current, the site programmable controller 414 can send a trip command, demonstrated in the example of FIG. 9 as a signal TRG, to an associated site circuit breaker 418 to provide an open circuit in the main power line 416, and can thus cease current flow to the power transmission system 404.

(54) Additionally, each of the power generator system(s) 402 includes a local programmable controller 420 and a local circuit breaker 422. As an example, the local programmable controller(s) 420 can each be configured as any of a variety of computing devices that can receive analog and/or digital inputs, process the analog and/or digital inputs, and provide analog and/or digital outputs based on the processed inputs. For example, the local programmable controller(s) 420 can each be configured as a computer, as a PLC, as a microcontroller, as a SCADA system, or any other of a variety of computing devices. The local programmable controller(s) 420 are configured to provide operational control of the respective one of the power generator system(s) 402. For example, the local programmable controller(s) 420 can send to and receive data from the site programmable controller 414 to provide coordinated operational control of the power generator system(s) 402. In addition, the local programmable controller(s) 420 are configured to monitor a current generated by the respective one of the power generator system(s) 402. In response to the detection of a fault condition based on the amplitude of the current, the local programmable controller 414 can send a trip command to the associated local circuit breaker 422 to provide an open circuit in the respective power line, and can thus cease current flow to the main power line 416.

(55) As described in greater detail herein, the programmable controller(s) 414 and 420 can sample the respective current and can determine a cycle current value corresponding to each given cycle (e.g., AC period) of the respective current. The programmable controller(s) 414 and 420 can thus calculate an average of the cycle current values over a predetermined number of cycles of the respective current. The calculated average current value can thus act as a dynamic current threshold for the programmable controller that can change with respect to the calculated average current value over time. The programmable controller(s) 414 and 420 can monitor the respective current on the respective power line relative to the dynamic current threshold to detect an overcurrent condition or fault condition (e.g., including arc fault conditions) in one of the respective power generator system(s) 402. In response to the programmable controller(s) 414 and 420 detecting an amplitude of the respective current that exceeds the dynamic current threshold, such as based on one or more programmable characteristics, the programmable controller(s) 414 and 420 can send a trip command to an associated circuit breaker(s) 416 and 422 to provide an open circuit in the respective power line, and can thus cease current flow in the respective power line.

(56) FIG. 10 illustrates an example of a power generator protection system 450. The power generator protection system 450 can correspond to any of a variety of power generator system types, such as fossil-fuel, solar power, wind power, or any of a variety of other types of power generator systems. The power generator protection system 450 can correspond to one of the power generator system(s) 402 in the example of FIG. 9. Therefore, reference is to be made to the example of FIG. 9 in the following description of the example of FIG. 10.

(57) The power generator protection system 450 includes at least one (demonstrated as “N”) power generator system 452, demonstrated as “POWER GENERATOR 1” through “POWER GENERATOR N”, where N is a positive integer. The power generator systems 452 can each correspond to one or more power generating elements, such as one or more solar panels, one or more wind turbines, or one or more driven turbines (e.g., fossil-fuel or nuclear powered), that are configured to conduct current to a main power line 454. In the example of FIG. 10, the current is demonstrated as currents I.sub.PWR1 through I.sub.PWRN, that are combined on the main power line 454 as a collective current I.sub.CPWR. The collective current I.sub.CPWR can be provided on the main power line 454 to a POI 456, such that the collective current I.sub.CPWR can be provided to the public power utility grid as power to be consumed by power customers. As an example, the power generator systems 452 can each also include additional supporting equipment, such as inverters (e.g., for solar power generators), transformers, and/or other equipment (e.g., enclosures).

(58) In the example of FIG. 10, the power generator protection system 450 includes a site programmable controller 458. The site programmable controller 458 is demonstrated as providing one or more control signal(s) CTRL to each of the power generator systems 452 to provide operational control of the power generator systems 452. For example, the control signal(s) CTRL can be digital and/or analog signals that provide power regulation setpoint conditions, activation/deactivation commands, status information, or any of a variety of other data that can provide or assist with operational control of the respective power generator systems 452.

(59) In addition, the site programmable controller 458 is demonstrated as coupled to the main power line 454 (e.g., through a transformer). It is to be understood that the main power line 454 can be provided as multiple separate conductors, such that the site programmable controller 458 can be coupled to separate portions of the main power line 454. The site programmable controller 458 can be configured to protect the power generator systems 452 from overcurrent conditions and/or from fault conditions (e.g., including arc fault conditions), as described in greater detail herein. The power generator protection system 450 also includes a site circuit breaker 460 that is configured to provide an open circuit in the main power line 454 in response to being triggered by the site programmable controller 458 via a trigger signal TRG. For example, the trigger signal TRG can correspond to a digital signal provided in a failsafe manner from a digital output of the site programmable controller 458. The site programmable controller 458 is configured to sample the collective current I.sub.CPWR to generate a cycle current value at each of a plurality of cycles of the collective current I.sub.CPWR. The site programmable controller 458 can thus generate a dynamic current threshold based on the current cycle values, as described in greater detail herein. As an example, the dynamic current threshold can be generated based on continuously averaging the cycle current values from sequential cycles of the collective current I.sub.CPWR. The site programmable controller 458 can further be configured to compare the collective current I.sub.CPWR with the dynamic current threshold, such that the site programmable controller 458 can trigger the site circuit breaker 460 via the signal TRG based on an amplitude of the collective current I.sub.CPWR relative to the dynamic current threshold.

(60) FIG. 11 illustrates another example of a power generator protection system 500. The power generator protection system 500 can correspond to a portion of the power generator protection system 450 in the example of FIG. 10. Therefore, reference is to be made to the examples of FIG. 10 in the following description of the example of FIG. 11.

(61) The power generator protection system 500 includes a site circuit breaker 502 and a site programmable controller 504. The site circuit breaker 502 is demonstrated as interconnecting portions of a power line 506 (e.g., corresponding to the main power line 454 in the example of FIG. 10) on which the collective current I.sub.CPWR propagates. As described in greater detail herein, the collective current I.sub.CPWR is demonstrated as bidirectional, such that the power generator protection system 500 can protect the associated power generator system(s) from overcurrent and/or fault conditions (e.g., including arc fault conditions) based on different directions of the collective current I.sub.CPWR. Thus, in response to being triggered by a trigger signal TRG provided from the site programmable controller 504, the site circuit breaker 502 can provide an open circuit condition for the power line 506, thus ceasing flow of the collective current I.sub.CPWR in the power line 506.

(62) The site programmable controller 504 can be configured to implement a power protection algorithm to monitor the collective current I.sub.CPWR and to provide the trigger signal TRG in response to an indication of an overcurrent condition or a fault condition (e.g., including arc fault conditions). The site programmable controller 504 includes a current sampler 508 that receives an analog power signal I.sub.PP from a transformer 510 that is coupled to the power line 506. For example, the transformer 510 include a variety of different components (e.g., a current conditioner, filters, etc.) to provide the analog power signal I.sub.PP as an analog signal having an amplitude that is proportional to the amplitude of the collective current I.sub.CPWR. For example, the site programmable controller 504 can receive the analog power signal I.sub.PP at an analog input.

(63) Therefore, the current sampler 508 is configured to sample the analog power signal I.sub.PP at a predetermined sampling rate (e.g., sixteen samples per period of the analog power signal I.sub.PP). As an example, the current sampler 508 can be configured as an algorithm that captures digital values of the analog power signal I.sub.PP at a predetermined sampling rate (e.g., via a digital-to-analog converter (DAC) in the site programmable controller 504). Because the analog power signal I.sub.PP is proportional to the collective current I.sub.CPWR, as described herein, the sampling of the collective current I.sub.CPWR (e.g., by the current sampler 508) can refer to the sampling of an analog signal (e.g., the analog power signal I.sub.PP) that corresponds directly or indirectly to the collective current I.sub.CPWR. The current sampler 508 can thus generate a current cycle value I.sub.CYC corresponding to a current amplitude for the respective cycle of the collective current I.sub.CPWR. The cycle current value I.sub.CYC can correspond to a type of amplitude representation, such as peak, peak-to-peak, or root-mean-square (RMS) current amplitude of the collective current I.sub.CPWR.

(64) The current sampler 508 can provide the cycle current value I.sub.CYC to a current buffer 512 that is configured to store the cycle current value of each of a sequence of cycles of the collective current I.sub.CPWR, and thus a predetermined number of sequential cycle current values I.sub.CYC. As an example, the predetermined number of the sequential cycle current values I.sub.CYC can be programmable based on the specific characteristics of the power generator protection system 450. The current buffer 512 can store a number of sequential cycle current values I.sub.CYC that can correspond to a variety of operational features of the power generator protection system 500, as described in greater detail herein. Therefore, the programmable aspect of the predetermined number of the sequential cycle current values I.sub.CYC can be based on a variety of desired operational characteristics of the power generator protection system 500.

(65) The site programmable controller 504 can also include an averaging component 514 that is configured to generate an average current value I.sub.AVG corresponding to an average of a plurality of cycle current values I.sub.CYC. As an example, the averaging component 514 can substantially continuously generate an average of the plurality of cycle current values I.sub.CYC, such as a subset (e.g., all) of the predetermined number of the sequential cycle current values I.sub.CYC in the current buffer 512. Alternatively, the averaging component 514 can generate an average of each consecutive set of the cycle current values I.sub.CYC in the current buffer over a given interval of time. As yet another example, the averaging component 514 can receive the current samples of the collective current I.sub.CPWR, such that the averaging component 514 can generate the average current value I.sub.AVG based on the digital samples directly. The averaging component 514 can provide the average current value I.sub.AVG to a current comparator 516, such that the current comparator 516 can generate a dynamic current threshold 518 based on the average current value I.sub.AVG. As an example, the dynamic current threshold 518 can correspond directly to the average current value I.sub.AVG, or can correspond to an adjusted version of the average current value I.sub.AVG (e.g., based on an offset value).

(66) Similar to as described previously regarding the current sampler 508, the current buffer 512, the averaging component 514, and the current comparator 516 can correspond to software algorithms in the site programmable controller 504. In addition or alternatively, one or more of the current sampler 508, the current buffer 512, the averaging component 514, and the current comparator 516 can be implemented as dedicated devices, such as an application specific integrated circuit (ASIC) or another programmable control device that can work with or as a part of the site programmable controller 504.

(67) In the example of FIG. 11, the current buffer 512 also provides one or more of the cycle current values I.sub.CYC to the current comparator 516. The current comparator 516 can thus analyze the cycle current value(s) I.sub.CYC relative to the dynamic current threshold 518 to determine the occurrence of an overcurrent condition or a fault condition (e.g., including arc fault conditions). In response to detecting the overcurrent condition or the arc fault condition based on the cycle current value(s) I.sub.CYC relative to the dynamic current threshold 518, the current comparator 516 can provide the trigger signal TRG to the site circuit breaker 502. As a result, the site circuit breaker 502 can provide an open circuit in the power line 506 to cease flow of the collective current I.sub.CPWR in the power line 506.

(68) The current comparator 516 can be configured to provide the trigger signal TRG based on any of a variety of conditions that can be indicative of an overcurrent or a fault condition (e.g., including arc fault conditions). In the example of FIG. 11, the current comparator 516 can be provided one or more programmable thresholds, demonstrated as a signal TH provided to the current comparator 516. As an example, the current comparator 516 can compare a single cycle current value I.sub.CYC with a programmable current difference threshold (e.g., provided via the signal TH) relative to the dynamic current threshold 518. Therefore, in response to single cycle current value I.sub.CYC having an amplitude that is greater than or less than the dynamic current threshold 518 by the programmable current difference threshold, the current comparator 516 can provide the trigger signal TRG. Based on comparing a single cycle current value I.sub.CYC to the dynamic current threshold 518, the current comparator 516 can provide the trigger signal TRG very rapidly (e.g., within 0.02 seconds), such that the site circuit breaker 502 can provide the open circuit very rapidly (e.g., within 0.05 seconds) in response to the trigger signal TRG. As a result, as described in greater detail herein, the power generator protection system 500 can provide for a significantly reduced arc flash incident energy (e.g., less than 10 calories/cm.sup.2) based on the substantially reduced duration of time of current associated with the arc flash event.

(69) As another example, the signal TH can also include a programmable threshold associated with a dynamic baseline current associated with the comparison. For example, the current comparator 516 can be configured to provide the trigger signal TRG in response to a plurality of cycle current values I.sub.CYC being greater than or less than the dynamic current threshold 518, such as by the programmable difference current threshold, for the programmable current threshold. The programmable difference current threshold can, for example, correspond to a predetermined number of sequential cycle current values I.sub.CYC (e.g., cycle current values I.sub.CYC in each of sequential cycles of the collective current I.sub.CPWR), as stored in the current buffer 512, such as all or less than all of the cycle current values I.sub.CYC stored in the current buffer 512 at a given time.

(70) As another example, the current comparator 516 can provide a statistical analysis of an aggregation of a subset of the cycle current values I.sub.CYC stored in the current buffer 512. Thus, the current comparator 516 can compare a characteristic of the statistical aggregation of the cycle current values I.sub.CYC with the dynamic current threshold 514, such as including the programmable difference current threshold and/or the programmable dynamic amplitude threshold. As an example, the current comparator 516 can analyze a plurality of the cycle current values I.sub.CYC stored in the current buffer 512 to provide an aggregate amplitude score that is compared with the dynamic current threshold 518. For example, the aggregate amplitude score can be an average of a plurality of cycle current values I.sub.CYC (e.g., less than all of the cycle current values I.sub.CYC stored in the current buffer 512) that can be compared with the dynamic current threshold 518. As another example, the aggregate amplitude score can be a median of the plurality of cycle current values I.sub.CYC, a difference between the first and last cycle current values I.sub.CYC in a given sequential range of cycle current values I.sub.CYC (e.g., relative to the programmable current difference threshold), a difference between high and low values of a given sequential range of cycle current values I.sub.CYC (e.g., such as with one or more extreme values removed), or any of a variety of other statistical manipulations of a set of cycle current values I.sub.CYC. Therefore, the current comparator 516 can provide a number of different ways of statistically analyzing a sequential set of the cycle current values I.sub.CYC with the dynamic current threshold 518 to provide the trigger signal TRG in response to a given comparison condition that is indicative of an overcurrent or a fault condition (e.g., including arc fault conditions).

(71) As yet another example, the current comparator 516 can compare sequential cycle current values I.sub.CYC on an individual basis. For example, the current comparator 516 can compare a given one of the cycle current values I.sub.CYC with a preceding one of the cycle current values I.sub.CYC. In this example, if the current comparator determines that the two sequential cycle current values I.sub.CYC have a difference that is greater than the programmable current difference threshold relative to the dynamic current threshold 518 (e.g., greater than or less than the dynamic current threshold 518), then the current comparator 516 can provide the trigger signal TRG. Therefore, the current comparator 516 can determine the indication of the overcurrent and/or fault condition in a variety of ways.

(72) As yet another example, the power generator protection system 500 can be configured to detect a sudden current direction reversal, such as can be indicative of an overcurrent or fault condition. For example, a fault condition can result in the collective current I.sub.CPWR through the site circuit breaker 502 suddenly reversing direction (e.g., based on an arc fault at one of the power generator systems 452). However, if the absolute value of the amplitude of the collective current I.sub.CPWR does not appreciably change, a typical programmable controller could be unable to identify the change in current direction. Therefore, the power generator protection system 500 can be configured to identify the change in direction of the collective current I.sub.CPWR and apply the change in direction in the algorithm for generating the dynamic current threshold 518 and/or the comparison of the cycle current value I.sub.CYC with the dynamic current threshold 518.

(73) For example, with respect to the collective current I.sub.CPWR, the site programmable controller 504 (e.g., via the current sampler 508) can be configured to identify the angle of the sequence of the collective current I.sub.CPWR. The site programmable controller 504 can measure the impedance angle, such as for a three-phase voltage/current aspect of the collective current I.sub.CPWR. The sequence angle of the collective current I.sub.CPWR can be observed based on a comparison of the collective current I.sub.CPWR (e.g., a set of samples for a given cycle of the collective current I.sub.CPWR) to a predetermined setpoint. As an example, the site programmable controller 504 can identify that, if the sequence angle has changed by more than the predetermined setpoint (e.g., approximately 30 degrees), then the site programmable controller 504 can identify that the collective current I.sub.CPWR has changed direction. In response to detecting the reversal of direction of the collective current I.sub.CPWR, the current comparator 516 can apply the signed amplitude of the cycle current value I.sub.CYC in generating the dynamic current threshold 518, thus effecting a large change in the amplitude of the dynamic current threshold 518. As another example, the current comparator 516 can apply the comparison of the signed amplitude of the cycle current value I.sub.CYC with the dynamic current threshold 518. Accordingly, the power generator protection system 500 can identify a reversal in the direction of the collective current I.sub.CPWR to identify a potential fault, even when the absolute amplitude of the collective current I.sub.CPWR is substantially the same before and after reversal.

(74) As described herein, the current comparator 516 can determine the indication of the overcurrent and/or fault condition (e.g., including arc fault conditions) based on implementing a dynamic current threshold 518. As a result, the instantaneous or time duration comparison of the collective current I.sub.CPWR is with respect to a dynamic (potentially fast or slow changing) current threshold, as opposed to a static threshold referenced to zero amps. Accordingly, the current comparator 516 can more accurately identify an overcurrent or fault condition (e.g., including arc fault conditions) to trigger the site circuit breaker 502 relative to typical power generator systems that cannot account for changing conditions in the power generator system. As a result, the power generator protection system 500 can result in a significantly safer environment for performing maintenance on the associated power generator protection system 450, similar to as described above in the examples of FIGS. 4-7.

(75) FIG. 12 illustrates an example of a power generator protection system 550. The power generator protection system 550 can correspond to any of a variety of power generator system types, such as fossil-fuel, solar power, wind power, or any of a variety of other types of power generator systems. The power generator protection system 550 can correspond to one of the power generator system(s) 402 in the example of FIG. 9. Therefore, reference is to be made to the example of FIG. 9 in the following description of the example of FIG. 12.

(76) The power generator protection system 550 includes at least one (demonstrated as “N”) power generator system 552, demonstrated as “POWER GENERATOR 1” through “POWER GENERATOR N”, where N is a positive integer. The power generator systems 552 can each correspond to one or more power generating elements, such as one or more solar panels, one or more wind turbines, or one or more driven turbines (e.g., fossil-fuel or nuclear powered), that are configured to conduct current from respective power lines 553 to a main power line 554. In the example of FIG. 12, the current is demonstrated as currents I.sub.PWR1 through I.sub.PWRN, that are combined on the main power line 554 as a collective current I.sub.CPWR. The collective current I.sub.CPWR can be provided on the main power line 554 to a POI 556, such that the collective current I.sub.CPWR can be provided to the public power utility grid as power to be consumed by power customers. As an example, the power generator systems 552 can each also include additional supporting equipment, such as inverters (e.g., for solar power generators), transformers, and/or other equipment (e.g., enclosures).

(77) In the example of FIG. 12, the power generator protection system 550 includes a site programmable controller 558. The site programmable controller 558 is demonstrated as providing one or more control signal(s) CTRL to each of the power generator systems 552 to provide operational control of the power generator systems 552. For example, the control signal(s) CTRL can be digital and/or analog signals that provide power regulation setpoint conditions, activation/deactivation commands, status information, or any of a variety of other data that can provide or assist with operational control of the respective power generator systems 552.

(78) In addition, the site programmable controller 558 is demonstrated as coupled to the main power line 554 (e.g., through a transformer). It is to be understood that the main power line 554 can be provided as multiple separate conductors, such that the site programmable controller 558 can be coupled to separate portions of the main power line 554. The site programmable controller 558 can be configured to protect the power generator systems 552 from overcurrent conditions and/or from fault conditions (e.g., including arc fault conditions), as described in greater detail herein. The power generator protection system 550 also includes a site circuit breaker 560 that is configured to provide an open circuit in the main power line 554 in response to being triggered by the site programmable controller 558 via a trigger signal TRG. For example, the trigger signal TRG can correspond to a digital signal provided in a failsafe manner from a digital output of the site programmable controller 558. The site programmable controller 558 is configured to sample the collective current I.sub.CPWR to generate a cycle current value at each of a plurality of cycles of the collective current I.sub.CPWR. The site programmable controller 558 can thus generate a dynamic current threshold based on the current cycle values, as described in greater detail herein. As an example, the dynamic current threshold can be generated based on continuously averaging the cycle current values from sequential cycles of the collective current I.sub.CPWR. The site programmable controller 558 can further be configured to compare the collective current I.sub.CPWR with the dynamic current threshold, such that the site programmable controller 558 can trigger the site circuit breaker 560 via the signal TRG based on an amplitude of the collective current I.sub.CPWR relative to the dynamic current threshold.

(79) In addition, in the example of FIG. 12, each of the power generator systems 552 includes a local programmable controller 562. The local programmable controller 562 is configured to provide operational control of the power generator systems 552. For example, the control signal(s) CTRL provided from the site programmable controller 558 can provide power regulation setpoint conditions, activation/deactivation commands, status information, or any of a variety of other data to the local programmable controller 562 in each of the power generator systems 562 to provide or assist with operational control of the respective power generator systems 552. As an example, the control signal CTRL can provide different data to each of the power generator systems 552, such as based on different characteristics of the different power generator systems 552.

(80) In addition, the local programmable controller 562 in each of the power generator systems 552 can be configured to protect the respective power generator system 552 from overcurrent conditions and/or from fault conditions (e.g., including arc fault conditions), as described in greater detail herein. As an example, the local programmable controller 562 can be configured to monitor the respective one of the currents I.sub.PWR1 through I.sub.PWRN on the respective one of the power lines 553. Each of the local programmable controllers 562 can control a respective local. circuit breaker 564 that is configured to provide an open circuit in the respective power line 553 in response to being triggered by the local programmable controller 562 via a respective trigger signal LTRG. For example, the trigger signal LTRG can correspond to a digital signal provided in a failsafe manner from a digital output of the respective local programmable controller 562. The local programmable controller 562 is configured to sample the respective one of the currents I.sub.PWR1 through I.sub.PWRN to generate a cycle current value at each of a plurality of cycles of the respective one of the currents I.sub.PWR1 through I.sub.PWRN. The local programmable controller 562 can thus generate a dynamic current threshold based on the current cycle values, similar to as described above. As an example, the dynamic current threshold can be generated based on continuously averaging the cycle current values from sequential cycles of the respective one of the currents I.sub.PWR1 through I.sub.PWRN. The local programmable controller 562 can further be configured to compare the respective one of the currents I.sub.PWR1 through I.sub.PWRN with the dynamic current threshold, such that the local programmable controller 562 can trigger the local circuit breaker 564 via the signal LTRG based on an amplitude of the respective one of the currents I.sub.PWR1 through I.sub.PWRN relative to the dynamic current threshold. As an example, the dynamic current threshold for each of the local programmable controllers 562 can be different for each of the power generator systems 552, such as based on individual characteristics or goals of the different power generator systems 552.

(81) As described herein, the power generator protection system 550 is not limited to including both a site programmable controller 558 and local programmable controllers 562 that are configured to provide protection against fault and/or arc flash conditions. For example, the power generator protection system 550 could instead include local programmable controllers 562 for each of the power generator systems 552, as well as a programmable relay system (e.g., the programmable relay system 10, 58, or 100 in the respective examples of FIGS. 1-3) to provide protection against fault and/or arc flash conditions.

(82) In the example of FIG. 12, the control signals CTRL are demonstrated as bidirectional, such that the local programmable controllers 562 can be configured to communicate with the site programmable controller 558. For example, in response to one of the local programmable controllers 562 determining that the respective one of the currents I.sub.PWR1 through I.sub.PWRN exceeds the dynamic current threshold, the respective local programmable controller 562 can provide a status signal that is an indication of the triggering of the local circuit breaker 564 to the site programmable controller 558. In response to receiving the status signal, the site programmable controller 558 can provide the trigger signal TRG to open the site circuit breaker 560. Therefore, the site programmable controller 558 can activate the site circuit breaker 560 instead of or in addition to one of the local circuit breakers 564 being activated in response to the respective local programmable controller 562 identifying that the respective one of the currents I.sub.PWR1 through I.sub.PWRN exceeds the dynamic current threshold.

(83) Additionally, in the example of FIG. 12, the site programmable controller 558 is demonstrated as providing a shutdown signal SD to each of the local programmable controllers 562. For example, the shutdown signal SD can correspond to a status of the site circuit breaker 560, such as to provide an indication of whether the site circuit breaker 560 is open or closed. As an example, in response to one of the local circuit breakers 564 being engaged to open the power line 553, the remaining power generator systems 552 can be configured to operate in a low-voltage ride through (LVRT) manner, such as dictated by a standard set by a relevant organization (e.g., the North American Electric Reliability Corporation (NERC)). Therefore, even if the site circuit breaker 560 is opened by the trigger signal TRG, such as based on a fault condition of one of the power generator systems 552, the LVRT manner could dictate that the remaining power generator systems 552 could continue operating, which could provide for an unsafe condition in maintaining or repairing the faulted one of the power generator systems 552. Therefore, the shutdown signal SD can be provided by the site programmable controller 558 (or in the alternative, a programmable relay system such as described above in the examples of FIGS. 1-7) to all of the local programmable controllers 562 to indicate that the site circuit breaker 560 has been opened. Accordingly, the local programmable controllers 562, in response to receiving the shutdown signal SD, can each provide the respective trigger signals LTRG to disconnect each of the power generator systems 552 from the respective power lines 553 via the respective local circuit breaker 564. As a result, the faulted one of the power generator systems 552 can be maintained or repaired in a safe manner in response to triggering of the site circuit breaker 560.

(84) FIG. 13 illustrates another example of a power generator protection system 600. The power generator protection system 600 can correspond to a portion of the power generator protection system 650 in the example of FIG. 12. Therefore, reference is to be made to the examples of FIG. 12 in the following description of the example of FIG. 13.

(85) The power generator protection system 600 includes a local circuit breaker 602 and a local programmable controller 604. The local programmable controller 604 can is demonstrated in the example of FIG. 13 as the “Xth” local programmable controller 604, and can thus correspond to one of the N local programmable controllers 562 in the example of FIG. 12. The local circuit breaker 602 is demonstrated as interconnecting portions of a power line 606 (e.g., corresponding to one of the power lines 553 in the example of FIG. 12) on which a respective one of the currents I.sub.PWR1 through I.sub.PWRN propagates. In the example of FIG. 13, the current is demonstrated as a current I.sub.PWRX, where X corresponds to the respective one of the N currents I.sub.PWR. As described in greater detail herein, the current I.sub.PWRX is demonstrated as bidirectional, such that the power generator protection system 600 can protect the associated power generator system(s) from overcurrent and/or fault conditions (e.g., including arc fault conditions) based on different directions of the current I.sub.PWRX. Thus, in response to being triggered by a trigger signal LTRG provided from the local programmable controller 604, the local circuit breaker 602 can provide an open circuit condition for the power line 606, thus ceasing flow of the current I.sub.PWRX in the power line 606.

(86) The local programmable controller 604 can be configured to implement a power protection algorithm to monitor the current I.sub.PWRX and to provide the trigger signal LTRG in response to an indication of an overcurrent condition or a fault condition (e.g., including arc fault conditions). The local programmable controller 604 includes a current sampler 608 that receives an analog power signal I.sub.PP from a transformer 610 that is coupled to the power line 606. For example, the transformer 610 include a variety of different components (e.g., a current conditioner, filters, etc.) to provide the analog power signal I.sub.PP as an analog signal having an amplitude that is proportional to the amplitude of the current I.sub.PWRX. For example, the local programmable controller 604 can receive the analog power signal I.sub.PP at an analog input.

(87) Therefore, the current sampler 608 is configured to sample the analog power signal I.sub.PP at a predetermined sampling rate (e.g., sixteen samples per period of the analog power signal I.sub.PP). As an example, the current sampler 608 can be configured as an algorithm that captures digital values of the analog power signal I.sub.PP at a predetermined sampling rate (e.g., via a DAC in the local programmable controller 604). Because the analog power signal I.sub.PP is proportional to the current I.sub.PWRX, as described herein, the sampling of the current I.sub.PWRX (e.g., by the current sampler 608) can refer to the sampling of an analog signal (e.g., the analog power signal I.sub.PP) that corresponds directly or indirectly to the current I.sub.PWRX. The current sampler 608 can thus generate a current cycle value I.sub.CYC corresponding to a current amplitude for the respective cycle of the current I.sub.PWRX. The cycle current value I.sub.CYC can correspond to a type of amplitude representation, such as peak, peak-to-peak, or RMS current amplitude of the current I.sub.PWRX.

(88) The current sampler 608 can provide the cycle current value I.sub.CYC to a current buffer 612 that is configured to store the cycle current value of each of a sequence of cycles of the current I.sub.PWRX, and thus a predetermined number of sequential cycle current values I.sub.CYC. As an example, the predetermined number of the sequential cycle current values I.sub.CYC can be programmable based on the specific characteristics of the power generator protection system 650. The current buffer 612 can store a number of sequential cycle current values I.sub.CYC that can correspond to a variety of operational features of the power generator protection system 600, as described in greater detail herein. Therefore, the programmable aspect of the predetermined number of the sequential cycle current values I.sub.CYC can be based on a variety of desired operational characteristics of the power generator protection system 600.

(89) The local programmable controller 604 can also include an averaging component 614 that is configured to generate an average current value I.sub.AVG corresponding to an average of a plurality of cycle current values I.sub.CYC. As an example, the averaging component 614 can substantially continuously generate an average of the plurality of cycle current values I.sub.CYC, such as a subset (e.g., all) of the predetermined number of the sequential cycle current values I.sub.CYC in the current buffer 612. Alternatively, the averaging component 614 can generate an average of each consecutive set of the cycle current values I.sub.CYC in the current buffer over a given interval of time. As yet another example, the averaging component 614 can receive the current samples of the current I.sub.PWRX, such that the averaging component 614 can generate the average current value I.sub.AVG based on the digital samples directly. The averaging component 614 can provide the average current value I.sub.AVG to a current comparator 616, such that the current comparator 616 can generate a dynamic current threshold 618 based on the average current value I.sub.AVG. As an example, the dynamic current threshold 618 can correspond directly to the average current value I.sub.AVG, or can correspond to an adjusted version of the average current value I.sub.AVG (e.g., based on an offset value).

(90) Similar to as described previously regarding the current sampler 608, the current buffer 612, the averaging component 614, and the current comparator 616 can correspond to software algorithms in the local programmable controller 604. In addition or alternatively, one or more of the current sampler 608, the current buffer 612, the averaging component 614, and the current comparator 616 can be implemented as dedicated devices, such as an ASIC or another programmable control device that can work with or as a part of the local programmable controller 604.

(91) In the example of FIG. 13, the current buffer 612 also provides one or more of the cycle current values I.sub.CYC to the current comparator 616. The current comparator 616 can thus analyze the cycle current value(s) I.sub.CYC relative to the dynamic current threshold 618 to determine the occurrence of an overcurrent condition or a fault condition (e.g., including arc fault conditions). In response to detecting the overcurrent condition or the arc fault condition based on the cycle current value(s) I.sub.CYC relative to the dynamic current threshold 618, the current comparator 616 can provide the trigger signal LTRG to the local circuit breaker 602. As a result, the local circuit breaker 602 can provide an open circuit in the power line 606 to cease flow of the current I.sub.PWRX in the power line 606.

(92) The current comparator 616 can be configured to provide the trigger signal LTRG based on any of a variety of conditions that can be indicative of an overcurrent or a fault condition (e.g., including arc fault conditions). In the example of FIG. 13, the current comparator 616 can be provided one or more programmable thresholds. For example, the one or more programmable thresholds can be provided via a respective one of the control signals, demonstrated in the example of FIG. 13 as a control signal CTRLX, provided to the local programmable controller 616. As an example, the current comparator 616 can compare a single cycle current value I.sub.CYC with a programmable current difference threshold (e.g., provided via the control signal CTRLX) relative to the dynamic current threshold 618. Therefore, in response to single cycle current value I.sub.CYC having an amplitude that is greater than or less than the dynamic current threshold 618 by the programmable current difference threshold, the current comparator 616 can provide the trigger signal LTRG. Based on comparing a single cycle current value I.sub.CYC to the dynamic current threshold 618, the current comparator 616 can provide the trigger signal LTRG very rapidly (e.g., within 0.02 seconds), such that the local circuit breaker 602 can provide the open circuit very rapidly (e.g., within 0.05 seconds) in response to the trigger signal LTRG. As a result, as described in greater detail herein, the power generator protection system 600 can provide for a significantly reduced arc flash incident energy (e.g., less than 10 calories/cm.sup.2) based on the substantially reduced duration of time of current associated with the arc flash event.

(93) As another example, the control signal CTRLX can also include a programmable threshold associated with a dynamic baseline current associated with the comparison. For example, the current comparator 616 can be configured to provide the trigger signal LTRG in response to a plurality of cycle current values I.sub.CYC being greater than or less than the dynamic current threshold 618, such as by the programmable difference current threshold, for the programmable current threshold. The programmable difference current threshold can, for example, correspond to a predetermined number of sequential cycle current values I.sub.CYC (e.g., cycle current values I.sub.CYC in each of sequential cycles of the current I.sub.PWRX), as stored in the current buffer 612, such as all or less than all of the cycle current values I.sub.CYC stored in the current buffer 612 at a given time.

(94) As another example, the current comparator 616 can provide a statistical analysis of an aggregation of a subset of the cycle current values I.sub.CYC stored in the current buffer 612. Thus, the current comparator 616 can compare a characteristic of the statistical aggregation of the cycle current values I.sub.CYC with the dynamic current threshold 614, such as including the programmable difference current threshold and/or the programmable dynamic amplitude threshold. As an example, the current comparator 616 can analyze a plurality of the cycle current values I.sub.CYC stored in the current buffer 612 to provide an aggregate amplitude score that is compared with the dynamic current threshold 618. For example, the aggregate amplitude score can be an average of a plurality of cycle current values I.sub.CYC (e.g., less than all of the cycle current values I.sub.CYC stored in the current buffer 612) that can be compared with the dynamic current threshold 618. As another example, the aggregate amplitude score can be a median of the plurality of cycle current values I.sub.CYC, a difference between the first and last cycle current values I.sub.CYC in a given sequential range of cycle current values I.sub.CYC (e.g., relative to the programmable current difference threshold), a difference between high and low values of a given sequential range of cycle current values I.sub.CYC (e.g., such as with one or more extreme values removed), or any of a variety of other statistical manipulations of a set of cycle current values I.sub.CYC. Therefore, the current comparator 616 can provide a number of different ways of statistically analyzing a sequential set of the cycle current values I.sub.CYC with the dynamic current threshold 618 to provide the trigger signal LTRG in response to a given comparison condition that is indicative of an overcurrent or a fault condition (e.g., including arc fault conditions).

(95) As yet another example, the current comparator 616 can compare sequential cycle current values I.sub.CYC on an individual basis. For example, the current comparator 616 can compare a given one of the cycle current values I.sub.CYC with a preceding one of the cycle current values I.sub.CYC. In this example, if the current comparator determines that the two sequential cycle current values I.sub.CYC have a difference that is greater than the programmable current difference threshold relative to the dynamic current threshold 618 (e.g., greater than or less than the dynamic current threshold 618), then the current comparator 616 can provide the trigger signal LTRG. Therefore, the current comparator 616 can determine the indication of the overcurrent and/or fault condition in a variety of ways.

(96) As yet another example, the power generator protection system 600 can be configured to detect a sudden current direction reversal, such as can be indicative of an overcurrent or fault condition. For example, a fault condition can result in the current I.sub.PWRX through the local circuit breaker 602 suddenly reversing direction (e.g., based on an arc fault at one of the power generator systems 552). However, if the absolute value of the amplitude of the current I.sub.PWRX does not appreciably change, a typical programmable controller could be unable to identify the change in current direction. Therefore, the power generator protection system 600 can be configured to identify the change in direction of the current I.sub.PWRX and apply the change in direction in the algorithm for generating the dynamic current threshold 618 and/or the comparison of the cycle current value I.sub.CYC with the dynamic current threshold 618.

(97) For example, with respect to the current I.sub.PWRX, the local programmable controller 604 (e.g., via the current sampler 608) can be configured to identify the angle of the sequence of the current I.sub.PWRX. The local programmable controller 604 can measure the impedance angle, such as for a three-phase voltage/current aspect of the current I.sub.PWRX. The sequence angle of the current I.sub.PWRX can be observed based on a comparison of the current I.sub.PWRX (e.g., a set of samples for a given cycle of the current I.sub.PWRX) to a predetermined setpoint. As an example, the local programmable controller 604 can identify that, if the sequence angle has changed by more than the predetermined setpoint (e.g., approximately 30 degrees), then the local programmable controller 604 can identify that the current I.sub.PWRX has changed direction. In response to detecting the reversal of direction of the current I.sub.PWRX, the current comparator 616 can apply the signed amplitude of the cycle current value I.sub.CYC in generating the dynamic current threshold 618, thus effecting a large change in the amplitude of the dynamic current threshold 618. As another example, the current comparator 616 can apply the comparison of the signed amplitude of the cycle current value I.sub.CYC with the dynamic current threshold 618. Accordingly, the power generator protection system 600 can identify a reversal in the direction of the current I.sub.PWRX to identify a potential fault, even when the absolute amplitude of the current I.sub.PWRX is substantially the same before and after reversal.

(98) As described herein, the current comparator 616 can determine the indication of the overcurrent and/or fault condition (e.g., including arc fault conditions) based on implementing a dynamic current threshold 618. As a result, the instantaneous or time duration comparison of the current I.sub.PWRX is with respect to a dynamic (potentially fast or slow changing) current threshold, as opposed to a static threshold referenced to zero amps. Accordingly, the current comparator 616 can more accurately identify an overcurrent or fault condition (e.g., including arc fault conditions) to trigger the local circuit breaker 602 relative to typical power generator systems that cannot account for changing conditions in the power generator system. As a result, the power generator protection system 600 can result in a significantly safer environment for performing maintenance on the associated power generator protection system 650, similar to as described above in the examples of FIGS. 4-7.

(99) Similar to as described above in the example of FIG. 12, In the control signal CTRLX is demonstrated as bidirectional, such that the local programmable controller 604 can be configured to communicate with a site programmable controller (e.g., the site programmable controller 558). For example, in response to the local programmable controller 604 determining that the current I.sub.PWRX exceeds the dynamic current threshold 618, the local programmable controller 604 can provide a status signal that is an indication of the triggering of the local circuit breaker 602 to the site programmable controller. In response to receiving the status signal, the site programmable controller can open the site circuit breaker. Additionally, as also described above in the example of FIG. 12, the local programmable controller 604 is demonstrated as receiving a shutdown signal SD. For example, the shutdown signal SD can correspond to a status of the site circuit breaker (e.g., the site circuit breaker 560), such as to provide an indication of whether the site circuit breaker is open or closed. Therefore, the local programmable controller 604, in response to receiving the shutdown signal SD, can provide the trigger signal LTRG to open the local circuit breaker 564.

(100) In view of the foregoing structural and functional features described above, methods in accordance with various aspects of the present disclosure will be better appreciated with reference to FIG. 14. While, for purposes of simplicity of explanation, the method of FIG. 14 is shown and described as executing serially, it is to be understood and appreciated that the present disclosure is not limited by the illustrated orders, as some aspects could, in accordance with the present disclosure, occur in different orders and/or concurrently with other aspects from that shown and described herein. Moreover, not all illustrated features may be required to implement method in accordance with an aspect of the present disclosure.

(101) FIG. 14 illustrates a method 650 for protecting a power generator system (e.g., the power generator systems 452 or 552). At 652, a current (e.g., the collective current I.sub.CPWR or the current I.sub.PWRX) propagating in a power line (e.g., the main power line 454 or one of the power lines 553) is monitored between a power grid POI (e.g., the POI 456) and the power generator system via an analog input (e.g., the analog current I.sub.PP) to a programmable controller (e.g., the site programmable controller 458 or one of the local programmable controllers 562). At 654, each cycle of the current is sampled to generate a plurality of current samples for each cycle of the current. At 656, a cycle current value (e.g., the cycle current value I.sub.CYC) is generated for each cycle of the current based on the plurality of current samples associated with the respective cycle of the current. At 658, a predetermined number of cycle current values is continuously stored in a time-wise manner. At 660, the predetermined number of cycle current values is substantially continuously averaged to generate a dynamic current threshold (e.g., the dynamic current threshold 518 or 618). At 662, the cycle current value associated with at least one of the plurality of cycles is compared with the dynamic current threshold. At 664, a digital output signal (e.g., the trigger signal TRG or the trigger signal LTRG) is provided from the programmable controller to trigger a circuit breaker (e.g., the site circuit breaker 460 or one of the local circuit breakers 564) based on an amplitude difference of the cycle current relative to the dynamic current threshold.

(102) What have been described above are examples of the disclosure. It is, of course, not possible to describe every conceivable combination of components or method for purposes of describing the disclosure, but one of ordinary skill in the art will recognize that many further combinations and permutations of the disclosure are possible. Accordingly, the disclosure is intended to embrace all such alterations, modifications, and variations that fall within the scope of this application, including the appended claims. Additionally, where the disclosure or claims recite “a,” “an,” “a first,” or “another” element, or the equivalent thereof, it should be interpreted to include one or more than one such element, neither requiring nor excluding two or more such elements. As used herein, the term “includes” means includes but not limited to, and the term “including” means including but not limited to. The term “based on” means based at least in part on.