Method for operating an energy supply system, energy supply system having a plurality of inverters and inverter

Abstract

The invention relates to a method for operating an energy supply system (11) having a plurality of inverters (10.X) and a system controller (28), which is in communicative connection with the inverters (10.X), wherein the energy supply system (11) has a mains connection (26), which is connected to an AC voltage mains (24), and wherein the inverters (10.X) exchange electrical exchange power (PINV,X) with the AC voltage mains (24) via the mains connection (26), so that the energy supply system (11) exchanges a total exchange power (PPOI) with the AC voltage mains (24), which comprises the respective electrical exchange powers (PINV,X). The system controller (28) determines individual inverter setpoint powers (PSPT,INV,X) depending on a system setpoint (PSPT,POI) for the total exchange power (PPOI) of the energy supply system (11) and transmits the individual inverter setpoint powers (PSPT,INV,X) to the controllers (50.X) of the inverters (10.X). The respective controllers (50.X) of the inverters (10.X) set the respective exchange powers (PINV,X) of the inverters (10.X) depending on the inverter setpoint powers (PSPT,INV,X). The controllers (50.X) of the inverters (10.X) are laid out to form the mains, and the inverters (10.X) provide individually adjustable instantaneous reserve power.

Description

[0001] METHOD FOR OPERATING A POWER SUPPLY SYSTEM, POWER SUPPLY SYSTEM WITH A PLURALITY OF INVERTERS AND INVERTER

[0002] TECHNICAL FIELD

[0003] The application relates to a method for operating a power supply system, as well as to a power supply system and an inverter. The power supply system comprises a plurality of inverters and a system controller. The system controller is communicatively connected to the inverters. The inverters of the power supply system have a common grid connection via which they exchange electrical power with an AC voltage grid.

[0004] STATE OF THE ART

[0005] Conventional power plants, particularly thermally operated power plants and hydroelectric power plants, comprise grid-synchronized rotating flywheels of the synchronous generators or turbines and the respective drive train. Such power plants exchange electrical power with an alternating current electrical network, whereby the entire flywheel of the plants is electromechanically effective and contributes significantly to the stabilization of the alternating current network. In particular, the inertia of the respective flywheel, due to the rotational energy stored in it, causes an inertia of the rotating voltage space vector of the conventional power plants relative to the voltage space vector in the alternating current network.As a result, phase shifts and / or frequency changes in the voltage space vector in the AC grid result in an instantaneous power change in the power supply systems, which is caused in particular by inductive effects and a phase angle difference between the voltage space vector of the flywheel and the voltage space vector of the grid voltage. In this respect, a conventional power supply system provides a so-called instantaneous reserve and limits the rate of change of the grid frequency of the AC grid, particularly in the event that power imbalances between the supply and outflow of electrical power, i.e., between generation and consumption in the AC grid, occur relatively quickly, for example, due to a fault in a transmission line in the AC grid.

[0006] The energy exchanged as instantaneous reserve power between the power supply system and the AC grid is extracted from or supplied to the rotating mass of the conventional power supply systems by decelerating or accelerating the respective flywheel. The exchanged power and the exchanged energy are limited overall by the physical properties of the power supply system. The provision of the instantaneous reserve ends as soon as the voltage space vector of the flywheel has synchronized with the voltage space vector of the grid and its rotation frequency has adjusted to the grid frequency, i.e., in particular, as soon as any drift in the grid frequency has been stopped, for example, after the power imbalance has been eliminated by additional frequency control mechanisms or a grid self-regulation effect.

[0007] Energy supply systems that exchange electrical power with the AC grid via power electronic converters, such as photovoltaic systems, wind turbines, or grid-connected energy storage systems, generally have no rotating masses and thus no mechanical inertia, virtually no mechanical storage capacity, and no significant overcurrent capacity. The power electronic converters of such energy supply systems, especially inverters, can be configured to exchange a given electrical power with an existing AC grid or can even form an island grid.

[0008] DE 10 2020 119 039 A1 discloses a system with inverters that operate with a voltage-impressing droop control and can respond "instantly" to grid events by changing the power. A system controller adjusts the droop control parameters. The adjustment includes, in particular, a change in the target frequency or, alternatively, the target power in response to a power change in order to return the system's power to a target grid power after a grid event. This solution makes it possible to precisely adjust the target grid power at the grid connection.

[0009] EP 3 783 765 A1 discloses a P(df / dt) inertia emulation, which can be implemented, for example, through superimposed controls. This also allows for the implementation of grid-following control concepts, which can be steady-state accurate at the grid connection, for example, if an integral component is used in the system controller.

[0010] TASK

[0011] The application is based on the object of providing a method for operating a power supply system and a power supply system by means of which the exchange of electrical energy between the power supply system with multiple inverters and an AC voltage grid can be further improved. It is also an object to provide an inverter for use in such a power supply system. SOLUTION

[0012] The object is achieved by a method having the features of patent claim 1, by a power supply system having the features of patent claim 23, and by an inverter having the features of claim 25. Preferred embodiments are specified in the dependent claims.

[0013] DESCRIPTION

[0014] A power supply system comprising a plurality of inverters and a system controller communicatively connected to the inverters has a grid connection to which the inverters are connected and which is connected to an AC voltage grid. In a method for operating such a power supply system, the inverters exchange electrical exchange power with the AC voltage grid via the grid connection, so that the power supply system exchanges a total exchange power with the AC voltage grid that includes the respective electrical exchange power of the inverters. The system controller determines individual inverter target powers depending on a system target value for the total exchange power of the power supply system. The system controller transmits the individual inverter target powers to the inverter controls.The respective inverter controls adjust the respective exchange power of the inverters depending on the inverter target power. This process is characterized by the fact that the inverter controls are designed to shape the grid, and the inverters provide individually adjustable instantaneous reserve power.

[0015] The method according to the application enables an energy supply system to be operated in such a way that it provides, via its grid connection, on the one hand, a total exchange power and, on the other hand, an instantaneous reserve power, which are each composed of individually adjusted contributions from the grid-shaping controlled inverters.

[0016] In one embodiment of the method, measured exchange powers of the respective inverters are transmitted to the system controller. The system controller continuously recalculates the inverter target powers based on the measured exchange powers and transmits them to the inverters. The controllers of the respective inverters then adjust their respective exchange powers based on the newly determined inverter target powers.

[0017] One advantage of the method is that the total exchange power at the grid connection can be adjusted more precisely while simultaneously providing instantaneous reserve. In particular, the contributions of the individual inverters to the total exchange power can be precisely adjusted by the system controller. Furthermore, all power contributions to the instantaneous reserve power can be adjusted with high precision, both at the grid connection and within the energy supply system. In particular, the total exchange power and the instantaneous reserve power at the grid connection can be individually distributed among the inverters within the energy supply system. The distribution among the inverters can be optimized, particularly with regard to the respective requirements of the energy sources, storage devices, or consumers connected to the inverters.This makes it possible to achieve a stationary, precise distribution of power between individual inverters in the energy supply system while simultaneously maintaining a high level of dynamics in the instantaneous reserve power at the grid connection.

[0018] The system controller is a unit, e.g., a processing unit, for the acquisition, signal processing, and control or regulation of the energy supply system as a whole. The system controller specifically regulates the total exchange power at the grid connection.

[0019] The electrical power controlled by the method and exchanged with the AC grid can be pure active power or pure reactive power. Alternatively or additionally, the method can be used to control power representing positive-sequence or negative-sequence power. Furthermore, the method can be used to control currents instead of power. These can be active currents or reactive currents used in positive-sequence and / or negative-sequence components in the control.

[0020] In one embodiment of the method, the system controller determines the individual inverter target powers by normalizing the system target value to the respective relative rated power of the respective inverter and adding an individual offset value, with the sum of the offset values ​​preferably being zero. The normalization can be carried out, for example, by dividing the rated power of the respective inverter by the sum of the rated powers of the inverters in the energy supply system. The individual offset can be used to take into account, in particular, individual conditions of a respective inverter, e.g. its age or its operating time, as well as individual conditions of the DC voltage sources or DC voltage sinks connected to the inverters, e.g. a current charge level of a connected energy storage device, a utilization of a connected consumer, e.g. an electrolyzer or similar.The different power distribution between individual inverters in the power supply system can be used, for example, to balance the charge levels and aging states of individual DC voltage sources connected to the inverters, such as batteries, or to control electrolyzers or other connected loads of different power classes. By setting the sum of the offset values ​​to zero, the inverters in the power generation system can then contribute more or less to the desired total exchange power depending on their individual circumstances. This allows the power contributions to be adjusted even more precisely, while simultaneously adjusting the total exchange power precisely.

[0021] In one embodiment of the method, the grid-shaping controls (50.X) react autonomously to grid events with an individually adjustable power response. For this purpose, the grid-shaping controls of the inverters each comprise, in particular, a voltage-impressing droop control and an inertia-generating control, which are interlinked within the framework of the grid-shaping control and together provide an instantaneous reserve power. The inverters use a respective droop control to adjust their respective exchange power based on a droop characteristic curve as a function of a droop characteristic reference power and a respective voltage curve deviation of a voltage curve of a grid voltage from a respective reference curve with reference to a droop setpoint. Depending on the power variable to which the control is applied, the droop setpoint can be, in particular, a setpoint frequency or a setpoint voltage amplitude.If the method is used to control the active power of a power supply system, the droop control can specify an f(P) relationship between a respective exchanged active power as a measure of the voltage curve deviation and a frequency or phase deviation relative to a target frequency. If the method is used to control the reactive power of a power supply system, the droop control specifies a U(Q) relationship between a respective exchanged reactive power as a measure of the voltage curve deviation and a voltage deviation relative to a target voltage amplitude. In the case of controlling a positive or negative sequence power, the droop setpoint includes corresponding setpoints for the positive and negative sequence components of the frequency or phase angle, as well as the voltage amplitude.

[0022] Using such droop control, the respective inverters can react to voltage curve deviations in the AC grid and supply or draw more or less electrical power by synchronously and quickly adjusting the frequency and amplitude of the voltage curve of the voltage supplied to the inverter on the grid side. The occurrence of an initial voltage curve deviation of the grid voltage from a reference voltage curve causes a deviation of the inverter's exchange active power with respect to the target frequency and a deviation of the inverter's exchange reactive power with respect to the target voltage amplitude from the respective droop characteristic reference power.The voltage waveform deviation is, in particular, a phase angle difference between the phase angle of the inverter's output voltage and the grid voltage, which causes the deviation in the exchange active power via an output-side impedance, or an amplitude difference between an amplitude of the inverter's output voltage and the grid voltage, which causes the deviation in the reactive power. The exchange active power and the exchange reactive power therefore serve as respective measures for the phase angle difference and the amplitude difference, respectively. In the case of active power control, the exchange active power is converted into a proportional change in the frequency of the inverter's output voltage in droop control using the droop characteristic.The droop control thus synchronizes the output voltage frequency to the grid frequency, but maintains the resulting phase angle difference, so that the inverter's exchange active power deviates from the droop characteristic reference power by a value that is essentially proportional to the deviation of the grid frequency from the target frequency. In particular, the power supply system can react to changes or jumps in the phase angle and / or the frequency of the voltage space vector of the grid voltage with a targeted variation of the active power, or to changes in the amplitude of the grid voltage with a targeted variation of the reactive power. The strength of the variation can be adjusted by the slope of the droop characteristic.

[0023] An advantage of droop control is that the frequency and amplitude of the voltage curve of the output voltage of the respective inverter is synchronized to the voltage curve of the AC voltage grid in such a way that an instantaneous power response with regard to active power and / or reactive power is made possible at the grid connection point of the energy supply system, which can be adjusted via the droop characteristic curve and is proportional to the deviation of the voltage curve of the output voltage from the specified frequency and voltage amplitude.The grid-shaping contribution of droop control occurs through a deviation of the actual inverter power from the target inverter power and continues until the deviation of the output voltage curve from the specified frequency and voltage amplitude is eliminated, for example, by a higher-level control and / or a return of the AC voltage of the AC grid to a pre-fault state. This can make an important contribution to grid shaping, e.g., in the form of highly dynamic grid services, particularly for frequency and voltage control. This enables a very fast, even instantaneous, direct grid-supporting response to grid events, which, depending on the power and energy reserves within the power supply system, enables a significant contribution to grid support.In one embodiment of the method, the inverters can use an inertia-generating control to vary an input value of the droop control, in particular the droop characteristic reference power, depending on an individual power deviation of the respective inverter in order to return the exchange power of the inverters to the respective inverter target power when there is a deviation of the output voltage curve from the voltage in the AC voltage grid and, consequently, a power reaction occurs due to the droop control. The individual power deviation of the respective inverter can correspond to a deviation of the measured individual exchange power from the inverter target power specified by the system controller.The dynamics of returning the exchange power of the inverters to the respective inverter target power can be set in the inertia-generating control, in particular by means of an inertia constant, which is multiplied by the (integrated) power deviation of the respective inverter when varying the droop characteristic reference power.

[0024] The advantage of inertia-based control is that the inertia of the resulting voltage space vector of the power supply system can be adjusted during grid events so that the resulting power and energy exchange with the power grid is proportional to the rate of change of the frequency or the amplitude of the grid voltage curve. Instantaneous reserve requirements can be met, and power supply systems operated with this method can shape the grid to the best of their ability.

[0025] The individual power and energy reserves of the sources and / or sinks connected to the inverters, which are available for grid shaping with this operating mode, can be optimally utilized using the adjustable inertia constants of the inertia-generating control. Compared to pure droop control, the inertia-generating control requires fewer energy reserves for grid shaping. Furthermore, the inertia-generating control enables the individual exchange power of the inverters and thus also the overall exchange power of the power supply system to be adjusted with high steady-state accuracy relative to the system setpoint, particularly in the case of a steady-state deviation of the output voltage curve from a voltage curve with the nominal frequency and nominal voltage.

[0026] In embodiments of the method, the grid-shaping controls of the inverters comprise a sign-dependent weighting of the deviation of the individual exchange power from the respective target power. In particular, the grid-shaping controls can comprise an asymmetry static that weights the deviation of the individual exchange power from the respective target power differently depending on the sign of the voltage curve deviation. Such an asymmetry static can, in particular, comprise an asymmetric characteristic curve that is used in the droop control and / or in the inertia-generating control of the inverters.

[0027] An asymmetry droop can, for example, be used in the respective droop control to adjust the frequency of the output voltage of the inverter either slowly or quickly in the event of a voltage curve deviation due to a grid frequency gradient, depending on the sign of the grid frequency gradient, i.e. in which direction the grid frequency changes.

[0028] Specifically, the asymmetry droop in the droop control can be implemented as an asymmetric droop characteristic or droop asymmetry droop, which, for example, translates a positive deviation of the exchange active power due to a falling grid frequency into a comparatively small tracking change in the frequency of the inverter's output voltage, so that a comparatively large phase angle difference arises and a correspondingly large amount of instantaneous reserve power is called up; conversely, a negative deviation of the exchange active power due to an increasing grid frequency can be translated into a comparatively large tracking change in the frequency of the inverter's output voltage, so that the phase angle difference remains comparatively small and correspondingly little instantaneous reserve power is called up.Alternatively, the droop asymmetry static can be configured in exactly the opposite way, for example to provide little instantaneous reserve power when the grid frequency decreases and a lot of instantaneous reserve power when the grid frequency increases.

[0029] Alternatively or additionally, an asymmetry droop can be used in the inertia-generating control to vary the droop characteristic reference power quickly or slowly in the event of an individual power deviation of the respective inverter, depending on the sign of the power deviation. An individual power deviation can occur in particular if the respective inverter target power is changed by the system controller and / or if there is a voltage curve deviation with a possible reaction of the droop control.

[0030] Specifically, the asymmetry statics in the inertia-generating control system can be implemented as an asymmetric inertia constant or inertia asymmetry statics. For example, a positive deviation in the exchange active power due to a decreasing grid frequency can be multiplied by a comparatively large inertia constant, so that the droop characteristic reference power varies comparatively strongly in a counteracting manner and correspondingly little instantaneous reserve power is called up. Conversely, a negative deviation in the exchange active power due to an increasing grid frequency can be multiplied by a comparatively small inertia constant, so that the droop characteristic reference power varies comparatively little in a counteracting manner and correspondingly much instantaneous reserve power is called up.Alternatively, the inertial asymmetry statics can be configured in the opposite way to provide a lot of instantaneous reserve power when the grid frequency decreases and a little instantaneous reserve power when the grid frequency increases.

[0031] This sign dependence of the asymmetry statics allows for individual adjustment of the instantaneous reserve power provided by an inverter for a given voltage waveform deviation. This at least indirectly takes into account the direction in which the exchange power of the respective inverter changes due to the underlying grid event, and this grid-shaping change in the exchange power is either permitted and, if necessary, amplified, or limited and, if necessary, suppressed.

[0032] The sign-dependent weighting of the deviation of the exchange power from a respective target power in the grid-forming control, for example expressed as a sign-dependent constant or gradient of a corresponding asymmetry static, can differ by at least a factor of 2 for the two signs of the voltage curve deviation, for example depending on the sign of a grid frequency gradient, for example in order to counteract a falling grid frequency, which indicates a critical power deficit in the AC grid, with a larger instantaneous reserve power than a rising grid frequency, which indicates a possibly less critical power surplus in the AC grid.Preferably, the weighting differs depending on the sign by at least a factor of 5, particularly preferably by at least a factor of 10, in particular in order to adjust the provision of an asymmetric instantaneous reserve power which is generated largely exclusively in the case of one sign of the voltage curve deviation and is absent as completely as possible in the case of an opposite voltage curve deviation.

[0033] In embodiments of the method, the asymmetry droop can additionally be dependent on the grid frequency. The grid frequency can, for example, be measured in the AC grid or approximated by the output frequency of the inverter. For example, the asymmetry droop can be set up using a case distinction so that instantaneous reserve power is only provided due to a grid frequency gradient if the grid frequency deviates from a nominal frequency in the same direction as the grid frequency gradient, i.e. if, for example, there is an overfrequency and the grid frequency continues to rise. Conversely, an instantaneous reserve power intended based on the asymmetry droop can be suppressed if the grid frequency gradient points in the direction of the nominal frequency, i.e. if, for example, there is an overfrequency and an already falling grid frequency should not be unnecessarily counteracted.Furthermore, the asymmetry statics can additionally or alternatively depend on the respective exchange power. This provides a further degree of freedom for individually adjusting the instantaneous reserve power provided by the respective inverter, for example, by limiting the instantaneous reserve power to a maximum exchange power or only starting at a minimum exchange power.

[0034] The power control speed of the droop control is typically faster than the power control speed of the inertia-generating control, so that the adjustment of the exchange power by the droop control when a voltage curve deviation occurs is faster than the variation of the droop characteristic reference power by the inertia-generating control (53. X) when a deviation of the exchange power from the inverter target power occurs.

[0035] The power supply system with the method according to the application responds quickly to changes in the power setpoint by means of droop control, on the one hand, and reacts to grid events by means of inertia-generating control with a predeterminable instantaneous reserve power, on the other hand. In particular, if a power deviation at the grid connection is caused by a reaction of the droop control to a voltage curve deviation, the control behavior and the disturbance behavior of the power supply system can be decoupled from one another. The synchronizing behavior of the droop control enables faster synchronization with other voltage sources in the power supply network, which leads to fewer compensating oscillations and better damping. At the same time, the inertia-generating component ensures that the exchange power during grid events is comparable to the inertia of a rotating mass, i.e. proportional to the gradient of the frequency orThe voltage amplitude is adjusted during the grid event, so that the exchange power can be adjusted to the system setpoint according to an adjustable inertia dynamic. This behavior enables the power supply system to make an optimal contribution to grid stability and energy supply.

[0036] This makes it possible to achieve very fast control behavior at the grid connection and, at the same time, to maintain the inertia of the voltage space vector despite excitation by grid events and disturbances. This takes into account the fact that the system setpoint for the total exchange power is often a quasi-stationary value that should not react or should react rather slowly to disturbances, and that, on the other hand, an instantaneous reserve of the energy supply system should be made available as quickly as possible. The combination of fast droop control and slower inertia-generating control makes it possible to parameterize the control behavior and the disturbance behavior separately and, in particular, to use separate feedforward controls for the respective output values. In one embodiment of the method, the total exchange power of the energy supply system is determined and, for example,In the system controller, a total power deviation of the total exchange power from the sum of the measured exchange powers of the inverters is determined.

[0037] The total power deviation can be standardized to the respective relative nominal powers of the respective inverters and the standardized partial power deviations thus determined can be taken into account when determining the inverter target powers, e.g. in the system controller.

[0038] In one embodiment of the method, the respective inertia-generating controls vary the droop characteristic reference power of the droop control using a feedforward control with the product of an individual feedforward control value and a first correction factor. Alternatively or additionally, the respective droop controls determine and influence the phase angle of the inverter's output voltage using a feedforward control with the product of the individual feedforward control value and a second correction factor. The individual feedforward control value can be formed in particular by the individual inverter's share of the system setpoint or by a weighted sum of the individual inverter's share of the system setpoint and the individual inverter setpoint power, wherein the weighted sum is formed in particular by means of two correction factors whose sum is equal to one.

[0039] In one embodiment of the method, the input value of the droop control, in particular the droop characteristic reference power, is varied within the framework of the inertia-generating control depending on the product of a first weighting factor and the individual deviation of the measured individual exchange power of the respective inverter from the inverter target power of the respective inverter. Furthermore, the input value of the droop control, in particular the droop characteristic reference power, can be varied depending on the product of a second weighting factor and the individual inverter contribution to the system deviation. For this purpose, an input value of the inertia-generating control can be formed from a sum of the individual power deviation and the individual contribution to the system deviation, weighted by the weighting factors.It may be provided that the sum of the first weighting factor and the second weighting factor results in the value one.

[0040] A power supply system comprising a plurality of inverters and a system controller communicatively connected to the inverters is configured to be operated using one of the methods described above. The controllers of the inverters of the power supply system can each have an asymmetry droop and be configured to provide an individually adjustable symmetrical or asymmetrical instantaneous reserve power. The power supply system is configured to provide an adjustable symmetrical or asymmetrical instantaneous reserve power at the grid connection.

[0041] At least one inverter is further provided, which is configured for use in such a power supply system. The inverter has a grid-shaping control system, which in particular comprises a droop control system and a superimposed inertia-generating control system for changing an input value of the droop control system, in particular a droop characteristic reference power. The inverter is preferably voltage-impressed controlled and can in particular comprise an asymmetry droop and provide an adjustable symmetrical or asymmetrical instantaneous reserve power.

[0042] In alternative embodiments, the controls can be set to currents instead of power. These can be active currents or reactive currents, which are used in the positive-sequence and / or negative-sequence components of the control system. This allows for high current accuracy at the grid connection.

[0043] The connection point of the power supply system to the AC grid can alternatively be any other point in the AC grid, e.g., a so-called point of stability (POS). The point of stability can be controlled, for example, by the described power supply system or by multiple power supply systems.

[0044] The described process can be used to meet the need for additional instantaneous reserve, particularly in regions with a high proportion of non-conventional energy supply systems, e.g., renewable energy systems, and / or with spatially extensive grid structures consisting of energy storage systems, photovoltaic systems, and / or wind turbines. The process and the energy supply system can, in particular, provide instantaneous reserve power and primary control power as part of grid system services, which can be offered, for example, on a corresponding control power or balancing energy market. So-called grid boosters or STATCOMs are examples of commercially available grid-shaping network resources. The provision of grid services is made possible at the grid connection of the energy supply system and thus extends beyond the control of individual inverters.The power delivery, particularly the inertial behavior in combination with other network-shaping properties at the grid connection, can be achieved with great precision and dynamics using the method and the power supply system as claimed in the application. The utilization of the available power reserves of the power supply system can be improved, so that the power supply system can effectively contribute to security of supply.

[0045] BRIEF DESCRIPTION OF THE CHARACTERS

[0046] In the following, the application is further explained and described using exemplary embodiments shown in the figures.

[0047] Fig. 1 shows schematically a known method for operating a power supply system,

[0048] Fig. 4-11 schematically show various concrete embodiments of the method according to the application for operating an energy supply system, and

[0049] Fig. 12-24 show time courses of various electrical quantities resulting from an excitation by an exemplary network event when applying the method according to the application with different parameters.

[0050] In the figures, identical or similar elements are designated by the same reference numerals. The figures are not to scale, and elements of individual figures may be used analogously in other figures.

[0051] FIGURE DESCRIPTION

[0052] Figure 1 schematically shows a known method for operating an energy supply system 11 with a number of inverters 10.X. The energy supply system 11 can comprise a plurality of generators, storage devices and / or consumers, in particular photovoltaic generators, battery storage devices and / or electrolyzers, which exchange, i.e., receive and / or supply, electrical power via respective inverters 10.X. The energy supply system 11 exchanges a total electrical exchange power PPOI with an AC voltage network 24 via a grid connection 26. The total exchange power Ppoi essentially comprises the individual exchange powers PINV.X, which are generated by the inverters 10.X as a function of individual inverter target powers PSPT,INV,X, and any power loss PL OSS, which, for example, drops in connecting cables between the inverters 10.X and the grid connection 26. The individual inverter target powers PSPT,INV,X are specified by a system controller 28 and transmitted to the inverters 10.X.

[0053] An inverter 10.X has a conventional control 20.X. A voltage curve U is an output value of the control 20.X of the inverter 10.X. The voltage curve U calculated in the control 20.X is set at the output of the inverter 10.X by means of a converter 30.X, for example by suitable timing of a suitable inverter bridge circuit of the inverter 10.X. At the output of the inverter 10.X, the individual exchange power PINV.X of the inverter 10.X results depending on the difference between the voltage curve U and the grid voltage curve. The total exchange power PPOI of the energy supply system 11 at the grid connection 26 results from the sum of the individual exchange powers PINV.X of the inverters 10.X, less the power loss PLOSS.

[0054] The control 20.X receives as input values ​​an inverter target power PSPT,INV,X from the system controller 28 as well as the measured individual exchange power PINV.X of the inverter 10.X.

[0055] The system controller 28 receives a system setpoint PSPT.POI and the measured total exchange power PPOI as input values ​​and comprises a controller 15, for example, a proportional or integral controller. The controller 15 compares the system setpoint PSPT.POI and the measured total exchange power PPOI and modifies the system setpoint PSPT.POI depending on any deviations therebetween. The system controller 28 also comprises an allocator 16, which allocates the system setpoint PSPT.POI, possibly adjusted by the controller 15, to the individual inverter setpoint powers PSPT,INV,X. The allocator 16 can be parameterized with system-specific properties, e.g., the relative rated powers of the inverters 10.X, as well as other parameters, such as individual offset values ​​POFS,X for allocating the system setpoint PSPT.POI to the individual inverter setpoint powers PSPT.INV.X.

[0056] Figure 12 shows an example of a time course of the setpoint and actual values ​​of the energy supply system 11 and the inverters 10.1, 10.2 when using a method according to Fig. 1.

[0057] Figure 2 schematically shows a method according to the application for operating a power supply system 11. In contrast to the known method according to Fig. 1, the feedback of the measured total exchange power PPOI via the controller 15 is omitted, and the inverter 10.X has a grid-shaping controller 50.X. The system controller 28 now has an allocator 32, which receives the system setpoint PSPT.POI and the sum of the measured exchange powers PINV.X of the inverters 10.X as input values. The allocator 32 calculates the individual inverter setpoint powers PSPT.INV.X from these input values.

[0058] In contrast to the known method according to Figure 1, the total exchange power PPOI is no longer regulated by minimizing its deviation from the system setpoint PSPT.POI using a controller 15, but rather by taking into account the sum of the measured exchange powers PINV,X when dividing the given system setpoint PSPT.POI among the individual inverter setpoints PSPT,INV,X by the allocator 32. This can ensure that the sum of the exchange powers PINV,X corresponds to the system setpoint PSPT.POI. However, any power loss PLOSS, in the energy supply system 11 is not taken into account and generates a corresponding deviation between the setpoint and the actual value at the grid connection 26.

[0059] Figure 3 schematically shows an embodiment of the method according to the application for operating the energy supply system 11. When calculating the individual inverter target powers PSPT,INV,X, the allocator 32 additionally takes into account a total power deviation PCOR, which corresponds to the difference between the measured total exchange power PPOI and the sum of the measured exchange powers PINV.X of the inverters 10.X. In contrast to the known method according to Figure 1, the total exchange power PPOI is thus not regulated, but rather controlled by the allocator 32 taking into account the total power deviation PCOR when dividing the given system target value PSPT.POI among the individual inverter target powers PSPT,INV,X.

[0060] By using the total power deviation PCOR in the allocator 32, in particular the power loss PL OSSare better taken into account, thus improving the steady-state accuracy of the control system. Furthermore, the influences of any other, essentially unknown participants in the power supply system 11 are also automatically taken into account, so that their possibly fluctuating power contributions have no influence on the steady-state accuracy of the power supply system 11.

[0061] The following Figures 4 to 11 schematically show various specific embodiments of the method according to the application for operating the energy supply system 11. Compared to Figures 1 to 3, the grid-shaping control 50.X with a droop control 51.X and an inertia-generating control 53.X as well as the system controller 28 are described in more detail. In particular, the droop control 51.X is designed as an active power controller and specifically uses a target frequency f SPT as the droop setpoint, so that the embodiments illustrated in Figures 4 to 11 specifically set the active power of the power generation plant 11 at the grid connection 26. In this respect, the reference symbol P in Figures 4 to 11 specifically designates an active power, and the further characterizing features of these methods are related to this active power. However, it is equivalently possible and encompassed by the subject matter of this application to relate the characterizing features of the method, and in particular the reference symbol P, as well as the associated variables, analogously to a reactive power or a positive-sequence or negative-sequence system variable of a power or a current, and the respective complementary variables.

[0062] Figure 4 schematically shows a concrete embodiment of the method according to the application for operating the energy supply system 11. The grid-shaping control 50.X comprises a droop control 51.X and an inertia-generating control 53.X.

[0063] The inertia control 53.X of the inverter 10.X receives as input values ​​an inverter target power PSPT,INV,X from the system controller 28 as well as the measured individual exchange power PINV,X of the inverter 10.X and determines from this a droop characteristic reference power PSPT,X.

[0064] The droop control 51.X receives as input the droop characteristic reference power PspT,x from the inertia-generating control 53.X of the inverter 10.X. From the droop characteristic reference power PSPT,X and a measured individual exchange power PiNv,x of the inverter 10.X, an individual droop inverter deviation APxi of the inverter 10.X is determined. Using a droop characteristic, specifically the frequency constant Kf, a frequency shift Af is determined. The frequency shift Af is added to the target frequency fspT of the AC voltage network 24. The resulting frequency f is converted into a phase angle 3 and output as a voltage curve 3 to the converter 30.X.

[0065] The inertia control 53.X of inverter 10.X receives an inverter setpoint power PSPT,INV,X as input value. From the inverter setpoint power PSPT,INV,X and a measured individual exchange power PINV,X of inverter 10.X, an individual power control deviation APINV,X of inverter 10.X is determined. This is referred to as individual deviation AP. X used in the inertia-generating control to generate the droop characteristic reference power PSPT,X as an output value via an integrator 1 / s and an inertia factor 1 / Ha. This droop characteristic reference power PSPT,X serves as the input value for the droop control 51 .X.

[0066] The other inverters 10.X of the power supply system 11 can be constructed in the same way as described above. The control system 50.X shown in Fig. 4 is designed to shape the grid in that, on the one hand, the droop control 51.X reacts directly to phase differences between the voltage curve 3 at the inverter 10.X and the grid voltage and the associated changes in the output power PINV,X, and, on the other hand, the inertia-generating control 53.X achieves the inverter target power PSPT,INV,X in the steady state. In principle, inverters 10.X with such a control system 50.X according to Figs. 4 to 11 (see below) can be combined with a system controller 28 according to Fig. 2 or Fig. 3.

[0067] The system controller 28 according to Fig. 4 has a dispatcher 32. As an input value, the system controller 28 receives a system setpoint PSPT.POI for the total exchange power PPOI of the energy supply system 11. From the system setpoint PSPT.POI and the respective relative nominal powers of the inverters 10.X, the dispatcher 32 determines the respective inverter setpoint powers PSPT,INV,X, whereby the respective relative nominal powers of the inverters 10.X correspond to the respective quotient of the respective nominal power P N ,x of an inverter 10.X and the sum of the rated powers PN,X of the inverters 10.X in the power supply system 11. An individual offset value POFS,X is added for each inverter 10.X to the portion of the system setpoint PSPT.POI standardized to the respective relative rated power. Preferably, the sum of the offset values ​​POFS.X is zero.

[0068] It is possible to correct the power of each inverter 10.X within system 11. For this purpose, system controller 28 receives the measured exchange power PINV.X of inverters 10.X and determines the total power deviation PCOR between the total exchange power PPOI at grid connection 26 and the sum PINV of the measured exchange power PINV,X of inverters 10.X in system 11. The total power deviation POOR is normalized to the relative nominal power of the respective inverter 10.X and added at the output of allocator 32 to the normalized and, if applicable, offset-modified portion of inverter 10.x in the system setpoint PSPT.POI. As an output value, system controller 28 thus generates the respective inverter setpoint powers PsPT,INV,X.

[0069] The illustrated embodiment makes it possible to implement a grid-shaping instantaneous reserve power, also known as plant-level inertia, at the level of the energy supply system 11 by having the inverters 10.X each provide an individually adjustable instantaneous reserve power. At the same time, the total exchange power PPOI is distributed among the inverters 10.X, taking power dispatching into account, and is thereby adjusted to the system setpoint PSPT.POI with high steady-state accuracy. The following information is exchanged between the system controller 28 and the respective inverter 10.X:

[0070] The system controller 28 transmits the individual inverter target power PSPT,INV,X for each inverter 10.X to the respective inverter 10.X. This is used in particular for power dispatching within system 11. The measured individual exchange powers PINV,X of the inverters 10.X in system 11 are transmitted from the inverters 10.X to the system controller 28. This is used in particular to correct for the influences of the power loss P LoS s on the stationary accuracy of the control of the total exchange power P PO i.

[0071] Figures 13 to 15 show exemplary time courses of the setpoint and actual values ​​for an energy supply system 11 and its inverters 10.1, 10.2 when using a method according to Fig. 4.

[0072] Figure 5 schematically shows an embodiment of the method according to the application, in which the power generation plant 11 can provide an asymmetric instantaneous reserve power. In addition to Fig. 4, the inertia-generating controller 53.X in Fig. 5 has an inertia asymmetry static 55.X, which is applied to the individual power control deviation APINV.X to calculate the individual deviation APx, from which the droop characteristic reference power PSPT,X is subsequently generated as an output value via the integrator 1 / s and the inertia factor 1 / Ha. Alternatively, the inertia factor 1 / Ha can already be integrated into the inertia asymmetry static 55.X, whereby the inertia asymmetry static 55.X can also be implemented as a case distinction with two different inertia factors 1 / Ha.

[0073] The inertia asymmetry statics 55. X in the example according to Fig. 5 has a comparatively small gradient for negative values ​​and a comparatively high gradient for positive values ​​of the individual power control deviation APINV,X. As a result, a negative individual power control deviation APINV,X is assigned a significantly smaller individual deviation AP X assigned as a positive individual power control deviation APINV,X of equal magnitude. In alternative embodiments, the ratios of the gradients of the positive and negative halves of the inertial asymmetry statics 55.X can be set exactly inversely, if required.

[0074] The dynamics of the resulting droop characteristic reference power PSPT , which is used as the input value for the droop control 51.X, thus depends, via the inertia asymmetry static 55.X, on the direction in which the exchange power PINV,X deviates from the respective inverter target power PSPT,INV,X. The sign-dependent gradient of the inertia asymmetry static 55.X can be used to individually set the inertia of the instantaneous reserve power of the inverter 10.X for a given voltage curve deviation with a given positive or negative sign and an associated individual power control deviation APINV,X. Figure 6 schematically shows a further embodiment of the method according to the application, in which the droop control 51.X has a droop asymmetry static 57.X in addition to or as an alternative to Fig. 5. The droop asymmetry statics 57. X can be the frequency constant K freplace (see Fig. 4) or alternatively dimensionless and with the frequency constant K f multiplied, if necessary within the framework of a corresponding sign-dependent case distinction. The droop asymmetry static 57. X is applied to the individual droop inverter deviation APxi and results in the frequency shift Af, which ultimately determines the voltage curve 3.

[0075] The droop asymmetry static 57.X in the example according to Fig. 6 has a comparatively small gradient for positive values ​​and a comparatively high gradient for negative values ​​of the individual droop inverter deviation APxi. As a result, a positive individual droop inverter deviation APxi is assigned a frequency shift Af that is significantly smaller in magnitude than a negative individual droop inverter deviation APxi of the same magnitude. In alternative embodiments, the ratios of the gradients of the positive and negative halves of the droop asymmetry static 57.X can be set exactly inversely, if necessary.

[0076] The dynamics of the resulting voltage curve 3, which is set by the converter 30.X at the output of the inverter 10.X, thus depends, via the droop asymmetry droop 57.X, on the direction in which the exchange power PINV,X deviates from the respective droop characteristic reference power PSPT,X. The sign-dependent slope of the droop asymmetry droop 57.X allows for the individual setting of the contribution that the droop control 51.X makes to the instantaneous reserve power of the inverter 10.X for a given voltage curve deviation with a given positive or negative sign and a related individual power control deviation APINV,X.

[0077] In summary, by means of an asymmetry statics according to Fig. 5 or Fig. 6, in particular with the inertia asymmetry statics 55.X and / or the droop asymmetry statics 57.X, a different weighting of the deviation of the exchange power PINV,X from the respective inverter target power PSPT,INV,X can be carried out depending on the sign of the voltage curve deviation, for example depending on the sign of a grid frequency gradient. The weighting can differ by at least a factor of 2, preferably by a factor of 5. Particularly preferably, the weighting can be expressed, for example, as the amount of an inertia orFrequency constant or as a gradient of the asymmetry statics, can be different by at least a factor of 10, so that the provision of an asymmetric instantaneous reserve power can be set in particular in such a way that an instantaneous reserve power is generated largely exclusively with one sign of the voltage curve deviation and is significantly reduced or even completely absent in the case of an opposite voltage curve deviation with the other sign.

[0078] Figure 7 shows an embodiment of the method according to the application, in which the asymmetry statics 55. X and / or 57. X are additionally dependent on the mains frequency f Netz and optionally depend on the exchange power PINV,X of the inverter 10.X. Depending on the current grid frequency fGrid, instantaneous reserve power is only provided due to a grid frequency gradient and the resulting individual power control deviation APINV,X or droop inverter deviation APxi if the grid frequency f Netz deviates from a nominal frequency in the same direction as the grid frequency gradient, for example when there is an overfrequency and the grid frequency fgrid continues to rise. Conversely, an instantaneous reserve power intended on the basis of the asymmetry droop can be suppressed if the grid frequency gradient points in the direction of the nominal frequency, for example when there is an overfrequency and an already falling grid frequency is not to be unnecessarily counteracted. The optional dependence of the asymmetry droop 55. X and / or 57. X on the exchange power PINV,X of the inverter 10.X can be used as a further degree of freedom, for example to define a power limitation and / or a dead band for the instantaneous reserve power, so that the instantaneous reserve power can be restricted to a maximum exchange power or only starts at a minimum exchange power.

[0079] Figures 16 and 17 show exemplary time courses of the setpoint and actual values ​​for a power supply system 11 and its inverters 10.1, 10.2 when using a method of one of Figures 5 to 7 with differently parameterized asymmetry statics 55. X, 57. X.

[0080] Figure 8 schematically shows another specific embodiment of the method according to the application. In contrast to Figures 4-7, the individual power control deviation AP| is calculated in the inertia-generating controller 53.X. N v,x is corrected to an adjustable extent by the individual deviation component APPOI,X of the system deviation APPOI. The individual deviation component APPOI,x of the system deviation APPOI results from the power control deviation APPOI at system connection point 26 and an individual standardization to the relative nominal power of the respective inverter 10.X.

[0081] In the plant controller 53.X, the individual power control deviation APINV.X, previously used exclusively in the inertia-generating controller 53.X, is now weighted with a first weighting factor Ki. The individual deviation component APPOI,x of the plant deviation APPOI,x is weighted with a second weighting factor K2. These weighted components are summed and multiplied in the inertia-generating controller 53.X, if necessary, by an inertia asymmetry static 55.X, and used as the individual deviation APx to generate the droop characteristic reference power PSPT,X as an output value via an integrator 1 / s and an inertia factor 1 / Ha. The sum of the weighting factors Ki and K2, with which the two control deviations are weighted, results in 1.

[0082] It is thus possible to compare the power control deviation APINV.X on the inverter 10.X with the power control deviation AP POi,x at the system connection point 26 should be weighted less, since the former path may have a greater delay. This then results in a higher weighting of the normalized power control deviation AP PO i,x at system connection point 26:

[0083] K 1 = K & < K2= l - K &

[0084] The system controller 28 sends the standardized, ie converted to the inverter 10.X, individual deviation component AP to the respective inverter 10.X. P oi,x of the plant deviation AP POi the power P P oi at grid connection 26 is transmitted relative to the plant setpoint PSPT.POI and, using the second weighting factor K2, is weighted relative to the individual power control deviation APINV.X in the inertia-generating control 53. X to calculate the droop characteristic reference power PSPT,X. This serves to ensure inertia accuracy at grid connection 26.

[0085] The transmission of this information can be useful in the presence of communication delays in the transmission of the individual exchange power PINV,X of the inverters 10.X in plant 11 to the plant controller 18. This can improve the dynamics of dispatching.

[0086] Alternatively or additionally, the individual deviation component APPOI, x of the system deviation APPOI of the power PPOI at the grid connection point 26 can also be formed in the inverter 10.X if the necessary signals, in particular the system deviation APPOI, are transmitted to the inverter 10.X.

[0087] The individual deviation APx of an inverter 10.X in the system 11 , which is then fed to the inertia integrator of the inertia-generating control 53.X of the inverter 10.X, can be calculated, for example, as follows: AP X = K a

[0088] Typically,

[0089] This allows the provision of an instantaneous reserve, also called plant-level inertia, and at the same time precise control of the inverter 10.X with the described power dispatching in the allocator 32 of the system controller 28, as well as precise control of the total exchange power PPOI at the grid connection 26.

[0090] Figure 8 also shows the optional delay element 34. This delays the system setpoint PSPT.POI by D sampling steps relative to the feedback signal of the total exchange power PPOI when forming the system deviation APPOI. This improves the dynamics of the control behavior in relation to the total exchange power PPOI at the grid connection 26.

[0091] The number of sampling steps D and thus the delay time can be adjusted depending on the communication delays during data transmission and signal processing between the system controller 28 and the inverter 10.X, as well as the dead times during the measured value acquisition of the total exchange power PPOI. A rate limiter of a feedforward control (see Figure 7) can also influence the selection of sampling steps D. The slower the feedforward control, the larger the number of sampling steps D should be.

[0092] This enables satisfactory operation despite delays in the transmission of required data between inverter 10.X and system controller 28. The tendency to oscillation is kept low and the response speed is improved.

[0093] Figure 19 shows exemplary time profiles of the setpoint and actual values ​​for a power supply system 11 and its inverters 10.1, 10.2 when using the method according to Fig. 8. Overall, the embodiment of the power supply system 11 according to Fig. 8 has a reduced tendency to oscillation, whereby dead times in the data transmission are taken into account and the synchronicity of different data channels is improved.

[0094] Figure 9 schematically shows an embodiment of the power supply system 11 with improved synchronization. By introducing a delay element 36 with the delay constant D2 in the system controller 28, the feedback of the total exchange power PPOI of the system can be delayed and thus better synchronized with the feedback of the measured exchange power PINV,X of the inverters 10.X. This can counteract oscillations. This delay element 36 can also be combined with other embodiments of this application.

[0095] By delaying the feedback of the total exchange power P POiBy D2 sampling steps through the delay element 36, the feedback of the total exchange power PPOI can be synchronized with the sum of the measured individual exchange powers PINV.X of the inverters 10.X, which are transmitted to the system controller 28 with a delay, particularly due to communication latencies. This can be used for the calculation of meaningful individual correction values ​​P C OR,X can be used. This improves the synchronization between the inverter-side and the system-side measurements. This reduces the tendency to oscillate during transient events, and improves the determination of the power loss PLOSS for precisely setting the total exchange power PPOI. Figure 18 shows exemplary time profiles of the setpoint and actual values ​​for a power supply system 11 and its inverters 10.1, 10.2 using the method according to Fig. 9.

[0096] Figure 10 schematically shows an embodiment of the energy supply system with pre-control to improve the control behavior of the energy supply system 10. By means of the embodiment shown with a double pre-control, which can intervene from the system controller 28 with adjustable weighting both in the respective inertia-generating control 53.X and in the respective droop control 51.X, a fast control behavior for the total exchange power P POi at the grid connection 26 and at the same time an inertia with regard to the disturbance behavior in the event of voltage curve deviations in the grid 24 can be realized.

[0097] Via the upper path shown in Figure 10, a feedforward control of the system setpoint PSPT.POI in the form standardized to the inverter 10.X PSPT.POI, x to the set voltage angle 3 and to the set droop characteristic reference power PSPT,X or alternatively to the set frequency f SPT of the grid voltage in the respective inverter 10.X. The system setpoint PSPT.POI, standardized for the inverter 10.X, is also referred to as the individual component PSPT.POI, x of the system setpoint PSPT.POI and is used here as a feedforward control value. The droop control 51.X converts the droop characteristic reference power PspT,x into a corresponding phase angle 3.

[0098] The feedforward control value and a first correction factor KXP are used to quickly adjust the droop characteristic reference power PSPT,X of the droop control 51. X to a changed system setpoint PSPT.POI, ie to a new load situation, so that the slow inertia integrator of the inertia control 53. X does not have to slowly adjust the droop characteristic reference power PSPT,X. The feedforward control value and a second correction factor K Xa, the phase angle A calculated by the droop control is directly adjusted to a changed plant setpoint PSPT.POI. This increases the dynamic response and reduces the tendency to oscillate.

[0099] For this purpose, the individual components PSPT.POI, x of the system setpoint PSPT.POI are transmitted from the system controller 28 to the inverters 10.X to the respective inverters 10.X. This corresponds to the relative nominal power of the system setpoint P S PT, POI standardized target power of the inverter 10.X. This enables pre-control for rapid implementation of the power setpoint specifications at grid connection 26. Furthermore, rapid control behavior for the individual exchange power PINV,X and thus the total exchange power PPOI is enabled.

[0100] About the first correction factor KXP and the second correction factor K X a the input tax paths can be weighted against each other.

[0101] Additional limiting elements can be used to limit the amplitude and rate of change of the feedforward control. This can reduce or prevent sudden changes, overshoot, and damping of resonance excitation.

[0102] Figures 20 to 22 show exemplary time profiles of the setpoint and actual values ​​for an energy supply system 11 and its inverters 10.1, 10.2 when using the method according to Fig. 10, wherein in Fig. 20 no communication delay is assumed and in Fig. 21 a significant communication delay in the transmission of the exchange power PINV,X of the inverters 10.1, 10.2 to the system controller 28 is assumed, and wherein the communication delay is taken into account in Fig. 22 by means of a delay element 36 (see Fig. 9).

[0103] Figure 11 shows an example of an embodiment of the energy supply system 11 in which various exemplary embodiments have been combined. In the embodiment according to Fig. 11, the double feedforward control of the inertia-generating control 53.X and the droop control 51.X shown in Fig. 10 is also modified such that the feedforward value is formed by a weighted sum of the individual inverter share in the system setpoint PSPT.POI,x and the individual inverter setpoint power PSPT,INV,X. The weighted sum is formed using two correction factors (3,K4), the sum of which is preferably equal to one. Other combinations of the illustrated exemplary embodiments are also possible, in particular with the use of an asymmetry static 55.X, 57.X in the inertia-generating control 53.X and / or in the droop control 51.X.

[0104] The exemplary embodiments illustrated in the figures offer satisfactory functionality with regard to the control and fault response of the power supply system 11, despite any communication-related delays in the transmission of required data between the inverter 10.X and the system controller 28. Even with any differences in the delay on different transmission channels, the tendency to oscillation is kept to a minimum. This applies in particular to the exemplary embodiment shown in Figures 11 or 12, where several functionalities are implemented together.

[0105] It is particularly advantageous that, even in the embodiment shown in Figure 11, where the individual functions from Figures 4 to 10 are implemented in combination, a decoupling of the individual functions is still achieved. This serves to reduce adverse interactions between them and results in a reduction in the tendency to oscillate, thus improving the adjustment speed.

[0106] Figures 23 and 24 show exemplary time courses of the setpoint and actual values ​​for an energy supply system 11 and its inverters 10.1, 10.2 when using the method according to Fig. 11 in different variants.

[0107] The following figures 12 to 24 show time courses of setpoints and actual values ​​of power P POiat a grid connection point 26 and power PINV,X at individual inverters 10.X of a power supply system 11. Using these figures, various properties of the controls according to Figs. 1 to 11 are discussed below. Without limiting the general validity, an exemplary power supply system 11 is considered, which comprises exactly two inverters 10.1, 10.2. The power of the inverters 10.1, 10.2 is controlled by their respective controls 50.1, 50.2, which in turn are influenced by the system controller 28, so that the total exchange power of the power supply system 11 with the grid 24 is controlled by the system controller 28 and an instantaneous reserve power is provided at the grid connection 26.The energy supply system 11 may include further sinks or sources whose influence is summarized in a power loss PLOSS, for example components such as transformers, cables, auxiliary units or smaller generation units that are not controlled by the system control.

[0108] The upper graph ("Grid Frequency") in Figures 12 to 24 shows an example of the grid frequency of grid 24, referred to here as "f_GRID." The middle graph ("Plant Level") shows the time profiles of the plant setpoint PSPT.POI, referred to here as P_POI_REF, and the total exchange power P POi, referred to here as P_POI. The lower graph (“Inverter Level”) shows the time profiles of the two individual inverter target powers PSPT,INV,X, referred to here as P_1_REF and P_2_REF, and the two associated individual exchange powers PINV.X, referred to here as P_1 and P_2. Thus, P_1_REF and P_2_REF represent the target values ​​and P_1 and P_2 the actual values ​​of the inverters 10.1 and 10.2 of the energy supply system 11, whose target power P_POI_REF is essentially divided between the target values ​​P_1_REF and P_2_REF and whose total power P_POI at the grid connection point 26 essentially comprises the powers P_1 and P_2.

[0109] Figures 12 to 24 show resulting time profiles when applying various embodiments of the method according to the application in the energy generation plant 11. Active power is shown as an example, whereby the active power is standardized to the rated power of the plant 11 as a whole (plant level, middle image in each case) or to the rated power of the respective individual inverter 10.1, 10.2 (inverter level, lower image) (unit “pu” = “per unit”).

[0110] The time profiles of the grid frequency f_GRID and the plant setpoint P_POI_REF are identical in Figures 12 to 24. In addition, identical individual offset values ​​POFS,X (not shown) affect the distribution of the plant setpoint P_POI_REF to the individual inverter setpoint powers P_1_REF and P_2_REF.

[0111] The time courses in Figures 12 to 24 have the following sections, each with specific boundary conditions: t < t the grid frequency f_GRID corresponds to a nominal frequency f| N iT of the network 24 and is, for example, 50 Hz; the system setpoint P_POI_REF and the offset values ​​POFS.X are equal to zero.

[0112] Ti < t < t2: the grid frequency f_GRID continues to correspond to the nominal frequency f| N iT of network 24; the plant setpoint P_POI_REF is +0.3 pu; the offset values ​​POFS,X remain zero.

[0113] T2 < t < t3: the grid frequency f_GRID continues to correspond to the nominal frequency fiNu; the plant setpoint P_POI_REF remains +0.3 pu; the offset value POFS.I for inverter 10.1 has been changed from zero to +0.1 pu, the offset value POFS,2 for inverter 10.2 has been changed from zero to -0.1 pu. T3 < t < t4: the grid frequency f_GRID decreases at a constant rate from the nominal frequency f| NiT to a smaller value T; the system setpoint P_POI_REF remains +0.3 pu; the offset values ​​POFS,X remain +0.1 pu and -0.1 pu, respectively.

[0114] T4< t < ts: the grid frequency f_GRID has the difference compared to the nominal frequency f| N iT reduced value fi; the system setpoint P_POI_REF remains +0.3 pu; the offset values ​​POFS,X remain +0.1 pu and -0.1 pu, respectively.

[0115] T5< t < te: the grid frequency f_GRID continues to have the reduced value fi; the plant setpoint P_POI_REF remains +0.3 pu; the offset values ​​POFS.X have changed from + / -0.1 pu to zero.

[0116] T6< t < t?: the grid frequency f_GRID continues to have the reduced value fi; the plant setpoint P_POI_REF is changed to -0.2 pu; the offset values ​​POFS.X remain zero.

[0117] T? < t < ts: the grid frequency f_GRID increases at a constant rate from the frequency h to the nominal frequency fiNu; the plant setpoint P_POI_REF remains -0.2 pu; the offset values ​​POFS.X remain zero.

[0118] T > ts: the grid frequency f_GRID corresponds to the nominal frequency f| N iT of network 24; the plant setpoint P_POI_REF remains -0.2 pu; the offset values ​​POFS,X remain zero.

[0119] Fig. 12 shows the behavior of a power generation plant 11 with a conventional control system according to Fig. 1 , in which the control 20.X is designed to be voltage-impressing and the total exchange power P_POI is processed in the plant controller 28 by means of the controller 15. The controller 15 is designed as an integral controller or as a proportional-integral controller and regulates the deviation between the total exchange power P_POI and the plant setpoint P_POI_REF to zero by modifying the plant setpoint P_POI_REF accordingly in the event of such deviations, passing it on to the allocator 16 and dividing it there among the inverter setpoint powers P_1_REF, P_2_REF taking into account the offset values ​​POFS.X.

[0120] Fig. 12 shows that by amplifying the integral component in controller 15 of system controller 28, rapid control behavior when the system setpoint P_POI_REF changes and rapid compensation of the control error of the total exchange power P_POI is achieved, see in particular the curve of the total exchange power P_POI at times h and te. On the other hand, the curve of the total exchange power P_POI at times ti and te shows a clear overshoot. A further disadvantage of the behavior according to Fig. 12 of the power generation system 11 with a control system according to Fig. 1 is that the reactions of the voltage-impressing controls 20. X in the case of a frequency change between t3 and t4 or between t? and ts are perceived by the system controller 28 as a control deviation at the grid connection 28 and are corrected based on the integral component in the controller 15 by changing the individual inverter target powers P_1_REF, P_2_REF. In Fig.12, the total exchange power P_POI therefore corresponds to the system setpoint P_POI_REF shortly after times t3 and t7.

[0121] Fig. 13 shows the behavior of a power generation plant 11 with the control system according to Fig. 3 or Fig. 4, in which, particularly compared to the control system according to Fig. 1, no controller 15 with integral components is used in the plant controller 28. Instead, a control deviation between the total exchange power P_POI and the plant setpoint P_POI_REF is corrected in the plant controller 28, taking into account the measured individual exchange powers P_1, P_2 of the inverters 10.1, 10.2 transmitted to the plant controller 28, as well as the measured or determined total exchange power P_POI, by adjusting the individual inverter setpoint powers P_1_REF, P_2_REF in the allocator 32, additionally taking into account the respective offset values ​​POFS,X. This results in a high steady-state power accuracy both at the inverters 10.1, 10.2 and at the grid connection 26.The transient response after a change in the system setpoint P_POI_REF itself or the inverter setpoint powers P_1_REF, P_2_REF when changing the offset values ​​POFS.X depends on the parameterization of the grid-shaping control 50.X in the inverters 10.1, 10.2, in the embodiment according to Fig. 4 in particular on the inertia factor 1 / H. S so that a higher inertia constant H s an even slower response to the changed setpoint.

[0122] Fig. 14 shows the behavior of a power generation plant 11 with the control according to Fig. 4, in which an optional gain factor K cin the allocator 32 of the system controller 28 is used to calibrate the measured values ​​P_POI and / or P_1, P_2. This allows the contributions of the inverters 10.1, 10.2 to the system target power P_POI_REF, determined in the allocator 32, to be standardized and, if necessary, offset-shifted, to be corrected by an adjustable, standardized control deviation between the total exchange power P_POI and the system target value P_POI_REF, in particular to compensate for any measurement inaccuracies at the inverters 10.1, 10.2 and / or at the grid connection 26, if necessary, with adjustable weighting. The amplification factor K c initially has the value 0 at time ti, ie a given deviation of the sum of the exchange powers P_1 , P_2 of the inverters 10.1 , 10.2 from the total exchange power P_POI is not compensated. In the middle between t1 and t2, the gain factor K cfrom 0 to 0.5. This reduces the deviation between the total exchange power P_POI and the plant setpoint P_POI_REF for a given power loss PLOSS, which, however, remains undercompensated. In the middle between t5 and t6, the gain factor K c from 0.5 to 1, so that the power loss PLOSS is exactly compensated and the total exchange power P_POI in the steady state corresponds to the system setpoint P_POI_REF. Halfway between t6 and t7, the gain factor Kc is changed from 1 to 1.5, so that the deviation of the sum of the exchange powers P_1, P_2 of the inverters 10.1, 10.2 from the total exchange power P_POI is overcompensated. This example is idealized in that no measurement inaccuracies occur and therefore with a gain factor K c with the value 1 the power loss PLOSS is exactly compensated.

[0123] The use of the control system shown in Fig. 4 is particularly suitable for energy supply systems 11 with low communication delays in the transmission of information between the system controller 28 and the inverters 10.X. However, if the feedback of the actual power values ​​P_1, P_2 to the system controller 28 is delayed, oscillations may occur, and the control and disturbance behavior may be slowed down overall.

[0124] Fig. 15 shows the behavior of a power generation plant 11 in which the inverters 10.1, 10.2 each have a grid-shaping control 50. X, which is designed, for example, according to Fig. 4, wherein the inverters 10.1 and 10.2 have different inertia factors 1 / H SAs a result, inverter 10.1 reacts to the frequency changes between t3 and t4 or between t? and ts with a significant symmetrical change in its exchange power P_1, while inverter 10.2 shows virtually no reaction to the frequency changes between t3 and t4 or between t? and ts. The energy generation system 11 as a whole therefore generates a symmetrical instantaneous reserve power at the grid connection 26, which essentially consists of the symmetrical contribution of inverter 10.1 and, in particular, counteracts a grid frequency gradient.

[0125] Figures 16 and 17 show the behavior of a power generation plant 11 with a control according to one of Figures 5 to 7, whereby by different setting of the asymmetry statics 55.X and / or 57.X in the controls 50.1, 50.2 of the inverter

[0126] 10.1. 10.2 various asymmetric instantaneous reserve powers are provided by the inverters 10.1. 10.2, which in turn result in a symmetric or asymmetric instantaneous reserve power of the energy generation plant 11 at the grid connection 26.

[0127] Fig. 16 shows the behavior of a power generation plant 11 in which the inverters

[0128] 10.1, 10.2 have identical asymmetry droops, which are configured so that the inverters 10.1, 10.2, and thus the power generation plant as a whole, provide asymmetric instantaneous reserve power. Specifically, the asymmetry droops are configured so that the inverters 10.1, 10.2 react to the positive grid frequency gradient between t7 and t8 with a significantly larger change in the exchange powers P_1 and P_2 than to the negative grid frequency gradient between t3 and t4. This behavior can be particularly advantageous for providing an overall asymmetric instantaneous reserve power by means of the power generation plant.

[0129] Fig. 17 shows the behavior of a power generation plant 11 in which the inverters 10.1, 10.2 have different asymmetry statics which are set up in such a way that the inverters 10.1, 10.2 each provide mirror-image asymmetric instantaneous reserve power, so that the power generation plant as a whole again provides symmetric instantaneous reserve power. Specifically, the asymmetry statics of the control 50.1 of the inverter 10.1 can be set such that the inverter 10.1 reacts to the negative grid frequency gradient between t3 and t4 with a significantly larger change in the exchange power P_1 than to the positive grid frequency gradient between t7 and t3, while the inverter 10.2 reacts in the opposite direction to the positive grid frequency gradient between t7 and t3 with a significantly larger change in the exchange power P_2 than to the negative grid frequency gradient between t3 and t4.The total exchange power P_POI behaves, in particular with regard to the grid frequency changes, independently of the sign of the grid frequency gradient, with changes of the same magnitude, so that the energy generation plant 11 as a whole provides a symmetrical instantaneous reserve power.

[0130] The behavior according to Fig. 17 can be advantageously applied in particular in a power generation plant 11 whose inverters 10.1, 10.2 can at least partially provide only asymmetrical instantaneous reserve power, e.g., due to limitations of the energy generators or consumers connected to the inverters 10.1, 10.2, which can, e.g., essentially only freely change their electrical power in one direction. Such a power generation plant 11 can nevertheless provide overall symmetrical instantaneous reserve power using the method according to the application, in that an asymmetrical behavior of individual inverters 10.1 is compensated by a mirror-image asymmetrical behavior of other inverters 10.2 of the power generation plant 11.

[0131] The fluctuations in the total exchange power P_POI occurring in Figures 15 and 16 at times t2 and ts are caused by the magnitude-varying behavior of inverters 10.1, 10.2 when changing the offset values ​​POFS.I and POFS,2. These fluctuations are inherently undesirable, since only the distribution of the system setpoint PSPT.POI between inverters 10.1, 10.2 should change, while the system setpoint PSPT.POI remains the same and the total exchange power P_POI should remain constant accordingly. Such undesirable fluctuations in the total exchange power P_POI can be reduced, in particular, by means of a feedforward control according to Figure 11.

[0132] Fig. 18 shows the behavior of a power generation plant 11 with a control system according to Fig. 9, in which possible communication delays can be taken into account by means of a delay element 36 with the delay constant D2 in the plant controller 28 in order to equalize the communication delays during the transmission of the actual power values ​​P_1, P_2 and the total exchange power P_POI. This significantly reduces oscillations, in particular, when the plant setpoint P_POI_REF changes.

[0133] Fig. 19 shows the behavior of a power generation plant 11 with a control system according to Fig. 8, in which—as an alternative or in addition to the delay element 36 according to Fig. 9—the individual power control deviation APINV.X in the inertia-generating controller 53.X of the inverters 10.X is corrected to an adjustable extent by the individual deviation component APPOI,X of the respective inverter 10.X to the plant deviation APPOI. This allows the tendency to oscillate to be further reduced, even with significant communication delays, particularly when the plant setpoint P_POI_REF changes, and the control behavior can be improved.

[0134] Fig. 20 shows the behavior of a power generation plant 11 with a control system according to Fig. 10, in which both the dynamics and the control behavior of the control system are further improved by means of a feedforward control, which intervenes from the plant controller 28 with adjustable weighting in both the respective inertia-generating control 53.X and the respective droop control 51.X. In the absence of significant communication delays in the power supply plant 11, the plant setpoint P_POI_REF is distributed among the inverters 10.1, 10.2 with high steady-state power accuracy, whereby a high steady-state power accuracy at the grid connection 26 is achieved by the feedback of both the total exchange power P_POI and the individual exchange powers P_1, P_2 of the inverters 10.1, 10.2 to the plant controller 28.In particular, the feedforward control achieves high dynamic response to changes in the system setpoint P_POI_REF and further improves the control behavior of the energy supply system 11. The dynamic response to changes in the power distribution between the inverters 10.1, 10.2 and to changes in the grid frequency occurs according to the set inertia of the inertia-generating controllers 53.X in the inverters 10.X. Fig. 21 shows the behavior of the energy generation system 11 with the control according to Fig. 10, whereby, in contrast to Fig. 20, there is a significant communication delay in the transmission of the exchange power P_1, P_2 of the inverters 10.1, 10.2 to the system controller 28.As a result, changes in the system setpoint P_POI_REF, for example, at times ti and te, result in oscillations in the exchange powers P_1, P_2, particularly a dynamic undershoot, which may potentially also extend into the total exchange power P_POI. Furthermore, this slows down the control and disturbance behavior, and thus the transient response, of the power supply system 11 overall.

[0135] Fig. 22 shows the behavior of the power generation plant 11 with the control according to Fig. 10 in the presence of a significant communication delay, wherein the communication delays are additionally taken into account in the plant controller 28 by applying a delay element 36 to the measured or determined total exchange power P_POI according to Fig. 6.

[0136] Fig. 23 shows the behavior of the power generation plant 11 with the control according to Fig. 11 in the presence of a significant communication delay and with correction of the individual power control deviation APINV.X in the inertia-generating controller 53. X with Ki=0.3 and K2=0.7, but without a delay by the delay element 34.

[0137] Fig. 24 shows the behavior of the energy generation plant 11 with the control according to Fig. 11 in the presence of a significant communication delay, wherein, in deviation from Fig. 21, the communication delays in the plant controller 28 are additionally taken into account by applying a delay element 36 to the measured or determined total exchange power P_POI according to Fig. 6.

[0138] LIST OF REFERENCE SYMBOLS

[0139] 10.X Inverter

[0140] 11 Energy supply system

[0141] 15 integral controllers

[0142] 16 allocators

[0143] 20.X Inverter control

[0144] AC network

[0145] 26 Mains connection

[0146] 28 System controller 30.X Converter 32 Distributor 34, 36 Delay elements

[0147] 50.X Inverter control

[0148] 51.X Droop control

[0149] 53.X inertia control

[0150] 55.X, 57.X Asymmetry- Statics

[0151] P|NV,X individual exchange power of the inverter PlNV sum of the individual exchange powers PPOI total exchange power PsPT.POl system setpoint

[0152] AS Voltage curve deviation $ Voltage curve PsPT.X Droop characteristic reference power PsPT,INV,X Inverter target power PcOR Total power deviation

[0153] Kl, K2, K3, K4 Weighting factor APPOI Plant deviation KXP Kxa Correction factors PSPT.POI ,x Individual standardized share of the plant setpoint APPOI,X Individual standardized share of the plant deviation APxi Individual droop inverter deviation A PlNV, X Power control deviation PoFS.X Individual offset value PN,X Nominal power of the inverter fsPT Setpoint frequency A PlNV, X Individual deviation Kf Frequency constant

[0154] Af frequency deviation

[0155] PLOSS power loss

Claims

PATENT CLAIMS 1. A method for operating an energy supply system (11) with a plurality of inverters (10.X) and a system controller (28) which is communicatively connected to the inverters (10.X), wherein the energy supply system (11) has a grid connection (26) which is connected to an AC voltage grid (24), and wherein the inverters (10.X) exchange electrical exchange power (PINV,X) with the AC voltage grid (24) via the grid connection (26), so that the energy supply system (11) exchanges a total exchange power (PPOI) with the AC voltage grid (24), which total exchange power comprises the respective electrical exchange powers (PINV,X), characterized in that the system controller (28) is dependent on a system setpoint (PSPT.POI) for the total exchange power (PPOI) of the energy supply system (11) determines individual inverter target powers (PSPT,INV,X), the system controller (28) transmits the individual inverter target powers (PSPT,INV,X) to the controls (50.X) of the inverters (10.X), the respective controls (50.X) of the inverters (10.X) set the respective exchange powers (PINV,X) of the inverters (10.X) depending on the inverter target powers (PSPT,INV,X), wherein the controls (50.X) of the inverters (10.X) are designed to be grid-forming and the inverters (10.X) provide individually adjustable instantaneous reserve power.

2. Method according to claim 1, wherein measured individual exchange powers (PINV.X) of the respective inverters (10.X) are transmitted to the system controller (28) and the system controller (28) continuously recalculates the inverter target powers (PSPT,INV,X) as a function of the measured exchange powers (PINV,X) and transmits them to the inverters (10.X).

3. Method according to claim 1 or 2, wherein the system controller (28) determines the inverter nominal power (PSPT,INV,X) by normalizing the system nominal value (PSPT.POI) to the respective relative nominal power of the respective inverter (10.X) and adding an individual offset value (POFS.X), the sum of the offset values ​​(POFS.X) preferably being zero.

4. Method according to one of claims 1 to 3, wherein the grid-shaping controls (50. X) react autonomously with an individually adjustable power response to grid events and in particular each comprise a droop control (51. X) and an inertia-generating control (53. X), 5. The method according to claim 4, wherein the inverters (10.X) set their respective exchange powers (PINV,X) by means of the respective droop control (51.X) on the basis of a droop characteristic as a function of a droop characteristic reference power (PSPT,X) and a respective voltage curve deviation of a voltage curve of a grid voltage from a respective reference curve with reference to a droop setpoint value (XSPT), wherein the droop setpoint value (XSPT) comprises in particular a setpoint frequency (fsp?) and / or a setpoint voltage amplitude (USPT), wherein the voltage curve deviation of the voltage curve is in particular a phase angle difference (A3) between the phase angle (A3) of the output voltage of the inverter (10.x) and the grid voltage or an amplitude difference between an amplitude of the output voltage of the inverter (10.X) and the grid voltage, wherein the phase angle difference (A3) orthe amplitude difference is represented in particular by the respective exchange power (PINV.X).

6. The method according to claim 4 or 5, wherein the inverters (10.X) vary an input value of the droop control (51.X), in particular the droop characteristic reference power (PSPT,X), by means of the inertia-generating control (53.X), depending on an individual power deviation (APINV,X) of the exchange power (PINV,X) of the respective inverter (10.X) from the inverter target power (PSPT,INV,X), in order to set the exchange power (PINV,X) of the inverters (10.X) to the respective inverter target power (PSPT,INV,X).

7. Method according to one of claims 4 to 6, wherein the grid-forming controls (50. X) comprise a sign-dependent weighting of the deviation of the individual exchange power (PINV,X) from the respective target power (PSPT,INV,X, PSPT,X), wherein the grid-forming controls (50. X) in particular comprise an asymmetry static (55. X, 57. X) which weights the deviation of the individual exchange power (PINV.X) from the respective target power (PSPT,INV,X, PSPT,X) differently depending on the sign of the voltage curve deviation.

8. The method according to claim 7, wherein the weighting for the different signs of the voltage curve deviation differs by at least a factor of 2, preferably by a factor of 5, particularly preferably by a factor of 10.

9. Method according to one of claims 7 or 8, wherein in the droop control (51 .X) the respective exchange power (PINV,X) is used as a measure of the voltage curve deviation and a respective deviation of the exchange power (PINV,X) from the droop characteristic reference power (PSPT,X) is weighted with a respective droop asymmetry static (57. X).

10. Method according to one of claims 7 to 9, wherein the individual power deviation (APINV,X) is weighted in the inertia-generating control (53.X) with a respective inertia asymmetry statics (55.X).

11. Method according to one of claims 7 to 10, wherein the asymmetry statics (55. X, 57. X) are additionally dependent on the mains frequency (f Ne tz) and / or the respective exchange performance (PINV.X).

12. Method according to one of claims 4 to 6, wherein the power control speed of the droop control (51.X) is faster than the power control speed of the inertia-generating control (53.X), so that the adjustment of the exchange power (PINV.X) by the droop control (51.X) upon occurrence of a phase angle difference (A3) is faster than the variation of the droop characteristic reference power (PSPT,X) by the inertia-generating control (53.X) upon occurrence of an individual power deviation (APINV.X) of the measured individual exchange power (PINV.X) from the inverter target power (PSPT,INV,X), in particular when this power deviation (APINV.X) is caused by a reaction to a phase angle difference (A3).

13. Method according to one of the preceding claims, wherein the total exchange power (PPOI) of the energy supply system (11) is determined and, in particular, in the system controller (28) a total power deviation (PCOR) of the total exchange power (PPOI) from the sum of the measured exchange powers (PINV.X) of the inverters (10.X) is determined.

14. The method according to claim 13, wherein the total power deviation (POOR) is standardized to the respective relative nominal powers (PN.X) of the respective inverters (10.X) and the standardized partial power deviations (PCOR,X) thus determined are taken into account when determining the individual inverter target powers (PSPT.INV.X), in particular in the system controller (28).

15. The method according to any one of claims 4 to 14, wherein the respective inertia-generating controllers (53. X) vary the droop characteristic reference power (PSPT,X) of the droop controller (51. X) using a feedforward control with the product of an individual feedforward control value and a first correction factor (KXP).

16. The method according to claim 15, wherein the respective droop controls (51.X) determine the phase angle (3) of the output voltage of the inverter (10.x) using a feedforward control with the product of the individual feedforward control value and a second correction factor (Kxa).

17. The method according to claim 15 or 16, wherein the individual feedforward control value is formed by the individual share of the inverter in the system setpoint (PSPT,POI,X) or by a weighted sum of the individual share of the inverter in the system setpoint (PSPT,POI,X) and the individual inverter setpoint power (PSPT,INV,X), wherein the weighted sum is formed in particular by means of two correction factors (K3,K4), the sum of which is preferably equal to 1.

18. Method according to one of claims 4 to 17, wherein the input value of the droop control, in particular the droop characteristic reference power (PSPT,X), is varied within the scope of the inertia-generating control (S3.X) as a function of the product of a first weighting factor (Ki) and the power deviation (APINV.X) of the respective inverter (10.X) from the inverter target power (PSPT,INV,X).

19. The method according to claim 18, wherein the input value of the droop control, in particular the droop characteristic reference power (PSPT,X), is varied depending on the product of a second weighting factor (K2) and the individual share of the inverter in the system deviation (APPOI,X).

20. The method according to claim 19, wherein an input value of the inertia-generating control (53. X) is formed from a sum of the individual power deviation (APINV,X) and the individual share of the system deviation (APPOI,X) weighted by the weighting factors (Ki, K2), wherein the sum of the first weighting factor (K1) and the second weighting factor (K2) preferably results in the value one.

21. Method according to one of the preceding claims, wherein the electrical powers controlled by the method are pure active powers or pure reactive powers, and / or wherein the electrical powers controlled by the method represent a positive-sequence system power or a negative-sequence system power, 22. Method according to one of the preceding claims, wherein the electrical powers controlled by the method are represented by electrical currents within the scope of the method, in particular by active currents or reactive currents in positive sequence system components and / or in negative sequence system components.

23. Energy supply system (11) with a plurality of inverters (10.X) and a system controller (28) which is communicatively connected to the inverters (10.X), wherein the energy supply system (11) is configured to be operated using a method according to one of the preceding claims.

24. Energy supply system (11) according to claim 23, wherein the controls (50.X) of the inverters (10.X) each have an asymmetry static (55.X, 57.X) and are designed to provide an individually adjustable symmetrical or asymmetrical instantaneous reserve power, wherein the energy supply system (11) is designed to provide an adjustable symmetrical or asymmetrical instantaneous reserve power at the grid connection (26).

25. Inverter (10.X) with a grid-shaping control (50.X) which comprises a droop control (51.X) and a superimposed inertia-generating control (53.X) for changing an input value of the droop control (51.X), in particular a droop characteristic reference power (PSPT,X), wherein the inverter (10.X) is designed for use in a power supply system (11) according to claim 23.

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