Hybrid power plants and methods for controlling hybrid power plants

Abstract

This invention relates to a hybrid power plant (100) for producing electricity to the grid, comprising multiple energy assets; a first renewable power generation unit, such as a wind turbine generator (WTG1, WTG2); and an energy storage unit (EA3, ESU), preferably a battery energy storage system (BES). The hybrid power plant has a power plant controller (PPC, 200) arranged to communicate with the multiple energy assets, and, when an underfrequency event occurs, the energy storage unit (ESU, BES) provides frequency support during an underfrequency event (UFE) by providing additional power (ΔP) as a function of the energy storage unit's state of charge (SoC) (SoC_mem) at the time of the underfrequency event. Therefore, in an underfrequency event, it is possible to obtain a more stable power output from the hybrid power plant.

Description

Technical Field

[0001] This invention relates to a hybrid power plant with multiple energy assets, including several renewable power generation units, each including a first renewable power generation unit and optionally a second renewable power generation unit and an energy storage unit (such as a large battery). The first renewable power generation unit includes multiple first wind turbine generators, and the second renewable power generation unit preferably includes a solar power unit. The invention also relates to corresponding methods for carrying out the invention, corresponding controllers, and corresponding computer program articles. Background Technology

[0002] Recently, as countries around the world are gradually transitioning to non-fossil energy systems, various renewable energy sources have gained increasing success in generating electricity for local power grids. However, power grids also have requirements for the effective integration of such renewable energy sources.

[0003] For example, the high penetration rate of wind turbines or wind turbine generators (WTGs) in the power grid has prompted requirements for wind turbine generators regarding how they should contribute to grid stability. These requirements are included in so-called grid specifications defined by transmission system operators (TSOs), which wind farms, sometimes referred to as wind farms, must adhere to when producing electricity for the grid.

[0004] Recently, a new trend has emerged in integrating various renewable energy sources into so-called hybrid power plants, which incorporate multiple energy assets, namely multiple power generation units (such as wind turbines and solar units) and energy storage systems (such as large batteries). Because local wind and solar energy can be complementary—for example, when winds are relatively strong and the sun may not be shining in the evening—there are expectations for the reliability of electricity produced by hybrid power plants.

[0005] Grid specifications may include requirements such as maintaining certain power transmission, voltage, and frequency, and may impose limits on the rate of change of these parameters, such as the so-called slope rate. These requirements are also expected to be imposed on future hybrid power plants; therefore, it is also important to be able to supply energy to these hybrid power plants in accordance with grid specifications.

[0006] Additionally, new challenges arise in integrating various power generation resources, such as wind and solar, due to their different characteristics, particularly their responsiveness to changing conditions and requirements. Overall, producing the maximum permissible amount of energy is also a primary objective, which can be challenging given the diverse power generation resources and their varying energy production qualities, such as stability over time, distance control within hybrid power plants, and response to changes and events in the power grid.

[0007] Therefore, improved hybrid power plants would be advantageous, especially more efficient and / or more reliable hybrid power plants.

[0008] Purpose of the invention

[0009] Another object of the present invention is to provide an alternative to the prior art.

[0010] In particular, the object of the present invention can be considered as providing a hybrid power plant that can solve the problem of generating electricity in accordance with grid specifications in the prior art, especially when changing certain parameters (such as frequency), while optimizing energy production. Summary of the Invention

[0011] Therefore, the above and several other objectives are intended to be achieved in the first aspect of the invention by providing a hybrid power plant connected to an associated power grid to produce electricity for said grid, the hybrid power plant comprising a plurality of energy assets including:

[0012] - The first renewable power generation unit, and

[0013] - An energy storage unit, preferably a battery energy storage system, is capable of storing energy from the first renewable power generation unit and supplying power to the grid when needed.

[0014] The hybrid power plant also includes a power plant controller arranged to communicate with the plurality of energy assets. The power plant controller is arranged to measure and / or receive information from the grid that an underfrequency event has occurred in the grid. When such an underfrequency event occurs, the power plant controller is further arranged to communicate with the energy storage unit to provide frequency support during the underfrequency event by providing additional power (ΔP) as a function of the charging state of the energy storage unit at the time of the underfrequency event.

[0015] This invention is particularly advantageous for obtaining hybrid power plants with different renewable power generation units, including energy storage units, wherein the hybrid power plant can provide improved frequency support during unpredictable underfrequency events, within predefined periods, by utilizing the energy storage units in a new and advantageous manner. Therefore, by implementing this invention, a more stable power output can be obtained from the hybrid power plant. This invention is not limited to, for example, startup situations, but can be implemented during normal power production and activated during underfrequency events, as will be understood by those skilled in the art. Regarding power production, simulations performed by the inventors and explained in more detail below show that, in certain circumstances, implementing this invention can advantageously improve the stability of power production, particularly frequency stability. Another advantage of this invention is providing sustainable and more predictable frequency support, even under multiple underfrequency events.

[0016] In the context of this invention, the term "underfrequency event" (UFE) can be defined as a deviation below a target frequency, preferably below a frequency dead zone defined by grid specifications and / or transmission system operator (TSO), such as approximately 50 Hz or approximately 60 Hz typically set by the TSO. Those skilled in the art will understand that these first-class dead zones for frequency control can be approximately 0.005 Hz, 0.01 Hz, 0.02 Hz, or 0.05 Hz, and even as low as 0.1 Hz or 0.5 Hz.

[0017] In the context of this invention, the term "hybrid power plant" will be broadly understood as a power plant capable of producing electricity for the power grid based on several energy sources, including but not limited to wind, solar, hydro, and thermal energy; that is, a hybrid power plant has a mixture of energy sources for electricity production. It should be understood that the hybrid power plant will be collectively controlled at some overall level of control to produce electricity, which is referred to in the present context as a power plant controller (PCC). Various energy assets may additionally or alternatively have some degree of local control, such as subordinate controllers. It should also be understood that a hybrid power plant can have a large geographical range; for example, the multiple energy assets may be distributed across several locations, such as 2, 5, 10, 15, or 20 kilometers apart, or even further, provided that the power plant controller can provide some degree of overall control according to the invention, particularly taking into account electrical losses and / or control and measurement delays.

[0018] In the context of this invention, a first renewable power generation unit includes multiple wind turbine generators, each wind turbine generator (WTG) comprising a tower and a rotor with at least one rotor blade (such as three blades). The rotor may be connected to a nacelle mounted on top of the tower and adapted to drive a generator located within the nacelle. The rotor is rotatable in the presence of wind. The rotational energy of the rotor blades caused by the wind is transferred to the generator via a shaft. Thus, the wind turbine generator is able to convert the kinetic energy of the wind into mechanical energy by means of the rotor blades, and subsequently into electrical energy by means of the generator. The generator may include a power converter for converting alternating current (AC) to direct current (DC) and a power inverter for converting DC to AC power injected into the power grid. The multiple wind turbine generators may be different or similar.

[0019] In the context of this invention, the second renewable power generation unit may include multiple solar energy units, each of which may have, for example, a photovoltaic (PV) solar panel, a concentrated solar power (CSP) unit, or other solar energy units capable of utilizing solar radiation and converting it into electrical energy.

[0020] In the context of this invention, an energy storage unit should be broadly understood as a unit capable of storing energy from a first and / or second renewable power generation unit that generates electricity during periods of surplus energy, and then storing the energy for a period of time until the demand for supplying energy to the power grid arises. Generally, the first and second renewable power generation units are renewable because they rely on renewable energy sources that are replenishable on a human timescale, such as from the sun, wind, rain, tides, waves, and / or geothermal resources.

[0021] Generally, energy storage units can also be used to store energy from the grid when energy is cheap and release it back into the grid when energy is expensive. This is known as "energy arbitrage." Therefore, it is understandable that for hybrid power plants relying on energy storage units, the stored energy may have a minimum size to ensure any significant use at a later time. Thus, it is assumed that the minimum amount of energy to be stored by the energy storage unit is 0.5 MWh, 1 MWh, 2 MWh, 3 MWh, 4 MWh, or 5 MWh. Similarly, the power supplied to the grid may be able to reach a minimum power level, such as at least 0.5 MW, 1 MW, 2 MW, 3 MW, 4 MW, or 5 MW, to impact the hybrid power plant in compliance with relevant grid regulations for electricity production. Alternatively, the ratio of energy storage unit power to the total power of the hybrid power plant may be at least 1%, 2%, 3%, 4%, or 5% to impact the grid. Alternatively, the ratio of energy storage unit power to the total power of the hybrid power plant can be up to 20%, 15%, 10%, 8%, 6%, 4%, or 2%, because energy storage units are typically the most expensive energy assets, both at any given moment and on average over a period of time.

[0022] Suitable energy storage units are preferably based on electrochemical storage, such as battery energy storage systems (BES), and more preferably include rechargeable lithium-ion batteries (LIBs). However, the present invention also considers other energy storage units, such as those based on mechanical storage (e.g., compressed air storage), electrical storage (e.g., so-called supercapacitors), thermal energy storage, or chemical energy storage (e.g., electricity-to-gas P2G), or other energy storage means suitable for energy storage in power plants and subsequent power delivery to the grid. When the energy storage unit is not based on electrical energy storage, such as compressed air or thermal storage, those skilled in the art will understand that the state of charge (SoC) can refer to a measurement of the amount of energy available to the energy storage unit.

[0023] In the context of this invention, the charging or discharging capability of an energy storage unit should be broadly interpreted as the amount of charge stored in the energy storage unit, and thus the amount of energy, and / or the rate of discharge or charging, typically a conventional measure of the energy storage unit's performance (e.g., energy / time). Note that the rate of discharge or charging of an energy storage unit (e.g., a battery) can be dynamic, i.e., it varies over time as a function of state of charge (SoC), maximum limits, user-defined limits, etc. Typically, the state of charge (SoC) is measured relative to the total capacity as a percentage, but other measures can also be used, such as the depth of discharge (DoD), which is the reciprocal of the SoC. It should be understood that energy storage units in this context typically have relatively high energy storage capabilities to have a significant impact on the power grid; therefore, the rate of discharge or charging and / or the state of charge (SoC) of an energy storage unit can be a combined or collective measurement for multiple distributed energy storage units (e.g., multiple BES, different or similar or identical BES), which will be readily understood by those skilled in the art of energy storage.

[0024] In the context of this invention, the first and second renewable power generation units and the energy storage unit can be collectively referred to as energy assets. In one embodiment, other energy assets, particularly fossil fuel-based (carbon-based) energy assets, can cooperate with the energy assets described in this invention, such as power generation units based on petroleum, coal, hydrocarbon gases, etc. In this technical field, energy assets can also be referred to as "energy actuators," a point that will be readily understood by those skilled in the art. These two terms will be used interchangeably in the following detailed description.

[0025] Similarly, within the context of this invention, the first energy asset can be considered a first renewable power generation unit. The first renewable power generation unit can then subsequently include multiple wind turbine generators (WTGs). These wind turbine generators can then again share or have common characteristics, such as multiple very similar or identical wind turbine generators in a large wind turbine array or wind farm. Likewise, the second energy asset can be considered a second renewable power generation unit. The second renewable power generation unit can then subsequently include multiple solar energy units. These solar energy units can then again share or have common characteristics, such as multiple very similar or identical solar energy units in a large solar energy array, such as PV units.

[0026] Available power should be understood as the amount of electricity that a renewable power generation unit can produce. Available power may vary over time. For wind turbine generators, it may depend on wind speed and / or wind direction; for solar units, it may depend on solar irradiance.

[0027] In one embodiment, the first renewable power generation unit may include multiple wind turbine generators, which are a preferred type of renewable power generation unit. Additionally or alternatively, the hybrid power plant may include a second renewable power generation unit, distinct from the first, which preferably includes multiple solar energy units as described above, such as photovoltaic (PV) solar panels, concentrated solar power (CSP) units, or other solar energy units capable of utilizing solar radiation and converting it into electrical energy. In other embodiments, the energy storage unit may also be capable of storing energy from the second renewable power generation unit, and the power plant controller may be further arranged to communicate with the second renewable power generation unit.

[0028] In a preferred embodiment, the additional power (ΔP) may be provided as a function of the state of charge (SoC) of the energy storage unit at the time of the underfrequency event throughout the entire duration of the underfrequency event. Therefore, those skilled in the art will understand that, depending on the duration of a typical underfrequency event and the frequency support required in terms of the corresponding power, it is possible to determine the recommended size and / or configuration of the energy storage unit for this embodiment. Alternatively, the additional power (ΔP) may be provided as a function of the state of charge (SoC) of the energy storage unit at the time of the underfrequency event for at least a portion of the duration of the underfrequency event (such as a calculated or estimated average UFE), such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the underfrequency event.

[0029] In other embodiments, the function may be a linear function of the charging state of the energy storage unit at the time of the underfrequency event, as this allows the energy storage unit to respond simply and robustly during the underfrequency event. It should be understood that this invention will typically be implemented in conjunction with other frequency control methods in actual hybrid power plants for other purposes, either internally due to plant constraints such as safety / production limitations, and / or externally from the TSO. Therefore, it should be understood that alternative frequency control regimes can be implemented in hybrid power plants, and the control of this invention is activated only during the UFE and without being overridden or downgraded by other frequency control regimes. Preferably, the slope of the linear function depends on the grid frequency (f), for example, by providing a frequency response table (lock-in table, LUT) or other dependencies available to a technician. Alternatively or additionally, the slope of the linear function may further depend on the configuration of the energy storage unit.

[0030] In some implementations, the power plant controller may be configured to maintain a predefined state of charge (SoC) from the energy storage unit to provide frequency support in the event of an underfrequency event. A SoC above the predefined SoC can be used for power generation from the hybrid power plant in the absence of an underfrequency event to ensure the stability of frequency support. Additionally, the power plant controller may be configured to prioritize charging the energy storage unit when the current SoC is lower than the predefined SoC from the energy storage unit to provide even further stability of frequency support during an underfrequency event.

[0031] In some implementations, the hybrid power plant may further include:

[0032] - A module for deriving estimates of electrical losses in hybrid power plants;

[0033] - A module for deriving measurements of power losses in a hybrid power plant based on the difference between integrated power production from these multiple energy assets and power measurements at the point of common coupling (PoC), and

[0034] - A regulator, which is arranged in the active power control loop of the power plant controller to apply estimates and measurements of electrical losses, the active power control loop being arranged to control the active power production of the hybrid power plant at the point of common coupling.

[0035] The regulator is used to calculate the available power from the first renewable power generation unit and / or the second renewable power generation unit. Therefore, if the power estimate might differ from the actual measurement, for example due to electrical losses, this implementation can compensate for and / or reduce this, thereby obtaining a better value for the available power.

[0036] In a second aspect, the present invention relates to a method for controlling a hybrid power plant connected to a power grid to produce electricity for the grid, the hybrid power plant comprising a plurality of energy assets, the plurality of energy assets including:

[0037] - The first renewable power generation unit, and

[0038] - An energy storage unit, preferably a battery energy storage system, is capable of storing energy from the first renewable power generation unit and supplying power to the grid when needed.

[0039] The method includes:

[0040] - Communicate with these multiple energy assets

[0041] - Measure and / or receive information from the power grid, namely, that an underfrequency event has occurred in the power grid, and

[0042] - When such an underfrequency event occurs, frequency support is provided during the underfrequency event by providing additional power (ΔP) as a function of the state of charge (SoC) of the energy storage unit at the time of the underfrequency event.

[0043] In a third aspect, the present invention relates to a power plant controller for controlling an associated hybrid power plant connected to an associated power grid to produce electricity for said grid, the hybrid power plant comprising multiple energy assets, the multiple energy assets including:

[0044] - The first renewable power generation unit, and

[0045] - An energy storage unit, preferably a battery energy storage system, is capable of storing energy from the first renewable power generation unit and supplying power to the grid when needed.

[0046] The power plant controller is configured to communicate with the plurality of energy assets, to measure and / or receive information from the grid indicating that an underfrequency event has occurred in the grid, and, when such an underfrequency event occurs, to further communicate with the energy storage unit to provide frequency support during the underfrequency event by providing additional power (ΔP) as a function of the state of charge (SoC) of the energy storage unit at the time of the underfrequency event.

[0047] In a fourth aspect, the present invention relates to a computer program article adapted to enable a computer system comprising at least one computer having a data storage device connected thereto to control a hybrid power plant according to the first and / or second aspects of the invention.

[0048] A particular, but not limited, advantage of this aspect of the invention is that, since the invention can be carried out by a computer program article that enables a computer system to perform the operations of the second aspect of the invention when downloaded or uploaded to the computer system.

[0049] In another aspect, the present invention relates to a data storage medium on which a computer program article may be provided (i.e., on any kind of computer-readable medium) or via a network.

[0050] Various aspects of the present invention can be combined with each other in any way. These and other aspects of the invention will be readily apparent from the following description with reference to the described embodiments. Attached Figure Description

[0051] The invention will now be described in more detail with reference to the accompanying drawings. These drawings illustrate one mode of carrying out the invention and should not be construed as limiting other possible implementations that fall within the scope of the appended claims.

[0052] Figure 1 This is a simplified schematic diagram of a power plant controller (PPC) for a hybrid power plant according to an embodiment of the present invention.

[0053] Figure 2 This is the power-frequency chart according to the present invention.

[0054] Figure 3 This is a schematic diagram of a hybrid power plant according to another embodiment of the present invention.

[0055] Figure 4 is a more detailed diagram of a hybrid power plant according to another embodiment of the present invention.

[0056] Figure 5 This is a schematic diagram of frequency deviation and the state of charge (SOC) of the energy storage unit during an underfrequency event (UFE).

[0057] Figure 6 A graph (A) schematically illustrates the frequency deviation curve over time.

[0058] Figure 7-8 shows the response of the hybrid power plant to... Figure 6 Simulation plots of four different cases of the frequency deviation curve (A) in the image.

[0059] Figure 9 Schematic illustration of having with Figure 6 Another graph showing a similar frequency deviation curve over time (B),

[0060] Figure 10-11 shows the response of the hybrid power plant to... Figure 9 Simulation plots of four different cases of the frequency deviation curve (B) in the image, and

[0061] Figure 12 It is a schematic system diagram illustrating the outline / details of the operation of a computer program article according to the present invention or a method according to the present invention. Detailed Implementation

[0062] Figure 1 This is a simplified schematic diagram of a power plant controller (PPC) 200 for a hybrid power plant according to an embodiment of the present invention.

[0063] Reference Figure 3 As shown in Figure 4, the hybrid power plant 100 includes an arrangement with the multiple energy assets (in...) Figure 1The power plant controller PPC200 (not shown) communicates with the power plant controller, which is configured to receive an active power reference P_REF,ext preferably from the transmission system operator (TSO), and to calculate the hybrid power plant reference Prefhpp using the hybrid active power controller 210 based on, for example, the desired operating mode of the hybrid power plant (such as frequency control, active power reduction, etc.).

[0064] The power plant controller (PPC) 200 is further arranged to respond to a first comparison for allocating setpoints PrefPGS, PS_1, PS_2, particularly Pset1...Pset,n, to the first and second renewable energy generation units, and allocating one or more corresponding setpoints PS_3, PrefESS, particularly Pset,ess1...Pset,essn, to the energy storage unit ESU, as shown in the reference. Figure 3 -4, so that power can be delivered from the hybrid power plant according to the received active power reference P_REF,ext, which is converted to Prefhpp, as in Figure 1 As shown in the diagram, the hybrid dispatcher 220 receives the Prefhpp control signal and calculates the PrefPGS control signal for the power generation units and the PrefESS control signal for the energy storage units or the system ESS. At the next level, the PrefPGS signal is then distributed or dispatched to the individual power generation units, such as WTG or PV, via the PGS dispatcher 230. Similarly, the PrefESS signal is then distributed or dispatched to the energy storage units, such as multiple batteries, at lower levels via the ESS dispatcher 240.

[0065] Figure 2 This is an illustrative power-frequency diagram according to the present invention, wherein, as in Figure 1 As shown, the power plant controller PPC 200 is arranged to communicate with the plurality of energy assets. The power plant controller is arranged to measure and / or receive information from the grid, namely that an underfrequency event (UFE) has occurred in the grid 1000, as shown in the figure. Figure 3 When such an underfrequency event occurs, the power plant controller is further configured to communicate with the energy storage unit (ESU) or BES to provide frequency support during the underfrequency event (UFE) (e.g., an unexpected frequency drop) by providing additional power ΔP as a function of the energy storage unit's state of charge (SoC) (hereinafter referred to as SoC_mem) at the time of the underfrequency event. Figure 2 It is illustrated in the diagram.

[0066] Figure 3This is a schematic diagram of a hybrid power plant according to another embodiment of the present invention. The hybrid power plant 100 is connected to an associated power grid 1000 to produce electricity for the grid, and the hybrid power plant includes multiple energy assets EA1, EA2 and EA3.

[0067] Therefore, the first renewable power generation unit EA1 or 1RPGU is part of plant 100, that is, in this embodiment, multiple wind turbine generators, WTG1 and WTG2, and the second renewable power generation unit EA2, 2RPGU, that is, in this embodiment, multiple solar energy units, PV1 and PV2. For simplicity, only two wind turbine generators and solar energy units are shown in this embodiment. Of course, those skilled in the art will understand that, within the teachings and principles of this invention, any number of renewable power generation units can be considered in principle.

[0068] Furthermore, the energy storage unit ESU or system ESS is part of plant 100, preferably a battery energy storage system BES, which is capable of storing energy from the first and second renewable power generation units (i.e., from wind turbine generators WTG1 and WTG2 and from solar units PV1 and PV2), and the energy storage unit is arranged to supply power to the grid 1000 when needed. The energy storage unit is referred to as a third energy asset EA3.

[0069] The hybrid power plant 100 also includes a power plant controller (PPC) 200, which is arranged to communicate with the plurality of energy assets (i.e., receive information about their status / conditions) and typically send control signals to each of them. The power plant controller is specifically arranged to receive, for example, an active power reference provided by the grid operator (as indicated on the left side of the PPC), and accordingly assign active power setpoints P_S1, P_S2, and P_S3 to the plurality of energy assets, as shown in... Figure 1 and 3 As shown in the diagram. Hybrid power plant reference Prefhpp is also used as an intermediate control signal. It can be mentioned that in some implementations, the WTG dispatcher can form part of the controller PPC200. P_REF is from the grid operator (TSO) (i.e. Figure 1 The Pref(ext) in the name of the power plant controller 200 may be a reference received from the user, but it may also come from another controller, such as a frequency controller, as indicated by the signal name Pref_freq_ctrl. The power plant controller 200 may include a wind turbine generator WTG dispatcher 230a, a PV dispatcher 230b, and a BES dispatcher 240, as shown in... Figure 3 It is illustrated in the diagram.

[0070] Generally, PPC 200 is expected to communicate directly with WTG1 and WTG2, and it will communicate with the energy storage BES and PV1 and PV2 via dedicated BES and PV controllers (similar to the power plant controller PPC, but specifically for PV and BES). These dedicated controllers will then assign setpoints to the individual PV array converters or individual ES converters (i.e., the PV and ES system consists of multiple units, like a wind power plant system). In the illustrated embodiment, controller PPC 200 communicates via a setpoint splitter, which then further assigns setpoints PS_1, PS_2, and PS_3 to the dispatcher for each energy asset.

[0071] It also takes into account the possibility of assigning setpoints to the WTG via a local controller. That is, the master PPC assigns setpoints to one or more slave PPCs, for example, for a large wind farm with a large number of wind turbine generators (such as more than 20 wind turbine generators or more than 40 wind turbine generators).

[0072] Figure 4 is a more detailed view of a hybrid power plant according to another embodiment of the present invention. Figures 4 (4A and 4B) are schematic diagrams of a hybrid power plant according to another embodiment of the present invention. Therefore, in addition to Figure 3 In addition to the hybrid power plant shown, hybrid power plant 100 also specifically includes a module 310 for deriving an estimate of the electrical losses in the hybrid power plant. Furthermore, a module 320 is presented for deriving a measured value of the electrical losses in the hybrid power plant based on the difference between the combined power production Pprod from the multiple energy assets (here EA1 is a WTG actuator, EA2 is a PV actuator, and EA3 is a BES actuator) and the power measurement Pmeas at the common coupling point (PoC) with the grid 1000. Furthermore, the power plant controller includes a regulator 300, which is an active power controller, arranged to apply the estimate of electrical losses and the measured value of electrical losses to the active power control loop in the power plant controller 200, the active power control loop being arranged to control the active power production of the hybrid power plant 100 at the common coupling point.

[0073] Figure 5 This is a schematic diagram of the frequency deviation (top) and the state of charge (SoC) of the energy storage unit during an underfrequency event (UFE) (bottom), schematically represented as the frequency line falling below the dashed "limit" at t_UFE, for example, from the frequency dead zone of the TSO. The state of charge (SoC) of the energy storage unit at the occurrence of the underfrequency event is also schematically shown; "SoC_memory" or simply SoC_mem in the following text. The energy storage unit is... Figure 3The third energy asset EA3, more specifically, is the battery energy system BES that causes the power output Pout_BES. Similarly, the energy storage unit... Figure 4B The actuator shown is called a "BES actuator" and provides additional power to the grid when needed in the event of an underfrequency event (UFE).

[0074] Figure 6 A graph (A) schematically illustrates the frequency deviation curve over time (in seconds). Thus, starting from an initial frequency of 50 Hz at approximately t = 0 seconds, the frequency abruptly drops to 49 Hz, remains at this level for about 300 seconds, then gradually increases back to 50 Hz for about 500 seconds, before dropping again to 49 Hz at about 650 seconds. Finally, shortly before 800 seconds, the frequency returns to the ideal value of 50 Hz. This frequency represents a typical frequency event with two frequency drops experienced in some power grids.

[0075] Figure 7-8 illustrates the response of a hybrid power plant to the energy source from... Figure 6 Simulation graphs of four different cases of the frequency deviation curve (A). In these simulations, ΔP represents the reference signal transmitted from the power plant controller (PCC) to the energy storage unit, and Pprod represents the actual power delivered from the energy storage unit to the grid, both of which are essentially the same when the state of charge (SoC) is above zero. Therefore, in Figure 7, the SoC is initially 40% of the energy storage unit (e.g., the battery energy system (BES), while in Figure 8, the SoC is initially 100% of the energy storage unit (e.g., the battery energy system (BES)). For comparison, the present invention... Figure 7A and Figure 8A This is not enabled in the diagram to facilitate demonstration of the invention at SoC_mem percentages of 40% and 100%. Figure 7B and Figure 8B The effect of implementation. For simulations without the present invention enabled (“No SoCMemory”), the response is the state-of-the-art response under conditions of performing a full discharge (i.e., transferring 100% of the energy).

[0076] When from Figure 7B When considering the effects of the present invention, it can be observed that the initial response Pprod from BES is more limited to about 40% ( Figure 7A Initially 100%, but the energy is not depleted when the BES then experiences a second frequency drop after 500 seconds. Therefore, the present invention is based on... Figure 6 The frequency event UFE provides greater stability over a longer period. Similarly, in Figure 8, the effect of the invention is evident because the energy or SoC in the BES is relatively high when the frequency drops for the second time after 500 seconds, again resulting in better stability over time.

[0077] Figure 9Schematic illustration of having with Figure 6 Another graph showing a similar frequency deviation curve (B) over time, but with a total of three frequency drops, thus requiring higher capacity of energy storage units to support the frequency during this underfrequency event (UFE). This frequency also represents a typical frequency event experienced by some power grids, accompanied by a subsequent series of frequency drops.

[0078] Figure 10-11 again illustrates the hybrid power plant response at two different initial SoC levels. Figure 9 Simulation plots of the frequency deviation curve (B) for four different cases are shown; Figure 10 shows 100%, and Figure 11 shows 50%. Similarly, for these simulations, ΔP indicates the reference signal transmitted to the energy storage unit, and Pprod indicates the actual power transmitted from the energy storage unit to the grid; these are essentially the same when the state of charge (SoC) is above zero. Therefore, Figure 10A and 11A The invention is particularly effective in terms of stability because... Figure 9 During the UFE curve B shown, the energy storage unit is able to deliver electricity for a relatively long period, thereby providing frequency support to the grid. Therefore, for example... Figure 11B As observed, the energy storage unit produced approximately 100% of its energy during the initial frequency drop and was depleted after about 500 seconds, while... Figure 11A As can be seen, the energy storage unit ESU implementing the present invention will perform frequency support for more than 1500 seconds. Therefore, the energy saved from producing approximately 50% (in this case, SoC_mem is also 50%) during the initial downclocking allows for longer frequency support during UFE.

[0079] Figure 12 This is a schematic system diagram illustrating the outline / details of the operation of a computer program article according to the invention or a method according to the invention. Therefore, a method for controlling a hybrid power plant; the hybrid power plant 100 is connected to a power grid 1000 to produce electricity for said power grid, the hybrid power plant comprising multiple energy assets:

[0080] Sa first renewable energy generation unit, EA1, 1RPGU, and

[0081] The Sb energy storage unit, EA3, ESU, preferably a battery energy storage system BES, is capable of storing energy from the first renewable power generation unit and supplying power to the grid when needed.

[0082] The method includes

[0083] S1 communicates with these multiple energy assets.

[0084] S2 measures and / or receives information from the power grid that an underfrequency event (UFE) has occurred in the power grid, and

[0085] S3 When such an underfrequency event occurs, frequency support is provided during the underfrequency event UFE by providing additional power ΔP as a function of the charging state SoC SoC_mem of the energy storage unit at the time of the underfrequency event, as shown in Figures 7-8 and 10-11.

[0086] In summary, the present invention relates to a hybrid power plant 100 for producing electricity to the grid. The hybrid power plant includes multiple energy assets: a first renewable generation unit (such as a wind turbine generator, WTG1, WTG2) and an energy storage unit, EA3, ESU, preferably a battery storage system BES. The hybrid power plant has a power plant controller PPC, 200 arranged to communicate with the multiple energy assets, and, when an underfrequency event occurs, the energy storage unit (EA3, ESU, BES) provides frequency support during the underfrequency event UFE by providing additional power ΔP as a function of the charging state SoC_mem of the energy storage unit at the time of the underfrequency event. Figure 2 This is illustrated schematically. Therefore, during underfrequency events, it is possible to obtain more stable power output from hybrid power plants.

[0087] This invention can be implemented using hardware, software, firmware, or any combination thereof. This invention, or certain features thereof, can also be implemented as software running on one or more data processors and / or digital signal processors.

[0088] The various elements of embodiments of the present invention can be implemented physically, functionally, and logically in any suitable manner, such as in a single unit, in multiple units, or as part of a separate functional unit. The present invention can be implemented in a single unit or physically and functionally distributed among different units and processors.

[0089] Although the invention has been described in conjunction with specific embodiments, it should not be construed as being limited in any way to the presented embodiments. The scope of the invention should be interpreted in accordance with the appended set of claims. In the context of the claims, the terms "comprising" or "including" do not exclude other possible elements or steps. Furthermore, references such as "a" or "an" should not be construed as excluding a plurality. The use of reference numerals for elements shown in the drawings in the claims should also not be construed as limiting the scope of the invention. Moreover, individual features mentioned in different claims may be advantageously combined, and mentioning these features in different claims does not preclude the possibility and advantage of combining features.

Claims

1. A hybrid power plant (100) connected to an associated power grid (1000) to produce electricity for the grid, the hybrid power plant comprising multiple energy assets, said multiple energy assets including: - The first renewable power generation unit, and - An energy storage unit, capable of storing energy from the first renewable power generation unit and supplying electricity to the power grid when needed. The hybrid power plant also includes a power plant controller arranged to communicate with the plurality of energy assets, and a response mechanism that determines the grid frequency is below the dead zone frequency. Determine the first charging state of the energy storage unit; A first curve is defined, representing the additional power supplied by the energy storage unit to the grid according to the grid frequency, wherein the first slope of the first curve is based on the first state of charge of the energy storage unit; and Based on the first curve and the grid frequency, a first amount of power is supplied from the energy storage unit to the grid until the grid frequency returns to the dead zone frequency; and After the grid frequency returns to within the dead frequency range, in response to determining that the grid frequency is below the dead frequency: Determine the second charging state of the energy storage unit that is lower than the first charging state of the energy storage unit; A second curve is defined, representing the additional power supplied by the energy storage unit to the grid according to the grid frequency, wherein the second slope of the second curve is based on the second charging state of the energy storage unit and is lower than the first slope; and According to the second curve and the frequency of the power grid, a second amount of power is supplied from the energy storage unit to the power grid until the frequency of the power grid returns to the dead zone frequency.

2. The hybrid power plant according to claim 1, wherein, The first renewable power generation unit includes multiple wind turbine generators.

3. The hybrid power plant according to claim 1 or 2, wherein, The hybrid power plant includes a second renewable power generation unit, which differs from the first renewable power generation unit and includes multiple solar energy units.

4. The hybrid power plant according to claim 3, wherein, The energy storage unit is also capable of storing energy from the second renewable power generation unit, and the power plant controller is further arranged to communicate with the second renewable power generation unit.

5. The hybrid power plant according to claim 1 or 2, wherein, The power plant controller is configured to retain a predefined level of charge from the energy storage unit to provide frequency support in the event of an underfrequency event. The level of charge from the energy storage unit above the predefined level can be used to generate electricity from the hybrid power plant (100) in the absence of an underfrequency event.

6. The hybrid power plant according to claim 5, wherein, The power plant controller is configured to prioritize charging the energy storage unit when the current charging state is lower than the preset charging level from the energy storage unit.

7. The hybrid power plant according to claim 3, further comprising: - A module for deriving estimates of electrical losses in hybrid power plants. - A module for deriving measurements of power losses in a hybrid power plant based on the difference between integrated power production from the multiple energy assets and power measurements at the common coupling point, and - A regulator, arranged in the active power control loop of the power plant controller, applies estimates and measurements of electrical losses. The active power control loop is arranged to control the active power production of the hybrid power plant at the point of common coupling. The regulator (300) is used to calculate the available power from the first renewable power generation unit and / or the second renewable power generation unit.

8. The hybrid power plant according to claim 1, wherein the energy storage unit is a battery energy storage system.

9. A power plant controller (200) for controlling an associated hybrid power plant (100) connected to an associated power grid (1000) to produce electricity to the grid, the hybrid power plant comprising a plurality of energy assets, said plurality of energy assets including: - The first renewable power generation unit, and - An energy storage unit, capable of storing energy from the first renewable power generation unit and supplying electricity to the grid when needed. The power plant controller is configured to communicate with the plurality of energy assets and to respond to determining that the grid frequency is below the dead zone frequency: Determine the first charging state of the energy storage unit; A first curve is defined, representing the additional power supplied by the energy storage unit to the grid according to the grid frequency, wherein the first slope of the first curve is based on the first state of charge of the energy storage unit; and Based on the first curve and the grid frequency, a first amount of power is supplied from the energy storage unit to the grid until the grid frequency returns to the dead zone frequency; and After the grid frequency returns to within the dead frequency range, in response to determining that the grid frequency is below the dead frequency: Determine the second charging state of the energy storage unit that is below the first charging state of the energy storage unit; A second curve is defined, representing the additional power supplied by the energy storage unit to the grid according to the grid frequency, wherein the second slope of the second curve is based on the second charging state of the energy storage unit and is lower than the first slope; and According to the second curve and the frequency of the power grid, a second amount of power is supplied from the energy storage unit to the power grid until the frequency of the power grid returns to the dead zone frequency.

10. A computer program article adapted to enable a computer system comprising at least one computer having a data storage device connected thereto to control a hybrid power plant according to any one of claims 1-8.

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