Control of power injected by a renewable energy production module into a microgrid by frequency control of a thermal electrical energy generation module

Abstract

This disclosure relates to a method for controlling the power injected by at least one renewable energy generation module into an islanded microgrid with respect to a main power distribution network. Such a method comprises: connecting a thermal power generation module to the islanded microgrid, generating an alternating voltage suitable for supplying the islanded microgrid; and controlling (101-103) a frequency setpoint (fGEM-D) of the alternating voltage generated by the thermal power generation module using a control law based on a function of the frequency setpoint as a function of the generated power measured across the terminals of the thermal power generation module, the function law exhibiting a hysteresis loop. Abstract Figure: Figure 7

Description

Title of the invention: Control of power injected by a renewable energy production module into a microgrid by frequency control of a thermal electrical energy generation module. Technical field

[0001] The present disclosure falls within the domain of electrical distribution networks, to which one or more variable renewable energy production modules, RENv, such as photovoltaic energy production modules or wind-generated electricity production modules are connected, for example. Previous technique

[0002] It is known to temporarily connect one or more generator sets to an electrical distribution network to compensate for a power outage due to an incident on the network or maintenance work, for example. The generator set then supplies electrical power to a sub-part of the distribution network's tree structure, which is called a microgrid, and which is temporarily disconnected from the main electrical distribution network: this is referred to as an islanded electrical microgrid.

[0003] Prior to implementing such a temporary power restoration method, current safety regulations require the electricity distribution network operator to disconnect all variable renewable energy production modules from the microgrid with an installed capacity exceeding 5 kW. This is because existing generators cannot absorb such power, and these variable renewable energy production modules can inject more power into the grid than is consumed at certain times. In such a case, the generator's protection system will open a circuit, thus cutting off power to the microgrid. Therefore, it is necessary to disconnect these variable renewable energy production modules before any work is carried out and then reconnect them after the work on the microgrid is completed.

[0004] This procedure is time-consuming and resource-intensive. Furthermore, it prevents any production of electrical energy by variable renewable energy production modules, such as photovoltaic panels, during the intervention, which represents a financial loss for both the producer and the operator, who must supply this lost energy equivalent in fuel. Finally, during the intervention, the energy supplying the microgrid is from fossil fuels and generates carbon dioxide emissions, whereas some of the energy consumed by customers of the islanded microgrid could be produced by the existing renewable energy modules. The generator set can generate pollution related to diesel fuel consumption on the one hand, and noise pollution on the other.

[0005] Some variable renewable energy production modules, particularly photovoltaic energy modules, typically include a photovoltaic panel that generates continuous power on the DC side of a DC / AC inverter, which converts it to AC power before it is fed into the grid. Some of these inverters are controlled by means of a power limiting function, called P(f). In a microgrid, this function represents an indirect means of controlling the maximum power injected by these inverters. This control is carried out by the voltage source, in other words, by the equipment that sets the frequency of the microgrid, and allows for the imposition of a maximum permissible value for the power injected by the inverter into the microgrid.If the power available at a given time to the renewable energy production module is less than this maximum power value imposed by the function P(f), the power injected by the inverter into the microgrid is equal to the available power. Otherwise, it is limited to this maximum power value imposed by the function P(f). The control laws for the power injected into the grid as a function of the frequency measured on the grid, for most known inverters, follow affine functions, as illustrated in [Fig. 1].

[0006] The coupling or decoupling of the renewable energy modules therefore occurs during an increase or decrease in the frequency of the electrical distribution network. It would be advantageous to exploit this characteristic to automatically control these couplings and decouplings from the generator sets that supply the islanded microgrids, thereby reducing the intervention time of technicians on the electrical distribution network on the one hand, and reducing the consumption of these thermal generator sets on the other.

[0007] However, in most electrical distribution networks, different generations and types of photovoltaic inverters coexist on the network, characterized by their decoupling frequency and whether or not the P(f) function is activated by default. It therefore proves particularly complex to determine a frequency control logic for the islanded microgrid that meets this need without prior knowledge of the type(s) of photovoltaic inverter(s) present on the microgrid. Summary

[0008] This disclosure improves the situation.

[0009] A method is proposed for controlling the power injected by at least one renewable energy production module into an islanded electrical microgrid with respect to a main electrical distribution network, which comprises: a. a connection, in the islanded electrical microgrid, of a thermal electrical energy generation module generating an alternating voltage suitable for supplying the islanded electrical microgrid; b. a control of a setpoint frequency value of the alternating voltage generated by the thermal electrical energy generation module from a control law established from a law of evolution of the setpoint frequency value as a function of a generated power measured at the terminals of the thermal electrical energy generation module, the law of evolution exhibiting a hysteresis cycle.

[0010] According to another aspect, a thermal power generation module is proposed, configured to generate an alternating voltage suitable for supplying an islanded electrical microgrid to a main electrical distribution network, the islanded electrical microgrid comprising at least one renewable energy production module. Such a thermal power generation module includes a processor configured to perform control of a frequency setpoint value of the generated alternating voltage based on a control law established from a law of evolution of the frequency setpoint value as a function of the generated power measured at the terminals of the thermal power generation module, the evolution law exhibiting a hysteresis loop.

[0011] According to another aspect, a computer program is proposed comprising instructions for implementing all or part of a process as defined herein when this program is executed by a processor. According to another aspect, a non-transient, computer-readable recording medium is proposed on which such a program is recorded.

[0012] Thus, in an islanded microgrid powered by one or more diesel generators, it is no longer necessary to disconnect all renewable energy production modules in the event of islanding. This reduces the need for human resources and the time required to prepare for intervention on the electrical distribution network. Furthermore, it is possible to increase green energy production in the islanded microgrid and reduce the fossil fuel consumption of the generators, by an estimated 50% depending on the configuration. This solution avoids the need for systematic disconnection of all renewable energy producers without risking a blackout.

[0013] Indeed, the proposed solution advantageously allows the use of the generator's frequency variation to force the coupling / decoupling of renewable energy production modules in the event of islanding. In particular, the proposed frequency control logic makes it possible to manage the coupling and decoupling of the renewable energy production modules according to production and consumption on the grid supplied by the generator.

[0014] The features described in the following paragraphs may optionally be implemented independently of each other or in combination with each other.

[0015] Such a power control method also implements a decoupling level processing method, according to which the control law includes, for a predetermined blocking period beginning when the frequency setpoint increases and reaches a first blocking threshold frequency according to the evolution law, a blocking of a minimum value of the frequency setpoint at a second blocking threshold frequency higher than the first blocking threshold frequency. The stability of the method is thus ensured by blocking a downward variation of the frequency for a given configurable period, for example, one hour. This ensures the proper operation of the inverters of the renewable energy modules for which the P(f) function is not activated.

[0016] The first and second blocking threshold frequencies are determined as a function of a decoupling frequency parameterized for an inverter of the renewable energy production module(s).

[0017] The hysteresis loop of the evolution law is parallelepiped-shaped and comprises: - a straight line showing the decrease in the frequency setpoint value as a function of an increase in the generated power measured from a starting power value, Pi, up to an ending power value, P2; - a straight line showing the increase in the frequency setpoint value as a function of a decrease in the measured generated power; and the lines of increase and decrease are parallel and shifted relative to each other in abscissa by a hysteresis value of power A P.

[0018] The control of the frequency setpoint value also includes the additional application of a maximum frequency setpoint value, a minimum frequency setpoint value, a limit value for the slope of increase of the frequency setpoint value as a function of time, a limit value for the slope of decrease of the frequency setpoint value as a function of time, and the limit value for the slope of increase is greater than the limit value for the slope of decrease, in absolute values. This ensures a well-controlled operating range, while ensuring a rapid rise in frequency to quickly stop variations in the power injected by the ENRv modules and a slow fall in frequency to avoid instabilities. Brief description of the drawings

[0019] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which: Fig. 1

[0020] [Fig.1] presents the representative curve of the function P(f) as implemented, according to prior techniques, in certain photovoltaic panel connection inverters. Fig. 2

[0021] [Fig.2] illustrates an islanded micro-network according to one embodiment. Fig. 3

[0022] [Fig.3] presents a curve representing the law of evolution of a setpoint frequency value as a function of a power measured at the terminals of a generator set according to an embodiment. Fig. 4

[0023] [Fig.4] illustrates a decoupling level treatment of the curve of [Fig.3] according to one embodiment. Fig. 5

[0024] [Fig.5] presents the treatment of [Fig.4] in the form of a block diagram according to one embodiment. Fig. 6

[0025] [Fig.6] illustrates the principle of a third stage of construction of a control law of the setpoint value of the frequency according to an embodiment. Fig. 7

[0026] [Fig.7] presents in synoptic form the control logic implemented in a controller of a generator set according to one embodiment. Fig. 8

[0027] [Fig.8] shows a block diagram of a generator set implementing the control logic of [Fig.7] according to one embodiment. Description of the implementation methods

[0028] The general principle of the technique which is the subject of this disclosure is to indirectly control the inverters of the variable renewable energy production modules of an islanded microgrid, by the frequency imposed by a thermal generator set forming the voltage source of the microgrid, by reducing the possible instabilities, and therefore the risk of blackouts that could cause customers to lose their power supply.

[0029] As mentioned above, variable renewable energy (VRE) production modules, such as photovoltaic or wind turbine modules, may include one or more converters, or inverters, which transform the direct current (DC) power generated by a photovoltaic panel, or the alternating or direct current (AC) power from a wind turbine, into alternating current (AC) power that can be injected into the electricity distribution network. Some VRE inverters present on the national electricity distribution network in France have an option to adjust the injected power P(f) according to the network frequency, as illustrated in [Fig. 1].

[0030] The curve P(f) represents the maximum power that can be injected into the grid by a renewable energy inverter. It is imposed by the inverter as a function of the measured frequency. Between this curve P(f) and the zero power line lies an operating region of the inverter, shown as hatched lines in [Fig. 1]: the power injected by the renewable energy inverter takes a value that lies within this hatched region, between the curve P(f) and 0 (losses are ignored in this example). The power imposed by the function P(f) therefore only affects the power injected by the renewable energy inverter when the available power exceeds the value of P(f).

[0031] The P(f) curve in [Fig. 1] has three important and configurable elements: - the value of the start-up frequency of the limitation of the maximum power injected by the inverter: fstart = fn + Y, where fn denotes the nominal frequency of the electrical distribution network, i.e., 50 Hz in the example in [Fig. 1] and throughout this document. For a measured frequency less than or equal to fstart = fn + Y, the inverter can inject all the installed power (Pn), and the injected power is equal to the available power (no clipping); - the value of the frequency at the end of the limitation of the maximum power injected by the inverter: ffin=fn+X. Beyond this frequency value ffin=fn+X, the power is completely clipped (0% of the injected power, regardless of the available power); - the value of the ramp between the starting point of the coordinate curve (Pn; fstart) and the ending point of the coordinate curve (0 ; ffin); for a measured frequency between fstart and ffin, the maximum power injected by the inverter is clipped by the law P(f) if the available power is greater than P(f). In practice, one of these 3 parameters may prove redundant, and only two of these three parameters, at the manufacturer's choice, are generally configurable on the human-machine interfaces (HMI) of most existing inverters.

[0032] The parameters usually used are fstart=50.2Hz and ffin=51.2Hz, i.e. a ramp of AP / Af= 1 [pu / Hz].

[0033] However, in France, only renewable energy inverters installed after June 2020 implement active control of the injected power based on the measured power according to such a function P(f). To prevent power injection into an islanded network without voltage regulation, the standard mandates decoupling protection based on the year of installation of the renewable energy inverter. The different types of inverters currently present on the national electricity distribution network in France are presented in Table 1 below.

[0034] [Tables 1] Inverter type P(f) activated by default Decoupling frequency (Hz) Installed power (GW) Probability of presence on the national grid (%) 1 NO 50.2 2 43 2 NO 50.4 0.3 7 3 NO 50.6 1.7 37 4 YES 51.5 0.6 13

[0035] It should be noted that this diversity of inverter types present on the national electricity distribution network makes it complex to control the power injected by a renewable energy module through frequency control imposed by a voltage source device, especially since, in the event of work on an islanded microgrid, it is difficult to know the exact distribution of the different inverter types and their installed power. Furthermore, in other countries, the number of inverter types present on the electricity distribution network may differ from four.

[0036] The frequency control solution which is the subject of this disclosure advantageously eliminates the need to disconnect all variable renewable energy production modules during an intervention on the electrical distribution network, and is suitable regardless of the types of inverters of the ENrv modules present on an islanded microgrid.

[0037] The following section describes an example of an embodiment in which a thermal power generation module, for example a diesel generator set, is temporarily connected to an islanded microgrid due to scheduled maintenance or a power outage on the main electricity distribution network. It is assumed that the islanded microgrid comprises several variable renewable energy (VRE) production modules, for example several photovoltaic energy production modules, as illustrated in [Fig. 2]. The following section describes an example applicable to the French electricity distribution network, comprising inverters of types 1 to 4 as mentioned above. This example can, of course, be generalized to any other electricity distribution network configuration, including more or fewer distinct inverter types (e.g., N>1 distinct inverter types), with or without a P(f) function enabled by default, and with decoupling frequency and installed power characteristics that may differ from those mentioned in Table 1 above.

[0038] A generator set 10 transforms a fossil fuel, for example diesel, into electrical energy and generates an alternating voltage, which supplies the islanded microgrid 11 during the maintenance intervention or outage. Several photovoltaic power generation modules PVi to PVn are also present on the microgrid 11. Each of these PV modules comprises a photovoltaic panel 12i, which supplies direct current power to a DC / AC inverter 122i, which converts it into alternating current power before injection into the microgrid 11. A set of loads Ci to Cm are connected to the microgrid 11 and consume the electrical energy supplied by the generator set 10 and the PV photovoltaic modules.

[0039] In one embodiment, a control logic for the setpoint value of the frequency fcEM d of the alternating voltage generated and supplying the micronetwork 11 is implemented in an automaton or a controller of the generator set 10, which must meet several objectives.

[0040] A first objective lies in taking into account the diversity of types of inverter settings 1224 that may exist on the microgrid 11 (see Table 1).

[0041] A second objective is to promote the maximum production of renewable energy to produce so-called "green" energy to meet an environmental priority and to allow the owners of the PV 1 to PVn photovoltaic energy production modules to benefit from the presence of the microgrid 11, by allowing them to sell the electricity produced to the operator of the electricity distribution network.

[0042] A third objective is to guarantee stable operation in the short and long term with regard to oscillatory variations between the set frequency and the active power of the inverters. Indeed, the "symmetrical" variation of type 4 PV inverters, for which the P(f) function is activated by default, is a source of instabilities, which must be compensated for.

[0043] To meet these needs, the proposed technique is based on a control logic for the setpoint value of the frequency fGEM d of the generated alternating voltage by the generator set 10 and supplying the microgrid 11. This control logic is governed by a control law f(P), which controls the frequency f as a function of the power P measured at the terminals of the generator set 10. Throughout this document, the convention "generator" is used for the measured power of the generator set 10: a positive power P corresponds to a power injected into the microgrid 11 by the generator set 10.

[0044] This control law f(P) operates according to a two-stage logic: - a first stage (see module 101 on [Fig.7]), implementing an evolution law presenting a hysteresis cycle, which ensures the proper functioning of type 4 inverters, or more generally of all inverters in which the P(f) setting is activated; - a second stage (see module 102 on [Fig.7]), which operates a decoupling level processing, and which ensures the proper functioning of type 1, 2 and 3 inverters, or more generally of all inverters in which the P(f) setting is not activated.

[0045] Such a control law f(P) is the setpoint to be imposed at each instant and to be respected according to the capacities of the generator set 10 and the variations in grid power. This control law can be implemented in the generator set's controller as a switchable option; for example, this option can be switched off when the generator set 10 is connected to an electrical grid that does not include renewable energy production modules.

[0046] The control law f(P) implemented in the controller of the generator set 10 is now presented in relation to Figures 3 to 6. This control law is established from a law of evolution of the frequency f as a function of the power measured at the terminals of the generator set, and is illustrated in [Fig.3].

[0047] The input data for this evolution law is the power measured at the terminals of the generator set 10, denoted Pmes, and represented on the x-axis of the curve in [Fig. 3]. This power Pmes is the AC power injected into the grid by the generator set 10. This evolution law ensures the proper operation of type 4 inverters, in which the P(f) setting is activated, and whose decoupling frequency is set at 51.5 Hz. It exhibits a parallelepiped hysteresis loop, which includes: - a "downward" line, i.e., a decrease in frequency resulting from an increase in measured power, from a first point with coordinates (Pb fstart) to a second point with coordinates (P2, ffin). The values ​​of Pi, P2, fstart, and ffin can be configured by an operator on a human-machine interface of the generator set 10. For example, values ​​can be chosen for these four parameters. optimized for all application cases, or adjust these values ​​on a case-by-case basis to obtain a fine-tuned optimization particularly suited to a given application, and especially to the characteristics of a particular generator set. As an example, Pi is set here to 15% of the installed power and P2 to 85% of the installed power. We therefore note Pi=0.15[pu] and P2=0.85[pu]; - a "rise line," that is, a line of increase in frequency resulting from a decrease in measured power, delimited by two endpoints with coordinates (P2-AP, ffin) and (PrAP, fstart). In an example, the hysteresis value AP is set at 0.1 pu (i.e., 10% of the installed power of the generator set). Note that the value of PI of 0.15 includes the value of AP; in other words, PI is equal to AP plus a small margin, here of 5%. This rise line is parallel to the fall line; - a zone located between the "ascent" and "descent" lines, which has a width AP and ensures stability against oscillations between frequency and power - two non-adjustment zones of f(P), in which the frequency can take a value chosen from the values ​​fstart and fmax, respectively chosen from the values ​​ffin and fn, where fn designates the nominal frequency, i.e. in this example 50 Hz; - two out-of-bounds zones, such that no measured power value can result in a frequency greater than fmax or less than fn.

[0048] In one embodiment, allowing optimization of this evolution law to the operation of type 4 inverters, the following is fixed: - fstart=51.2Hz; - ffin=50.2Hz; - fmax=51.55Hz, where f _ + A f with and J max J decoupling J margin J decoupling ' ' = 0.05Hz.

[0049] This margin A is necessary to ensure that the ENRv inverter takes into account a measured frequency higher than the threshold set for its decoupling frequency, and therefore that it opens its internal circuit breaker. The value of the margin A must cover the error in frequency generation relative to the frequency setpoint imposed by the generator set and the error in frequency measurement at the ENRv inverter.

[0050] The hysteresis zone between the "rising" and "falling" lines implies two possible evolutions of the frequency, depending on the sign of the derivative of the power with respect to time.

[0051] Following a high inflection point (i.e., when the measured power Pmes stops increasing and starts to decrease): - for a variation in measured power less than AP, the frequency f is kept constant; - for a variation in measured power greater than AP, the frequency f increases along the "rise line".

[0052] Following a low inflection point (i.e., when the measured power Pmes stops decreasing and starts increasing): - for a variation in measured power less than AP, the frequency f is kept constant; - for a variation in measured power greater than AP, the frequency f decreases along the "falling line".

[0053] The larger the range of variation of the function f(P), the more the ramp is AP The gentler the frequency variation, the smaller the power variation per kW: this results in greater stability. Indeed, stability increases (A / W). with the magnitude of the P2-Pi range, which is 0.8p.u. in the example of [Fig.3]. For a diesel generator set, care must be taken to ensure that the magnitude of the P2-Pi range does not get too close to 0 pu, as the generator set is not capable of absorbing power.

[0054] In other embodiments, other values ​​can be chosen for all of these parameters, and in particular for Pi P2 and AP, depending on the stability sought and the configuration of the islanded micro-network to which the generator set is connected.

[0055] The AP parameter also impacts control stability: it ensures a constant frequency value for changes in the monotonicity of the measured power variation. Its value can be chosen within a range, for example, from 0.05p.u. to 0.5p.u. Furthermore, the tuning accuracy of both the inverter of the renewable energy production module and the generator set increases with the range of frequency variation (ffin-fstart). In the example in [Fig. 3], ffin-fstart = 1 Hz, which is advantageous because it is the value already mandated by the standard applied to Type 4 inverters. Other values ​​can also be considered, depending in particular on the characteristics of the inverters integrated into the renewable energy production modules present on the islanded microgrid.

[0056] The various numerical values ​​proposed above ensure satisfactory stability of the frequency control, while taking into account certain compromises. However, these values ​​can be configured according to the application. It should be noted that, although the most stable control is that for which the frequency is constant and the power injected by the renewable energy modules into the islanded microgrid does not vary, this solution is not optimal because it implies a complete decoupling of the renewable energy modules from the microgrid, and therefore a financial and green energy loss.

[0057] The evolution law described above in relation to [Fig.3] drives a frequency setpoint value which can be denoted fhystereSiS(PmeS), which feeds a second stage of construction of the frequency control law as a function of the power measured at the terminals of the generator set 10, presented below in relation to [Fig.4],

[0058] Figure 4 shows a fictitious variation of the hysteresis frequency SiS(Pmes) as a function of time. The decoupling level treatment of the curve

[0059] representative of this variation ensures stability by temporarily blocking the decrease in frequency, if the latter exceeds a decoupling frequency threshold of a type 1, type 2, or type 3 inverter. In figure 4, we have represented fseuiidécouplage i=50.2Hz, which is the decoupling frequency of a type 1 inverter, fSeuiidécouplage2=50.4Hz, which is the decoupling frequency of a type 2 inverter, and fSeuiidécouplage3=50.6Hz, which is the decoupling frequency of a type 3 inverter (i.e. f , . E {50.2; 50.4; 50.6} where i is the type of inverter, i E {1; 2; 3} ). It should be noted that we could generalize from 3 to N decoupling frequency thresholds, where N>0, in a network which would include N types of inverters presenting N distinct decoupling frequencies for which the function P(f) is not activated. When the frequency setpoint imposed by the evolution law fhysteresisS(Pmes) of [Fig.3] increases and reaches a first blocking threshold frequency equal to / decoupling threshold & fmargin f decoupling threshold 2 ' / margin OR f .... , A f on prohibits the frequency setpoint value from taking J decoupling threshold 3 J margin' t -ir a value lower than a second blocking threshold frequency, which is higher than the first blocking threshold frequency by a value equal to 2 A fmargin = 0.1 Hz. Thus, the minimum frequency setpoint is blocked for a configurable duration of one hour, for example, at fseuu decoupling i+0.05 Hz, fseuu decoupling 2+0.05 Hz, or fseuu decoupling 3+0.05 Hz. In another embodiment, the blocking duration can be set to thirty minutes, 1 hour 30 minutes, or even two hours, depending on the configuration of the islanded microgrid and the desired compromise between stability and power utilization. , . , _ A. The new , or j = 1, 2 or 31 renewable energy production modules. In particular, this blocking time can be optimized based on the ratio of the following power levels: - the installed power of the generator set; - the installed power of the renewable energy modules present on the islanded microgrid; - the charging power (i.e. the installed charging power or the expected charging curve). Thus, for example, this duration can be reduced to optimize the production of renewable energy, when it is estimated that there is no significant risk from the point of view of the installed power, i.e. when the installed power of the generator set is much greater than the installed power of the renewable energy modules.

[0060] With reference to Figure 4, it is therefore understood that the frequency setpoint value blocking is active and that a time counter is activated as soon as the frequency increases (fhysteresis (Pti ) > f hysteresis (PtiA ) where and Pti denote the powers measured at two successive time instants ti-1 and h) and reaches the first blocking threshold frequency ( ■^"decoupling threshold jf margin “ f hysteresis The setpoint frequency value is immediately blocked (downward) at the second blocking threshold frequency, f .... , .+ A f Thus, as soon as the frequency exceeds f.... . A we switch the frequency to 'J decoupling threshold j J margin' f .... . .+ A in order to ensure that the inverters measure a value 17 decoupling threshold j margin lower than their decoupling threshold before blocking and that they measure a value higher than their decoupling threshold after blocking. Blocking is performed at f + A f J decoupling threshold j J margin'

[0061] This second stage of control law construction ensures the proper operation of type 1, 2, or 3 inverters, or more generally, of all inverters in which the P(f) control function is not activated. The output of this second stage of control law construction yields a frequency setpoint value corresponding to the control law, which is denoted f(Pmes).

[0062] Figure 5 illustrates this principle of processing by decoupling levels in the form of a block diagram, receiving as input the frequency setpoint value imposed by the evolution law fhystereSiS(PmeS) of Figure 3 (more simply denoted fhystereSiS(P) on Figure 5), and delivering as output the frequency setpoint value responding to the control law, denoted f(Pmes) (more simply denoted f(P) on Figure 5).

[0063] A third stage in the construction of the control law is fed by the function f(P) and delivers at its output the setpoint value of the frequency of the alternating voltage generated by generator set 10, denoted fGEM d- This value fGEM d is calculated by applying limitations to the minimum and maximum values ​​of the frequency, as well as its rate of change, as illustrated in [Fig.6]. This ensures a well-controlled operating range.

[0064] In one embodiment, four limits are defined: - a minimum frequency value, fmin=50Hz, corresponding to the value of the nominal frequency in the electrical distribution network; - a maximum value of the frequency, fmax=51.55Hz, defined as follows: f - max ff ' \ + A f = 4 + A f ; J max \ J decoupling / 4 margin J decoupling margin - a limit value for the frequency variation ramp on the upstroke <=2[Hz!s\ ' Ccttc value is chosen because it corresponds to a usual value frequency variation of an inverter or generator (rotating group of (genset type). It ensures a sufficiently rapid increase in frequency to quickly stop variations in the power injected by the modules of renewable energy production, while avoiding excessively rapid variations such as "jumps in frequency " ; - a limit value for the frequency variation ramp on the descent -0.000125 [Hz / s] , which is set to a low value to allow a slow reaction of the evolution of the frequency as a function of the measured power f(Pmes), to avoid instabilities.

[0065] These values ​​are given as an example of an embodiment. Other values ​​may also be chosen, to adapt to the particular configuration of the islanded microgrid, and in particular to the installed power of the renewable energy production modules present on the network, and to the type of inverters they integrate.

[0066] In particular, the choice of the frequency ramp decay limit value allows the entire power variation range to be covered in more than two hours. This choice therefore ensures a sufficiently slow frequency decay to protect the islanded microgrid against "yo-yo" type instability, even for renewable energy (REV) module inverters with an installed capacity greater than the installed capacity of the generator set. For a generator set dedicated to use in an islanded microgrid where the installed capacities of the REV modules are low, and below the installed capacity of the generator set, this frequency ramp decay limit value can be reduced.

[0067] The different modules of the control logic implemented in a controller of a generator set according to one embodiment are summarized in synoptic form in [Fig.7].

[0068] As illustrated in relation to [Fig. 3], the module referenced 101 controls the evolution law of the frequency setpoint value as a function of the measured power, according to a hysteresis cycle; it delivers a sub-function fhysteresis(Pmes)-H, which is specifically dedicated to controlling the power injected by type 4 renewable energy inverters with an activated P(f) function. The module referenced 102, arranged in series with the first module referenced 101, receives as input the sub-function fhysteresis(Pmes) delivered by the latter, to which it applies decoupling level processing, in order to control the power injected by type 1, 2, or 3 renewable energy inverters without an activated P(f) function. It delivers as output a sub-function denoted f(Pmes) or f(P).

[0069] The third stage referenced 103 of the control logic of [Fig.7] applies limitations in value and derivative to the frequency setpoint value f(P), which it transforms into a setpoint fGEM d which controls the frequency of the alternating voltage generated by the generator set 10.

[0070] It should be noted that for a generator set intended for use in an islanded microgrid comprising only ENRv inverters of type 4 or later (i.e. only ENRv inverters with a power regulation function based on the frequency P(f) activated), the implementation of the decoupling level processing module 102 is optional.

[0071] Figure 8 shows a block diagram of a generator set according to one embodiment. As indicated above, such a generator set 10 is configured to supply an alternating voltage at the frequency fGEM_D to the electrical network to which it is connected. It comprises an engine referenced 10i, for example a diesel engine, an alternator referenced 102, and a set of electronic converters referenced 103, from whose output an alternating voltage at the frequency fGEM_D is available to be injected into the electrical network to which the generator set 10 is connected. It also comprises one or more processor(s) PROC capable of controlling the execution and reading of the measurement of the power generated at the terminals of the generator set.It also includes a MEM memory storing at least instructions from a computer program and accessible by the PROC processor(s) to implement the process described above in relation to Figures 2 to 8 when the PROC processor(s) of the storage system execute(s) the program instructions. In particular, the PROC processor(s) calculate(s) the setpoint value of the frequency fGEM d of the alternating voltage generated at the output of the generator set. 10, depending on the measured power Pmes, from the control law described above. Such a system also includes an INT interface, allowing an operator to parameterize the different variables of the evolution law, stored in the MEM memory, such as the values ​​of the parameters Ph P2, AP, ffin, fstart, blocking times of the minimum frequency value for processing by decoupling levels, etc., as described above in relation to Figures 3 to 7.

[0072] It should be noted that [Fig. 8] shows only one example of a generator set on which the invention can be implemented. In particular, other generator sets on which the invention can be implemented may not include electronic converters, which are an optional component. Industrial application

[0073] The object of this description may find applications in the upkeep, management and maintenance of electrical distribution networks to which variable renewable energy production modules are connected, in particular for the purpose of optimizing the share of green energy in the network.

Claims

Demands

1. A method for controlling the power injected by at least one renewable energy production module (PVrPVn) into an electrical microgrid (11) islanded with respect to a main electrical distribution network, characterized in that it comprises: a. a connection, in said islanded electrical microgrid (11), of a thermal electrical energy generation module (10) generating an alternating voltage suitable for supplying said islanded electrical microgrid; b. a control (101-103) of a frequency setpoint value of said alternating voltage generated by said thermal electrical energy generation module (10) from a control law established from an evolution law of said frequency setpoint value as a function of a generated power measured across the terminals of said thermal electrical energy generation module, said evolution law having a hysteresis cycle.

2. Power control method according to claim 1, characterized in that it also implements a decoupling level treatment (102), according to which said control law includes, during a determined blocking time beginning when said frequency setpoint value increases and reaches a first blocking threshold frequency according to said evolution law, a blocking of a minimum value of said frequency setpoint value at a second blocking threshold frequency greater than said first blocking threshold frequency.

3. Power control method according to claim 2, characterized in that said first and second blocking threshold frequencies are determined as a function of a decoupling frequency parameterized for an inverter (122-i- 122-n) of said at least one renewable energy production module.

4. A power control method according to any one of claims 1 to 3, characterized in that said hysteresis loop of said evolution law is parallelepiped-type and comprises: - a straight line of decrease of said frequency setpoint value as a function of an increase in said generated power measured at starting from a starting power value (PJ, and up to an ending power value (P2); - a straight line of increase of said frequency setpoint value as a function of a decrease of said measured generated power; and in that said increasing and decreasing lines are parallel and offset from each other in abscissa by a power hysteresis value A P.

5. A power control method according to any one of claims 1 to 4, characterized in that said control of said frequency setpoint value also comprises an additional application of: - a maximum frequency setpoint value (fmax); - a minimum frequency setpoint value (fmin); - a limit value of the slope of increase of said frequency setpoint value as a function of time; - a limit value of the slope of decrease of said frequency setpoint value as a function of time; and in that said limit value of the slope of increase is greater than said limit value of the slope of decrease, in absolute values.

6. Thermal power generation module (10) configured to generate an alternating voltage suitable for supplying an islanded electrical microgrid (11) with respect to a main electrical distribution network, said islanded electrical microgrid comprising at least one renewable energy production module (PVj-PVn), characterized in that it comprises a processor configured to execute control of a frequency setpoint value of said generated alternating voltage from a control law established from an evolution law of said frequency setpoint value as a function of absorbed power measured at the terminals of said thermal power generation module, said evolution law having a hysteresis cycle.

7. Thermal electrical energy generation module (10) according to claim 6, characterized in that said processor is also configured to perform the steps of the power control process according to any one of claims 1 to 5.

8. Thermal electrical energy generation module (10) according to claim 6 or 7, characterized in that it also includes a human-machine interface for inputting at least one parameter of said control law.

9. Computer program comprising instructions for carrying out the method according to any one of claims 1 to 5 when this program is executed by a processor of a thermal electrical energy generation module according to any one of claims 6 to 8.

10. A non-transient, computer-readable recording medium on which is recorded a program for implementing the method according to any one of claims 1 to 5 when this program is executed by a processor of a thermal electrical energy generation module according to any one of claims 6 to 8.

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