Control method and device for frequency support of grid-connected system, computer device and medium

Abstract

This application relates to a control method, apparatus, computer equipment, and medium for frequency support in a grid-connected system. The grid-connected system includes an energy storage unit and a renewable energy generation unit. The energy storage unit includes a rechargeable battery pack and a discharge battery pack. The method includes: in response to a power regulation command for the grid-connected system, acquiring a first current state of charge (SOC) of the rechargeable battery pack, a second current SOC of the discharge battery pack, the maximum available power of the renewable energy generation unit, and grid frequency deviation data; determining a comprehensive SOC of the energy storage unit based on the first and second SOCs; and determining a target power regulation strategy for the grid-connected system based on the comprehensive SOC, frequency deviation data, and the maximum available power of the renewable energy generation unit, to control the power generation of the energy storage unit and the renewable energy generation unit. This method can extend the battery pack's lifespan while ensuring grid frequency stability.

Description

Technical Field

[0001] This application relates to the field of power control technology, and in particular to a control method, device, computer equipment and medium for frequency support in a grid-connected system. Background Technology

[0002] Currently, the high penetration rate of renewable energy generation, including wind power, in the power grid is leading to its increasing participation in grid frequency support. This reduces the reserve burden on synchronous generators and improves grid stability and reliability. Furthermore, with decreasing energy storage costs, energy storage batteries are widely used in the power grid, offering advantages in mitigating the impact of renewable energy generation fluctuations in grid frequency regulation scenarios.

[0003] However, related technologies typically fix the state of charge (SOC) and charge / discharge power of energy storage batteries without considering battery aging. Furthermore, energy storage batteries only participate in frequency support for a short period of time, which results in low support efficiency of energy storage batteries in frequency support. Frequent charge / discharge cycles also accelerate battery aging and can easily lead to safety hazards. Summary of the Invention

[0004] Therefore, it is necessary to provide a control method, device, computer equipment, and medium for grid-connected system frequency support that can extend the service life of energy storage batteries while ensuring grid frequency stability, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a control method for frequency support in a grid-connected system. The grid-connected system includes an energy storage unit and a renewable energy generation unit. The energy storage unit includes a rechargeable battery pack and a discharge battery pack. The rechargeable battery pack is used to store electrical energy generated by the renewable energy generation unit and / or the power grid to which the grid-connected system is connected. The discharge battery pack is used to supply electrical energy to the power grid. The method includes:

[0006] In response to power regulation commands for the grid-connected system, the system acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0007] The combined state of charge of the energy storage unit is determined based on the first current state of charge and the second current state of charge.

[0008] Based on the comprehensive state of charge, frequency deviation data, and the maximum available power of renewable energy generation units, the target power regulation strategy of the grid-connected system is determined;

[0009] According to the target power regulation strategy, the power generation of energy storage units and renewable energy generation units is controlled to compensate for the frequency deviation of the power grid.

[0010] In one embodiment, determining the overall state of charge of the energy storage unit based on a first current state of charge and a second current state of charge includes: determining a first remaining state of charge of the rechargeable battery pack based on the first current state of charge and a preset depth of discharge; determining a second remaining state of charge of the discharge battery pack based on the second current state of charge and a preset depth of discharge; and determining the overall state of charge of the energy storage unit based on the difference between the first remaining state of charge and the second remaining state of charge.

[0011] In one embodiment, the target power regulation strategy of the grid-connected system is determined based on the integrated state of charge, frequency deviation data, and the maximum available power of the renewable energy generation unit, including: determining the power regulation demand based on the frequency deviation data and the preset frequency regulation threshold; and determining the target power regulation strategy of the grid-connected system based on the integrated state of charge, power regulation demand, and the maximum available power of the renewable energy generation unit.

[0012] In one embodiment, determining power regulation demand based on frequency deviation data and a preset frequency regulation threshold includes: determining a first demand for power regulation when the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold; wherein the first demand includes increasing or decreasing the power generation of the grid-connected system; and determining a second demand when the absolute value of the frequency deviation data is less than or equal to the preset frequency regulation threshold; wherein the second demand includes maintaining the power generation of the grid-connected system.

[0013] In one embodiment, the preset frequency regulation threshold includes a first preset frequency regulation threshold and a second preset frequency regulation threshold; when the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold, determining the power regulation demand as the first demand includes: when the frequency deviation data is greater than the first preset frequency regulation threshold, determining the power regulation demand as reducing the power generation of the grid-connected system; when the frequency deviation data is less than the second preset frequency regulation threshold, determining the power regulation demand as increasing the power generation of the grid-connected system.

[0014] In one embodiment, when the power regulation demand is the second demand, the target power regulation strategy of the grid-connected system is determined based on the overall state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the energy storage unit from the overall state of charge to a preset state of charge; when the power regulation demand is the first demand, the target power regulation strategy of the grid-connected system is determined based on the overall state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the power generation of the grid-connected system to the power corresponding to the first demand.

[0015] In one embodiment, the power regulation command includes at least two of a primary frequency modulation power command, a secondary frequency modulation power command, and a scheduling power command.

[0016] Secondly, this application also provides a control device for frequency support of a grid-connected system. The grid-connected system includes an energy storage unit and a renewable energy generation unit. The energy storage unit includes a rechargeable battery pack and a discharge battery pack. The rechargeable battery pack is used to store electrical energy generated by the renewable energy generation unit and / or the power grid to which the grid-connected system is connected. The discharge battery pack is used to supply electrical energy to the power grid. The device includes:

[0017] The acquisition module is used to acquire, in response to power regulation commands for the grid-connected system, the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0018] The state determination module is used to determine the overall state of charge of the energy storage unit based on the first current state of charge and the second current state of charge.

[0019] The strategy determination module is used to determine the target power regulation strategy of the grid-connected system based on the integrated state of charge, frequency deviation data and the maximum available power of renewable energy generation units;

[0020] The control module is used to control the power generation of the energy storage unit and the renewable energy generation unit according to the target power regulation strategy in order to compensate for the frequency deviation of the power grid.

[0021] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0022] In response to power regulation commands for the grid-connected system, the system acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0023] The combined state of charge of the energy storage unit is determined based on the first current state of charge and the second current state of charge.

[0024] Based on the comprehensive state of charge, frequency deviation data, and the maximum available power of renewable energy generation units, the target power regulation strategy of the grid-connected system is determined;

[0025] According to the target power regulation strategy, the power generation of energy storage units and renewable energy generation units is controlled to compensate for the frequency deviation of the power grid.

[0026] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0027] In response to power regulation commands for the grid-connected system, the system acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0028] The combined state of charge of the energy storage unit is determined based on the first current state of charge and the second current state of charge.

[0029] Based on the comprehensive state of charge, frequency deviation data, and the maximum available power of renewable energy generation units, the target power regulation strategy of the grid-connected system is determined;

[0030] According to the target power regulation strategy, the power generation of energy storage units and renewable energy generation units is controlled to compensate for the frequency deviation of the power grid.

[0031] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0032] In response to power regulation commands for the grid-connected system, the system acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0033] The combined state of charge of the energy storage unit is determined based on the first current state of charge and the second current state of charge.

[0034] Based on the comprehensive state of charge, frequency deviation data, and the maximum available power of renewable energy generation units, the target power regulation strategy of the grid-connected system is determined;

[0035] According to the target power regulation strategy, the power generation of energy storage units and renewable energy generation units is controlled to compensate for the frequency deviation of the power grid.

[0036] The aforementioned control method, apparatus, computer equipment, and medium for frequency support in a grid-connected system, in response to a power regulation command for the grid-connected system, acquire a first current state of charge (SOC) of the rechargeable battery pack, a second current SOC of the discharge battery pack, the maximum available power of the renewable energy generation unit, and frequency deviation data of the power grid. The rechargeable battery pack is used to store electrical energy generated by the renewable energy generation unit and / or the power grid connected to the grid-connected system, while the discharge battery pack is used to supply electrical energy to the power grid. Based on the first and second current SOCs, the comprehensive SOC of the energy storage unit is determined. Based on the comprehensive SOC, frequency deviation data, and the maximum available power of the renewable energy generation unit, a target power regulation strategy for the energy storage unit and the renewable energy generation unit in the grid-connected system is determined. Based on the target power regulation strategy, the power generation of the energy storage unit and the renewable energy generation unit is controlled to compensate for the frequency deviation of the power grid. Therefore, firstly, designing the energy storage unit as a physically decoupled structure of rechargeable and discharge battery packs avoids the technical problem of accelerated battery aging caused by frequent charge-discharge cycles when responding to grid frequency deviations, which is common in related technologies. Secondly, determining the comprehensive state of charge (SOC) of the energy storage unit based on the individual SOCs of the rechargeable and discharge battery packs provides a quantitative indicator that can comprehensively evaluate the operating status and regulation capability of the energy storage unit. Furthermore, based on the comprehensive SOC, frequency deviation data, and the maximum available power of the renewable energy generation unit, the grid-connected system can collaboratively decide on the target power regulation strategy based on the grid frequency deviation data and its own operating status and regulation capability. This ensures that the grid-connected system responds quickly and reliably to power regulation commands while mitigating the lifespan degradation of the battery packs in the energy storage unit, thereby achieving a dynamic balance between frequency support efficiency and energy storage cost. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is an application environment diagram of the control method for frequency support in a grid-connected system in one embodiment;

[0039] Figure 2 This is a flowchart illustrating a control method for frequency support in a grid-connected system in one embodiment.

[0040] Figure 3 This is a schematic diagram of the power regulation signal of the energy storage unit in one embodiment;

[0041] Figure 4 This is a schematic diagram of the operation simulation of the energy storage unit in one embodiment;

[0042] Figure 5 This is a flowchart illustrating the process of determining the overall state of charge in one embodiment;

[0043] Figure 6a This is a schematic diagram of the power regulation process of the energy storage unit under extremely high integrated state of charge in one embodiment;

[0044] Figure 6b This is a schematic diagram of the power regulation process of the energy storage unit under extremely low overall state of charge in one embodiment;

[0045] Figure 7 This is a flowchart illustrating the control method for frequency support in a grid-connected system in another embodiment;

[0046] Figure 8 This is a structural block diagram of a control device for frequency support in a grid-connected system in one embodiment;

[0047] Figure 9 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0049] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0050] The grid-connected system frequency support control method provided in this application embodiment can be applied to, for example... Figure 1In the application environment shown, terminal 102 communicates with server 104 via a network. A data storage system can store the data that server 104 needs to process. The data storage system can be integrated onto server 104, or it can be located on the cloud or other network servers. Terminal 102 can be, but is not limited to, various personal computers, laptops, smartphones, tablets, etc. Server 104 can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services.

[0051] In some embodiments, server 104 may be located on the power grid side, on the grid connection side, or at a remote operation and maintenance terminal.

[0052] In one exemplary embodiment, such as Figure 2 As shown, a control method for frequency support in a grid-connected system is provided, which is then applied to... Figure 1 Taking server 104 as an example, the following steps are taken: S201-S204. Wherein:

[0053] S201, in response to a power regulation command for the grid-connected system, acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0054] In some embodiments, the power regulation command is a control command for the grid-connected system triggered by real-time fluctuations in the grid frequency. Optionally, the power regulation command can originate from... Figure 1 Terminal 102 in the middle.

[0055] The grid-connected system includes an energy storage unit and a renewable energy generation unit. The renewable energy generation unit is used to convert renewable energy into electrical energy. For example, the renewable energy generation unit can be a wind farm. The energy storage unit includes a rechargeable battery pack and a discharge battery pack. The rechargeable battery pack only performs charging cycles and is used to absorb and store electrical energy generated by the renewable energy generation unit and / or the grid to which the grid-connected system is connected. The discharge battery pack only performs discharging cycles and is used to release electrical energy to the grid in response to power regulation commands.

[0056] The maximum available power of a renewable energy generation unit is the maximum theoretical power that renewable energy can still generate in maximum power point tracking mode.

[0057] For example, after responding to a power regulation command for the grid-connected system, the real-time state of charge (SOC) of the charging battery pack (i.e., the first current SOC), the real-time SOC of the discharging battery pack (i.e., the second current SOC), the maximum available power of the renewable energy generation unit, and the grid frequency deviation data can be obtained. The grid frequency deviation data is the difference between the actual frequency and the rated frequency of the grid. If the grid side has computing capabilities, the frequency deviation data can be obtained directly from the grid side; if the grid side does not have computing capabilities, the real-time frequency of the grid can be obtained from the grid side, and the frequency deviation data can be calculated based on the real-time frequency and the rated frequency stored locally.

[0058] Optionally, the first current state of charge and the second current state of charge can be calculated using the following formula (1).

[0059] (1)

[0060] in, Indicates either the first current state of charge or the second current state of charge. Indicates the initial state of charge of a rechargeable or discharged battery pack, and indicates the power regulation signal of the energy storage unit. .

[0061] like Figure 3 The diagram shows the power regulation signal of the energy storage unit. The horizontal axis represents time (t), and the vertical axis represents the power regulation signal of the energy storage unit. Figure 3 It can be seen that the power regulation signal of the energy storage unit frequently alternates between positive and negative over time. The charging battery pack absorbs electrical energy only when the value of the power regulation signal of the energy storage unit is negative, while the discharging battery pack releases electrical energy only when the value of the power regulation signal of the energy storage unit is positive. This decouples the charging and discharging processes of the energy storage unit, eliminating the need for the same battery pack to frequently switch between charging and discharging over time.

[0062] S202, determine the overall state of charge of the energy storage unit based on the first current state of charge and the second current state of charge.

[0063] The first and second current states of charge are used to characterize the operating states of the charging battery pack and the discharging battery pack, respectively. However, in order to evaluate the overall operating state of the energy storage unit, it is necessary to determine the comprehensive state of charge of the energy storage unit based on the first and second current states of charge, so as to characterize the overall operating state of the energy storage system.

[0064] For example, mathematical operations can be performed on the first current state of charge and the second current state of charge to obtain the combined state of charge of the energy storage unit. For instance, a weighted sum of the first current state of charge and the second current state of charge can be performed to obtain the combined state of charge.

[0065] like Figure 4 The diagram shows a simulation of the energy storage unit's operation. The rechargeable battery pack ESA and the discharge battery pack ESB in the energy storage unit are connected to the AC bus via a PCS (Power Conversion System). The bus enables power exchange (i.e., energy exchange) between the energy storage unit, the renewable energy generation unit, and the grid. In the first operating condition, the charging energy of the rechargeable battery pack is equal to the discharging energy of the discharge battery pack. Under this condition, the energy storage unit operates optimally; the rechargeable battery pack is not overcharged, and the discharge battery pack is not over-discharged, which helps to delay battery aging and extend its lifespan. In the second operating condition, the charging energy of the rechargeable battery pack is greater than the discharging energy of the discharge battery pack. Under this condition, the total energy of the energy storage unit is surplus, and the rechargeable battery pack gradually approaches its charging limit, making it difficult to continue charging and storing energy. At this point, it is necessary to control the discharge of the discharge battery pack appropriately to avoid the energy storage unit's lifespan degradation due to overcharging. In the third operating condition, the charging energy of the rechargeable battery pack is less than the discharging energy of the discharge battery pack. Under this condition, there is a power shortage in the energy storage unit. Therefore, the discharge battery pack gradually approaches the lower limit of discharge and is difficult to continue discharging and releasing power. At this time, it is necessary to control and utilize the surplus power of renewable energy generation units and / or the grid to properly charge the rechargeable battery pack to avoid the discharge battery being unable to provide frequency support to the grid.

[0066] like Figure 4 S shown oc,min The first current state of charge S oc,A Second current state of charge S oc,B The minimum threshold in the second current state of charge S oc,B Approaching S oc,min In such cases, it is necessary to limit the discharge power of the battery pack or stop discharging to avoid damage to the battery pack due to over-discharge; S oc,max The first current state of charge S oc,A Second current state of charge S oc,B The maximum threshold in the first current state of charge S oc,A Approaching S oc,max In such cases, it is necessary to limit the charging power of the battery pack or stop charging to avoid damage to the battery pack due to overcharging.

[0067] S203 determines the target power regulation strategy for the grid-connected system based on the integrated state of charge, frequency deviation data, and the maximum available power of the renewable energy generation units.

[0068] The target power regulation strategy may include the respective power regulation rules of energy storage units and renewable energy generation units in the process of providing frequency support to the power grid.

[0069] In some embodiments, the target power regulation strategy may include the power regulation range, power regulation direction, and regulation sequence of the energy storage unit and the renewable energy generation unit, respectively.

[0070] For example, different combinations of integrated state of charge, different frequency deviation data, and different maximum available power correspond to different target power regulation strategies. Therefore, a mapping relationship between integrated state of charge, frequency deviation data, maximum available power, and regulation strategy can be pre-constructed, and the corresponding mapping relationship can be selected from multiple pre-constructed mapping relationships based on the real-time acquired integrated state of charge, frequency deviation data, and maximum available power, and the regulation strategy in the selected mapping relationship can be determined as the target regulation strategy.

[0071] S204, according to the target power regulation strategy, controls the power generation of the energy storage unit and the renewable energy generation unit to compensate for the frequency deviation of the power grid.

[0072] In some embodiments, after determining the target power regulation strategy, the power generation of the energy storage unit can be adjusted according to the power regulation range, power regulation direction, and power regulation sequence corresponding to the energy storage unit in the target power regulation strategy, and the power generation of the renewable energy power generation unit can be adjusted according to the power regulation range, power regulation direction, and power regulation sequence corresponding to the renewable energy power generation unit, thereby rationally allocating the output of the energy storage unit and the renewable energy power generation unit in frequency support, realizing compensation for grid frequency deviation, and thus ensuring the stability of grid frequency.

[0073] The aforementioned control method for frequency support in a grid-connected system, in response to a power regulation command for the grid-connected system, acquires the first current state of charge (SOC) of the rechargeable battery pack, the second current SOC of the discharge battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the power grid. The rechargeable battery pack is used to store electrical energy generated by the renewable energy generation unit and / or the power grid connected to the grid, while the discharge battery pack is used to supply electrical energy to the power grid. Based on the first and second current SOCs, the comprehensive SOC of the energy storage unit is determined. Based on the comprehensive SOC, the frequency deviation data, and the maximum available power of the renewable energy generation unit, the target power regulation strategy for the energy storage unit and the renewable energy generation unit in the grid-connected system is determined. Based on the target power regulation strategy, the power generation of the energy storage unit and the renewable energy generation unit is controlled to compensate for the frequency deviation of the power grid. Therefore, firstly, designing the energy storage unit as a physically decoupled structure of rechargeable and discharge battery packs avoids the technical problem of accelerated battery aging caused by frequent charge-discharge cycles when responding to grid frequency deviations, which is common in related technologies. Secondly, determining the comprehensive state of charge (SOC) of the energy storage unit based on the individual SOCs of the rechargeable and discharge battery packs provides a quantitative indicator that can comprehensively evaluate the operating status and regulation capability of the energy storage unit. Furthermore, based on the comprehensive SOC, frequency deviation data, and the maximum available power of the renewable energy generation unit, the grid-connected system can collaboratively decide on the target power regulation strategy based on the grid frequency deviation data and its own operating status and regulation capability. This ensures that the grid-connected system responds quickly and reliably to power regulation commands while mitigating the lifespan degradation of the battery packs in the energy storage unit, thereby achieving a dynamic balance between frequency support efficiency and energy storage cost.

[0074] In practical applications, grid frequency fluctuations are continuous and complex. Therefore, to ensure grid frequency stability, the power generation of the grid-connected system needs to be adjusted across multiple time scales. However, when related technologies employ grid-connected systems including energy storage units and renewable energy generation units to support grid frequency, the system can only respond to a single regulation command and adjust power within the single time scale corresponding to that command to suppress grid frequency deviations. Therefore, this single, independent response mode cannot match the continuous and complex fluctuations in grid frequency, resulting in inconsistent and insufficient frequency support provided by the grid-connected system, thus affecting the recovery speed and stability of the grid frequency.

[0075] In some embodiments, the power regulation command includes at least two of the following: primary frequency modulation power command, secondary frequency modulation power command, and scheduling power command.

[0076] Among them, the dispatch power command is a basic power adjustment command issued according to the overall power supply and demand plan of the power grid, which is used to ensure the long-term energy balance of the power grid. The adjustment time scale corresponding to the dispatch power command can be on the order of minutes to hours. The primary frequency regulation power command is an instantaneous power adjustment command issued when the real-time frequency of the power grid deviates from the rated frequency. It is used to provide instantaneous frequency support to the power grid and avoid the deterioration of the frequency deviation. The adjustment time scale corresponding to the primary frequency regulation power command is on the order of seconds. The secondary frequency regulation power command is used to eliminate the small frequency deviation of the power grid after the first power adjustment, so as to achieve accurate compensation for the frequency deviation of the power grid. The adjustment time scale corresponding to the secondary frequency regulation power command is on the order of minutes.

[0077] Furthermore, in S203 above, the target power regulation strategy of the grid-connected system is determined based on the comprehensive state of charge, frequency deviation data, and the maximum available power of the renewable energy generation unit. This includes: determining the operating status of the renewable energy generation unit based on the relationship between the maximum available power of the renewable energy generation unit and the total power to be regulated corresponding to the power regulation command; and further, the target power regulation strategy of the grid-connected system can be determined based on the comprehensive state of charge, frequency deviation data, and the operating status of the renewable energy generation unit.

[0078] Specifically, the total power P to be adjusted corresponding to the power adjustment command _w_ref The adjustable power P can be the power to be adjusted corresponding to a single frequency modulation power command. w_pri The power P to be adjusted corresponding to the secondary frequency modulation power command w_sec and the power P to be adjusted corresponding to the dispatch power command. w_dis sum.

[0079] For example, based on the maximum available power P of the renewable energy generation unit _w_MPPT The relationship between the magnitude of the total power to be regulated corresponding to the power regulation command is used to determine the operating status of the renewable energy generation unit, specifically including: in P _w_ref ≤P _w_MPPT In the case of P, it indicates that the renewable energy generation unit is in a state where it can provide frequency support to the grid. At this time, the renewable energy generation unit and the energy storage unit can work together to maintain grid frequency fluctuations. Specifically, in P... _w_ref <P w_dis In the case of P, the operating state of the renewable energy power generation unit can be represented as the power regulation direction of the renewable energy power generation unit being to reduce the power generation; while in P _w_ref >P _w_MPPTIn this case, it indicates that the operating status of the renewable energy generation unit is such that the maximum power generation of the renewable energy generation unit is still insufficient to meet the total power to be regulated corresponding to the power regulation command. In this case, the output of the energy storage unit to maintain grid frequency fluctuations may be much greater than the output of the renewable energy generation unit to maintain grid frequency fluctuations.

[0080] In this embodiment, the target power regulation strategy can be determined in response to at least two power regulation commands among the primary frequency regulation, secondary frequency regulation, and dispatch power commands. This breaks through the technical barrier of related technologies that can only respond to commands on a single time scale. It enables the target power regulation strategy to cover the entire process of the grid-connected system from the moment of frequency deviation to the medium-term stable support and long-term recovery of the power grid. This improves the frequency support efficiency and response capability of the grid-connected system. In turn, while providing reliable and stable frequency support to the power grid, it ensures the economic operation of the grid-connected system.

[0081] For example, such as Figure 5 As shown, in S202 above, the comprehensive state of charge of the energy storage unit is determined based on the first current state of charge and the second current state of charge, including the following S501-S503. Wherein:

[0082] S501, determine the first remaining state of charge of the rechargeable battery pack based on the first current state of charge and the preset depth of discharge.

[0083] The preset discharge depth can be the optimal discharge depth corresponding to the energy storage unit. It should be noted that the preset discharge depth can be flexibly set according to the battery model and aging degree, etc., and this application embodiment does not limit it. For example, the preset discharge depth can be 0.5.

[0084] The first state of remaining charge is used to characterize the ratio between the capacity of the rechargeable battery pack that can still be used for charging and the total capacity of the rechargeable battery pack.

[0085] Optionally, the minimum safe remaining capacity ratio of the discharge battery pack can be determined based on the optimal depth of discharge, and then the first remaining state of charge can be determined based on the difference between the first current state of charge and the minimum safe remaining capacity of the discharge battery pack.

[0086] S502, determine the second remaining state of charge of the discharge battery pack based on the second current state of charge and the preset depth of discharge.

[0087] Correspondingly, the second remaining state of charge is used to characterize the ratio between the capacity of the discharge battery pack that can continue to be used for discharge and the total capacity of the discharge battery pack.

[0088] Optionally, the maximum safe remaining capacity percentage of the rechargeable battery pack can be determined based on the optimal depth of discharge, and then the second remaining state of charge can be determined based on the difference between the maximum safe remaining capacity percentage of the rechargeable battery pack and the second current state of charge.

[0089] S503, determine the overall state of charge of the energy storage unit based on the difference between the first state of charge and the second state of charge.

[0090] For example, the overall state of charge of the energy storage unit is determined based on the difference between the first and second remaining states of charge. The process can be expressed as the following formula (2).

[0091] (2)

[0092] in, This is the first current state of charge. This is the second current state of charge. Indicates the preset discharge depth. This is the first residual charge state. This is the second residual charge state.

[0093] In some embodiments, the overall state of charge (SBC) is used to characterize the overall charging and discharging capability of the energy storage unit. The SBC value ranges from -1 to 1. When the SBC value is close to 0, it indicates that the charging and discharging of the energy storage unit is in an energy balance state, without overcharging or over-discharging. The closer the SBC is to 1, the more energy the charging battery pack stores is greater than the energy the discharging battery pack releases, with the discharge margin exceeding the charging margin, making overcharging of the charging battery pack more likely. Conversely, the closer the SBC is to -1, the more energy the discharging battery pack releases is greater than the energy the charging battery pack stores, with the charging margin exceeding the discharging margin, making over-discharging of the discharging battery pack more likely. Therefore, the overall operating state of the energy storage unit can be determined based on the SBC value, thereby determining the target power regulation strategy based on the overall operating state. This is beneficial for optimizing the state of the charging and discharging battery packs while the energy storage unit provides frequency support to the grid, avoiding damage to the battery packs due to overcharging or over-discharging and reducing their service life.

[0094] Furthermore, since different combinations of integrated state of charge, different frequency deviation data, and different maximum available power correspond to different target power regulation strategies, the integrated state of charge can be divided into multiple intervals based on its numerical value to facilitate the construction of the mapping relationship between integrated state of charge, frequency deviation data, maximum available power, and regulation strategy.

[0095] For example, the overall state of charge can be divided into five intervals: NB=[-1,-0.6], N=(-0.6,-0.2], ZE=(-0.2,0.2], P=(0.2,0.6], and PB=(0.6,1].

[0096] This embodiment calculates the remaining state of charge (SOC) based on the preset depth of discharge and the current SOC of each functional battery pack. Then, based on the difference between the first and second SOCs, it determines the overall SOC of the energy storage unit. This solves the technical problem that related technologies cannot comprehensively evaluate the operating status of composite energy storage units, thereby providing a unified quantitative standard for determining the target power regulation strategy. Furthermore, it ensures that the energy storage unit can maximize its support efficiency and delay battery pack aging while providing frequency support to the power grid.

[0097] In some exemplary embodiments, the target power regulation strategy of the grid-connected system is determined based on the integrated state of charge, frequency deviation data, and the maximum available power of the renewable energy generation units. This includes: determining the power regulation demand based on the frequency deviation data and a preset frequency regulation threshold; and determining the target power regulation strategy of the grid-connected system based on the integrated state of charge, power regulation demand, and the maximum available power of the renewable energy generation units.

[0098] Among them, the preset frequency regulation threshold can be the primary frequency regulation dead zone, used to distinguish whether the current state of the power grid is a normal state or an emergency state.

[0099] For example, the process of determining power regulation demand based on frequency deviation data and a preset frequency regulation threshold may include: determining the current state of the power grid based on the relationship between the frequency deviation data and the preset frequency regulation threshold, and then determining the power regulation demand of the grid-connected system corresponding to the current state based on the current state of the power grid.

[0100] For example, power regulation requirements can be to reduce the power generation of the grid-connected system, increase the power generation of the grid-connected system, or keep the power generation of the grid-connected system unchanged.

[0101] Furthermore, after determining the power regulation demand, the target power regulation strategy of the grid-connected system can be determined based on the comprehensive state of charge, power regulation demand, and the maximum available power of the renewable energy generation unit, and the power generation of the grid-connected system can be adjusted in accordance with the target power regulation strategy of the grid-connected system.

[0102] Optionally, the above-mentioned determination of power adjustment requirements based on frequency deviation data and preset frequency modulation threshold may specifically include: determining the power adjustment requirement as the first requirement when the absolute value of the frequency deviation data is greater than the preset frequency modulation threshold; and determining the power adjustment requirement as the second requirement when the absolute value of the frequency deviation data is less than or equal to the preset frequency modulation threshold.

[0103] The first requirement includes increasing or decreasing the power generation capacity of the grid-connected system; the second requirement includes maintaining the power generation capacity of the grid-connected system.

[0104] For example, without considering the direction of the frequency deviation, we only determine the relationship between the absolute value of the frequency deviation data and the preset frequency regulation threshold. If the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold, it indicates that the grid frequency deviation is relatively serious and the operating state is an emergency state. At this time, the primary goal is to provide frequency support for the grid. Accordingly, the power regulation requirement can be determined as increasing or decreasing the power generation of the grid-connected system. Conversely, if the absolute value of the frequency deviation data is less than or equal to the preset frequency regulation threshold, it indicates that the grid frequency deviation has not reached the minimum value required for frequency support. At this time, the grid operating state is a normal state, and the primary goal is to optimize the operating state of the energy storage unit. Accordingly, the power regulation requirement can be determined as maintaining the power generation of the grid-connected system.

[0105] In other words, the power regulation direction of the energy storage unit and the renewable energy generation unit in the target power regulation strategy can be determined according to the power regulation requirements.

[0106] This embodiment achieves objective, rapid, and standardized identification of the grid's operating status by comparing the grid's frequency deviation data with a preset frequency regulation threshold in real time. This fundamentally avoids the technical problems of relying on experience-based judgment or slow response in related technologies. Secondly, by accurately dividing power regulation needs into first and second needs, the target power regulation strategy of the grid-connected system can be determined according to different power regulation needs. This allows the power regulation of the grid-connected system to accurately match the real-time operating status of the grid, thereby improving the response speed and reliability of the grid-connected system in participating in grid frequency support.

[0107] For example, the preset frequency regulation threshold includes a first preset frequency regulation threshold and a second preset frequency regulation threshold; when the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold, determining the power regulation demand as the first demand includes: when the frequency deviation data is greater than the first preset frequency regulation threshold, determining the power regulation demand as reducing the power generation of the grid-connected system; when the frequency deviation data is less than the second preset frequency regulation threshold, determining the power regulation demand as increasing the power generation of the grid-connected system.

[0108] The first preset frequency modulation threshold is a positive value, while the second preset frequency modulation threshold is a negative value.

[0109] When the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold, the power regulation demand is determined as the primary demand. When the frequency deviation data is greater than the first preset frequency regulation threshold, it is known from the characteristics of the power grid that the power grid itself generates excess power. Therefore, it is necessary to reduce the power supply of the grid-connected system, and thus the power regulation demand is determined as reducing the power generation of the grid-connected system. Conversely, when the frequency deviation data is less than the first preset frequency regulation threshold, it is known from the characteristics of the power grid that the power grid itself generates insufficient power. Therefore, it is necessary to increase the power supply of the grid-connected system, and thus the power regulation demand is determined as increasing the power generation of the grid-connected system.

[0110] Furthermore, since different combinations of integrated state of charge, different frequency deviation data, and different maximum available power correspond to different target power regulation strategies, different power regulation requirements can be divided according to the magnitude of different frequency deviation data, so as to facilitate the construction of the mapping relationship between integrated state of charge, frequency deviation data, maximum available power and regulation strategy.

[0111] For example, the second demand can be represented as X, increasing the power generation of the grid-connected system can be represented as A, and decreasing the power generation of the grid-connected system can be represented as B. Therefore, based on the five intervals in which the comprehensive state of charge is divided, there are a total of 15 mapping relationships between the comprehensive state of charge and frequency deviation data, namely {PB,B}, {PB,X}, {PB,A}, {P,B}, {P,X}, {P,A}, {ZE,B}, {ZE,X}, {ZE,A}, {N,B}, {N,X}, {N,A}, {NB,B}, {NB,X}, {NB,A}.

[0112] Based on the determination that the power regulation demand is the first demand, this embodiment further determines the power regulation direction in the power regulation demand according to the first preset frequency threshold and the second preset frequency threshold, providing a reliable data source for subsequently determining the power regulation direction in the target power regulation strategy.

[0113] Based on the above embodiments, in step S203, the target power regulation strategy of the grid-connected system is determined according to the comprehensive state of charge, power regulation demand, and the maximum available power of the renewable energy generation unit. Specifically, this includes: when the power regulation demand is a second demand, the target power regulation strategy of the grid-connected system is determined based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the energy storage unit from the comprehensive state of charge to a preset state of charge; when the power regulation demand is a first demand, the target power regulation strategy of the grid-connected system is determined based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the power generation of the grid-connected system to the power corresponding to the first demand.

[0114] For example, when the power regulation demand is the second demand, it indicates that the grid's operating state is non-emergency. Correspondingly, the mapping relationship between the comprehensive state of charge (SBC) and frequency deviation data can be one of {PB,X}, {P,X}, {ZE,X}, {N,X}, or {NB,X}. In this case, the grid does not have an urgent power regulation demand on the grid-connected system. Therefore, the target power regulation strategy for the energy storage unit and the renewable energy generation unit needs to be determined based on the SBC and the maximum available power of the renewable energy generation unit, with the goal of adjusting the energy storage unit from the comprehensive SBC to a preset SBC. Since the closer the comprehensive SBC value is to 0, the closer the charging and discharging of the energy storage unit is to equilibrium, the preset SBC is ZE = (-0.2, 0.2).

[0115] In some embodiments, the energy storage unit decouples the charging and discharging processes; that is, the rechargeable battery pack only participates in charging while the discharging battery pack only participates in discharging. However, in practical application scenarios, in the above... Figure 4 Based on this, when the renewable energy power generation unit generates more electricity and / or the power grid is in a situation where the power grid has a surplus, the excess electricity will be stored in the rechargeable battery pack in the energy storage unit. This also leads to the rechargeable battery pack storing more and more electrical energy. According to the above formula (2), in this case, the value of the comprehensive state of charge is higher. Conversely, when the renewable energy power generation unit generates more electricity than the power grid can supply, the discharge battery pack in the energy storage unit needs to supplement the power grid. This also leads to the discharge battery pack releasing more and more electrical energy. According to the above formula (2), in this case, the value of the comprehensive state of charge is lower.

[0116] like Figure 6a The schematic diagram of the power regulation process of the energy storage unit under extremely high combined state of charge is shown below. Figure 6b The diagram shown illustrates the power regulation process of the energy storage unit under extremely low overall state of charge. The horizontal axis represents time, and the vertical axis represents the current state of charge. M corresponds to... N corresponds to .

[0117] like Figure 6aAs shown, when there is a large amount of renewable energy generation units and / or grid power generation, the grid will have a surplus of electricity. The rechargeable battery pack will continuously absorb and store the surplus electrical energy. According to the above formulas (1) and (2), at this time, the first current state of charge value is high, the second current state of charge value is low, and the overall state of charge value is high. In this case, in order to avoid damage to the rechargeable battery pack due to overcharging, the target power regulation strategy may include allowing the discharge battery pack to discharge appropriately to consume the electrical energy stored in the rechargeable battery pack until the overall state of charge value reaches a relatively balanced range, and then stopping the discharge of the discharge battery pack.

[0118] like Figure 6b As shown, when the power generation of the renewable energy generation unit is insufficient to meet the power demand of the grid, the discharge battery pack in the energy storage unit needs to continuously release electrical energy to supplement the power supply of the grid. According to the above formulas (1) and (2), at this time, the first current state of charge value is low, the second current state of charge value is high, and the overall state of charge value is low. In this case, in order to avoid damage to the charging battery pack due to over-discharge, the target power adjustment strategy may include increasing the charging power of the charging battery pack and reducing the discharging power of the discharge battery pack to make up for the discharge margin of the discharge battery pack until the overall state of charge value reaches a relatively balanced range.

[0119] For example, when the mapping relationship between the comprehensive state of charge (SBC) and frequency deviation data is {PB, X}, the SBC value is extremely high. In this case, the primary goal of the grid-connected system is to reduce the SBC [PB] to [ZE]. Based on the power regulation signal of the energy storage unit, the charging battery pack can be prevented from absorbing and storing energy, or the charging power of the charging battery pack can be reduced to the minimum charging power. Meanwhile, the discharging battery pack can be allowed to continuously discharge at the maximum discharge power to consume the surplus energy of the energy storage unit. At the same time, the output of the renewable energy generation unit can be reduced to below the maximum available power while meeting the power to be regulated corresponding to the basic dispatch power command. This actively reduces the total output of the grid-connected system, creates optimal conditions for the net discharge of the energy storage unit, and accelerates the reduction of the excessively high SBC.

[0120] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {P, X}, and the SBC value is too high, the primary goal of the grid-connected system is to reduce the SBC [P] to [ZE]. In this case, the charging and discharging power of the battery pack can be appropriately reduced based on the power regulation signal of the energy storage unit, and the discharging battery pack can be moderately discharged. At the same time, the output of the renewable energy generation unit can be set between the maximum available power and the power to be regulated corresponding to the basic dispatch power command, thereby allocating part of the available power of the renewable energy generation unit to the battery pack to optimize the charging and discharging process, so that the SBC of the energy storage unit can efficiently and smoothly approach [ZE].

[0121] When the mapping relationship between the integrated state of charge (SBC) and frequency deviation data is {ZE, X}, the SBC has reached the preset SBC. The goal of the grid-connected system is to maintain this state and compensate for minor fluctuations in the grid frequency. In this case, the charging power of the rechargeable battery pack and the discharging power of the discharge battery pack can be fine-tuned based on the power regulation signal from the energy storage unit.

[0122] In addition, when the mapping relationship between the integrated state of charge and frequency deviation data is {ZE, X}, in P _w_ref <P _w_dis In this case, the grid-connected system needs to reduce its total output to track P. _w_ref At this point, P can be used first. _w_dis -P _w_ref This portion of the power reduction is used to charge the energy storage unit, thereby meeting power regulation requirements while storing excess electrical energy from the renewable energy generation unit in the energy storage unit to improve utilization; in P _w_dis ≤P _w_ref ≤P _w_MPPT Under these circumstances, if the total standby power corresponding to the grid-connected system power regulation command is within the adjustable range of the renewable energy generation unit, then the renewable energy generation unit can be controlled to precisely adjust its power generation to P. _w_ref This is to meet the total power demand of the grid-connected system. Simultaneously, based on real-time feedback of the overall state of charge (SPC), the charging or discharging power of the energy storage unit can be slightly adjusted, thereby stabilizing the SPC near a preset SPC and achieving power point tracking (PPT) and maintenance of the energy storage unit's operating status. _w_ref >P _w_MPPT In cases where the renewable energy generation unit operates at its maximum available power but still cannot reach the total power to be regulated corresponding to the power regulation command, the renewable energy generation unit can be controlled to maintain its maximum power generation while the energy storage unit's battery pack discharges to compensate for the P. _w_ref - P _w_MPPTThis power gap is filled by using energy storage units to supplement the insufficient power of renewable energy generation units in order to meet power regulation requirements.

[0123] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {N, X}, and the SBC value is low, the primary goal of the grid-connected system is to raise the SBC [N] to [ZE]. In this case, based on the power regulation signal of the energy storage unit, the charging power of the rechargeable battery pack can be prioritized to increase, while the discharging power of the discharge battery pack can be reduced to decrease the energy consumption of the energy storage unit. At the same time, the power generation capacity of the renewable energy generation unit can be increased as close as possible to its maximum available power, and the surplus power exceeding the power to be regulated corresponding to the basic dispatch power command can be directed to the rechargeable battery pack. This provides energy to the energy storage unit in an economical and proactive manner, working in synergy with the energy storage unit to improve its SBC and accelerate the improvement of the excessively low SBC.

[0124] When the mapping relationship between the integrated state of charge (SBC) and frequency deviation data is {NB, X}, the SBC value is extremely low. In this case, the primary goal of the grid-connected system is to raise the SBC from the [NB] zone to [ZE]. Based on the power regulation signal from the energy storage unit, the discharge operation of the battery pack can be prohibited or its discharge power reduced to the minimum, while the rechargeable battery pack continues to charge at its maximum charging power. Simultaneously, the power generation capacity of the renewable energy generation unit can be increased to its maximum available power, ensuring that all available electrical energy generated is prioritized for charging the rechargeable battery pack. If the maximum available power of the renewable energy generation unit still cannot meet the energy demand of the rechargeable battery pack, the grid-connected system is controlled to absorb additional power from the grid, prioritizing energy replenishment for the rechargeable battery pack in the energy storage unit.

[0125] For example, when power regulation demand is the primary demand, it indicates that the power grid is in an emergency state with an urgent power regulation requirement. Correspondingly, the mapping relationship between the integrated state of charge (SBC) and frequency deviation data can be one of {PB, A}, {P, A}, {ZE, A}, {N, A}, {NB, A}, {PB, B}, {P, B}, {ZE, B}, {N, B}, or {NB, B}. In this case, with the goal of regulating the grid-connected system's power generation to the power corresponding to the primary demand, the target power regulation strategy for the energy storage unit and the renewable energy generation unit needs to be determined based on the integrated SBC and the maximum available power of the renewable energy generation unit.

[0126] For example, when the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {PB, A}, if the grid frequency is too low while the SBC of the energy storage unit is extremely high, there is a risk of overcharging. In this case, the primary goal is to meet the grid's demand for increased power generation for the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the discharge battery pack can be controlled to discharge at its maximum discharge power to provide the main power support output for the grid, while the charging battery pack is prohibited from charging. Under these circumstances, the value of the SBC will also decrease accordingly. At the same time, the power generation of the renewable energy generation unit is increased to its maximum available power, working in conjunction with the energy storage unit to meet the demand for increased power generation of the grid-connected system. Thus, while achieving grid frequency support, the discharge process of the discharge battery pack is efficiently utilized to reduce the excessively high SBC.

[0127] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {P, A}, and the grid frequency is too low while the SBC of the energy storage unit is too high, the primary goal is to meet the grid's demand for increased power generation for the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the discharge battery pack can be controlled to discharge at a higher power to provide the main power support output for the grid, while the charging power of the charging battery pack can be reduced or it can be put into a standby state. Under these circumstances, the value of the SBC will also decrease accordingly. At the same time, the power generation of the renewable energy generation unit is increased to its maximum available power, working in conjunction with the energy storage unit to meet the demand for increased power generation of the grid-connected system. Thus, while achieving grid frequency support, the discharge process of the discharge battery pack is used to bring the high SBC closer to the preset SBC.

[0128] When the mapping relationship between the overall state of charge (SOC) and frequency deviation data is {ZE, A}, if the grid frequency is too low but the SOC of the energy storage unit is in the optimal range, the primary goal is to meet the grid's demand for increased power generation for the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the discharge battery pack can be prioritized to discharge rapidly to provide instantaneous power support, while the power of the rechargeable battery pack can be flexibly fine-tuned to assist in the power balance of the energy storage unit. Under these circumstances, the SOC remains at a good level. At the same time, the power generation of the renewable energy generation unit is increased to its maximum available power, working in conjunction with the energy storage unit to meet the demand for increased power generation of the grid-connected system. This ensures reliable grid frequency support while maintaining the healthy and sustainable operation of the energy storage unit.

[0129] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {N, A}, and the grid frequency is too low while the SBC of the energy storage unit is also low, the primary objective is to meet the grid's demand for increased power generation for the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the discharge battery pack can be controlled to discharge at a power within the safe discharge margin, and the charging power of the charging battery pack can be reduced to save the energy available to the energy storage unit. In this case, it is necessary to avoid further reduction in the SBC. At the same time, the power generation of the renewable energy generation unit should be increased to its maximum available power to assume the main responsibility for power increase, and work with the energy storage unit to meet the demand for increased power generation of the grid-connected system. Thus, while prioritizing grid frequency support, the operating status of the energy storage unit can be maintained to the maximum extent.

[0130] When the mapping relationship between the comprehensive state of charge (SOC) and frequency deviation data is {NB, A}, if the grid frequency is too low and the SOC of the energy storage unit is extremely low, there is a risk of over-discharge. In this case, it is important to meet the grid's demand for increased power generation while ensuring the safety of the energy storage unit. Specifically, based on the power regulation signal of the energy storage unit, the discharge power of the battery pack can be reduced or the discharge can be prohibited to avoid over-discharge. The instantaneous power fluctuations or predicted surplus of the renewable energy generation unit and / or grid connection can be used to charge the battery pack to improve the first current SOC. At the same time, the power generation of the renewable energy generation unit can be increased to its maximum available power to undertake most of the frequency support output. If its output is still insufficient, the battery pack can be called upon for short-term support with the minimum necessary power. Thus, while meeting the grid's demand for increased power generation, the safety of the energy storage unit can be ensured.

[0131] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {PB, B}, if the grid frequency is too high and the SBC of the energy storage unit is extremely high, there is a risk of overcharging. In this case, the primary goal is to meet the grid's demand for reduced power generation for the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the charging battery pack can be controlled to charge at maximum charging power to absorb excess energy from the grid-connected system, and the discharge of the battery pack can be prohibited. Under these circumstances, the value of the SBC will also decrease accordingly. At the same time, the power generation of the renewable energy generation unit is reduced, and it works in conjunction with the energy storage unit to meet the demand for reduced power generation of the grid-connected system. Thus, while supporting the grid frequency, the charging process of the charging battery pack is efficiently utilized to alleviate the excessively high SBC.

[0132] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {P, B}, and the grid frequency is too high while the SBC of the energy storage unit is too high, the primary goal is to meet the grid's demand for reduced power generation from the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the charging battery pack can be controlled to charge at a higher charging power to absorb excess energy from the grid-connected system, and the discharge power of the discharging battery pack can be reduced or it can be put into a standby state. Under these circumstances, the value of the SBC will also decrease accordingly. At the same time, the power generation of the renewable energy generation unit is reduced, and it works in conjunction with the energy storage unit to meet the demand for reduced power generation from the grid-connected system. Thus, while supporting the grid frequency, the charging process of the charging battery pack is used to bring the high SBC closer to the preset SBC.

[0133] When the mapping relationship between the overall state of charge (SOC) and frequency deviation data is {ZE, B}, if the grid frequency is too high but the SOC of the energy storage unit is in the optimal range, the primary goal is to meet the grid's demand for reduced power generation from the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the charging battery pack can be flexibly controlled to charge at an appropriate power and / or the discharging power of the discharging battery pack can be reduced. Under these circumstances, the SOC remains at a good level. At the same time, the power generation of the renewable energy generation unit is reduced, working in synergy with the energy storage unit to meet the demand for reduced power generation from the grid-connected system. This ensures reliable grid frequency support while maintaining the healthy operation of the energy storage unit.

[0134] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {N, B}, and the grid frequency is too high while the SBC of the energy storage unit is too low, the primary goal is to meet the grid's demand for reduced power generation for the grid-connected system. Specifically, based on the power regulation signal of the energy storage unit, the power generation of the renewable energy generation unit can be reduced to meet the demand for reduced power generation. Under this premise, the charging battery pack can be controlled to charge at low power to ensure the recovery of its first current state of charge, and the discharge of the battery pack should be prohibited. In this case, it is necessary to avoid excessive reduction of power generation demand, which would affect the necessary energy replenishment of the energy storage unit. Thus, while prioritizing grid frequency support, the lower SBC of the energy storage unit can be gradually restored.

[0135] When the mapping relationship between the overall state of charge (SBC) and frequency deviation data is {NB, B}, if the grid frequency is too high while the SBC of the energy storage unit is extremely low, there is a risk of over-discharge. In this case, it is important to meet the grid's demand for reduced power generation and to urgently improve the SBC of the energy storage unit to ensure its safety. Specifically, based on the power regulation signal of the energy storage unit, the charging battery pack can be controlled to charge at the maximum safe power to absorb surplus energy and improve the first current SBC, while discharging the battery pack is prohibited. At the same time, the power generation of the renewable energy generation unit is reduced to create optimal conditions for charging the charging battery pack. Thus, while meeting the demand for reduced power generation to support the grid frequency, the extremely low SBC is improved.

[0136] This embodiment clarifies the core objectives according to power regulation requirements, determines the target power regulation strategy by combining the comprehensive state of charge and the maximum available power of renewable energy, and accurately allocates the power processing of the energy storage unit and the renewable energy generation unit. This achieves both a smooth recovery of the energy storage unit to the preset state of charge under the second requirement, avoiding battery pack life loss caused by extreme comprehensive state of charge and reserving capacity for subsequent power regulation, and a rapid response of the grid-connected system to power regulation commands under the first requirement, providing frequency support to the grid and adjusting the charging power of the charging battery pack and the discharging power of the discharging battery pack according to the comprehensive state of charge to maintain the preset state of charge.

[0137] Based on the above embodiments, in an exemplary embodiment, an optional control method for grid-connected system frequency support is provided, such as... Figure 7 As shown, it may include:

[0138] S701, in response to a power regulation command for the grid-connected system, acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0139] S702, determine the first remaining state of charge of the rechargeable battery pack based on the first current state of charge and the preset depth of discharge.

[0140] S703, determine the second remaining state of charge of the discharge battery pack based on the second current state of charge and the preset depth of discharge.

[0141] S704. Determine the overall state of charge of the energy storage unit based on the difference between the first state of charge and the second state of charge.

[0142] S705 determines that the power adjustment requirement is the primary requirement when the absolute value of the frequency deviation data is greater than the preset frequency modulation threshold.

[0143] The preset frequency regulation thresholds include a first preset frequency regulation threshold and a second preset frequency regulation threshold; when the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold, the power regulation demand is determined as the first demand, including: when the frequency deviation data is greater than the first preset frequency regulation threshold, the power regulation demand is determined to be a reduction in the power generation of the grid-connected system; when the frequency deviation data is less than the second preset frequency regulation threshold, the power regulation demand is determined to be an increase in the power generation of the grid-connected system.

[0144] S706: If the absolute value of the frequency deviation data is less than or equal to the preset frequency modulation threshold, the power regulation requirement is determined as the second requirement.

[0145] S707, when power regulation demand is the secondary demand, aims to regulate the energy storage unit from the comprehensive state of charge to the preset state of charge, and determines the target power regulation strategy of the grid-connected system based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit.

[0146] S708, when power regulation demand is the primary demand, aims to regulate the power generation of the grid-connected system to the power corresponding to the primary demand, and determines the target power regulation strategy of the grid-connected system based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit.

[0147] S709 controls the power generation of energy storage units and renewable energy generation units according to the target power regulation strategy to compensate for the frequency deviation of the power grid.

[0148] The specific processes of S701-S709 described above can be found in the description of the above method embodiments. Their implementation principles and technical effects are similar, and will not be repeated here.

[0149] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0150] Based on the same inventive concept, this application also provides a control device for grid-connected system frequency support to implement the control method for grid-connected system frequency support described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the control device for grid-connected system frequency support provided below can be found in the limitations of the control method for grid-connected system frequency support described above, and will not be repeated here.

[0151] In one exemplary embodiment, such as Figure 8 As shown, a control device for frequency support in a grid-connected system is provided, comprising: an acquisition module 810, a status determination module 820, a strategy determination module 830, and a control module 840, wherein:

[0152] The acquisition module 810 is used to acquire, in response to a power regulation command for the grid-connected system, a first current state of charge of the charging battery pack, a second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the grid.

[0153] The state determination module 820 is used to determine the comprehensive state of charge of the energy storage unit based on the first current state of charge and the second current state of charge.

[0154] The strategy determination module 830 is used to determine the target power regulation strategy of the grid-connected system based on the integrated state of charge, frequency deviation data and the maximum available power of the renewable energy generation units.

[0155] The control module 840 is used to control the power generation of the energy storage unit and the renewable energy generation unit according to the target power regulation strategy in order to compensate for the frequency deviation of the power grid.

[0156] In some embodiments, the state determination module 820 is specifically configured to determine the first remaining state of charge of the rechargeable battery pack based on the first current state of charge and the preset depth of discharge; determine the second remaining state of charge of the discharge battery pack based on the second current state of charge and the preset depth of discharge; and determine the comprehensive state of charge of the energy storage unit based on the difference between the first remaining state of charge and the second remaining state of charge.

[0157] In some embodiments, the policy determination module 830 includes:

[0158] The demand determination unit is used to determine the power regulation demand based on frequency deviation data and preset frequency modulation threshold.

[0159] The strategy determination unit is used to determine the target power regulation strategy of the grid-connected system based on the integrated state of charge, power regulation requirements, and the maximum available power of renewable energy generation units.

[0160] In some embodiments, the demand determination unit includes:

[0161] The first determining subunit is used to determine the power adjustment requirement as the first requirement when the absolute value of the frequency deviation data is greater than the preset frequency modulation threshold.

[0162] The second determining subunit is used to determine the power adjustment requirement as the second requirement when the absolute value of the frequency deviation data is less than or equal to the preset frequency modulation threshold.

[0163] In some embodiments, the first determining subunit is specifically used to determine that the power regulation demand is to reduce the power generation of the grid-connected system when the frequency deviation data is greater than a first preset frequency regulation threshold; and to determine that the power regulation demand is to increase the power generation of the grid-connected system when the frequency deviation data is less than a second preset frequency regulation threshold.

[0164] In some embodiments, the strategy determination module 830 is specifically configured to, when the power regulation demand is a second demand, determine a target power regulation strategy for the grid-connected system based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the energy storage unit from the comprehensive state of charge to a preset state of charge; and when the power regulation demand is a first demand, determine a target power regulation strategy for the grid-connected system based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the power generation of the grid-connected system to the power corresponding to the first demand.

[0165] Each module in the frequency support control device of the aforementioned grid-connected system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0166] In one exemplary embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 9As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores the first current state of charge of the rechargeable battery pack, the second current state of charge of the discharged battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the power grid. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a control method for frequency support in a grid-connected system.

[0167] Those skilled in the art will understand that Figure 9 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0168] In one exemplary embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0169] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0170] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0171] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0172] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0173] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A control method for frequency support in a grid-connected system, characterized in that, The grid-connected system includes an energy storage unit and a renewable energy generation unit. The energy storage unit includes a rechargeable battery pack and a discharge battery pack. The rechargeable battery pack is used to store electrical energy generated by the renewable energy generation unit and / or the power grid to which the grid-connected system is connected. The discharge battery pack is used to provide electrical energy to the power grid. The method includes: In response to a power regulation command for the grid-connected system, the system acquires the first current state of charge of the charging battery pack, the second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and the frequency deviation data of the power grid. The overall state of charge of the energy storage unit is determined based on the first current state of charge and the second current state of charge. The target power regulation strategy of the grid-connected system is determined based on the integrated state of charge, the frequency deviation data, and the maximum available power of the renewable energy generation unit. According to the target power regulation strategy, the power generation of the energy storage unit and the renewable energy generation unit is controlled to compensate for the frequency deviation of the power grid.

2. The method according to claim 1, characterized in that, Determining the overall state of charge of the energy storage unit based on the first current state of charge and the second current state of charge includes: The first remaining state of charge of the rechargeable battery pack is determined based on the first current state of charge and the preset depth of discharge. The second remaining state of charge of the discharge battery pack is determined based on the second current state of charge and the preset depth of discharge; The overall state of charge of the energy storage unit is determined based on the difference between the first state of residual charge and the second state of residual charge.

3. The method according to claim 1, characterized in that, The step of determining the target power regulation strategy for the grid-connected system based on the integrated state of charge, the frequency deviation data, and the maximum available power of the renewable energy generation unit includes: Based on the frequency deviation data and the preset frequency modulation threshold, the power adjustment requirement is determined; The target power regulation strategy of the grid-connected system is determined based on the overall state of charge, the power regulation requirements, and the maximum available power of the renewable energy generation unit.

4. The method according to claim 3, characterized in that, The step of determining the power adjustment requirement based on the frequency deviation data and the preset frequency modulation threshold includes: If the absolute value of the frequency deviation data is greater than the preset frequency regulation threshold, the power regulation demand is determined as the first demand; wherein, the first demand includes increasing or decreasing the power generation capacity of the grid-connected system; If the absolute value of the frequency deviation data is less than or equal to the preset frequency regulation threshold, the power regulation requirement is determined as the second requirement; wherein, the second requirement includes maintaining the power generation capacity of the grid-connected system.

5. The method according to claim 4, characterized in that, The preset frequency modulation threshold includes a first preset frequency modulation threshold and a second preset frequency modulation threshold; determining the power adjustment requirement as the first requirement when the absolute value of the frequency deviation data is greater than the preset frequency modulation threshold includes: If the frequency deviation data is greater than the first preset frequency regulation threshold, the power regulation requirement is determined to be to reduce the power generation of the grid-connected system. If the frequency deviation data is less than the second preset frequency regulation threshold, the power regulation requirement is determined to be to increase the power generation capacity of the grid-connected system.

6. The method according to claim 4, characterized in that, The step of determining the target power regulation strategy for the grid-connected system based on the integrated state of charge, the power regulation demand, and the maximum available power of the renewable energy generation unit includes: When the power regulation demand is the second demand, with the goal of adjusting the energy storage unit from the comprehensive state of charge to the preset state of charge, the target power regulation strategy of the grid-connected system is determined based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit. When the power regulation demand is the first demand, the target power regulation strategy of the grid-connected system is determined based on the comprehensive state of charge and the maximum available power of the renewable energy generation unit, with the goal of regulating the power generation of the grid-connected system to the power corresponding to the first demand.

7. The method according to any one of claims 1-6, characterized in that, The power regulation command includes at least two of the following: primary frequency modulation power command, secondary frequency modulation power command, and scheduling power command.

8. A control device for frequency support in a grid-connected system, characterized in that, The grid-connected system includes an energy storage unit and a renewable energy generation unit. The energy storage unit includes a rechargeable battery pack and a discharge battery pack. The rechargeable battery pack is used to store electrical energy generated by the renewable energy generation unit and / or the power grid to which the grid-connected system is connected. The discharge battery pack is used to provide electrical energy to the power grid. The device includes: The acquisition module is used to acquire, in response to a power regulation command for the grid-connected system, a first current state of charge of the charging battery pack, a second current state of charge of the discharging battery pack, the maximum available power of the renewable energy generation unit, and frequency deviation data of the power grid. The state determination module is used to determine the comprehensive state of charge of the energy storage unit based on the first current state of charge and the second current state of charge. The strategy determination module is used to determine the target power regulation strategy of the grid-connected system based on the integrated state of charge, the frequency deviation data, and the maximum available power of the renewable energy generation unit. The control module is used to control the power generation of the energy storage unit and the renewable energy generation unit according to the target power regulation strategy, so as to compensate for the frequency deviation of the power grid.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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