Coordinated control of an aggregate to provide a primary frequency setting

Abstract

The invention relates to a method for controlling a virtual power plant, composed of a battery and hydroelectric power plants, connected to an electrical grid. The virtual power plant is subjected to an overall power setpoint exceeding the battery's operational limit. A first setpoint is sent to a local controller of a hydroelectric power plant, without taking into account hydroelectric power measurements, but according to a priority order and the battery's limits. Next, a second setpoint is provided, based on the measurement of the overall power of the hydroelectric power plants. Simultaneously, the battery receives a third setpoint adjusted according to the overall setpoint and the hydroelectric power measurements. The setpoints aim to maintain the temporal stability of the overall power supplied by the virtual power plant, in accordance with the requested power setpoint. Abstract figure: Figure 1

Description

Title of the invention: Coordinated control of an aggregate to provide primary frequency control technical field

[0001] The present invention relates to the field of hydroelectric power plants, in particular of the "run-of-river" type, and battery storage systems interfaced by power electronic converters (inverters), connected on the same synchronous electrical network.

[0002] Aggregations of decentralized sources, also called “virtual power plants” or “VPP” (“Virtual Power Plant” in English), participate in the primary frequency regulation of the network.

[0003] The present invention relates more particularly to a method of controlling such a virtual power plant, as well as to a centralized controller implementing such a method and to a computer program intended to be executed by such a centralized controller.

[0004] This control method makes it possible to control in a coordinated manner a battery and a set of run-of-river hydroelectric power plants, having different dynamic characteristics, to provide an aggregated primary frequency control service, in particular when the network is in an "Alert State" or in an "Emergency State".

[0005] This service can in particular be integrated into the “FCR” (“Frequency Containment Reserve” in English), which is the primary frequency control service of the European electricity system, and more particularly the expected operation of the so-called “limited reservoir” (LER or “Limited Energy Reservoir” in English) aggregates when the network is in “Alert State” or “Emergency State”, triggered by criteria on the network frequency. Previous technique

[0006] Today, more and more new technologies, such as battery storage systems, are being installed in electrical grids to provide grid services, such as primary frequency regulation. Frequency regulation has historically been provided by conventional means of production (hydroelectric, thermal, nuclear, etc.), and this has a cost for the producer, because to ensure the reserve associated with frequency regulation, the generating units must maintain a reserve and therefore be operated below their nominal power.

[0007] The use of batteries to provide this frequency regulation service can optimize conventional power generation equipment. Indeed, if the entire reserve is provided by batteries, which frees up a constraint on conventional generators, which can then be operated at their nominal power.

[0008] Numerous battery-based frequency control projects have already been built in France and the rest of the world.

[0009] Today, some existing means of production, such as run-of-river hydropower, have existing active power flexibility capacities which are not exploited in practice, but which can, from a technical point of view, be activated on an ad hoc basis to provide primary frequency reserve in the event of a major incident on the network causing a significant variation in frequency.

[0010] The aggregation of a battery with one or more run-of-river hydroelectric power plants can optimize both the sizing of the battery and the use of the hydroelectric power plants, from a technical and economic point of view.

[0011] In normal operation (frequency close to the reference value, i.e. 50 Hz in France), hydroelectric power plants can be placed at their optimal operating point, which depends in particular on the incoming hydraulic flow, while the battery ensures the entire frequency adjustment (it discharges when the frequency is low, and recharges when the frequency is high).

[0012] In exceptional circumstances (large frequency variations), the hydroelectric power plants connected to the battery can temporarily increase or decrease their output to provide additional primary reserve, supplementing the power supplied or absorbed by the battery. In this way, the deoptimization of the hydroelectric power plants is limited to these exceptional events, and it is possible to supply the grid with a power reserve exceeding the battery's maximum capacity. Thus, the battery sizing can be optimized, which can improve the profitability of a project.

[0013] Patent application FR3133714A1 describes a known method of control, implemented by a centralized controller, of a virtual power plant composed of a battery and a set of hydroelectric power plants, in order to perform a primary adjustment of the frequency of the electrical network.

[0014] This document describes a mechanism whereby a battery power adjustment setpoint, calculated on the basis of the total power produced by the entire hydroelectric power plant at a given time, is provided to a local battery controller. The battery power adjustment setpoint is intended to modify the battery control by the local controller in order to compensate for a variation in the total power relative to an overall setpoint power for the entire hydroelectric power plant.

[0015] According to this mechanism, a power adjustment setpoint for a hydroelectric power plant, calculated on the basis of a grid frequency measurement, is also provided to a corresponding local controller. The power adjustment setpoint of the hydroelectric plant is intended to cause a variation in the power produced by said hydroelectric plant in accordance with a battery management strategy.

[0016] However, a difficulty arises in the event of exceptional frequency incidents, during which it is desirable for the virtual power plant to provide, for a prolonged period, a power reserve greater than that which can be provided by the battery alone.

[0017] Patent application FR3133714A1 does not provide sufficient information to enable a person skilled in the art to control a virtual power plant in such a way as not only to activate but also to maintain a sufficient power response from the virtual power plant in such scenarios.

[0018] There is therefore a need for a control mechanism for a virtual power plant capable of responding effectively to exceptional frequency incidents by offering an adequate power reserve over time. Summary

[0019] This disclosure improves the situation.

[0020] According to one aspect, a method is proposed for controlling, implemented by a control entity, a virtual power plant connected to an electrical network, the virtual power plant comprising at least one battery and a set of hydroelectric power plants, the virtual power plant being subject to an overall power setpoint exceeding an operational power limit of the battery, the method comprising: a provision of a first power adjustment setpoint to a local controller of a hydroelectric power station of the set of hydroelectric power stations, the first adjustment setpoint taking into account a priority order of the hydroelectric power stations and the operational power limit of the battery, and the first adjustment setpoint not taking into account any power measurement;and after the provision of the first power adjustment setpoint, a provision of a second power adjustment setpoint to the local controller of the hydroelectric plant, the second power adjustment setpoint taking into account the overall power measurement of the entire hydroelectric plant group, in which, upon the provision of the second power adjustment setpoint, the battery is subjected to a third power adjustment setpoint which takes into account the overall power setpoint and the overall power measurement of the entire hydroelectric plant group, and; in which the supplies of the adjustment setpoints contribute to maintaining a temporal stability of an overall power of the virtual plant in accordance with the overall power setpoint.

[0021] According to one aspect, a computer program is proposed comprising instructions for the implementation of the process described herein when this program is executed by a control entity of a virtual power plant connected to an electrical network, the virtual power plant comprising at least one battery and a set of hydroelectric power plants.

[0022] According to one aspect, a data storage medium is also proposed that stores the instructions of the computer program described herein.

[0023] According to one aspect, a control entity of a virtual power plant connected to an electrical network is also proposed, the virtual power plant comprising at least one battery and a set of hydroelectric power plants, the virtual power plant being subject to an overall power setpoint exceeding an operational power limit of the battery, the control entity being configured to implement: a provision of a first power adjustment setpoint to a local controller of a hydroelectric power plant of the set of hydroelectric power plants, the first adjustment setpoint taking into account a priority order of the hydroelectric power plants and the operational power limit of the battery, and the first adjustment setpoint not taking into account any power measurement;and after the provision of the first power adjustment setpoint, a provision of a second power adjustment setpoint to the local controller of the hydroelectric plant, the second power adjustment setpoint taking into account an overall power measurement of the entire hydroelectric plant group, in which, upon the provision of the second power adjustment setpoint, the battery is subjected to a third power adjustment setpoint which takes into account the overall power setpoint and the overall power measurement of the entire hydroelectric plant group, and; in which the supplies of the adjustment setpoints contribute to maintaining a temporal stability of an overall power of the virtual plant in accordance with the overall power setpoint.

[0024] Providing the first adjustment setpoint allows for the management of an overall power setpoint that exceeds the battery's operational power limit by intelligently distributing the excess among the hydroelectric power plants, taking into account their priority order. This approach ensures better use of available resources and prevents overloading the battery.

[0025] Providing the second adjustment setpoint allows the power distribution to be adjusted dynamically. This makes it possible to react to fluctuations and adapt the instructions based on the actual performance of the hydroelectric power plants, which improves the responsiveness and reliability of the virtual power plant for primary frequency adjustment.

[0026] The temporal stability of the overall power supplied by the virtual power plant makes it possible to avoid rapid fluctuations that could compromise the stability of the electrical network.

[0027] The proposed method, the proposed computer program, the proposed control entity and the proposed data storage medium may optionally include certain additional functions as defined below.

[0028] In one example, the first power adjustment instruction takes into account at least one parameter of the hydroelectric plant among: availability, available capacity, response time, power limitation.

[0029] These parameters make it possible to improve the coordination between the different means of production and their efficient use.

[0030] In one example, the first power adjustment setpoint takes into account an estimated power regulation gain of the hydroelectric plant after a first delay, and the supply of the second power adjustment setpoint is implemented after a second delay greater than the first delay.

[0031] This can help to avoid overcompensation or excessive response delays, thus optimizing frequency regulation.

[0032] In one example, the second power adjustment setpoint is periodically updated based on a fluctuation in an overall power measurement of the hydroelectric plants and / or a fluctuation in an environmental parameter of at least one hydroelectric plant in the set of hydroelectric plants.

[0033] This can allow a more precise response to network needs, a finer adjustment of available resources and a faster compensation of possible discrepancies between a setpoint power and an associated power measurement.

[0034] In one example, the operational power limit of the battery takes into account a state of charge of the battery and / or a thermal condition.

[0035] This improves battery usage under safe conditions.

[0036] In one example, the provision of the first adjustment setpoint is carried out during a rapid variation of a frequency of the electrical network.

[0037] For example, the frequency variation may be greater than 50 MHz, or greater than 100 MHz, or greater than 150 MHz, or greater than 200 MHz in a period of less five minutes, or less than two minutes, or less than one minute, or less than 40 seconds, or less than 20 seconds, or less than 10 seconds.

[0038] In one example, The overall power setpoint is adjusted, if necessary, after the first adjustment setpoint is provided and before the second adjustment setpoint is provided, and The second adjustment instruction takes into account the overall adjusted power instruction.

[0039] Adjusting the overall setpoint allows for a response to changes in production and demand conditions before applying the second setpoint. This can enable more precise regulation and improved responsiveness of the power plant.

[0040] In one example, the second adjustment instruction includes compensation for at least one unforeseen power variation of at least one hydroelectric power plant in the set of hydroelectric power plants.

[0041] This can improve the stability of the plant's response to the overall power setpoint.

[0042] In one example, a first decision tree is used to determine the first adjustment instruction.

[0043] In one example, a second decision tree is used to determine the second adjustment instruction.

[0044] The use of decision trees to determine adjustment instructions allows for a structured and predictable approach to decision-making.

[0045] In one example, the method includes providing a set of initial power adjustment instructions to local controllers of a plurality of hydroelectric power plants in the hydroelectric power plant set, the set of initial adjustment instructions taking into account a priority order and not taking into account any power measurement, and the provision of the set of initial adjustment instructions including the provision of the first adjustment instruction.

[0046] By providing a set of simultaneous instructions to several power plants, the proposed method improves load distribution and reduces the response time of the virtual power plant. This allows for faster and better-coordinated activation of hydroelectric power plants.

[0047] In one example, the method includes a verification of the hydroelectric plant's capacity to respond to the first adjustment setpoint or the second adjustment setpoint.

[0048] Verifying the ability of the power plants to follow instructions prevents overloading or underutilization of resources. This allows for real-time adjustments to the instructions based on the actual capacities of the power plants, thus improving the distribution of power.

[0049] In one example, the second adjustment setpoint takes into account a comparison between a power measurement of the hydroelectric plant after the provision of the first adjustment setpoint and a target value.

[0050] This comparison makes it possible to verify that the control unit is correctly following the initial setpoint and, in case of a discrepancy, to adjust the second setpoint accordingly. This can allow for greater precision in adjusting the power delivered by the control unit.

[0051] In one example, the decision tree adjusts the adjustment instructions for hydroelectric power plants according to an iterative analysis, until the overall power reaches a stable value within a defined tolerance range.

[0052] This improves the stability of the virtual power plant's response to network requirements. Brief description of the drawings

[0053] Other features, details and advantages will become apparent from reading the detailed description below and from analyzing the accompanying drawings, in which: Fig. 1

[0054] [Fig.1] illustrates, in the form of a decision tree, the provision of at least one first power adjustment instruction, in an example of an embodiment. Fig. 2

[0055] [Fig.2] illustrates, in the form of a decision tree, a supply of at least one first power adjustment instruction, in an example implementation. Fig. 3 Fig. 4 Fig. 5 Fig. 6

[0056] [Fig.3], [Fig.4], [Fig.5] and [Fig.6] illustrate the results of a simulation of implementation work of providing initial power adjustment instructions according to the decision tree of [Fig.1]. Fig. 7

[0057] [Fig.7] illustrates, in the form of a decision tree, a supply of at least one second power adjustment instruction, in an example implementation. Fig. 8

[0058] [Fig.8] illustrates, in the form of a decision tree, a supply of at least one second power adjustment instruction, in an example implementation. Fig. 9

[0059] [Fig.9] illustrates, in the form of a decision tree, the provision of at least one second power adjustment instruction, in an example embodiment. Fig. 10

[0060] [Fig. 10] illustrates, in the form of a decision tree, the provision of at least one second power adjustment instruction, in an example embodiment. Fig. 11 Fig. 12 Fig. 13 Fig. 14

[0061] [Fig.11], [Fig.12], [Fig.13] and [Fig.14] illustrate results of a simulation of the implementation of the provision of second power adjustment instructions according to the decision trees in Figures 7 and 9. Description of the implementation methods

[0062] The drawings and description may not only serve to make this disclosure better understood, but may also contribute to its definition, if necessary.

[0063] The proposed technique relates to the control of a virtual power plant comprising a battery and a set of hydroelectric power plants, for example of the "run-of-river" type.

[0064] The virtual power plant can also be referred to by the acronym "VPP" for "virtual power plant" in English, or by the term aggregate.

[0065] Reference is now made to a known method of controlling a virtual power plant.

[0066] This method is implemented by a two-level control architecture, in which the battery and the hydroelectric power plants are each controlled by a local controller, and a centralized controller communicates with the local controllers via communication links.

[0067] The centralized controller, or control entity, refers to a device or system responsible for managing, monitoring, and adjusting the operation of a virtual power plant. The control entity's function is to coordinate all the production resources of the virtual power plant. The control entity can, for example, be a server or software installed on such a server. The control entity receives frequency measurements from the grid and power measurements from the production resources of the virtual power plant and decides whether to generate and transmit instructions to the local controllers to increase or decrease the power delivered by each production resource.

[0068] In this control architecture, the local battery controller is configured to perform a primary frequency adjustment of the electrical network, i.e. a response The power output is proportional to the frequency variation, based on a control gain that can be transmitted by the central controller, a measurement of the electrical grid frequency, and the nominal electrical grid frequency. The control gain can also be a fixed or variable parameter directly implemented in the local battery controller. It is also known to add a battery power adjustment setpoint provided by the central controller to the frequency regulation setting.

[0069] The overall battery setpoint, denoted Pref, can thus be expressed as follows: K is the primary reserve control gain (typically expressed in MW / Hz), f is the frequency measurement of the electrical network, / 0 is the nominal frequency of the electrical network. Pq^ the battery power adjustment setting.

[0070] In the control architecture, the local controllers of the hydroelectric power plants are configured to perform level regulation, i.e. regulation of the power or flow of a hydroelectric power plant by the corresponding local controller as a function of the measurement of the level of its reservoir or the measurement of the incoming hydraulic flow.

[0071] Such regulation can, for example, increase the power (or flow rate) setpoint when the tank level is too high in order to lower the tank level, and conversely, reduce the power (or flow rate) setpoint when the level is too low in order to raise the tank level. One or more setpoint levels can be provided for this purpose. Such regulation can be implemented by a Proportional-Integral ("PI") controller implemented at the local controller level.

[0072] The level control function or dynamic level control (referred to as "RGZ") of a hydroelectric power plant is designed to regulate the level of the hydraulic reservoir supplying the plant with water to a setpoint level. This function is important for the safety of hydraulic installations and therefore must not be deactivated when a hydroelectric power plant is integrated within a virtual power plant. Level control must therefore remain the priority over other setpoints.

[0073] However, a power adjustment setpoint provided by the centralized controller can be added to the level regulation setting.

[0074] The overall setpoint of a hydroelectric power plant, denoted Prefhsim, can thus be expressed as follows: Prgz + Pfiexavec: Prgz the power setpoint determined by the local controller for level regulation purposes, and Pflex is the power adjustment setpoint provided by the centralized controller.

[0075] The battery control system relies on measurements from power sensors connected to the local controllers of the hydroelectric power plants. The power measurements are transmitted by the local controllers of the hydroelectric power plants to the central controller.

[0076] This allows the centralized controller to monitor in real time the overall power from the hydroelectric plants of the virtual power plant and to compensate for variations in overall power in real time by an adjustment of the setpoint Pn transmitted to the local battery controller. Jbat

[0077] This compensation is carried out in such a way that the total power, denoted Pvpp, of the virtual power plant, i.e. the sum of the powers of the battery and the hydroelectric power plants, complies with the following equation: PVpp = Pofpp-K^f - f 0), with Pow a desired overall power setpoint at the global level of the virtual power plant, which according to this equation is the power produced by the virtual power plant when the current frequency of the electrical grid is equal to the nominal frequency, K a constant that represents the regulating energy of the virtual power plant, f the current frequency of the electrical grid, and the nominal frequency of the electrical network, which is for example set at 50 Hz in Europe.

[0078] In other words, the battery power adjustment setpoint Pq is adjusted to compensate for measured power fluctuations from all the hydroelectric plants of the virtual power plant, denoted Ptohydm-. The setpoint Pobat is calculated by the following equation:

[0079] The known method for controlling a virtual power plant, as described, has certain limitations when it comes to managing exceptional situations on the electrical grid, such as sudden and significant frequency variations. In particular, the method does not provide a mechanism for effectively responding to the constraints imposed by such exceptional situations, where it becomes necessary to activate and maintain a large power reserve over a prolonged period.

[0080] In the European Union, electricity grid regulation imposes strict requirements for responding to frequency deviations, particularly in "alert" and "emergency" situations. These states, defined by the regulations European regulations impose specific constraints on limited energy storage systems and, by extension, on aggregates composed of these storage systems, i.e., on virtual power plants like the one described.

[0081] The alert state is declared when the absolute deviation of the frequency from the nominal frequency fQ (for example, 50 Hz in Europe) exceeds 50 MHz for more than 15 minutes, or exceeds 100 MHz for more than 5 minutes, but does not exceed 200 MHz. In this case, regulations may require the aggregator to freeze its power setpoint Pot.pp to stabilize the situation.

[0082] The state of emergency or "emergency state" is declared when the absolute deviation of the frequency from the nominal frequency / 0 exceeds 200 mHz.

[0083] Furthermore, according to European regulations, the power reserve must be fully activated in less than 30 seconds to meet network security requirements.

[0084] In both situations, any power variation within the aggregate independent of the frequency variation, linked for example to the activation of level control at a hydroelectric power plant, can lead to an unwanted power variation at the aggregate level if it is not properly compensated by another unit in the aggregate, and thus render the power response of the VPP non-compliant. This situation can pose a risk to the stability of the electrical grid, and the VPP operator may be penalized by the grid operator for non-compliance of the service provided.

[0085] During exceptional frequency incidents where the overall Pow setpoint must be fixed and the aggregate must provide a significant power variation for a certain duration, the activation sequence of the hydroelectric power plant reserves must be executed very precisely. In these situations, the battery can become saturated at its maximum (or minimum) power, thus limiting its ability to compensate for all power variations in the hydroelectric power plants and maintain the overall VPP power at its setpoint level. In these situations, the Pfiex adjustment setpoints of the hydroelectric power plants must be calculated dynamically using a specific method for managing these adjustment setpoints.

[0086] However, the known method does not provide any algorithm for calculating the Pflex setpoints of hydroelectric power plants that is effective in the event of an exceptional frequency event, such as a grid alert or emergency state.

[0087] There is therefore a need for a control process capable, specifically, of managing the power setpoints of hydroelectric power plants in these situations.

[0088] To this end, an objective of the proposed technique is to provide primary frequency reserve in the event of a significant frequency deviation of the network requiring a significant activation of the reserve at the VPP level, in particular in scenarios where the network is in a state of alert or emergency.

[0089] The general principle of the proposed technique is based on controlling hydroelectric power plants by modifying their power adjustment instructions in order to optimize the activation of their reserve, taking into account their physical characteristics such as their response times and their level regulation dynamics, and supplementing the reserve with the power of the battery which, in this situation, may approach, or reach, its operational power limit.

[0090] The battery's operational power limit refers to the maximum or minimum power that the battery can safely deliver or absorb for a given period without risk of damage or malfunction. This limit is determined by the battery's technical characteristics (e.g., its nominal capacity, state of charge, temperature) and may vary depending on the operating conditions. For example, if a battery can deliver a maximum power of 12 MW, its operational power limit may be set at 10 MW to avoid reaching extreme physical limits and thus preserve the battery's lifespan.

[0091] With this control strategy, the sizing of the battery can be optimized, and hydroelectric power plants are used to provide additional frequency reserve to that of the battery in the event of large frequency deviations for which the power of the battery alone is insufficient.

[0092] An example of an embodiment of the proposed technique is now described. Unless otherwise specified, all the detailed actions can be implemented by the centralized controller.

[0093] A global setpoint Pvpp of the virtual power plant is calculated as a function of a basic setpoint P$vpp and the frequency f of the electrical network measured at a given instant f.

[0094] The overall setpoint Pvpp can, for example, be calculated in the same way as in the known process, namely according to the following formula: PVPP-P^p

[0095] The present exposition focuses on situations where the basic Pqspp instruction is fixed, that is to say, constant over time. Such situations correspond to scenarios where the state of the network switches either to an alert state or an emergency state, in accordance with European regulations.

[0096] Of course, disregarding these regulatory considerations, the proposed method is also applicable to situations where the basic setpoint Pow is variable over time. In such situations, the virtual power plant's power target can be updated according to variations in the basic setpoint.

[0097] To better illustrate the scenarios where the basic instruction Po,.pp is fixed, let us consider two distinct moments.

[0098] At a first instant 6, before the transition to an alert or emergency state, the total power p^ (fj Pro(iuite) by the hydroelectric power plants is measured and transmitted to the central controller. At the first instant, the battery adjustment setpoint is assumed to be zero: p A ) _ q. Similarly, at the first instant, the contribution of the hydroelectric power plants to the power reserve: p L j _ q. Thus, the setpoint of J 1 / The base at the first instant is equal to the sum of the hydroelectric powers measured at the first instant: n A j _ p LY 1 / 1 /

[0099] At a second instant ^2 where the measured frequency f(t2) is such that the network enters an alert or emergency state, the basic setpoint is fixed, that is, it is kept constant and can no longer be modified to take into account subsequent frequency variations. Thus, n L j _ n L ] _ n À YF OwW “ P^pp^ 1 / “ Ptothydrn\t J

[0100] Thus, in the case of control in accordance with the known process, with PrefM = -K(f-f') + and in an initial situation where the hydroelectric power plants do not contribute to the reserve (Pfiex - 0) and the battery adjustment setpoint is initially zero (Pobat — 0), then P^ is equal to the sum of the hydroelectric powers measured at the moment preceding the transition to an alert or emergency state of the network which causes this setpoint to freeze.

[0101] At the second instant, a target power P is also calculated. This target power corresponds to the power that the battery should provide to ensure the primary frequency regulation on its own, i.e., if the battery were not associated with the set of hydroelectric power plants, and if the battery had no power limit.

[0102] For example, the power target can be calculated by applying the following formula: Peibl^-Kif-f,}.

[0103] The power target is compared to an operational power limit of the battery in order to calculate a reserve setpoint which the hydroelectric power plants are responsible for activating.

[0104] In a situation where the power target Pcibie is positive and greater than the maximum power Pmax^, of the battery in injection (discharge) then the hydroelectric power adjustment setpoint Pref^^ is calculated as the difference between the power target P target and Pmax^.

[0105] In a situation where the target power Pcibie is negative and less than the maximum power of the battery during charging Pmn^, then the hydroelectric power setpoint PrefMtl> is calculated as the difference between the minimum power of the battery and the target power Ptarget-

[0106] In other situations, then the hydroelectric power setpoint can be set to a zero value, the primary frequency control can be ensured exclusively by the battery and the control of the virtual power plant can be implemented in the same way as the known method.

[0107] These different situations can be translated into the following instructions: IF Pcibie > THEN PrefhyA.o = Pcibie" ^maxM IF Pcibie < THEN Pref hydm = Pminbat “ Pcibie , and IF Pmax P ^P,^ THEN Pref, , =0. M target "u,lbat J hydro

[0108] In situations where a non-zero hydroelectric setpoint Prefhyd[a is determined, it can be distributed among the different hydroelectric power plants, for example in the form of adjustment setpoints Pfiex-

[0109] According to a possible distribution, a two-phase coordination is implemented.

[0110] During a first phase, initial adjustment instructions are transmitted to the local controllers of a sufficient number of hydroelectric power plants, following a predefined order of priority, to ensure that the total target power is reached in 30 seconds, taking into account the dynamic characteristics of each power plant.

[0111] During a second phase, the adjustment instructions are regulated in a closed loop, in order to follow as closely as possible the overall hydroelectric setpoint PrefMm and to compensate for the power variations of individual hydroelectric power plants for example related to their level regulation dynamics.

[0112] In parallel with the calculation and sending of power adjustment instructions to the hydroelectric plants, an adjustment instruction Pq bat is calculated and sent to the battery in order to finely regulate the overall power at the VPP level, according to the effective power produced and measured at the level of all the hydroelectric plants.

[0113] Reference is now made to Figures 1 and 2, each of which details a flowchart of a possible algorithm suitable for implementing phase initial activation of a hydroelectric power reserve, or "first phase" in examples of implementation of the proposed technique.

[0114] As a reminder, in the event of a significant frequency deviation triggering the alert or emergency state of the network, the power setpoint of the virtual power plant (i.e., the power outside the setting or in other words the power that the virtual power plant would supply if the current network frequency was equal to the nominal network frequency) must be fixed, according to the European rules in force defining the behavior of limited energy assets participating in primary frequency regulation (FCR).

[0115] This amounts, in the context of the present exposition, to fixing the value of P <xw,.

[0116] Figure 1 presents, in the form of a decision tree, a possible set of instructions that can be executed by the centralized controller, in an example embodiment, to calculate the power adjustment setpoints of each hydroelectric power plant in the case where P target > P"®!* and > 0-

[0117] In this case, one objective is to increase the power produced by hydroelectric power plants to provide upside reserve. This situation corresponds to a grid alert or emergency state that requires a significant reserve call from the virtual power plant, exceeding the maximum operational power of the battery alone.

[0118] During initialization of the algorithm at block 11, a total power to be distributed among the hydroelectric power plants is determined from the previously calculated quantity Prefh^ro, and by adding a margin Pmarge. This margin can be set in such a way as to anticipate and compensate for the potential non-response of one or more power plants, for example (i.e., coverage in case of unforeseen circumstances). Thus, the remaining total power P to be distributed among the hydroelectric power plants can be defined as Prestmite = Pn.fh„im + Pmarge — P target ' Pmuxbat+ Pmarge.

[0119] The number of hydroelectric power stations is A, where N > 1, and they are ranked according to a priority order, from rank 1 to rank A.

[0120] During the initialization of the algorithm at block 11, a counter' is initialized: i = 0.

[0121] In block 12, the value of the meter is compared to the number A of hydroelectric power stations.

[0122] If i = A, then the algorithm has already considered in turn all the hydroelectric power plants of the virtual power plant; this is a stopping criterion for the algorithm. The calculation of the power adjustment setpoints P fiex is stopped at block 14 and is considered complete.

[0123] If i < N, then the algorithm has not considered all the hydroelectric plants in the virtual power plant. The value of counter1 is incremented by 1 in block 13, and then the hydroelectric plant with rank 1 is considered in block 15.

[0124] If the rank 1 hydroelectric plant is not available to participate in the primary frequency adjustment, a zero setpoint is assigned to the rank ' hydroelectric plant in block 17 and the algorithm continues its operation in block 12.

[0125] If the rank 1 hydroelectric plant is available to participate in the primary frequency adjustment, then the value of the total Postante power to be distributed is checked at block 16.

[0126] If the value of Prêtante is equal to zero, that is to say if there is no remaining need for power reserve, then a zero setpoint is assigned to the hydroelectric plant of rank ' in block 17 and the algorithm continues its operation in block 12.

[0127] If the value of Prêtante is greater than zero, i.e., if there remains a need for reserve power, then a positive setpoint Pfiex(i), which corresponds to all or part of Prestante, is assigned to the z-rank hydroelectric power plant in block 18. The value of Pfiex(i) respects a predefined initial maximum setpoint Pfiex(i) for the z-rank power plant.

[0128] In other words, "... . ... ,, \. Pfiex (i) = mm\P / lex_ (i), PrestantJ

[0129] Pflex. .(j ) is the maximum permissible power variation setpoint for the response of the rank * hydroelectric power plant to the demand of the virtual power plant in the initial phase of activation of the hydroelectric power reserve.

[0130] When a non-zero adjustment setpoint Pfiex(i) is determined for a rank 1 power plant in block 18, the power that will actually be released by this power plant 30 seconds after the provision of Pf[ex(i) is determined or estimated in block 19.

[0131] Indeed, due to slow response times and / or gains that may exist on the local controllers of hydroelectric power plants, the adjustment setpoint Pflex(i) may not be met within 30 seconds. A parameter denoted K3Qs is then defined for each power plant to calculate its expected contribution as a function of the adjustment setpoint according to the following formula:

[0132] For example, for a hydroelectric power plant of rank & which responds linearly to a setpoint with a response time of 60 seconds, it can be determined that Half the power of the adjustment setpoint will be supplied by this power plant after 30 seconds. In this case, the value of the parameter K30s can be set to K30(k) = 0.5

[0133] Finally, in block 20, the value of the remaining power to be distributed, Premaining, is updated by subtracting the expected contribution from the rank ' power plant: p — pp (A, then the algorithm continues its operation in block 12. z remaining * remaining * 3 QsVv

[0134] In this way, the global setpoint Prefh^m is totally distributed across all or part of the available power plants (within the limit of the sum of all the limits Pflex_init )•

[0135] Each hydroelectric power plant is considered iteratively, one by one following a pre-established priority order, to distribute the total power to be allocated. The decision tree in [Fig. 1] does not take into account any power measurement of any individual hydroelectric power plant or any total power measurement of all the hydroelectric power plants.

[0136] Similarly, Figure 2 presents a possible set of instructions that can be executed by the centralized controller, in an example embodiment, to calculate the power adjustment setpoints of each hydroelectric power plant in the case where Pcihb < Pmin^ and P™fhyiro < 0-

[0137] In this case, one objective is to reduce the power produced by hydroelectric power plants to provide reserve down, in the event of a significant rise in the network frequency placing the network in a state of alert or emergency, and requiring a significant call for reserve from the virtual power plant, exceeding the minimum operational power of the battery alone.

[0138] The instructions shown in [Fig.2] are identical to those in [Fig.1], with the following exceptions.

[0139] These exceptions are due to the fact that, in [Fig.2], it is a matter of activating a power reserve on the downside by distributing negative power (i.e. by reducing hydroelectric production) to meet the demand on the network.

[0140] In block 11, the remaining P is calculated according to the following formula: Prestante ~ ' Margin, where P remaining and Prefh^ni have negative values, and P margin has a positive value.

[0141] In block 16, the outcomes of the verification of the total power value Prestante to be distributed are as follows: either Prestante is equal to 0, in which case a zero setpoint is assigned to the rank i hydroelectric power plant in block 17, If the remaining P is less than 0, then in block 18, the setpoint P for a control unit of rank ' is negative. It is determined according to the following formula: Pflex (î) ~ ~Pflex. . ? ^remaining where Pfiex, (l) is a positive value defining the maximum power reduction allowed for the rank ' power plant during the reserve activation phase of hydroelectric power.

[0142] At block 19, the power released after 30 seconds is calculated according to the formula P3^- -^3050 *PfJ$

[0143] A practical example is provided to illustrate the operation of the algorithm in [Fig. 1] for activating an upstream hydroelectric power reserve. In this example, it is assumed that five hydroelectric power plants are aggregated with a battery in a virtual power plant.

[0144] The individual characteristics of the hydroelectric power plants are provided in Table 1. [Tables 1] Central Priority Order ^30s Available Parameter Pfiex. (MW) • imt Parameter pf'^ (MW) A 1 0.5 Yes 1.6 2 B 2 0.7 No 2 2.5 C 3 1 No 1.5 2 D 4 0.75 Yes 1.2 1.5 E 5 1 Yes 2 2.5

[0145] The individual characteristics of the hydroelectric power plants taken into account Table 1 includes the availability of power plants, their available capacity, their response time, and their power limitations.

[0146] The order of priority is established here on the basis of the individual characteristics provided.

[0147] It should be noted that the order of priority can be fixed by taking into account more or fewer individual characteristics of the power plants, including, for example, energy conversion efficiency, local environmental conditions, plant maintenance history, operational flexibility, and capacity to supply auxiliary services, a need for level regulation of the power plant's tanks, regulatory constraints, production costs, etc...

[0148] The order of priority can be fixed by taking into account a combination of individual characteristics of the power plants.

[0149] For example, available power plants can be classified according to their estimated power regulation gain after a given delay (for example 30 seconds), this gain being a function of their response time and their available capacity.

[0150] The order of priority can also be fixed arbitrarily without taking into account any individual characteristics of the power plants.

[0151] The Pflex parameter is not used in the initial activation phase of the hydroelectric reserve. Its definition and usage methods are specified later in this document.

[0152] The battery characteristics are Pmax^ = 10 MW, and Pminhat = -10 MW.

[0153] The virtual power plant parameters for frequency tuning are: Æ=60MW / Hz, and / 0 = 50Hz.

[0154] The power margin is P margin = 1 MW.

[0155] Consider an incident in which the electrical network frequency suddenly changes from 50 Hz to 49.8 Hz. The power target is then calculated using the following formula: Ptarget^-K(f-f0) = -60x (49.8-50) = 12 MW.

[0156] The virtual power plant must then provide 12 MW of reserve power on the upside. Since the battery's operational power limit is 10 MW, the contribution of the hydroelectric power plants is necessary, and a minimum of 2 MW must be activated within 30 seconds to reach a total of 12 MW within 30 seconds at the virtual power plant. The battery is considered fast and capable of supplying the full 10 MW in less than 30 seconds.

[0157] There are 5 hydroelectric power plants so N - 5.

[0158] Following the logic diagram presented in the previous section, the following steps are implemented successively.

[0159] The condition P target > Pmax is indeed verified, and we have: PrefilyâF = Peible-P^M= 12- 10= 2 MW. We add the margin: Remaining P ~ P^f^ydn+ PnMrSe = 2+ 1=3 MW. We initialize the counter i = 0.

[0160] First iteration: i < N so we increment the counter —> i = 1. Is the Tier 1 power plant (Power Plant A) available? Yes, it is available. Is the remaining power to be distributed > 0? Remaining power - 3, therefore yes. We calculate the adjustment setpoint for the A control unit. Pfkx( 1 ) = min(PfiexJl), Postante) = min ( 1,6, 3) = 1,6 MW' We calculate the expected power in 30 seconds with this instruction. Ao s d) =K 3O X1) xPfie X (A) = 0.5 x 1.6 = 0.8 MW. We update the remaining power to be distributed. Prestante = Presse-D = 3-0.8= 2.2 MW.

[0161] 2nd iteration: i < N so we increment the counter —> i = 2. Is the second-tier power plant (power plant B) available? No, it is not available. Therefore, she cannot participate and is assigned a zero instruction. P z U2)=0MW. The remaining power to be distributed remains unchanged. P t ,=9 9 MW * 11 remaining •

[0162] 3rd iteration: i < N so we increment the counter —> / = 3. Is the Tier 3 power plant (C power plant) available? No, it is not available. Therefore, she cannot participate and is assigned a zero instruction. P / te (3)=0MW. The remaining power to be distributed remains unchanged: Posting — ^W.

[0163] 4th iteration: i < N so we increment the counter —> i = 4. Is the Tier 4 power plant (Power Plant D) available? Yes, it is available. Is the remaining power to be distributed > 0? Prestante = 2.2 MW so Yes. We calculate the adjustment setpoint for the D control unit. / * / / „(4) =min(P / ; 'j4), = min(1.2, 2.2) = 1.2 MW' We calculate the expected power in 30 seconds with this setpoint. iW4) = Æ30s(4) xPflex^ = 0.75 x 1.2 = 0.9 MW. We update the remaining power to be distributed. Remaining P ~ Remaining P ~ P

[0164] 5th iteration: i < N so we increment the counter —> i = 5. Is the rank 5 power plant (power plant E) available? Yes, it is available. Is the remaining power to be distributed > 0? Remaining power = 13 MW, so yes. We calculate the adjustment setpoint for the E control unit. Pfiex ( 5 ) = min ( Pfiex^), PresM ) = min ( 2, 1,3) = 1.3 MW - We calculate the expected power in 30 seconds with this setpoint. P 30s (5) *Pfiex(5) = lx 1.3= 1.3MW. We update the remaining power to be distributed. Lending power = Remaining power 'P^ = 1.3 - 1.3 = 0 MW.

[0165] 6th iteration: i = N —> end of loop.

[0166]

[0167]

[0168]

[0169] The adjustment instructions calculated in this example to distribute the instruction of Initial hydroelectric power is summarized in Table 2. [Tables 2] Pfiex power plant (MW) A 1.6 B 0 C 0 D 1.2 E 1.3 These instructions are transmitted to the hydroelectric power plants so that they can provide the required power to ensure activation of the reserve within 30 seconds. In parallel with sending these instructions to the hydroelectric power plants, the battery reacts to the frequency variation by supplying its maximum power almost instantaneously. Indeed, according to the battery regulation law P' ~ K^ff\ + P' ^ors9ue 'a frequency f drops significantly, the term Pref^ increases sharply as a function of this frequency variation. The centralized controller constantly monitors the evolution of the overall hydroelectric power output in response to the sent commands. The objective is to reach the total power demand in less than 30 seconds, but without exceeding the overall setpoint at the virtual power plant level. Thanks to the power margin (Pmarge) included in the hydroelectric setpoint allocation algorithm, it is likely that the aggregate response of the hydroelectric plants will even exceed the overall setpoint (Pefh^rû) at some point. If the total power variation

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177] If hydroelectric exceeds the overall Prefbydm setpoint, then the centralized controller can send adjustment commands to the battery so that it reduces its power according to the hydroelectric overrun, so that the overall power of the virtual power plant is properly regulated. The reserve contribution Preservehvd,.o of the hydroelectric power plants is monitored by calculating at each instant the difference between the total measured hydroelectric power, i.e., the sum of the powers Phydrot of each hydroelectric power plant, and the overall setpoint without adjustment Povpp, according to the following formula: Preservehvd(i) — Phydrot(i) — Pp(i) The control of the battery adjustment setpoint Pob t can be adjusted to compensate for power fluctuations from all the hydroelectric power plants in the aggregate. An example of a method applicable to real-time control of the battery adjustment setpoint is described in patent application FR3133714A1. According to this example of a process, the Pobai setpoint can thus be calculated using the following formula: “^'pp " hydrofy Assuming that the battery power P meets the Prefb^ setpoint, that is to say- assuming the battery is not fully charged, then Pb^Pref^-K^ Conversely, when the battery is saturated with power and cannot comply with the Pref^ P^ * Prefba setpoint and therefore p^ * Since Prefba is a function of Pohat, which in turn is a function of the hydroelectric power V, the activation of a hydroelectric power reserve The proposed technique can be used to obtain a battery adjustment setpoint Pq such that the battery is not saturated with power. Thus, calculating the adjustment setpoints for hydroelectric power plants using the proposed technique can provide the additional primary reserve to avoid, or at least limit, the occurrence of situations where the battery is saturated with power. A possible simulation of the implementation of the algorithm in [Fig.1], in an example of an embodiment, was carried out with the same parameters as those presented in the example in Tables 1 and 2 where a hydroelectric power reserve is activated upwards. The result of the simulation is shown in figures 3 to 6.

[0178] Fig. 3 shows, from the instant following the frequency drop (33), the result (32) of the calculation of the target power P target = 12 MW and the results (31) of the calculation of the adjustment setpoints of the hydroelectric power plants: ^(1) = 1.6^, P / to (3)=0MW, P / fo (4) = 1.2MW, and PfieA5) = 1.3 MW.

[0179] Fig. 4 shows the evolution of their power outputs after the instructions were sent to the requested hydroelectric power plants.

[0180] Power plants B and C remain (42, 43) at constant power because their adjustment setpoint is zero since they were indicated as unavailable to participate in the reserve.

[0181] Power plant A provides (41) about 0.8 MW of power 30 seconds after the triggering event (i.e., at time t = 10 + 30 = 40 s), which is consistent with the estimate made in block 19 of the algorithm in [Fig.1].

[0182] The D plant provides (44) about 0.9 MW of power 30 seconds after the triggering event (i.e., at time t = 10 + 30 = 40 s), which is consistent with the estimate made in block 19 of the algorithm in [Fig.1].

[0183] The E plant provides (45) about 1.3 MW of power 30 seconds after the triggering event (i.e., at time t = 10 + 30 = 40 s), which is consistent with the estimate made in block 19 of the algorithm in [Fig.1].

[0184] Fig. 5 shows the evolution (51) of the total power of the hydroelectric plants, which reaches and then exceeds the desired reserve complement (2 MW) in a time of less than 30 seconds, in particular thanks to the margin parameter.

[0185] Figure 5 also shows the initial saturation (53, 54) of the battery power (power limited to 10 MW while the setpoint rises to 12 MW) as well as the variation (52) of the adjustment term Pob, which evolves as a function of the total power of the hydroelectric plants, until it reaches a minimum value of -4 MW. From this point on, the battery power desaturates and falls approximately 2 MW below the maximum power. This 2 MW corresponds to the 2 MW overshoot of the total power of the hydroelectric plants, which ultimately produce a variation of +4 MW for a demand of +2 MW.

[0186] Finally, Figure 6 shows the total power of the virtual power plant, that is, the sum (61) of the powers of the hydroelectric power plants and the battery, and the overall setpoint Pref (62) of the virtual power plant. It can be seen that the overall setpoint is not reached immediately. This phase corresponds to the moment when the The battery saturates at full power and the hydroelectric plants respond more slowly. The overall response time is well under 30 seconds thanks to the proposed control strategy.

[0187] Figures 3 to 6 illustrate a battery saturation sequence following a frequency drop, an initial distribution of adjustment setpoints for hydroelectric power plants to provide additional reserve in less than 30 seconds, an overshoot of the hydroelectric contribution after a certain time, then a decrease in battery power to compensate for the overshoot of the total hydroelectric power in order to correctly follow the overall setpoint at the virtual power plant level.

[0188] This first phase therefore makes it possible to meet the dynamic criterion of reserve release in 30 seconds. However, over time, this distribution is not optimal because the hydroelectric power plants find themselves in a situation of over-stressing.

[0189] It is desirable to limit the demand on hydroelectric power plants as much as possible while ensuring the service provided meets the required standards. Limiting the demand on hydroelectric power is particularly necessary to minimize the feedback from level control functions, which can counteract the adjustment setpoint and thus cancel, at least partially, the reserve provided. The feedback from a level control function of a hydroelectric power plant is all the more significant when the demand Pfiex on that hydroelectric power plant is high.

[0190] Reference is now made to Figures 7 to 10, each of which details a flowchart of a possible algorithm suitable for implementing the regulation phase of the hydroelectric power reserve, or "second phase," in examples of embodiments of the proposed technique. This second phase follows the first phase, or initial phase of activation of the hydroelectric power reserve, as described in connection with Figures 1 to 6.

[0191] During the second phase, the power adjustment commands of the hydroelectric plants are controlled in a fine and dynamic manner, in order to activate just enough reserve to provide the necessary hydroelectric demand to complement the demand on the battery, while limiting the over-demand on the hydroelectric plants.

[0192] This regulatory phase comprises two parts.

[0193] During the first part of the regulation phase, the Pflex adjustment setpoints of the hydroelectric power plants are reduced when there is over-activation of the reserve relative to demand. The first part of the regulation phase begins once the power outputs of the hydroelectric power plants have stabilized following The initial sending of instructions at the beginning of the initial activation phase of the hydroelectric power reserve. For example, the first part of the regulation phase can begin approximately one to two minutes after the frequency event that triggers the alert or emergency state, depending on the dynamic characteristics of the hydroelectric power plants.

[0194] During a second part of the regulation phase, the Pfiex adjustment commands of the hydroelectric power plants are adjusted to compensate for the effects of the level regulation functions which, after a certain time, begin to counteract the reserve provided by the hydroelectric power plants.

[0195] As a reminder, the reserve contribution of all hydroelectric power plants can be obtained by applying the following formula: P reserve hydro(i) / Pref where is a measure of the sum of the powers of the power plants hydroelectric.

[0196] Alternatively, each power measurement phyârJ^ can be deduced from a measurement of an environmental parameter of the power plant i, such as a water flow measurement at the power plant l.

[0197] Figure 7 presents a possible set of instructions that can be executed by the centralized controller during the first part of the regulation phase. The scenario considered is that of an initial frequency drop that has led to an upward activation of reserve capacity, and where the reserve supplied by the hydroelectric power plants exceeds or is about to exceed the initial demand. Executing the instructions in Figure 7 has the effect of reducing all or part of the adjustment commands for the hydroelectric power plants in order to avoid, or at least limit, an overactivation of the hydroelectric power reserve.

[0198] During this first part of the regulation phase, it is desirable that the power adjustment instructions Pfiex of hydroelectric power plants be gradually reduced in order to both limit the overactivation of the reserve and ensure network stability.

[0199] A power margin logic is applied here, so that the reduction of the setpoints PfUx is only activated if the overactivation exceeds a power margin Pmarge, in order to maintain a stabilized power. Thus, the hydroelectric power reserve is maintained at a level corresponding to the sum of the overall setpoint Prefh^ra and the power margin Pmarge.

[0200] This margin allows for consideration of the risk that one or more hydroelectric power plants may not be able to precisely follow the Pfiex adjustment instructions after their reduction. Without this margin, there is a risk that the battery will become saturated again if the total power supplied by the hydroelectric plants is insufficient to meet demand. The margin (Pmarge) is set at a value such that, even in the event of variations in the response of the power plants, the hydroelectric power reserve remains high enough to stabilize the grid and prevent overloading the battery.

[0201] In block 71, a triggering condition is checked. In the scenario of Figure 7, the triggering condition is the presence of an upward reserve surplus. This condition is met when the overall setpoint Pref^ is positive and ^Preserve^Jj} -Prefhxir> Pmarge- As long as the condition is not met, no subsequent instruction is implemented. The check performed in block 71 can be repeated over time.

[0202] In the following description of the actions implemented in blocks 72 to 80, we are in a scenario where, at a current time, the triggering condition is verified in block 71 and is fulfilled.

[0203] The algorithm initialization is implemented in block 72. A counter1 is initialized: i = N + 1. A remaining variable P is initialized according to the following formula: Remaining pressure ~ lL; Preservehydro (î) ~ Prefhydm - Pmarge-

[0204] In block 73, the value of counter i is compared to a value of a stopping criterion, in this case 1.

[0205] If i = 1, then the algorithm has already considered in turn all the hydroelectric power plants of the virtual power plant at the current time, and the algorithm's stopping criterion is met. The calculation of the power adjustment setpoints Pfiex is stopped at block 75 and is considered complete for the current time.

[0206] If i > 1, then the algorithm has not considered all the hydroelectric plants in the virtual power plant at the current time. The value of the counter * is incremented by one unit in the reverse direction at block 74, and then the hydroelectric plant with rank 1 is considered at block 76.

[0207] In this way, the Nth rank hydroelectric plant, last in the order of priority, is considered first in the first iteration where i = N, and the 1st rank hydroelectric plant, first in the order of priority, is considered last in the last iteration, where i - 1.

[0208] The value of the total Posting power to be distributed is checked at block 76.

[0209] If the value of Prestante is equal to zero, that is, if there is no need at the current time to modify the hydroelectric power reserve, then block 77 provides for maintaining the previously assigned setpoint The hydroelectric power plant at rank z has an unchanged value. The algorithm continues its operation at block 73.

[0210] If the value of Prestante is greater than zero, that is to say if there remains a need at the current time for modification of the hydroelectric power reserve, then the value of the setpoint p^J^ previously assigned to the hydroelectric power plant of rank » is checked in block 78.

[0211] If the instruction p^ej^ is already zero, then block 77 is designed to maintain it at zero. The algorithm continues its operation in block 73.

[0212] If the instruction Pfiex(i) is positive, then block 79 provides for reducing Pfiex(i) by applying a correction term AP. AP corresponds to all or part of Prestante, without exceeding P«cx(i). In other words, A p _ ■ / „ t *\ p V — 1 ' ^restante)

[0213] The variable Prestante is updated at block 80 by subtracting the AP correction term, then the algorithm continues its operation at block 73.

[0214] Similarly, [Fig. 8] presents a possible set of instructions that can be executed by the centralized controller, in one embodiment, to adjust the power adjustment setpoints of each hydroelectric power plant during the first part of the regulation phase. The scenario considered is that of an initial frequency increase that has led to a downward reserve activation, and where the downward reserve provided by the hydroelectric power plants exceeds or is about to exceed the initial demand. Executing the instructions in [Fig. 8] has the effect of increasing all or part of the adjustment setpoints of the hydroelectric power plants in order to avoid, or at least limit, an overactivation of the downward hydroelectric power reserve.

[0215] The instructions shown in [Fig.8] are identical to those in [Fig.7], with the following exceptions.

[0216] These exceptions are due to the fact that, in [Fig.8], it is a matter of increasing hydroelectric power by distributing positive power to compensate for a surplus of reserve on the decline.

[0217] In block 71, the verified triggering condition is the presence of a surplus reserve on the downside. This condition is met when the overall PrefMru setpoint is negative and ^Préserre^Çi ) -Prefwr^ ' P margins WHERE ^Preserve^J i ) and Prefhytm have negative values, and Pmarge has a positive value.

[0218] In block 72, the variable Prestante is initialized according to the formula: Prestante “^LPréserve^g ( I ​​) ” P™fMrg + Pmarge-

[0219] In block 76, the outcomes of the verification of the total power value Prestante to be distributed are as follows: either Prestante is equal to 0, in which case at block 77 no change in the adjustment setpoint Pfiex(i) is implemented, or Prestante is less than 0, in which case at block 78 the value of the adjustment setpoint Pf]ex ( i ) is verified.

[0220] In block 79, the value of the correction term AP is A „ _ iD fn Y ~ f[ex L remaining)

[0221] Reference is now made to Figures 9 and 10, which describe the second part of the regulation phase.

[0222] As a reminder, the power setpoint Prefhvdrg of a hydroelectric power plant participating in a primary frequency regulation service is composed of two terms: Prefhsdrg - Prgz + Pfiex.

[0223] The term Prgz corresponds to the level regulation of the power plant. The term Pfiex. non-zero is the power adjustment setpoint corresponding to the activation of a power reserve. This reserve is activated upwards or downwards depending on the sign of P fiex-

[0224] The initial application of a non-zero adjustment setpoint Pfiex(i) to a hydroelectric power plant shifts the operating point of the power plant, increasing or decreasing the outflow from the reservoir, which results in a level variation.

[0225] From the perspective of the power plant's level control, the activation of the reserve, whether increasing or decreasing, is seen as a disturbance. The term Prgz tends to vary inversely with Pfiex in order to reduce or cancel this disturbance.

[0226] In the event of a frequency drop that triggers an upward reserve activation, after a certain time, the action of the level control functions reduces the power output of the hydroelectric power plants. In this situation, the control process can compensate for this decrease by raising the adjustment setpoints within the limits of the available power.

[0227] Figure 9 presents a possible set of instructions that can be executed by the centralized controller during the second part of the regulation phase. The scenario considered is that of an initial frequency drop that has led to an upward reserve activation, and where the level regulation dynamics of the hydroelectric power plants are causing, or are about to cause, a drop in hydroelectric power that prevents compliance with the initial setpoints. Executing the instructions in Figure 9 has the effect of increasing all or part of the adjustment setpoints of the hydroelectric power plants to maintain their collective response. power at the desired level, that is to say at the expected level of contribution to the power reserve of the virtual power plant.

[0228] These instructions can be repeated over time, for example at regular intervals of one or more seconds, in order to compensate for power drops related to level regulation functions, along the evolutions of Prgz which continue as long as the values ​​of Pfiex are positive.

[0229] In block 81, a triggering condition is checked. In the scenario of Figure 9, the triggering condition is the presence of a lack of reserve on the upside. This condition is met when the overall PrefMro setpoint is positive and ^,Présen>ek d (i) -Pref, < 0-. As long as the condition is not met, no subsequent instruction is implemented. The check performed in block 81 can be repeated over time.

[0230] In the following description of the actions implemented in blocks 82 to 92, we are in a scenario where, at a current time, the triggering condition is verified in block 81 and is fulfilled.

[0231] The algorithm initialization is implemented in block 82. A counter * is initialized: i = 0. A variable Prestante is initialized according to the following formula: P remaining ~ Prefhydn ' l^P reservehydm (î) + Pmarge'

[0232] In block 83, the value of counter1 is compared to a value of a stopping criterion, in this case N.

[0233] If i = N, then the algorithm has already considered, in turn, all the hydroelectric power plants of the virtual power plant at the current time, and the algorithm's stopping criterion is met. The calculation of the power adjustment setpoints Pfiex is stopped at block 85 and is considered complete for the current time. A delay is set at block 86. After the delay expires, the instructions are repeated, starting again at block 81.

[0234] If i < N, then the algorithm has not considered all the hydroelectric plants of the virtual power plant at the current time. The value of the counter * is incremented by one unit in block 84, and then the availability of the hydroelectric plant with rank » is considered in block 87.

[0235] In this way, the first-rank hydroelectric plant, the first in the order of priority, is considered first in the first iteration where i = 1, and the last-rank hydroelectric plant in the order of priority is considered last in the last iteration, where i = N.

[0236] If the Tier 1 power plant is unavailable, then it is planned to maintain block 89 the PfleJf] instruction previously assigned to this control unit remains unchanged. The algorithm continues its operation at block 83.

[0237] If the rank power plant is available, the value of the total power P remaining to be distributed is checked at block 88.

[0238] If the value of Postante is equal to zero, that is, if there is no current need for modification of the hydroelectric power reserve, then block 89 is designed to maintain the previously assigned Ppefy setpoint for this power plant at an unchanged value. The algorithm continues its operation in block 83.

[0239]

[0240]

[0241]

[0242] If the value of Prestante is greater than zero, that is to say if there remains a need at the current time for modification of the hydroelectric power reserve, then the value of the setpoint Pj-^ij previously assigned to the hydroelectric power plant of rank ' is checked at block 90. For the purposes of this verification, maximum values ​​of the hydroelectric power plant adjustment setpoints, denoted Pflex, are used. A positive p / A value defines the maximum power increase allowed for the rank ' power plant during the hydroelectric power reserve regulation phase. The Pfiexmav values ​​can be chosen to be equal to the P fiex values. Conversely, the Pjiex values ​​can be chosen to be different from the Pfiex values. • ifiit If the setpoint P^le^ is not less than the value p / A, then it is expected at block 89 maintains its value unchanged. The algorithm continues its operation at block 83.

[0243] If the setpoint Pfiex(i) is less than the value p / A, then block 91 provides for increasing Pfiex(i) by applying a correction term AP. AP corresponds to all or part of Prestante, without exceeding the difference between / A and Pflex(Î) ■

[0244] In other words, AP = min(p / fex (ï) -P (l),Prestante\ \ mat jlex /

[0245] The variable Prestante is updated at block 92 by subtracting the correction term AP, then the algorithm continues its operation at block 83.

[0246] Similarly, [Fig. 10] presents a possible set of instructions These instructions can be executed by the centralized controller, in one example, to adjust the power adjustment commands of each hydroelectric power plant during the second part of the regulation phase. The scenario considered is that of an initial frequency increase that has led to a downward activation of reserve capacity, and where the level regulation dynamics of the hydroelectric power plants are causing, or are about to cause, a rise in hydroelectric power that prevents compliance with the initial commands. Executing the instructions in [Fig. 10] has the effect of lowering all or part of the adjustment commands of the hydroelectric power plants to maintain their collective power response at the desired level, i.e., at the level of expected contribution to the virtual power plant's reserve capacity.

[0247] The instructions shown in [Fig. 10] are identical to those in [Fig. 9], with the following exceptions.

[0248] These exceptions are due to the fact that, in [Fig. 10], it is a matter of reducing hydroelectric power by distributing negative power to compensate for a lack of reserve on the downside.

[0249] In block 81, the verified triggering condition is the presence of a reserve deficit on the downward side. This condition is met when the overall PrefMro setpoint is negative and ^Pré*™^) -Prefhydra > 0-

[0250] In block 82, the remaining variable P is initialized according to the formula: Remaining P ~ P™fh*!™ ' ^jPreservehydn (t) + Pmarge-

[0251] In block 88, the outcomes of the verification of the total Posting power value to be distributed are as follows: either the remaining P is equal to 0, in which case no change to the adjustment setpoint is implemented in block 89, either P remaining is less than 0, in which case at block 90 the value of the adjustment setpoint Pfiex ( i ) is verified.

[0252] In block 90, the outputs of the adjustment setpoint value verification The following are Pflex(O): either the setpoint p LA is not greater than a value L\, in which case it * flex . UI mm\ / block 89 is scheduled to maintain its value unchanged and the algorithm continues its operation at block 83, either the setpoint Pfiex{î} is greater than the value l\, in which case it is planned Pflex . in min\ / in block 91 to reduce Pjiex(i) by applying a corrective term ÆP — lïiaxi.Py / gj-. (l) P Prestante] \ mm fiex /

[0253] Minimum values ​​of the adjustment setpoints for hydroelectric power plants, denoted Pfiev, are used here. A negative value / A defines the reduction 'min Pflex - U maximum power allowed for the rank ' power plant during the hydroelectric power reserve regulation phase.

[0254] The negative correction term AP is subtracted from the remaining variable P in block 92.

[0255] A possible simulation of the implementation of the algorithms in Figures 7 and 9, in an example embodiment, was carried out with the same parameters as those presented in the example in Tables 1 and 2 where a hydroelectric power reserve is activated upwards.

[0256] The result of the simulation is shown in Figures 11 to 14.

[0257] This simulation shows the continuation of the behavior of the virtual power plant during and after the activation phase of the reserve as illustrated in figures 3 to 6.

[0258] The frequency drop of the network from the nominal frequency of 50 Hz to a frequency of 49.8 Hz takes place at time t = 10 s.

[0259] In this illustrative example, only control units 1, D, and E are available to participate in primary frequency tuning. Control units B and C are unavailable.

[0260] Figure 11 shows the time evolution (111) of the power setpoint Pfle&$ transmitted to the local controller of the power plant A and the time evolution (112) of the power Phvdr^ / ^ produced by the power plant A.

[0261]

[0262] Figure 12 shows the time evolution (121) of the power setpoint P ri (d\ transmitted to the local controller of the power plant D and the time evolution (122) of the power Ph drJ^ produced by the power plant D. Figure 13 shows the time evolution (131) of the power setpoint Pfiex(E) transmitted to the local controller of the power plant E and the time evolution (132) of the power Ph dr^E^ produced by the power plant E.

[0263] These temporal evolutions illustrate: the activation phase of the adjustment instructions in order to have a rapid activation of the reserve (to meet the 30-second dynamic criterion), then the initial setpoint reduction phase to reduce the excess reserve to the increase (here, it refers to the decrease in the setpoint p^j^} at time t = 100 s), and the decrease in hydroelectric power linked to the level regulation functions of the power plants: this can be seen here through the decrease of », ( 4) and of », , (neither between t = 100 s and r hydrAf^-J r hydroy1^} t = 500 s.

[0264] Increasing the adjustment instructions p (^Pn (D^Pn (e) to approximately T l-PX\ f ï IPX\ / ï l£X\ 7 t = 500 s aims to compensate for the first power drop related to the level regulation functions.

[0265] Then, the level regulation functions continue to act, with decreases in P. , fai and in », , [ ni visible between t = 500 s and t = 900 s, which again leads to rhydrA™} * hydrAy) an increase in p just before t = 900 s to compensate for these new decreases.

[0266] Finally, the overall operation of the virtual power plant in the simulation is illustrated in [Fig.14], which represents, as a function of time, the frequency (141) of the network, the total hydroelectric power (142), the power (143) of the battery, and the overall power (144) of the virtual power plant.

[0267] This simulation confirms that the proposed technique makes it possible, in a situation where the virtual power plant is subjected to an overall power setpoint exceeding an operational battery power limit: to reach this overall power setpoint within a given time, here within a timeframe of less than thirty seconds, and to then maintain temporal stability of the overall power of the virtual power plant in accordance with the overall power setpoint.

[0268] This expression means that the control entity continuously and dynamically adjusts the energy production of all the power plants constituting the virtual power plant (battery and other energy sources) to ensure that the total power delivered corresponds stably to the overall setpoint. This implies avoiding excessive fluctuations in the power delivered over time.

[0269] Compared to conventional control techniques for electrical production means, involving for example proportional-integral type controllers or any other control technique based on linear automation, the proposed technique is more robust for application cases where the electrical network is placed in a state of alert or emergency.

[0270] Indeed, the proposed technique is adapted to means of production having very different, and potentially non-linear, dynamic characteristics, for which the classic control techniques of linear automation do not work correctly and would risk causing instabilities in the network.

[0271] This disclosure is not limited to the examples described above, which are merely examples, but encompasses all the variations that a person in the trade may consider in the context of the protection sought.

[0272] For example, although the embodiment examples described focus mainly on run-of-river hydroelectric power plants, the proposed technique can be applied to other types of power plants having a sufficiently fast response capability to cooperate with a battery in such a way as to provide a frequency regulation service.

[0273] For example, although the described embodiments mention the use of a fixed priority order for allocating adjustment commands among hydroelectric power plants, a flexible allocation is also possible. For example, priorities can be dynamically adjusted based on the instantaneous availability of the power plants, their capacity to respond to demand, or weather conditions impacting power plant production.

[0274] The provision of power adjustment instructions may also take into account data from external sources, such as grid demand forecasts or weather forecasts. This data can be integrated into the algorithms described to refine the adjustments of the hydroelectric power plants and the battery, in order to anticipate reserve or frequency regulation requirements.

[0275] In variants where the battery reaches its operational power limit, the algorithm can provide specific corrective measures to redistribute power more quickly to hydroelectric power plants or other available units. Controlled overload mechanisms for hydroelectric power plants can also be integrated to compensate for battery saturation for a short period.

[0276] Mechanisms for optimizing response times for adjustment commands can be integrated to further improve the temporal performance of the virtual power plant. For example, the delays for providing power adjustment commands can be automatically adjusted according to the actual dynamics of each power plant at the time of the incident.

[0277] The proposed technique can also be adapted for hybrid networks that combine synchronous and asynchronous networks, taking into account the specific characteristics of frequency regulation in these contexts. Such an adaptation involves adjustments to the algorithm for calculating the adjustment setpoints in order to balance these different parts of the network.

[0278] Machine learning algorithms can be introduced to monitor and adjust in real time the response of hydroelectric power plants and the battery, based on past performance and anticipated trends. This type of predictive monitoring allows for better adaptation of adjustment instructions to the dynamics of the power plants.

[0279] It is also possible to provide for a dynamic adjustment of the distribution of adjustment instructions according to failures or sudden unavailability of certain hydroelectric power plants, using redundancy mechanisms within the aggregate to ensure the continuity of the frequency regulation service.

Claims

Demands

1. A method for controlling, implemented by a control entity, a virtual power plant connected to an electrical network, the virtual power plant comprising at least one battery and a set of hydroelectric power plants, the virtual power plant being subject to an overall power setpoint exceeding an operational power limit of the battery, the method comprising: providing a first power adjustment setpoint to a local controller of a hydroelectric power plant from the set of hydroelectric power plants, the first adjustment setpoint taking into account a priority order of the hydroelectric power plants and the operational power limit of the battery, and the first adjustment setpoint not taking into account any power measurement;and after the provision of the first power adjustment setpoint, a provision of a second power adjustment setpoint to the local controller of the hydroelectric plant, the second power adjustment setpoint taking into account the overall power measurement of the set of hydroelectric plants, in which, upon the provision of the second power adjustment setpoint, the battery is subjected to a third power adjustment setpoint which takes into account the overall power setpoint and the overall power measurement of the set of hydroelectric plants, and in which the provisioning of the adjustment setpoints contributes to maintaining a temporal stability of an overall power of the virtual plant in accordance with the overall power setpoint.

2. A method according to the preceding claim, wherein the first power adjustment setpoint takes into account at least one parameter of the hydroelectric plant among: availability, available capacity, response time, power limitation.

3. A method according to any one of the preceding claims, wherein the first power adjustment setpoint takes into account a gain estimated power regulation of the hydroelectric plant after a first delay, and the provision of the second power adjustment setpoint is implemented after a second delay longer than the first delay.

4. A method according to any one of the preceding claims, wherein the second power adjustment setpoint is periodically updated based on a fluctuation in an overall power measurement of the hydroelectric plants and / or a fluctuation in an environmental parameter of at least one hydroelectric plant in the set of hydroelectric plants.

5. A method according to any one of the preceding claims, wherein: the overall power setpoint is adjusted, if necessary, after the provision of the first adjustment setpoint and before the provision of the second adjustment setpoint, and the second adjustment setpoint takes into account the adjusted overall power setpoint.

6. A method according to any one of the preceding claims, wherein the second adjustment instruction includes compensation for at least one unforeseen power variation of at least one hydroelectric power plant in the set of hydroelectric power plants.

7. A method according to any one of the preceding claims, wherein a first decision tree is used to determine the first adjustment instruction.

8. A method according to any one of the preceding claims, wherein a second decision tree is used to determine the second adjustment instruction.

9. A method according to any one of the preceding claims, comprising providing a set of first power adjustment instructions to local controllers of a plurality of hydroelectric power plants in the hydroelectric power plant set, the set of first adjustment instructions taking into account an order of priority and not taking into account any power measurement, and providing the set of first adjustment instructions including the provision of the first adjustment instruction.

10. A method according to any one of the preceding claims, comprising a verification of the hydroelectric plant's ability to respond to the first adjustment setpoint or the second adjustment setpoint.

11. A method according to any one of the preceding claims, wherein the second adjustment setpoint takes into account a comparison between a power measurement of the hydroelectric plant after the provision of the first adjustment setpoint and a target value.

12. A method according to any one of the preceding claims, wherein the decision tree adjusts the adjustment instructions of the hydroelectric power plants according to an iterative analysis, until the overall power reaches a stable value within a defined tolerance range.

13. A computer program comprising instructions for implementing the method according to any one of the preceding claims when this program is executed by a control entity of a virtual power plant connected to an electrical network, the virtual power plant comprising at least one battery and a set of hydroelectric power plants.

14. Control entity of a virtual power plant connected to an electrical grid, the virtual power plant comprising at least one battery and a set of hydroelectric power plants, the virtual power plant being subject to an overall power setpoint exceeding an operational power limit of the battery, the control entity being configured to implement: a provision of a first power adjustment setpoint to a local controller of a hydroelectric power plant from the set of hydroelectric power plants, the first adjustment setpoint taking into account a priority order of the hydroelectric power plants and the operational power limit of the battery, and the first adjustment setpoint not taking into account any power measurement;and after the provision of the first power adjustment setpoint, a provision of a second power adjustment setpoint to the local controller of the hydroelectric plant, the second power adjustment setpoint taking into account an overall power measurement of the entire hydroelectric plant, in which, upon the provision of the second power adjustment setpoint, the battery is subjected to a third power adjustment setpoint which takes into account the setpoint; overall power and overall power measurement of all hydroelectric power plants, and in which the supplies of the adjustment setpoints contribute to maintaining a temporal stability of an overall power of the virtual plant in accordance with the overall power setpoint.