Power management in an energy distribution system

Abstract

An arrangement for power management in an energy distribution system, a method for power management in an energy distribution system and an arrangement for implementing the method for power management in the energy distribution system, wherein a feed/return unit and a control unit are provided, where the control unit is configured to sense a present actual system state and to take the sensed actual system state as a basis for prompting energy output or energy intake (energy out/intake, energy feed/return) by the feed/return unit in order to allow continuous correction and dynamic support of an energy distribution system or in an energy distribution system.

Claims

1. An arrangement for power management in an energy distribution network, the arrangement being configured to dynamically support the energy distribution network and compensate for network disturbances in the energy distribution network via energy output/intake to/from the energy distribution network, the arrangement comprising: an energy feed/return unit for feeding/returning energy to/from the energy distribution network and having a direct current intermediate circuit; at least two different electrical energy storage devices connected to the direct current intermediate circuit of the energy feed/return unit and having different response times; and a control unit configured to: ascertain a prevailing actual network state of the energy distribution network by measuring electrical variables of the energy distribution network, said electrical variables including at least one of voltage, current, phase position and frequency, and compare the ascertained prevailing actual network state with a desired network state, control, dependent on the comparison, the energy feed/return unit to output energy to the energy distribution network or receive energy from the energy distribution network, and select and coordinate the at least two electrical energy storage devices in accordance with their respective response times to cover a required response time period during network disturbances.

2. The arrangement for power management in the energy distribution network as claimed in claim 1, wherein the energy feed/return unit comprises a converter which is operable in one of a two quadrant operation or four quadrant operation, said converter being at least one of (i) a line commutated inverter in the two quadrant operation and (ii) a direct current intermediate circuit that is connected to the converter operable in one of the two quadrant operation or four quadrant operation.

3. The arrangement for power management in the energy distribution network as claimed in claim 1, wherein the at least two different electrical energy storage devices comprise a chemical energy storage device and at least one of (i) a mechanical energy storage device and a thermal energy storage device.

4. The arrangement for power management in the energy distribution network as claimed in claim 1, further comprising: a capacitor which is connected to the direct current intermediate circuit of the energy feed/return unit.

5. The arrangement for power management in the energy distribution network as claimed in claim 1, wherein the arrangement is connected to the energy distribution network and the energy distribution network comprises a local low voltage network; and wherein a gas operated combustion engine/generator unit controllable via the control unit is connected to the energy distribution network.

6. A method for power management in an energy distribution network via an arrangement configured to dynamically support the energy distribution network and compensate for network disturbances in the energy distribution network via energy output/intake to/from the energy distribution network, the arrangement including an energy feed/return unit for feeding/returning energy to/from the energy distribution network and having a direct current intermediate circuit, at least two different electrical energy storage devices connected to the direct current intermediate circuit of the energy feed/return unit and having different response times and a control unit, the method comprising: ascertaining, by the control unit, a prevailing actual network state of the energy distribution network by measuring electrical variables of the energy distribution network, said electrical variables including at least one of voltage, current, phase position and frequency, and compare the ascertained prevailing actual network state with a desired network state; controlling, by the control unit, dependent on the comparison, the energy feed/return unit to output energy to the energy distribution network or receive energy from the energy distribution network; and selecting and coordinating, by the control unit, the at least two electrical energy storage devices in accordance with their respective response times to cover a required response time period during network disturbances.

7. The method for power management in an energy distribution network as claimed in claim 6, wherein the energy feed/return unit comprises a converter which is operable in one of a two quadrant operation or four quadrant operation, said converter being at least one of (i) a line commutated inverter in the two quadrant operation and (ii) a direct current intermediate circuit that is connected to the converter operable in one of the two quadrant operation or four quadrant operation.

8. An arrangement for implementing a method for power management in an energy distribution network, the method comprising ascertaining a prevailing actual network state of the energy distribution network by measuring electrical variables of the energy distribution network, said electrical variables including at least one of voltage, current, phase position and frequency, and comparing the ascertained prevailing actual network state with a desired network state, by controlling, dependent on the comparison, the energy feed/return unit to output energy to the energy distribution network or receive energy from the energy distribution network, and by selecting and coordinating the at least two electrical energy storage devices in accordance with their respective response times to cover a required response time period during network disturbances, the arrangement comprising: an energy feed/return unit for feeding/returning energy to/from the energy distribution network and having a direct current intermediate circuit; at least two different electrical energy storage devices connected to the direct current intermediate circuit of the energy feed/return unit and having different response times; and a control unit configured to ascertain the prevailing actual network state of the energy distribution network by measurement of electrical variables of the energy distribution network, said electrical variables including at least one of the voltage, current, phase position and frequency, and to compare the ascertained prevailing actual network state with the desired network state, control, dependent on the comparison, the energy feed/return unit to output energy to the energy distribution network or receive energy from the energy distribution network, and select and coordinate the at least two electrical energy storage devices in accordance with their respective response times to cover the required response time period during the network disturbances.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its design and advantages are described in detail hereinunder with reference to an exemplary embodiment with reference to the figures. Lines (continuous and also broken) that are illustrated in the figures between elements characterize functional, logical and/or physical connections, such as electrical signal or data cables between the elements, by way of which signals, data, amongst others, can be transferred or rather exchanged between the elements, in which figures:

(2) FIG. 1 illustrates a schematic illustration of a network compensating arrangement for an electrical energy distribution network having a static energy feed/regeneration unit, a combustion engine/generator unit and a control unit (LGC) in accordance with an embodiment of the invention; and

(3) FIG. 2 is a flowchart of the method in accordance with the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

(4) FIG. 1 shows a network compensating arrangement for an electrical energy distribution network for the purpose of continuously correcting network disturbances and dynamically supporting the energy distribution network.

(5) With specific reference to FIG. 1, illustrated therein is a network compensating arrangement 1 for a local low voltage network 2 that is supplied with electrical energy (effective/supporting power 34) via various energy generators 5, 6, 7 for the purpose of continuously correcting network disturbances and for dynamically supporting the low voltage network 2.

(6) In detail, FIG. 1 illustrates one of these energy generators, a gas-operated combustion engine/generator unit 5; two further energy generators 6, 7 are schematically illustrated, and can be other types of combustion engine/generator units, such as diesel-operated combustion engine/generator units or also other types of energy sources.

(7) The gas-operated combustion engine/generator unit 5 combines a gas-operated combustion engine 17 with a generator 18. Both the gas-operated combustion engine 17 and the generator 18 are controlled via a respective control unit, in this case a closed loop engine control/management system 19 or rather a closed loop generator control/management system 20. By way of example, it is thus possible, with these closed loop control units, to automatically control ignition, the point in time at which ignition occurs, and fuel mixture preparation of the gas-operated combustion engine/generator unit 5, or rather of the gas-operated combustion engine 17 in order thus to influence the operating and power state of the gas-operated combustion engine/generator unit 5.

(8) As illustrated in the FIG. 1, each energy generator 5, 6, 7 is connected to the low voltage network 2 by a controllable switch 8.

(9) Due to the special characteristics of a combustion engine/generator unit, such as sluggish performance of the fuel of the combustion engine and/or inertia of rotating components of the combustion engine/generator unit (dynamic effects), it can occur that the combustion engine/generator unit generates energy peaks in the case of (actual) rotational speeds of the combustion engine that deviate from desired rotational speeds and this has a disturbing effect on the energy distribution network, in this case the low voltage network 2.

(10) In addition, it is possible, for example, that due to a drop or an increase in the network voltage in the energy distribution network or rather low voltage network 2 (e.g. short circuit in the network), for network disturbances to occur that in turn produce a loading or unloading effect on the combustion engine/generator unit.

(11) It is possible via the illustrated network compensating device 1 to continuously correct such network disturbances (that are caused by network and/or energy generators) and to dynamically support the low voltage network 2.

(12) As illustrated in the FIG. 1, the network compensating arrangement 1 comprises a static energy feed/return unit (hereinunder referred to as an energy feed/return unit) 3 and also a measuring unit, a closed loop control unit and a control unit, a local grid controller (LGC), 4.

(13) The energy feed/return unit 3 and the LGC 4 are coupled to one another such that the energy feed/return unit 3, within the scope of an intelligent power/energy management system (for the low voltage network 2), can be controlled via the LGC 4.

(14) As is also illustrated in FIG. 1, the LGC 4 is connected for this purpose to the low voltage network 2 via a connection line 21, as a consequence of which the LGC 4 ascertains, via an electronic measuring unit 22 or rather equipped with a corresponding electronic measuring unit 22, the prevailing actual network state of the low voltage network 2, in this case the electrical variables: voltage U, current I and frequency F.

(15) By way of comparing the ascertained actual network state with one (or more) predetermined desired states, or also other states, limit values amongst others, the LGC 4 is able to recognize any type of network disturbance in the low voltage network 2.

(16) The LGC 4 is further configured such that, dependent on the ascertained actual network state, or the actual, desired comparison, and a possibly recognized network disturbance, it controls the energy feed/return unit 3 and the power/energy management system, as explained hereinunder in detail.

(17) In short, the LGC 4 coordinates/manages (as the central control unit) the entire system, explained here, with all its units (generator-transfer-storage units), in particular the energy feed/return unit 3 and the or rather its energy/power management system, dependent on the state of the low voltage network 2 to compensate for respective disturbances in a dynamic, prompt and/or surge-free manner, and also to protect the components of the entire system or rather of the generator-transfer-storage units from damage as a result of a limit value being exceeded.

(18) As illustrated in the FIG. 1, the energy feed/return unit 3 is coupled at the energy transfer point/input point 9 to the low voltage network 2, by a controllable switch 8.

(19) As further illustrated in the FIG. 1, the energy feed/return unit 3 comprises a line commutated converter 10, which can be operated in the two quadrant drive operation based on quickly switching a power semiconductor, a local grid inverter (LGI), and also a direct voltage intermediate circuit 11 that is connected to the LGI 10 and is referred to hereinunder also only as a direct voltage circuit.

(20) In accordance with the present disclosed embodiments, the LGI 10 is able to feed energy to the direct voltage intermediate circuit 11, and also to draw energy from the direct voltage intermediate circuit 11. Likewise in accordance with the present disclosed embodiments, the LGI 10 is able, via the energy input point 9, draw energy from the low voltage network 2, and also to feed (return) energy to the low voltage network 2 energy (effective energy, supporting energy 34) and reactive power 33 (in order to maintain the network current) in the low voltage network 2, in other words on the network side to phase shift electrical variables, in particular current and voltage, with respect to one another.

(21) As also illustrated in FIG. 1, for the purpose of converting energy into a chemical or rather mechanical form of energy and for correspondingly storing this energy, via a DC-DC inverter 12, 13, energy storage modules 14, 15, in this case a Li-battery 14 and a flywheel storage device 15, are connected to the direct voltage intermediate circuit 11.

(22) Further chemical, mechanical and/or thermal energy storage devices can be provided in an appropriate arrangement and circuit.

(23) Thermal, chemical and mechanical energy storage devices of this type, such as the illustrated Li-battery 14 or rather the flywheel storage device 15 are characterized by aging effects, such as also their charging and discharging that occurs in the time period ofgreater several milliseconds.

(24) As is further evident in FIG. 1, the direct voltage intermediate circuit 11 is connected to an electrical (also referred to here as physical) energy storage device 16, in this case a capacitor.

(25) Electrical or rather physical energy storage devices of this type, such as the capacitor 16, render it possible (in contrast/different to the thermal, chemical and mechanical energy storage devices) to perform a charging and discharging procedure in a highly dynamic manner, in a short space of time, i.e., in the region of one or several milliseconds and in an aging resistant manner.

(26) It is possible via these energy storage devices 14, 15 and that are connected to the direct current intermediate circuit (when the LGI is used in accordance with the specification) to generate the reactive power 33 (rendering it possible to maintain the network current) in the low voltage network 2 or rather to introduce the effective energy into the low voltage network 2 or draw said effective energy therefrom.

(27) Thus, it is possible via the energy feed/return unit 2 and its energy storage device 14, 14, 16, to compensate in particular for specified symmetrical, cyclic fluctuations in energy levels in the low voltage network 2, such as an acyclic energy excess or rather a shortage of energy in the low voltage network 2, caused for example by the gas-operated combustion engine/generator unit 5, and consequently to compensate for network disturbances.

(28) The transport of energy is encumbered with response times according to the physical or rather chemical characteristics of the selected energy storage device, 14, 15 and the electrical characteristics of its inverter or rather the inverters 12, 13. The selected energy storage devices 14, 15 are therefore selected according to the required response time, arranged and accordingly coordinated via the intelligent power management (by means of the LGC) in order in combination to cover the required response time period in the case of network disturbances.

(29) Thus, highly dynamic correction variables are derived from the physical storage device 16, and less dynamic correction variables are derived from the chemical storage device 14 and the mechanical storage device 15. The limit for drawing energy from the physical storage device 16 or rather from the chemical/mechanical energy storage device 14, 15 is defined according to economic restraints.

(30) Energy is automatically charged into the physical energy storage device 16 in the direct current intermediate circuit 11 via the desired set value/intermediate circuit voltage.

(31) The charge state of the chemical and mechanical energy storage device 14, 15 is accordingly monitored via the LGC 4 and controlled such that its charge state is maintained at approx. 80%-90%.

(32) The chemical and mechanical energy storage device 14, 15 can be charged with energy (to the preferred 80%-90% charge state) controllable via the LGC 4, via a preceding disturbance-free operation, of the gas-operated combustion engine/generator unit 5, or of another energy source (not illustrated), such as an inverter unit that is operated by waste heat (exhaust gas micro turbine) or such, based on renewable energies, or also by way of the low voltage network 2 (and LGI 10) itself.

(33) A charge of the energy storage device 16 above a specified voltage limit value is converted into thermal energy by using a highly dynamic chopper 25 that is connected to the direct voltage intermediate circuit 11 with the aid of an ohmic resistor 26 (overcharge protection).

(34) Once the storage charge of the physical energy storage device 16 or rather the chemical/mechanical storage device 14, 15 is completed, the energy that is made available from a generator source of this type is supplied via the energy feed/return unit 3 or rather via the LGI 10 or also directly to the low voltage network 2. The LGC 4 performs the corresponding control.

(35) In order to control the participating generator-transfer-storage units in a closed loop and open loop manner within the scope of the power/energy management, the LGC 4, as illustrated in FIG. 1, is equipped with a model 23 of the generator-transfer-storage units, such as also with a process display archive 24 that contains operating events of the participating generator-transfer-storage units.

(36) Based on the model 23 and/or the process display archive 24, responses of the participating generator-transfer-storage units (within the scope of the coordination/management) are determined and coordinated in order to thus (pre-)control the entire system with all participating components surge-free and dynamically in a suitable manner, and to thereby compensate dynamically and in a surge-free manner for the network disturbances, arising by way of example from a closed loop control technology-related defect in the case of the gas-operated combustion engine/generator unit 5 or static effects in the case of the closed loop control technology-related transfer distances. An, otherwise generally provided or rather necessary, energetic over-dimensioning of the gas-operated combustion engine/generator unit 5 is omitted, the gas-operated combustion engine/generator unit 5 is unburdened of currents that do not contribute to the effective power by this control of the LGC within the scope of the power/energy management process.

(37) Thus, by way of example also via the LGC 4, the closed loop control units 19, 20 of the gas-operated combustion motor 17 and the generator 18 are coordinated with one another using control technology dependent on the requirements of the low voltage network 2 in order to thus dynamically compensate (by way of example) for deviations of the gas-operated combustion engine 17 from the prevailing operating point or energy peaks in the form of excess rotational speeds in the case of gas-operated combustion engine 17 via correspondingly influencing ignition, the point in time at which ignition occurs and fuel mixture preparation (engine management).

(38) For the purpose of the dynamic open loop control of the power output of the gas-operated combustion engine 17, a partial switch-off of ignition circuits is appropriate and it is also appropriate to influence the point in time at which ignition occurs. This type of procedure is also coordinated by the LGC 4 via correspondingly controlling and coordinating the closed loop control units 19, 20 of the gas-operated combustion engine 17 and the generator 18.

(39) In the event of an electrical load shedding, the rotational speeds of the gas-operated combustion engine 17 tend to over-vibrate (which leads to energy peaks in the low voltage network 2) because, due to the special characteristics of a gas-operated combustion engine, the energy supply cannot be stopped promptly. When controlled by the LGC 4, it is then possible with these energy peaks to charge the energy storage devices 16 or rather 14, 15 of the energy feed/return unit 3, the energy storage devices being connected to the direct voltage intermediate circuit 11. The over-charge protection for the physical energy storage device 16 is ensured by the chopper 25 and the ohmic resistor 26.

(40) The LGC 4 also controls the energy feed/return unit 3 so that in a static steady feed state of the gas-operated combustion engine/generator unit 5, the form of the electrical variables is not influenced. In other words, if the voltage, current, phase position and the frequency in the low voltage network 2 corresponds in a static manner to the desired set value (and is detected as such by the LGC 4), the energy feed/return unit 3 can be deactivated or switched into a stand-by operation.

(41) The LGC 4 also controls the reactive power (output/intake) 33 or the effective/supporting power (output/intake) 34 of the energy feed/return unit 3 at the energy input point 9 such that the closed loop control unit 20 of the generator does not recognize a deviation from the operating conditions and the closed loop control units 19, 20 do not cause any control loop control activities, or rather defect recognition and limitation in the case of gas-operated combustion engine/generator unit 5.

(42) As further illustrated in FIG. 1, the local low voltage network 2 is further coupled (by a connection/connection cable 29) to a medium voltage network 27.

(43) A medium voltage switch 28 is arranged in the connection/connection cable 29 and the medium voltage switch is likewise controlled by the LGC 4. An electronic measuring unit 22 is also provided at this location, and the LGC 4 ascertains respective electrical variables by the electronic measuring unit.

(44) Consequently, it becomes possible that, dependent on the network state and energy feed condition, an under voltage release is delayed in a need-orientated manner.

(45) FIG. 1 further illustrates an alternative energy supply 30 of the energy feed/return unit 3.

(46) As clear from FIG. 1, the energy feed/return unit 3 supplies a potential-free auxiliary winding (reactive power winding) of a transformer 32 with a higher voltage. This winding is embodied according to a required permanent reactive power. In order to supply the supporting power for a short period of time, such as for a few 100 ms, the overload capability of this winding, cables and the energy feed/return unit 3 is exploited.

(47) Although the invention has been further illustrated and described in detail with reference to the preferred exemplary embodiments, the invention is not limited to the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the protective scope of the invention.

(48) FIG. 2 is a flowchart of a method for power management in an energy distribution network. The method comprises ascertaining the prevailing actual network state of the energy distribution network (2), as indicated in step 210. Next, an energy output/intake (energy feed/return) of an energy feed/return unit (3) into the energy distribution network (2) dependent on the ascertained actual network state is implemented, as indicated in step 220.

(49) While there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the methods described and the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.