There is implemented an on-board controller including a single ground terminal, which can accurately detect a disconnection fault of a ground wire while avoiding erroneous detection due to a temporary voltage abnormality or current abnormality. A voltage at the positive electrode of a smoothing electrolytic capacitor is monitored. In addition, a current flowing through a shunt resistor is also monitored. Based on the monitored current value, there is calculated a voltage range (voltage threshold) at the positive electrode of the smoothing electrolytic capacitor in the case of disconnection of a ground wire. Thus, it is determined whether the ground wire has been disconnected by comparing the calculated voltage threshold with the monitored positive-side voltage described above.

There is implemented an on-board controller including a single ground terminal, which can accurately detect a disconnection fault of a ground wire while avoiding erroneous detection due to a temporary voltage abnormality or current abnormality. A voltage at the positive electrode of a smoothing electrolytic capacitor is monitored. In addition, a current flowing through a shunt resistor is also monitored. Based on the monitored current value, there is calculated a voltage range (voltage threshold) at the positive electrode of the smoothing electrolytic capacitor in the case of disconnection of a ground wire. Thus, it is determined whether the ground wire has been disconnected by comparing the calculated voltage threshold with the monitored positive-side voltage described above.

Aspects of the present disclosure are directed to increasing protection against electric shocks when a person is working on an electrical system. In some embodiments, the electrical system includes at least two different circuits and a safety module. An emergency signal input is provided on the safety module, and when an external emergency signal is received via the emergency signal input, the safety module shuts off a configured first circuit the associated switch and at least one further circuit via the associated switch if the safety module still receives the emergency signal at the emergency signal input after a predetermined period of time.

A monitoring and load controlling system for a switchboard, according to one embodiment of the present specification, comprises: a gateway which acquires respective temperature information of circuit breakers included in a switchboard, and respective current amount information of lines corresponding to the circuit breakers, acquires respective capacity information of the circuit breakers on the basis of the acquired temperature information, and, on the basis of the acquired capacity information and current amount information, detects a circuit breaker corresponding to a line in need of load regulation; and a load controlling device which regulates the load of said line by stopping the operation of at least one device among devices connected to the detected circuit breaker.

A method and apparatus for tertiary control with over-current protection. In one embodiment, the method comprises calculating at least one unconstrained optimal net intertie target for an area of a power network; calculating, for each resource within the area, optimal scheduled current to achieve the at least one unconstrained optimal net intertie target; calculating, using the optimal scheduled currents and a plurality of stress coefficients, net scheduled current for each power line segment within the area; comparing the net scheduled currents to corresponding stress thresholds to identify any stress violations; reducing, when the comparing step identifies one or more stress violations, the optimal scheduled current for one or more resources contributing to the one or more stress violations; and calculating, when the comparing step identifies the one or more stress violations, updated optimal scheduled current for one or more resources not contributing to the one or more stress violations.

A circuit including a source, a load, and an isolation circuit for controllably isolating the load from the source. The isolation circuit is disposed between the source and the load. The isolation circuit includes at least one insulated-gate bipolar transistor (IGBT) and at least one gate turn-off thyristor (GTO) in parallel with the insulated-gate bipolar transistor. When no fault condition exists, the GTO is configured to be ON to couple the load to the source. When a fault condition exists, the at least one IGBT is configured to turn ON. After the at least one IGBT turns ON, the at least one GTO is configured to turn OFF. After a predetermined amount of time, reflecting the post fabrication alteration to the GTO's minority carrier lifetime (e.g. electron irradiation), after the at least one GTO turns OFF, the at least one IGBT is configured to turn OFF. Alternatively, the circuit is used as an inverter switch, where at the command to turn ON is supplied, the at least one IGBT is turned ON, followed by the at least one SGTO. When commanded to turn OFF the at least one SGTO is turned OFF followed by the at least one IGBT. This alternative configuration allows the robust, controllable switching speeds of IGBTs and the superior conduction efficiency of SGTOs. The two configurations mentioned above utilize a wide range of SGTO performance, thus the ability to control the SGTOs turn-off speed by reducing its minority carrier lifetime after the device is processed is of large importance. The efficiency of all uses of the circuit can be optimized with the judicious selection of SGTO minority carrier lifetime and the ratio of active area between the SGTO and IGBT devices. In all cases there is a balance between the time the circuit can achieve hard turn-off without current commutation, the conduction efficiency of the circuit and the maximum amount of controllable current. In all cases both the conduction efficiency of the circuit is higher than an IGBT-only based circuit, and the switching performance is higher than a GTO-only based circuit.

A circuit including a source, a load, and an isolation circuit for controllably isolating the load from the source. The isolation circuit is disposed between the source and the load. The isolation circuit includes at least one insulated-gate bipolar transistor (IGBT) and at least one gate turn-off thyristor (GTO) in parallel with the insulated-gate bipolar transistor. When no fault condition exists, the GTO is configured to be ON to couple the load to the source. When a fault condition exists, the at least one IGBT is configured to turn ON. After the at least one IGBT turns ON, the at least one GTO is configured to turn OFF. After a predetermined amount of time, reflecting the post fabrication alteration to the GTO's minority carrier lifetime (e.g. electron irradiation), after the at least one GTO turns OFF, the at least one IGBT is configured to turn OFF. Alternatively, the circuit is used as an inverter switch, where at the command to turn ON is supplied, the at least one IGBT is turned ON, followed by the at least one SGTO. When commanded to turn OFF the at least one SGTO is turned OFF followed by the at least one IGBT. This alternative configuration allows the robust, controllable switching speeds of IGBTs and the superior conduction efficiency of SGTOs. The two configurations mentioned above utilize a wide range of SGTO performance, thus the ability to control the SGTOs turn-off speed by reducing its minority carrier lifetime after the device is processed is of large importance. The efficiency of all uses of the circuit can be optimized with the judicious selection of SGTO minority carrier lifetime and the ratio of active area between the SGTO and IGBT devices. In all cases there is a balance between the time the circuit can achieve hard turn-off without current commutation, the conduction efficiency of the circuit and the maximum amount of controllable current. In all cases both the conduction efficiency of the circuit is higher than an IGBT-only based circuit, and the switching performance is higher than a GTO-only based circuit.

A method for circuit breaker failure (CBF) protection in a power substation is disclosed. The power substation includes a first circuit breaker (CB), a second CB coupled to the first CB, a feeder coupled to the first CB and the second CB, a power plant coupled to the feeder, a first plurality of CBs coupled to the first CB, and a second plurality of CBs coupled to the second CB. The method includes sending a first stage tripping command to the first CB and the second CB to trip the first CB and the second CB responsive to a non-high current tripping command being active for a first period of time, and one of a current condition and an energization condition being satisfied for the first period of time, sending a first second-stage tripping command to the first plurality of CBs to trip the first plurality of CBs responsive to the non-high current tripping command being active for a second period of time, and one of the current condition and the energization condition being satisfied for the second period of time, and sending a second second-stage tripping command to the second plurality of CBs to trip the second plurality of CBs responsive to the non-high current tripping command being active for a third period of time, and one of the current condition and the energization condition being satisfied for the third period of time. The second period of time and the third period of time may be longer than the first period of time.

A power restoration system comprising a feeder, a plurality of power sources available to provide power to the feeder, a plurality of normally closed reclosing devices electrically coupled along the feeder, at least one normally open recloser electrically coupled to the feeder, and a plurality of normally closed switches electrically coupled along the feeder between each adjacent pairs of normally closed reclosing devices. Each switch is assigned a position code having a value for each of the plurality of power sources that determines when the switch will open in response to the fault current and which power source the switch is currently receiving power from, where timing control between the reclosing devices and the switches allows the switch to be selectively opened to isolate the fault within a single feeder section between each pair of adjacent switches or between each switch and a reclosing device.

Provided is a nano grid protection device for a nano grid including a distributed power supply, a large power grid including the nano grid protection device, and a method for controlling the nano grid protection device. In an embodiment, the nano grid is connected with a bus through the nano grid protection device and a main grid is connected with the bus through a main grid protection device. In an embodiment, the nano grid protection device includes: a signal unit, configured to detect and send current information passing through the nano grid protection device, the current information including the magnitude and direction of the current; a controller, configured to determine, based upon the received current information, whether to send a trip signal or not; and an execution mechanism, configured to execute a trip operation of the nano grid protection device upon receiving the trip signal.