Method, computer program product and power source for regulating an electricity distribution network

Abstract

The invention relates to a regulation process for a distribution network comprising a main source, of one or more power sources, configured to apply to said network to which one or more loads are connected a voltage V and a frequency f of the power P circulating on said network. If a change in one of the frequency f or the voltage V is detected on said network, said process comprises a step of regulating, during primary regulation, the other of the frequency f and the voltage V, which has not changed, by said main source, so as to keep the ratio V / f constant.

Description

Technical Field

[0001] The present invention relates to a regulation process of a distribution network. In particular, the present invention proposes a regulation process of a distribution network that is independent of the primary reserve at its disposal.

[0002] In particular, the present invention proposes a regulatory process for stabilizing the network regardless of the primary reserve state.

[0003] The process is particularly suitable for regulating microgrids, especially those with high renewable energy penetration. Background Art

[0004] The stability of distribution networks has always been a concern for operators of said networks. Distribution networks have traditionally been designed to respond to a standard known as the "N-1 standard", which allows these networks to withstand the occurrence of faults without seriously affecting the stability of the network, thus preventing general blackout situations.

[0005] To meet the N-1 criterion, the interconnected networks share their sources of electrical energy production and propose operating schemes that enable appropriate reactions when faults occur on the network.

[0006] According to these schemes, it is envisaged to cut off some loads in order to start other energy sources, such as gensets or virtual synchronous generators.

[0007] In this regard, compliance with the N-1 criterion includes determining the size of the primary reserve ("spinning reserve") of energy sufficient to respond immediately to a given event as part of the primary regulation.

[0008] Such primary regulation particularly involves adjusting the frequency or voltage of the distribution network via droop in order to respond to load demand or to compensate for faults occurring on the distribution network.

[0009] A so-called secondary regulation can then be carried out later in order to reset the distribution network to its initial state.

[0010] Primary reserves are relatively flexible once they are tapped by a forecasted and stable energy production source, such as a generator.

[0011] However, once the primary reserve is insufficient to respond to load demand or faults on the network, droop regulation will inevitably lead to blackouts.

[0012] Furthermore, as soon as the sources of electrical energy production involve intermittent sources, such as renewable energy sources, the determination of the size of the primary reserve becomes complicated.

[0013] This complexity is exacerbated by the fact that distribution networks are micro-grids that operate autonomously.

[0014] Furthermore, intermittent sources usually exhibit only low inertia and react in a decentralized and uncoordinated manner when faults or load demands occur, thus worsening the instability of the network. Such behavior of intermittent sources cannot stabilize the network.

[0015] Finally, droop regulation can generate traffic changes that can be detrimental to all equipment running the network.

[0016] It has been possible to propose properties that can be assigned to synchronous generators with intermittent sources, called virtual synchronous generators.

[0017] However, this solution is not always satisfactory since there are no standards governing the operation of virtual synchronous generators to allow them to stabilize the network.

[0018] An object of the invention is to propose a process for controlling a generator making it possible to ensure the stability of the distribution network.

[0019] Another object of the invention is to propose a process for controlling a generator making it possible to increase the penetration of renewable energy sources.

[0020] Another object of the invention is to propose a process for controlling the generators in such a way that the stability of the network is guaranteed also when the primary reserves are insufficient.

[0021] Finally, another object of the invention is to propose a process for controlling a generator that provides protection against damage to pieces of equipment (especially electrosensitive equipment) operating a network. Summary of the invention

[0022] The object of the present invention is at least partially achieved by a regulation process of a distribution network, which includes a main source among one or more power sources, which is configured to apply a voltage V and a frequency f of the power P circulating on the network to the network to which one or more loads are connected.

[0023] If one of the frequency f or the voltage V detected on the network changes, the process comprises a regulation step performed by the primary source during primary regulation of the other of the frequency f and the voltage V that has not changed, so as to keep the ratio V / F substantially constant.

[0024] By "substantially constant" is meant a ratio that can vary by approximately 5% about a set point value.

[0025] Thus, according to the invention, maintaining the ratio V / f makes it possible to stabilize the network without taking into account the primary reserves, in response to a load demand or the appearance of a fault on the network.

[0026] Furthermore, since the regulation is independent of primary reserves, a larger contribution of renewable energy, for example 100%, can be considered.

[0027] Furthermore, maintaining a substantially constant ratio V / f makes it possible to maintain a constant flow in the load, in particular electrically sensitive equipment, thereby preventing wear or overheating of the motor of the load.

[0028] Finally, the process according to the invention can be implemented on a pre-existing electricity distribution network.

[0029] According to one mode of implementation, the primary source comprises a regulator for performing the regulating step.

[0030] According to one mode of implementation, the regulator measures the frequency f and the voltage V of the power distribution network, advantageously at regular time intervals.

[0031] According to one mode of implementation, the primary source is intermittent.

[0032] According to one mode of implementation, the primary source may not apply power and comprise, for example, an electric motor whose shaft is not connected.

[0033] The primary source may include an energy storage system such as a flywheel, a battery, or the like.

[0034] According to one implementation mode, the primary source is a renewable energy source, and in particular, the renewable energy source comprises at least one source selected from solar energy, wind energy, energy.

[0035] According to one mode of implementation, the primary source comprises an inverter configured with a control law giving it the behavior of a synchronous generator, so that the primary source forms a virtual synchronous generator.

[0036] According to one mode of implementation, the one or more power sources also comprise other sources, advantageously intermittent sources and even more advantageously renewable sources.

[0037] According to one mode of implementation, the primary regulation is followed by a secondary regulation which allows the frequency f and the voltage V of the network to return to predetermined values.

[0038] The invention also relates to a computer program comprising instructions which, when executed by a computer, lead to the implementation of the regulation process according to the invention.

[0039] The invention also relates to a power source configured to apply to a network a voltage V and a frequency f of a power P circulating on said network and provided with a computer program according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other characteristics and advantages will emerge from the following description of a mode of implementation of a regulation process of an electricity distribution network according to the invention, given as a non-limiting example, with reference to the accompanying drawings, in which:

[0041] Figure 1 is a schematic representation of an electrical distribution network upon which the present invention may be implemented;

[0042] Figure 2 is a representation of the functional modules of the master source and the regulator that can be implemented in the context of the present invention;

[0043] Figure 3A represents the voltage (vertical axis) delivered by a network forming generator (curve A1 ) and a synchronous generator (curve B1 ) as a function of time (horizontal axis) as part of a first simulation of the invention;

[0044] Figure 3B represents the active power (vertical axis) delivered by the network forming generator (curve A2) and the synchronous generator (curve B2) as a function of time (horizontal axis) as part of a first simulation of the invention;

[0045] Figure 3C represents the reactive power (vertical axis) delivered by the network forming generator (curve A3) and the synchronous generator (curve B3) as a function of time (horizontal axis) as part of a first simulation of the invention;

[0046] Figure 3D represents the frequency f (vertical axis) delivered by the network forming generator (curve A4) and the synchronous generator (curve B4) as a function of time (horizontal axis) as part of a first simulation of the invention;

[0047] Figure 4A represents the active power (vertical axis) delivered by the inverter as a function of time (horizontal axis) as part of a second simulation of the present invention;

[0048] Figure 4B represents the power frequency (vertical axis) delivered by the inverter as a function of time (horizontal axis) as part of a second simulation of the present invention;

[0049] Figure 4C represents the current (vertical axis) delivered by the inverter as a function of time (horizontal axis) as part of a second simulation of the present invention;

[0050] Figure 4D represents the voltage (vertical axis) delivered by the inverter as a function of time (horizontal axis) as part of a second simulation of the present invention;

[0051] Figure 5Arepresents the active power (vertical axis) delivered by the two inverters as a function of time (horizontal axis) as part of a third simulation of the present invention;

[0052] Figure 5B represents the power frequency (vertical axis) delivered by two inverters as a function of time (horizontal axis) as part of a third simulation of the present invention;

[0053] Figure 5C represents the current (vertical axis) delivered by two inverters as a function of time (horizontal axis) as part of a third simulation of the present invention;

[0054] Figure 5D Shown is the voltage (vertical axis) delivered by two inverters as a function of time (horizontal axis) as part of a third simulation of the present invention. DETAILED DESCRIPTION

[0055] The invention described in detail below implements a regulation process for an electricity distribution network equipped with a source, called the primary source, among one or more power sources, configured to impose on the network a voltage V and a frequency f of a power P circulating on the network and intended to be consumed by the loads.

[0056] In particular, the primary source is suitable for keeping constant the ratio between the voltage V and the frequency f of the power P circulating on the network.

[0057] "Power source" refers to any source that can selectively deliver electric current or apply voltage.

[0058] By way of example and without limitation, the power source may include a synchronous generator, an asynchronous generator, a voltage source.

[0059] Although the present invention is generally described in the context of a power distribution network, the present invention may be advantageously implemented in a microgrid.

[0060] A "micro-network" ("microgrid") is a local electrical network designed to produce and distribute electrical energy in an isolated area far from large electrical energy production centers. For example, the isolated area is an island, a mountainous area, or a desert area. The microgrid principle also applies when a building, a region, a campus, or other entity connected to a large-scale distribution network is designed to manage its energy production in a different way and increase its resilience.

[0061] The main attraction of microgrids is that they operate autonomously (in island mode, not connected to the public grid) and are located close to the consumption area (load). Thus, the losses inherent to long-distance distribution networks are limited.

[0062] Furthermore, according to the present invention, a "distribution network" may include an electricity distribution network or an electricity transmission network or an electrical sub-transmission network.

[0063] Now refer to Figure 1 , Figure 2 , FIG. 3A to FIG. 3D , FIG. 4A to FIG. 4D and FIG. 5A to FIG. 5D The present invention is described in detail.

[0064] Figure 1 An electric power distribution network 10 is represented.

[0065] The distribution network comprises one or more power sources, among which there is a source called a primary source 20 configured to apply to the network a voltage V and a frequency f of a power source P circulating (or distributed) on the distribution network 10 .

[0066] In other words, the primary sources 20 may form a network.

[0067] The primary source 20 may comprise a synchronous generator, in particular a generator set.

[0068] Alternatively, the primary source 20 may include an intermittent energy source. More specifically, the intermittent energy source may include a renewable energy source, and may include, for example, photovoltaic panels, wind turbines, marine turbines, thermodynamic machines.

[0069] The intermittent energy source may be equipped with an inverter configured with a control law that imparts to the intermittent energy source a synchronous generator behavior such that the primary source forms a virtual synchronous generator.

[0070] The one or more power sources may also include other sources, advantageously intermittent sources 21, and even more advantageously renewable energy sources. For example, renewable energy sources may include photovoltaic panels, wind turbines, marine turbines, thermodynamic machines.

[0071] Additionally or alternatively, the one or more power sources may include one or more batteries 22 .

[0072] Still additionally or alternatively, the one or more power sources may include one or more generators 23, such as synchronous generators, asynchronous generators, or a combination of both.

[0073] The process according to the invention comprises, as part of the primary regulation, a regulation step which keeps the ratio of voltage V to frequency f substantially constant.

[0074] In particular, as soon as the frequency f of the electric power P circulating on the network changes, the regulation step consists in regulating the voltage V so as to keep the ratio of the voltage V to the frequency f substantially constant.

[0075] In an equivalent manner, as soon as the voltage V of the electric power P circulating on the network changes, the regulation step consists in regulating the frequency f so as to keep the ratio of voltage V to frequency f substantially constant.

[0076] Such changes in the frequency and / or voltage of the power P circulating on the distribution network may occur during load demand or during the presence of a fault.

[0077] This regulation is implemented by the master sources that form the network.

[0078] In this regard, the primary source 20 may include a regulator R configured to provide regulation in accordance with aspects of the present invention.

[0079] In particular, the regulator can measure the frequency f and the voltage V of the electric power P

[0080] In a particularly advantageous manner, the measurements are performed at regular time intervals, for example every second.

[0081] Such measurements make it possible to establish the state of the network and to detect the occurrence of events such as load demand or the presence of faults.

[0082] Figure 2 is a schematic representation of an embodiment of regulation according to the present invention.

[0083] Specifically, Figure 2 denoted a primary source 20 connected to an electricity distribution network 10 which distributes power P to loads 30 .

[0084] The main source 20 is linked to a regulator equipped with submodules, in particular a module 20a for regulating frequency, a module 20b for regulating voltage, and a control module 20c for said module 20a for regulating frequency and said module 20b for regulating voltage.

[0085] The module 20a for regulating the frequency requires the primary source 20 to adjust the frequency of the power circulating on the network to a given frequency.

[0086] The module 20b for regulating the voltage requires the primary source 20 to adjust the voltage of the power circulating on the network to a given voltage.

[0087] The control module 20c indicates to the modules 20a and 20b respectively the frequency f and the voltage V that the primary source must apply to the network.

[0088] Advantageously, the voltage V and the frequency f of the power P circulating on the network are measured by the control module 20 c .

[0089] This proposed regulation makes it possible to maintain a balance between consumed power and produced power at any time independently of the state of the optional primary reserve.

[0090] Regulation may also incorporate droop modulation of frequency and / or voltage if sufficient primary reserves are immediately available to respond to a given event.

[0091] The regulation proposed according to the invention is also advantageous because it does not require communication between the various pieces of equipment (especially energy sources) connected to the network.

[0092] The primary regulation may be followed by a secondary regulation making it possible to restore the frequency f and the voltage V of the network to predetermined values.

[0093] The invention also relates to a computer program comprising instructions which, when executed by a computer, lead to the implementation of the process according to the invention.

[0094] The invention also relates to a power source configured to apply to a network a voltage V and a frequency f of a power P circulating on said network and provided with a computer program according to the invention.

[0095] Various simulations of the process according to the invention have been carried out.

[0096] According to a first example, the inventors simulated the behavior of a combination of a network forming generator (or "grid former") and a synchronous generator.

[0097] in this regard, FIG. 3A to FIG. 3D 1 and 2 show results related to a numerical simulation of network regulation after a drop in active power on the network at time t=t0.

[0098] In particular, Figure 3A Represents the voltage (vertical axis) delivered by the network forming generator (curve A1 ) and the synchronous generator (curve B1 ) as a function of time (horizontal axis).

[0099] Figure 3B Represents the active power (vertical axis) delivered by the network forming generator (curve A2) and the synchronous generator (curve B2) as a function of time (horizontal axis).

[0100] Figure 3C Represents the reactive power (vertical axis) delivered by the network forming generator (curve A3) and the synchronous generator (curve B3) as a function of time (horizontal axis).

[0101] Figure 3D Represents the frequency f (vertical axis) delivered by the network forming generator (curve A4) and the synchronous generator (curve B4) as a function of time (horizontal axis).

[0102] At t=t0, the voltage delivered by the generator is formed by the network (curve A1, Figure 3A ) and reactive power (curve A3, Figure 3C ) decreases by about 10%. From this point on, the synchronous generator starts at t1 = t0 + 20s and synchronizes with the network (curves B1, B2, B3, B4).

[0103] At time t1, the synchronous generator regulates the frequency f of the electric power it delivers on the network so as to keep the ratio V / f at a predetermined value corresponding to the ratio of the setpoint voltage and the setpoint frequency of the network. This regulation takes place in a primary regulation phase extending between time t1 and time t2=t0+50s.

[0104] According to a second example, the inventors simulated the behavior of a network forming inverter.

[0105] Figure 4A represents the active power (vertical axis) delivered by the inverter as a function of time (horizontal axis).

[0106] Figure 4B represents the frequency of the power delivered by the inverter (vertical axis) as a function of time (horizontal axis).

[0107] Figure 4C represents the current delivered by the inverter (vertical axis) as a function of time (horizontal axis).

[0108] Figure 4D represents the voltage delivered by the inverter (vertical axis) as a function of time (horizontal axis).

[0109] At time t0, a load demand of 150 kW occurs. The inverter then has sufficient primary reserve to respond to the load demand using droop.

[0110] At time t1 = t0 + 10s, a fault occurs on the network. The network takes the form of a 660kW load demand ( Figure 4A Since the primary reserve is insufficient in this case, the inverter adjusts the frequency f of the power it delivers during the primary control phase extending between time t1 and time t2=t0+20s ( Figure 4B ) and voltage V( Figure 4D ) Both. At this stage, according to an aspect of the invention, regulation is performed so as to keep the ratio V / f constant, thereby stabilizing the network.

[0111] The secondary regulation phase starts at time t2 in order to reset the network to the state required by the operator.

[0112] According to a third example, the inventors simulated the behavior of two inverters that may form a network.

[0113] Figure 5A represents the active power (vertical axis) delivered by each inverter as a function of time (horizontal axis).

[0114] Figure 5B The frequency of the power delivered by each inverter (vertical axis) is represented as a function of time (horizontal axis).

[0115] Figure 5C The current delivered by each inverter (vertical axis) is shown as a function of time (horizontal axis).

[0116] Figure 5D The voltage delivered by each inverter (vertical axis) is shown as a function of time (horizontal axis).

[0117] At time t0, a load demand of 150 kW occurs. The inverters then adjust their frequencies ( Figure 5B ) and its voltage ( Figure 5D ) in order to keep the ratio V / f substantially constant. This first regulation extends between time t0 and time t1=t0+10s, from which the network is subjected to a second 495kW load demand ( Figure 5A ).

[0118] At time t1 = t0 + 10s, the two inverters adjust the frequency again ( Figure 5B ) and voltage ( Figure 5D ) in order to keep the ratio V / f constant according to aspects of the invention, thereby stabilizing the network.

[0119] The secondary regulation phase starts at time t2 in order to reset the network to the state required by the operator.

[0120] These simulations show that regulation according to aspects of the invention can be implemented on a network powered by one or more power sources, in particular one or more inverters that can form a network.

[0121] The generality of the proposed approach enables its application in a large number of pre-existing distribution networks.

Claims

1. A method for regulating a distribution network, said distribution network comprising a main source among one or more power sources, said main source being configured to apply to said network to which one or more loads are connected a voltage V and a frequency f of a power P circulating on said network, said method comprising, during primary regulation, a step of regulating the frequency f by said main source so as to keep the ratio V / f constant, if a change in the voltage V is detected on said network.

2. The method according to claim 1, wherein: The primary source includes a regulator for performing the regulating step.

3. The method according to claim 2, wherein: The regulator measures the frequency f and the voltage V of the power distribution network, the measurements being performed at regular time intervals.

4. The method according to any one of claims 1 to 3, wherein: The primary source is intermittent.

5. The method according to claim 4, wherein: The primary source is a renewable energy source.

6. The method according to claim 4, wherein: The primary source comprises an inverter configured with a control law giving it synchronous generator behavior, such that the primary source forms a virtual synchronous generator.

7. The method according to any one of claims 1 to 3, wherein: The power distribution network also includes other sources.

8. The method according to any one of claims 1 to 3, wherein: The primary regulation is followed by a secondary regulation which restores the frequency f and the voltage V of the network to predetermined values.

9. The method according to any one of claims 1 to 3, wherein: One of the power sources of the distribution network has a primary reserve, and the method comprises, before the regulating step, a step of evaluating whether the primary reserve is sufficient to respond to a load demand or a fault that may occur on the network.

10. The method according to claim 9, wherein: Once the primary reserves are assessed to be sufficient to respond to a load demand or fault, the assessing step further comprises implementing regulation based on injecting at least some of the primary reserves into the network to respond to the load demand or fault.

11. The method according to claim 1, wherein: If a change in frequency f is detected on the network, the method also comprises regulating the voltage V by the primary source during primary regulation so as to keep the ratio V / f constant.

12. The method according to claim 5, wherein: The renewable energy source includes at least one source selected from solar energy and wind energy.

13. The method according to claim 7, wherein: The other sources include intermittent sources or renewable energy sources.

14. A computer program product comprising instructions which, when executed by a computer, result in the implementation of the method according to one of claims 1 to 13.

15. A power source configured to apply to a network a voltage V and a frequency f of a power P circulating on said network and provided with a computer program product according to claim 14.

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