Energy storage system control method and energy storage system

Abstract

The present application provides an energy storage system control method and an energy storage system, wherein, when applied to an energy storage system, the method includes: determining the analog power characteristic parameters corresponding to the energy storage system based on a preset virtual synchronous machine control strategy; constructing a damping power formula of the energy storage system according to the analog power characteristic parameters corresponding to the energy storage system; determining the charge and discharge power corresponding to each battery cluster according to the state of charge of each battery cluster and the damping power formula of the energy storage system; and controlling each battery cluster to charge and discharge according to the charge and discharge power corresponding to each battery cluster. The present application can, under the premise of stable operation of the energy storage system, have a power regulation capability similar to that of a synchronous generator, thereby making the charge and discharge process of each battery unit more balanced, while avoiding a complex SOC calculation process, reducing the consumption of computing resources and time, and improving the response speed of the energy storage system.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage system control, and in particular to an energy storage system control method and an energy storage system. Background Art

[0002] When single-phase or three-phase multiple energy storage converters (Power Conversion System, PCS) in the energy storage system are operated in parallel off-grid, the state of charge (SOC) of the battery clusters corresponding to the multiple PCSs may be different. The reason for this difference may be the different initial states of the battery clusters, or slight differences in the charge and discharge circuits, or other reasons. The difference in SOC of the battery clusters corresponding to the multiple PCSs will result in a smaller available capacity of the energy storage system and low battery cluster utilization during the life cycle. The SOC control problem when PCSs are operated in parallel is a pain point in the industry.

[0003] The SOC control method in the prior art usually needs to calculate the difference between the SOCs of the battery clusters corresponding to the multiple PCSs, so as to achieve SOC control.

[0004] However, this implementation requires a lot of calculations, and during the SOC control process, the stability of the energy storage system is difficult to guarantee. Summary of the invention

[0005] The purpose of the present application is to provide an energy storage system control method and an energy storage system in view of the above-mentioned deficiencies in the prior art, so as to solve the problem of low stability when controlling the charge state of each battery cluster of the energy storage system in the prior art.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] In a first aspect, an embodiment of the present application provides an energy storage system control method, which is applied to an energy storage system, wherein the energy storage system at least includes: a plurality of battery clusters connected in parallel, each of the battery clusters includes a battery unit and an energy storage converter, and the method includes:

[0008] Based on a preset virtual synchronous machine control strategy, determining a simulated power characteristic parameter corresponding to the energy storage system, wherein the simulated power characteristic parameter includes a damping coefficient corresponding to each of the battery clusters;

[0009] According to the simulated power characteristic parameters corresponding to the energy storage system, a damping power formula of the energy storage system is constructed, and the damping power formula is used to characterize the charging and discharging power of each battery cluster when each energy storage converter is stable at the same frequency and the damping coefficient of the virtual synchronous machine corresponding to each battery cluster should meet the conditions;

[0010] Determining the charge and discharge power corresponding to each of the battery clusters according to the charge state of each of the battery clusters and the damping power formula of the energy storage system;

[0011] According to the charging and discharging power corresponding to each battery cluster, each battery cluster is controlled to charge and discharge.

[0012] In a possible implementation, the damping power formula is: ,in, is the power of the first battery cluster, is the damping coefficient corresponding to the first energy storage converter, is the power of the second battery cluster, is the damping coefficient corresponding to the second energy storage converter, is the power of the nth battery cluster, is the damping coefficient corresponding to the nth energy storage converter, and n is a positive integer.

[0013] In a possible implementation, the same-frequency stability is used to indicate that the electrical angular frequency output by each of the energy storage converters is stable and the frequencies output by each of the energy storage converters are the same.

[0014] In a possible implementation, constructing a damping power formula of the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system includes:

[0015] Determine the output frequency equation corresponding to each energy storage converter in the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system;

[0016] A damping power formula of the energy storage system is generated according to the output frequency equation.

[0017] In a possible implementation, determining the output frequency equation corresponding to each energy storage converter in the energy storage system according to the simulated power characteristic parameter corresponding to the energy storage system includes:

[0018] Determine the electrical angular frequency formula corresponding to the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system;

[0019] Input the device parameters of each battery cluster into the electrical angle frequency formula, and obtain multiple steady-state formulas based on the same frequency stability;

[0020] Based on the same frequency stability, the multiple steady-state formulas are transformed to obtain the output frequency equation.

[0021] In a possible implementation, generating a damping power formula of the energy storage system according to the output frequency equation includes:

[0022] According to the preset constraints, the output frequency equation is simplified to obtain the damping power formula of the energy storage system.

[0023] In a possible implementation manner, the damping coefficient of the virtual synchronous machine corresponding to each of the battery clusters is positively correlated with the state of charge of each of the battery clusters.

[0024] In a possible implementation, determining the charge and discharge power corresponding to each battery cluster according to the state of charge of each battery cluster and the damping power formula of the energy storage system includes:

[0025] Determining a damping coefficient corresponding to each of the battery clusters according to the charge state of each of the battery clusters;

[0026] The charge and discharge power corresponding to each battery cluster is determined according to the damping power formula of the energy storage system and the damping coefficient corresponding to each battery cluster.

[0027] In a possible implementation, determining the damping coefficient corresponding to each of the battery clusters according to the state of charge of each of the battery clusters includes:

[0028] Obtaining system parameters of the energy storage system;

[0029] Determining an initial damping maximum value and an initial damping minimum value corresponding to the energy storage system according to system parameters of the energy storage system;

[0030] The damping coefficient corresponding to each of the battery clusters is determined according to the initial damping maximum value, the initial damping minimum value and the charge state of each of the battery clusters.

[0031] In a possible implementation, determining the damping coefficient corresponding to each battery cluster according to the initial damping maximum value, the initial damping minimum value, and the state of charge of each battery cluster includes:

[0032] Calculating a damping difference between the initial damping maximum value and the initial damping minimum value;

[0033] Calculating the product of the damping difference and the state of charge of each of the battery clusters;

[0034] The damping coefficient corresponding to each battery cluster is determined according to the product and the charge and discharge state of each battery cluster.

[0035] In a possible implementation, if the first battery cluster is in a discharging state;

[0036] The step of determining the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster comprises:

[0037] The sum of the product and the initial damping minimum value is used as the damping coefficient corresponding to the first battery cluster.

[0038] In a possible implementation, if the first battery cluster is in a charging state;

[0039] The step of determining the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster comprises:

[0040] The difference between the initial damping maximum value and the product is used as the damping coefficient corresponding to the first battery cluster.

[0041] In a second aspect, another embodiment of the present application provides an energy storage system, the energy storage system comprising: a plurality of battery clusters connected in parallel and a control device, the control device being used to execute the energy storage system control method described in the first aspect.

[0042] The beneficial effects of the present application are as follows: by determining the analog power characteristic parameters corresponding to the energy storage system based on a preset virtual synchronous machine control strategy, the damping power formula of the energy storage system is constructed according to the analog power characteristic parameters corresponding to the energy storage system, so as to characterize the charging and discharging power of each battery cluster when each energy storage converter is stable at the same frequency and the conditions that the damping coefficient of the virtual synchronous machine corresponding to each battery cluster should satisfy, so that the charging and discharging power corresponding to each battery cluster can be determined according to the state of charge of each battery cluster and the damping power formula of the energy storage system, and the charging and discharging of each battery cluster can be controlled according to the charging and discharging power corresponding to each battery cluster, so that under the premise of stable operation of the energy storage system, the energy storage system can have a power regulation capability similar to that of a synchronous generator, so that the charging and discharging process of each battery unit can be made more balanced, and at the same time, the charging and discharging control of the energy storage system can be realized without calculating the difference in the state of charge between the battery units, thereby avoiding a complex SOC calculation process, reducing the consumption of computing resources and time, and improving the response speed of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A schematic diagram of the structure of an energy storage system provided in an embodiment of the present application;

[0045] Figure 2 A schematic diagram of a flow chart of an energy storage system control method provided in an embodiment of the present application;

[0046] Figure 3 A schematic diagram of a flow chart for constructing a damping power formula for an energy storage system in the energy storage system control method provided in an embodiment of the present application;

[0047] Figure 4 A schematic diagram of a flow chart for determining the output frequency equation corresponding to each energy storage converter in the energy storage system in the energy storage system control method provided in the embodiment of the present application;

[0048] Figure 5 A control block diagram of a virtual synchronization machine provided in an embodiment of the present application;

[0049] Figure 6 A schematic diagram of a flow chart for determining the charge and discharge power corresponding to each battery cluster in the energy storage system control method provided in an embodiment of the present application;

[0050] Figure 7 A schematic diagram of a flow chart for determining the damping coefficient corresponding to each battery cluster in the energy storage system in the energy storage system control method provided in an embodiment of the present application;

[0051] Figure 8 Another flowchart diagram of determining the damping coefficient corresponding to each battery cluster in the energy storage system in the energy storage system control method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0052] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0053] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0054] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0055] The state of charge control method in the prior art usually needs to calculate the difference between the state of charge of the battery clusters corresponding to multiple PCSs, so as to achieve the state of charge balance. However, this implementation method requires a lot of calculations, and the stability of the energy storage system is difficult to ensure during the state of charge balance process.

[0056] Based on the above problems, the embodiment of the present application proposes a control method for an energy storage system, which determines the analog power characteristic parameters corresponding to the energy storage system based on a preset virtual synchronous machine control strategy, and then constructs a damping power formula for the energy storage system according to the analog power characteristic parameters corresponding to the energy storage system, so as to characterize the conditions that the charging and discharging power of each battery cluster and the damping coefficient of the virtual synchronous machine corresponding to each battery cluster should satisfy when each energy storage converter is stable at the same frequency, so that the charging and discharging power corresponding to each battery cluster can be determined according to the state of charge of each battery cluster and the damping power formula of the energy storage system, and the charging and discharging of each battery cluster can be controlled according to the charging and discharging power corresponding to each battery cluster, so that the stability of the energy storage system can be guaranteed when each battery unit is charged and discharged, and at the same time, the charging and discharging control of the energy storage system can be realized without calculating the difference in the state of charge between each battery unit, thereby avoiding a complex SOC calculation process, reducing the consumption of computing resources and time, and improving the response speed of the energy storage system.

[0057] First, an energy storage system involved in the energy storage system control method provided in an embodiment of the present application is exemplarily described.

[0058] Figure 1 A schematic diagram of a structure of an energy storage system provided in an embodiment of the present application, referring to Figure 1 As shown, the energy storage system provided by the embodiment of the present application includes at least: a plurality of battery clusters connected in parallel, each battery cluster includes a battery unit and an energy storage converter. After the battery unit and the energy storage converter are connected in series, they are connected to the bus to charge and discharge to the grid, or discharge to the load.

[0059] Optionally, an energy storage converter is used to realize energy conversion and bidirectional flow between the battery unit and the power grid or load.

[0060] Optionally, the energy storage system also includes a battery management system (BMS) to monitor the operating status of each battery in the battery unit and ensure the safe and reliable operation of the battery unit.

[0061] Optionally, the energy storage system also includes an energy management system (EMS) for interacting with the PCS and the BMS to execute the energy storage system control method provided in the embodiment of the present application to control the charging and discharging of each battery unit.

[0062] It can be understood that before charging and discharging each battery cell, the steps of the energy storage system control method provided in the embodiment of the present application can be executed to control each battery cell to be charged and discharged in a balanced manner. It is also possible that during the charging and discharging process of each battery cell, the steps of the energy storage system control method provided in the embodiment of the present application can be executed to adjust the charging and discharging process of each battery cell within an adjustment cycle, and after the current adjustment cycle ends, each battery cell is controlled to be charged and discharged in a balanced manner.

[0063] The energy storage system control method provided in the embodiments of the present application is described in detail below in combination with multiple embodiments.

[0064] Figure 2 A schematic diagram of a flow chart of the energy storage system control method provided in the embodiment of the present application, referring to Figure 2 As shown, the method is applied to a control device in the above energy storage system, such as the above EMS, and the method includes:

[0065] S201. Determine the simulated power characteristic parameters corresponding to the energy storage system based on a preset virtual synchronous machine control strategy.

[0066] It can be understood that simulating the operating mechanism of the synchronous motor in the control link of the energy storage converter can enable the energy storage system to have the ability to actively support the power grid, thereby enhancing the stability and response speed of the energy storage system. Therefore, based on the preset virtual synchronous machine control strategy, the simulated power characteristic parameters corresponding to the energy storage system can be determined, so that the energy storage system can be more friendly to the power grid and have power regulation capabilities similar to synchronous generators, controlling the charging and discharging process of the energy storage system to be more balanced.

[0067] The virtual synchronous machine control strategy is used to indicate a strategy for adding the power characteristics of the synchronous machine into the control process of the energy storage converter of the energy storage system, thereby realizing the function of the virtual synchronous machine.

[0068] Optionally, virtual inertia and damping can be established based on a preset virtual synchronous machine control strategy to simulate the rotational inertia and damping provided by the mechanical shaft and winding in the synchronous generator, thereby obtaining simulated power characteristic parameters corresponding to the energy storage system. The simulated power characteristic parameters include the damping coefficient corresponding to each battery cluster and the rotational inertia corresponding to each battery cluster.

[0069] S202. Construct a damping power formula of the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system.

[0070] Optionally, after obtaining the simulated power characteristic parameters corresponding to the energy storage system, a damping power formula of the energy storage system can be constructed according to the power characteristics of the synchronous motor and the characteristics of the energy storage system to optimize the control process of each energy storage converter.

[0071] Exemplarily, a double closed-loop control method can be adopted, and the reactive power droop control method can be used to simulate the characteristics of electric excitation voltage regulation, so as to characterize the control characteristics of the energy storage converter, thereby constructing a damping power formula for the energy storage system.

[0072] The damping power formula is used to characterize the charging and discharging power of each battery cluster when each energy storage converter is in the same frequency and stable state, and the conditions that the damping coefficient of the virtual synchronous machine corresponding to each battery cluster should meet.

[0073] S203 : Determine the charge and discharge power corresponding to each battery cluster according to the charge state of each battery cluster and the damping power formula of the energy storage system.

[0074] Optionally, the state of charge of each battery cluster in the energy storage system can be obtained through the battery management system (EMS). The state of charge (SOC) refers to the ratio of the electric energy stored in each battery cluster unit at the current moment to the electric energy that can be stored when it is fully charged, reflecting the remaining capacity and available time of the battery cluster.

[0075] Optionally, after obtaining the damping power formula of the energy storage system, the damping coefficient corresponding to each battery cluster can be adjusted according to the state of charge (SOC) of each battery cluster, and the charge and discharge power corresponding to each battery cluster can be calculated according to the damping coefficient corresponding to each battery cluster and the damping power formula of the energy storage system, thereby realizing the adjustment of the charge and discharge power of each battery cluster and controlling each battery cluster to charge and discharge in a balanced manner.

[0076] S204 , controlling each battery cluster to charge and discharge according to the charge and discharge power corresponding to each battery cluster.

[0077] Optionally, after the charge and discharge power corresponding to each battery cluster is obtained, each battery cluster may be controlled to be charged and discharged according to the charge and discharge power corresponding to each battery cluster.

[0078] Exemplarily, the charge and discharge power corresponding to each battery cluster can be used as the charge and discharge power that each battery cluster should bear during the charge and discharge process, and sent to the cluster-level battery management system in each battery cluster, so that the cluster-level battery management system can adjust the charge and discharge rate of the battery cells in each battery cluster according to the charge and discharge power, and monitor and adjust the charge and discharge status of the battery cells, thereby ensuring that the battery cells in each battery cluster are charged and discharged with the corresponding charge and discharge power.

[0079] In this embodiment, the simulated power characteristic parameters corresponding to the energy storage system are determined based on the preset virtual synchronous machine control strategy, and then the damping power formula of the energy storage system is constructed according to the simulated power characteristic parameters corresponding to the energy storage system, so as to characterize the charging and discharging power of each battery cluster when each energy storage converter is stable at the same frequency and the conditions that the damping coefficient of the virtual synchronous machine corresponding to each battery cluster should satisfy, so that the charging and discharging power corresponding to each battery cluster can be determined according to the charge state of each battery cluster and the damping power formula of the energy storage system, and the charging and discharging of each battery cluster can be controlled according to the charge and discharge power corresponding to each battery cluster, so that under the premise of stable operation of the energy storage system, the power regulation capability similar to that of the synchronous generator can be possessed, so that the charging and discharging process of each battery unit can be made more balanced, and at the same time, the charging and discharging control of the energy storage system can be realized without calculating the difference in the charge state between the battery units, thereby avoiding the complex SOC calculation process, reducing the consumption of computing resources and time, and improving the response speed of the energy storage system.

[0080] In one possible implementation, the damping power formula is: , where P1 is the power of the first battery cluster, D1 is the damping coefficient corresponding to the first energy storage converter, P2 is the power of the second battery cluster, D2 is the damping coefficient corresponding to the second energy storage converter, Pn is the power of the nth battery cluster, Dn is the damping coefficient corresponding to the nth energy storage converter, and n is a positive integer.

[0081] Optionally, the damping power formula can characterize the charging and discharging power of each battery cluster and the damping coefficient of the virtual synchronous machine corresponding to each battery cluster when each energy storage converter is stable at the same frequency. Based on the damping power formula, the damping coefficient of each battery cluster can be adjusted to adjust the charging and discharging power of each battery cluster, so that the charge state of each battery cluster can be balanced. Among them, the damping coefficient is used to simulate the rotational inertia and damping provided by the mechanical shaft and winding of the synchronous generator.

[0082] In a possible implementation, the same-frequency stability is used to indicate that the electrical angular frequencies output by each energy storage converter are stable and the frequencies output by each energy storage converter are the same.

[0083] The electrical angular frequency output by each energy storage converter is used to simulate the electrical angular frequency corresponding to the speed of the synchronous generator, and the frequency output by each energy storage converter is used to indicate the charge and discharge frequency of the battery cluster where each energy storage converter is located. By stabilizing the same frequency, it can ensure that the energy storage converter has a high degree of stability and accuracy when outputting electric energy.

[0084] In one possible implementation, Figure 3 A schematic diagram of a flow chart for constructing a damping power formula for an energy storage system in the energy storage system control method provided in an embodiment of the present application, referring to Figure 3 As shown, in the above S202, according to the simulated power characteristic parameters corresponding to the energy storage system, a damping power formula of the energy storage system is constructed, including:

[0085] S301. Determine an output frequency equation corresponding to the energy storage system according to simulated power characteristic parameters corresponding to the energy storage system.

[0086] Optionally, after obtaining the simulated power characteristic parameters corresponding to the energy storage system, the output frequency of each energy storage converter in the energy storage system can be analyzed according to the power characteristics of the synchronous motor and the characteristics of the energy storage system to obtain the output frequency equation corresponding to the energy storage system.

[0087] The output frequency equation is used to characterize the conditions that the output frequency of each energy storage converter should satisfy when the energy storage converters are in a stable co-frequency state.

[0088] S302. Generate a damping power formula for the energy storage system according to the output frequency equation.

[0089] Optionally, after obtaining the output frequency equation, it is possible to characterize the conditions that the output frequency of each energy storage inverter should meet when the energy storage inverters are in the same frequency and stable. On this basis, in order to enable the energy storage system to have a power regulation capability similar to that of a synchronous generator, the damping power formula of the energy storage system can be generated according to the output frequency equation.

[0090] The output frequency equation of the energy storage system is determined by the simulated power characteristic parameters corresponding to the energy storage system, and the damping power formula of the energy storage system is generated based on the output frequency equation, which can accurately calculate the damping capacity of the energy storage system in suppressing low-frequency oscillations of the power system.

[0091] In one possible implementation, Figure 4 A schematic diagram of a flow chart for determining the output frequency equation corresponding to each energy storage converter in the energy storage system in the energy storage system control method provided in the embodiment of the present application, referring to Figure 4 As shown, the above S301 determines the output frequency equation corresponding to the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system, including:

[0092] S401. Determine an electrical angular frequency formula corresponding to the energy storage system according to simulated power characteristic parameters corresponding to the energy storage system.

[0093] Optionally, after obtaining the simulated power characteristic parameters corresponding to the energy storage system, a control block diagram of a virtual synchronous generator (VSG) can be obtained. Figure 5 The control block diagram of the virtual synchronization machine provided in the embodiment of the present application is shown in FIG. Figure 5 As shown, when the energy storage system is connected to the grid and operated, the debugging instruction Pm can be set by the EMS through communication, and finally the power P emitted by the PCS is equal to the debugging instruction Pm of the EMS.

[0094] Among them, Pm is the debugging instruction, P is the active power, Q is the reactive power, Qref is the reactive rated value, k is the reactive voltage regulation coefficient, E* is the internal potential amplitude, Ud_ref is the d-axis voltage reference value, Uq_ref is the q-axis voltage reference value, ω* is a fixed parameter, s represents the system response to the time derivative of the input signal, θ is the impedance angle, Js is the moment of inertia, and D is the damping coefficient.

[0095] However, when operating off-grid or in a microgrid, the common node frequency is not fixed, ω* is a fixed parameter, Pm can be determined by PCS, and the actual output power is determined by the load.

[0096] Therefore, taking the first battery cluster in the energy storage system as an example, when it is off-grid or microgrid operated, the electrical angular frequency formula corresponding to the energy storage system can be obtained as shown in the following formula (1):

[0097] (1)

[0098] Where P is the power generated by the PCS in the battery cluster, P m is the debugging instruction, ω is the electrical angular frequency, D1 is the damping coefficient corresponding to the first energy storage converter, ω* is a fixed parameter, and Js is the moment of inertia.

[0099] S402 , input the device parameters of each battery cluster into the electrical angular frequency formula, and obtain a steady-state formula based on the same frequency stability.

[0100] Optionally, the device parameters of each battery cluster are input into an electrical angular frequency formula, and based on the same frequency stability, after the electrical angular frequencies output by multiple PCSs in the energy storage system are finally stabilized, the frequencies output by each PCS must be the same, and the steady-state formula is obtained as shown in the following formula (2):

[0101] (2)

[0102] Among them, P1 is the power generated by the PCS in the first battery cluster, Pn is the power generated by the PCS in the nth battery cluster, P m is the debugging instruction, ω* is a fixed parameter, D1 is the damping coefficient corresponding to the first energy storage converter, D n is the damping coefficient corresponding to the nth energy storage converter, and Js is the moment of inertia.

[0103] S403. Obtain an output frequency equation according to a steady-state formula.

[0104] For example, according to the final value theorem and the steady-state formula, the following formula (3) can be obtained:

[0105] (3)

[0106] For example, based on formula (3), the output frequency equation can be obtained as follows:

[0107] (4)

[0108] Among them, P1 is the power generated by the PCS in the first battery cluster, P n is the power generated by the PCS in the nth battery cluster, P m is the debugging instruction, D1 is the damping coefficient corresponding to the first energy storage converter, D n is the damping coefficient corresponding to the nth energy storage converter, and Js is the moment of inertia.

[0109] By determining the electrical angular frequency formula corresponding to the energy storage system through the simulated power characteristic parameters corresponding to the energy storage system, the dynamic response characteristics of the energy storage system can be understood more accurately. By inputting the device parameters of each battery cluster into the electrical angular frequency formula and obtaining the steady-state formula based on the same frequency stability, the output frequency equation can be obtained according to the steady-state formula. The response behavior of the energy storage system under various disturbances can be characterized, thereby ensuring the reliability and safety of the energy storage system.

[0110] In a possible implementation, the above S302 generates a damping power formula of the energy storage system according to the output frequency equation, including:

[0111] According to the preset constraints, the output frequency equation is simplified to obtain the damping power formula of the energy storage system.

[0112] For example, based on formula (4), the preset constraint condition is: setting the debugging instruction Pm to 0. According to the constraint condition, the damping power formula of the energy storage system can be obtained by simplifying the output frequency equation.

[0113] The above is an exemplary description of the process of constructing the damping power formula of the energy storage system. The following is an exemplary description of the process of determining the charging and discharging power corresponding to each battery cluster according to the charge state of each battery cluster and the damping power formula of the energy storage system.

[0114] In a possible implementation, the damping coefficient corresponding to each battery cluster is positively correlated with the state of charge of each battery cluster.

[0115] It can be understood that in VSG, the damping coefficient reflects the energy storage system's ability to suppress frequency fluctuations and is an important indicator of system stability. In order to maintain the stability of the power grid, the energy storage system needs to have certain damping characteristics to suppress frequency fluctuations. As an energy storage unit, the SOC of the battery cluster directly affects the damping characteristics of the energy storage system. Therefore, the damping coefficient can be adjusted according to the positive correlation adjustment strategy through the SOC of the battery cluster to meet the needs of system stability.

[0116] In one possible implementation, Figure 6 A schematic diagram of a flow chart for determining the charge and discharge power corresponding to each battery cluster in the energy storage system control method provided in the embodiment of the present application, referring to Figure 6 As shown, the above S203 determines the charge and discharge power corresponding to each battery cluster according to the charge state of each battery cluster and the damping power formula of the energy storage system, including:

[0117] S601 : Determine a damping coefficient corresponding to each battery cluster according to the charge state of each battery cluster.

[0118] Optionally, the damping coefficient corresponding to each battery cluster may be calculated according to the charge state of each battery cluster.

[0119] Optionally, the damping coefficient corresponding to the state of charge of each battery cluster may also be obtained according to the state of charge of each battery cluster and a pre-stored mapping relationship between the state of charge and the damping coefficient.

[0120] S602 : Determine the charge and discharge power corresponding to each battery cluster according to the damping power formula of the energy storage system and the damping coefficient corresponding to each battery cluster.

[0121] Optionally, after the damping coefficient of each battery cluster is obtained, the damping coefficient of each battery cluster may be input into a damping power formula, thereby calculating the charge and discharge power corresponding to each battery cluster.

[0122] By determining the damping coefficient corresponding to each battery cluster through the charge state of each battery cluster, and determining the charging and discharging power corresponding to each battery cluster according to the damping power formula of the energy storage system and the damping coefficient corresponding to each battery cluster, the response speed of the energy storage system to external disturbances can be optimized, so that the energy storage system can recover to a stable state more quickly.

[0123] In one possible implementation, Figure 7 A schematic diagram of a flow chart for determining the damping coefficient corresponding to each battery cluster in the energy storage system in the energy storage system control method provided in the embodiment of the present application, referring to Figure 7 As shown, the above S601 determines the damping coefficient corresponding to each battery cluster according to the charge state of each battery cluster, including:

[0124] S701. Obtain system parameters of the energy storage system.

[0125] Among them, the system parameters of the energy storage system may include battery discharge rate, energy conversion efficiency, cycle life, energy capacity, power capacity, discharge depth, energy density and specific energy, etc.

[0126] S702: Determine an initial maximum damping value and an initial minimum damping value corresponding to the energy storage system according to system parameters of the energy storage system.

[0127] Optionally, the initial damping maximum value Dmax and the initial damping minimum value Dmin corresponding to each battery cluster may be obtained according to a pre-stored mapping relationship between system parameters of the energy storage system and the initial damping maximum value Dmax and the initial damping minimum value Dmin corresponding to each battery cluster.

[0128] S703 : Determine a damping coefficient corresponding to each battery cluster according to the initial damping maximum value, the initial damping minimum value, and the state of charge of each battery cluster.

[0129] Optionally, after obtaining the initial damping maximum value Dmax and the initial damping minimum value Dmin, the damping coefficient Dn corresponding to each battery cluster may be calculated according to the initial damping maximum value Dmax, the initial damping minimum value Dmin and the state of charge SOCn of each battery cluster.

[0130] By obtaining the system parameters of the energy storage system and determining the initial damping maximum value and the initial damping minimum value corresponding to the energy storage system through the system parameters of the energy storage system, the damping coefficient corresponding to each battery cluster is determined according to the initial damping maximum value, the initial damping minimum value and the charge state of each battery cluster. This can more accurately match the damping coefficient of each battery cluster, which helps the energy storage system to adjust its response strategy more quickly when facing external disturbances, thereby maintaining the stability and safety of the energy storage system and improving the overall energy efficiency of the energy storage system.

[0131] In one possible implementation, Figure 8 Another flow chart of determining the damping coefficient corresponding to each battery cluster in the energy storage system in the energy storage system control method provided in the embodiment of the present application, referring to Figure 8As shown, the above S703 determines the damping coefficient corresponding to each battery cluster according to the initial damping maximum value, the initial damping minimum value and the charge state of each battery cluster, including:

[0132] S801, calculating the damping difference between the initial maximum damping value and the initial minimum damping value.

[0133] Exemplarily, the damping difference ΔD between the initial damping maximum value Dmax and the initial damping minimum value Dmin may be calculated.

[0134] S802: Calculate the product of the damping difference and the state of charge of each battery cluster.

[0135] Exemplarily, the product ΔD*SOCn of the damping difference ΔD and the state of charge SOCn of each battery cluster is calculated respectively.

[0136] S803 : Determine the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster.

[0137] Optionally, after obtaining the product ΔD*SOCn of the state of charge and the damping difference of each battery cluster, the damping coefficient corresponding to each battery cluster can be calculated according to the product ΔD*SOCn of the state of charge and the damping difference of each battery cluster and the charge and discharge state of each battery cluster.

[0138] By calculating the damping difference between the initial damping maximum value and the initial damping minimum value, and calculating the product of the damping difference and the charge state of each battery cluster, and determining the damping coefficient corresponding to each battery cluster based on the product and the charge and discharge state of each battery cluster, it is possible to ensure that the battery cluster operates within a safe range and under appropriate conditions, thereby reducing the loss and aging rate of the battery cluster, and also improving the utilization rate of the battery cluster and the efficiency of the overall energy storage system.

[0139] In a possible implementation, taking any battery cluster in the energy storage system as a first battery cluster as an example, if the first battery cluster is in a discharging state, the above S803 determines the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster, including:

[0140] The sum of the product and the initial damping minimum value is taken as the damping coefficient corresponding to the first battery cluster.

[0141] Optionally, the sum of the product ΔD*SOCn of the state of charge of the battery cluster and the damping difference and the initial damping minimum value Dmin is calculated as the damping coefficient corresponding to the first battery cluster.

[0142] For example, if the first battery cluster is in a discharging state, the damping coefficient corresponding to the first battery cluster can be calculated using the following formula (5):

[0143] Di = Dmin+(Dmax - Dmin)*SOCi(5)

[0144] Wherein, Di is the damping coefficient corresponding to the first battery cluster, SOCi is the state of charge of the first battery cluster, Dmax is the initial damping maximum value, and Dmin is the initial damping minimum value.

[0145] In a possible implementation, taking any battery cluster in the energy storage system as a first battery cluster as an example, if the first battery cluster is in a charging state, the above S803 determines the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster, including:

[0146] The difference between the initial damping maximum value and the product is used as the damping coefficient corresponding to the first battery cluster.

[0147] Optionally, the difference between the initial damping maximum value Dmax and the product ΔD*SOCn of the state of charge of the battery cluster and the damping difference is calculated as the damping coefficient corresponding to the first battery cluster.

[0148] For example, if the first battery cluster is in a charging state, the damping coefficient corresponding to the first battery cluster can be calculated using the following formula (6):

[0149] Di = Dmax - (Dmax - Dmin)*SOCi (6)

[0150] Wherein, Di is the damping coefficient corresponding to the first battery cluster, SOCi is the state of charge of the first battery cluster, Dmax is the initial damping maximum value, and Dmin is the initial damping minimum value.

[0151] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0152] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or part of the technical solution that contributes to the prior art or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program code.

[0153] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A method for controlling an energy storage system, characterized in that: Applied to an energy storage system, the energy storage system at least comprises: a plurality of battery clusters connected in parallel, each of the battery clusters comprises a battery unit and an energy storage converter, the method comprises: Based on a preset virtual synchronous machine control strategy, determining a simulated power characteristic parameter corresponding to the energy storage system, wherein the simulated power characteristic parameter includes a damping coefficient corresponding to each of the battery clusters; According to the simulated power characteristic parameters corresponding to the energy storage system, a damping power formula of the energy storage system is constructed. The damping power formula is used to characterize the charging and discharging power of each battery cluster and the damping coefficient of the virtual synchronous machine corresponding to each battery cluster when the energy storage converters are in the same frequency and stable. The damping power formula is: ,in, is the power of the first battery cluster, is the damping coefficient corresponding to the first energy storage converter, is the power of the second battery cluster, is the damping coefficient corresponding to the second energy storage converter, is the power of the nth battery cluster, is the damping coefficient corresponding to the nth energy storage converter, where n is a positive integer; Determining the charge and discharge power corresponding to each of the battery clusters according to the charge state of each of the battery clusters and the damping power formula of the energy storage system; According to the charging and discharging power corresponding to each battery cluster, each battery cluster is controlled to charge and discharge.

2. The energy storage system control method according to claim 1, characterized in that: The same-frequency stability is used to indicate that the electrical angular frequencies output by each of the energy storage converters are stable and the frequencies output by each of the energy storage converters are the same.

3. The energy storage system control method according to claim 1, characterized in that: The damping power formula of the energy storage system is constructed based on the simulated power characteristic parameters corresponding to the energy storage system, including: Determining an output frequency equation corresponding to the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system; A damping power formula of the energy storage system is generated according to the output frequency equation.

4. The energy storage system control method according to claim 3, characterized in that: Determining the output frequency equation corresponding to the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system includes: Determine the electrical angular frequency formula corresponding to the energy storage system according to the simulated power characteristic parameters corresponding to the energy storage system; Input the device parameters of each battery cluster into the electrical angle frequency formula, and obtain a steady-state formula based on the same frequency stability; According to the steady-state formula, the output frequency equation is obtained.

5. The energy storage system control method according to claim 3, characterized in that: Generating the damping power formula of the energy storage system according to the output frequency equation includes: According to the preset constraints, the output frequency equation is simplified to obtain the damping power formula of the energy storage system.

6. The energy storage system control method according to claim 1, characterized in that: The damping coefficient corresponding to each of the battery clusters is positively correlated with the state of charge of each of the battery clusters.

7. The energy storage system control method according to claim 6, characterized in that: Determining the charge and discharge power corresponding to each battery cluster according to the charge state of each battery cluster and the damping power formula of the energy storage system includes: Determining a damping coefficient corresponding to each of the battery clusters according to the charge state of each of the battery clusters; The charge and discharge power corresponding to each battery cluster is determined according to the damping power formula of the energy storage system and the damping coefficient corresponding to each battery cluster.

8. The energy storage system control method according to claim 7, characterized in that: Determining the damping coefficient corresponding to each battery cluster according to the state of charge of each battery cluster includes: Obtaining system parameters of the energy storage system; Determining an initial damping maximum value and an initial damping minimum value corresponding to the energy storage system according to system parameters of the energy storage system; The damping coefficient corresponding to each of the battery clusters is determined according to the initial damping maximum value, the initial damping minimum value and the charge state of each of the battery clusters.

9. The energy storage system control method according to claim 8, characterized in that: Determining the damping coefficient corresponding to each battery cluster according to the initial damping maximum value, the initial damping minimum value and the charge state of each battery cluster includes: Calculating a damping difference between the initial damping maximum value and the initial damping minimum value; Calculating the product of the damping difference and the state of charge of each of the battery clusters; The damping coefficient corresponding to each battery cluster is determined according to the product and the charge and discharge state of each battery cluster.

10. The energy storage system control method according to claim 9, characterized in that: If the first battery cluster is in a discharge state; The step of determining the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster comprises: The sum of the product and the initial damping minimum value is used as the damping coefficient corresponding to the first battery cluster.

11. The energy storage system control method according to claim 9, characterized in that: If the first battery cluster is in a charging state; The step of determining the damping coefficient corresponding to each battery cluster according to the product and the charge and discharge state of each battery cluster comprises: The difference between the initial damping maximum value and the product is used as the damping coefficient corresponding to the first battery cluster.

12. An energy storage system, characterized in that: include: A plurality of battery clusters connected in parallel and a control device, wherein the control device is used to execute the energy storage system control method according to any one of claims 1 to 11.

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