Stability analysis method and device of energy storage system, electronic equipment and storage medium

Abstract

The invention discloses a stability analysis method and device of an energy storage system, electronic equipment and a storage medium. The method comprises the following steps: constructing an equivalent circuit model of the energy storage system; constructing a time domain nonlinear model based on the equivalent circuit model and a control loop of the energy storage system; under a steady-state working condition, performing small-signal linearization processing on the time-domain nonlinear model to obtain a time-domain linear small-signal model; obtaining a direct current side small signal impedance model according to the time domain linear small signal model; and performing stability analysis based on the direct current side small signal impedance model to obtain a stability analysis result of the energy storage system. Through the method, the direct current side small signal impedance model corresponding to the energy storage system can be obtained, so that a basis is provided for stability analysis of the energy storage system, and stability analysis of the energy storage system is realized.

Description

Technical Field

[0001] The present application belongs to the field of energy storage technology, and in particular relates to a stability analysis method, device, electronic device and storage medium for an energy storage system. Background Art

[0002] Energy storage refers to the process of storing energy through a medium or device and releasing it when needed. Energy storage is an important technology to adapt to the new energy power generation system. In the field of energy storage, complex energy storage systems such as direct-mounted DC energy storage systems and cascaded energy storage systems have stronger regulation capabilities of flexible DC transmission systems than traditional energy storage systems, are more suitable for the application scenarios of offshore wind power output through flexible DC, have lower system network losses, higher economic benefits and higher operational reliability, etc.

[0003] For this energy storage system composed of complex power electronic devices, how to improve its operational stability is a very important issue. Therefore, it is necessary to analyze the system stability and the key factors affecting the system stability.

[0004] At present, the research on converter valves of flexible DC transmission systems has been relatively mature. However, the research on energy storage systems with multiple cascaded energy storage valve submodules has just started. The industry still lacks stability analysis solutions for complex energy storage systems such as DC direct-mounted energy storage systems and cascaded energy storage systems. Summary of the invention

[0005] The present application provides a stability analysis method, device, electronic device and computer-readable storage medium for an energy storage system, which can realize stability analysis of a complex energy storage system.

[0006] In a first aspect, the present application provides a stability analysis method for an energy storage system, comprising:

[0007] Construct an equivalent circuit model of the energy storage system;

[0008] Constructing a time-domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system;

[0009] Under steady-state conditions, the above-mentioned time-domain nonlinear model is subjected to small-signal linearization processing to obtain a time-domain linear small-signal model;

[0010] The DC side small signal impedance model is obtained according to the above time domain linear small signal model;

[0011] Based on the DC side small signal impedance model, a stability analysis is performed to obtain the stability analysis result of the energy storage system.

[0012] By establishing an equivalent circuit model of the energy storage system, the time domain nonlinear model derived from the equivalent circuit model and the control loop of the energy storage system is used to derive and analyze the dynamic characteristic equations of various variables inside the energy storage system through small signal linearization processing, thereby obtaining the DC side small signal impedance model corresponding to the energy storage system, thereby providing a basis for the stability analysis of the energy storage system, and can be effectively applied to the stability analysis of complex energy storage systems such as DC direct-mounted energy storage systems and cascaded energy storage systems.

[0013] In some implementations of the first aspect, constructing an equivalent circuit model of the energy storage system includes:

[0014] Simplify the above energy storage system to obtain a simplified energy storage system topology;

[0015] Construct an equivalent circuit of the battery module in the simplified energy storage system topology above;

[0016] Construct an equivalent circuit of the power module in the simplified energy storage system topology;

[0017] An equivalent circuit model of the energy storage system is constructed according to the number of energy storage valve submodules put into the energy storage system under stable working conditions, the equivalent circuit of the battery module and the equivalent circuit of the power module.

[0018] Simplifying the network topology of the energy storage system can effectively reduce the difficulty of constructing the equivalent circuit model and improve the efficiency of establishing the impedance model of the energy storage system.

[0019] In some implementations of the first aspect, the step of constructing a time-domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system includes:

[0020] Based on the above equivalent circuit model, a nonlinear analytical model of the electrical part of the above energy storage system is constructed;

[0021] According to the control parameters of the control loop of the energy storage system, a nonlinear analytical model of the control part of the energy storage system is constructed.

[0022] In some implementations of the first aspect, under steady-state conditions, performing small signal linearization processing on the time-domain nonlinear model to obtain a time-domain linear small signal model includes:

[0023] Performing small signal linearization processing on the nonlinear analytical model of the electrical part to obtain a time domain linear small signal model corresponding to the electrical part;

[0024] The nonlinear analytical model of the control part is subjected to small signal linearization processing to obtain a time domain linear small signal model corresponding to the control part.

[0025] According to the simplified equivalent circuit model of the energy storage system, the time domain small signal models of the electrical part and the control part are constructed respectively, and based on this construction, the DC side small signal impedance model of the energy storage system is obtained, which can simplify the establishment process of the DC side small signal impedance model while ensuring the accuracy of the model.

[0026] In some implementations of the first aspect, the DC side small signal impedance model is obtained according to the time domain linear small signal model, including:

[0027] The time domain linear small signal model is converted to the frequency domain to obtain the above-mentioned DC side small signal impedance model.

[0028] In some implementations of the first aspect, the stability analysis based on the DC side small signal impedance model is performed to obtain a stability analysis result of the energy storage system, including:

[0029] Adjusting electrical parameters of a circuit part to obtain a DC impedance curve of the energy storage system in a first adjustment state;

[0030] Adjusting the control parameters of the control part to obtain a DC impedance curve of the energy storage system in a second adjustment state;

[0031] According to the DC impedance curve of the energy storage system in the first adjustment state and the DC impedance curve of the energy storage system in the second adjustment state, key influencing factors affecting the stability of the energy storage system are determined.

[0032] By adjusting the electrical parameters of the circuit part and the control parameters of the control part respectively, the DC impedance curve of the energy storage system under different adjustment states can be obtained. It is then possible to accurately determine the impact of changes in each electrical parameter and control parameter on the impedance characteristics and negative damping range of the energy storage system, providing a basis for analyzing the stability of the energy storage system.

[0033] In some implementations of the first aspect, adjusting the electrical parameters of the circuit portion to obtain a DC impedance curve of the energy storage system in a first adjustment state includes:

[0034] Adjust the line equivalent resistance to obtain the DC impedance curve under different line equivalent resistances.

[0035] In some implementations of the first aspect, adjusting the electrical parameters of the circuit portion to obtain a DC impedance curve of the energy storage system in a first adjustment state includes:

[0036] Adjust the line equivalent inductance to obtain the DC impedance curve under different line equivalent inductances.

[0037] In some implementations of the first aspect, adjusting the electrical parameters of the circuit portion to obtain a DC impedance curve of the energy storage system in a first adjustment state includes:

[0038] The equivalent capacitance of the energy storage valve submodule in the energy storage system is adjusted to obtain DC impedance curves under different equivalent capacitances.

[0039] In some implementations of the first aspect, adjusting the control parameters of the control part to obtain a DC impedance curve of the energy storage system in the second adjustment state includes:

[0040] The control parameters of the outer loop controller are adjusted to obtain the DC impedance curve under different outer loop control parameters.

[0041] In some implementations of the first aspect, adjusting the control parameters of the outer loop controller to obtain a DC impedance curve under different outer loop control parameters includes:

[0042] Adjust the proportional adjustment coefficient of the outer loop controller to obtain the DC impedance curve under different proportional adjustment coefficients; or,

[0043] The integral adjustment coefficient of the outer loop controller is adjusted to obtain the DC impedance curve under different integral adjustment coefficients.

[0044] In some implementations of the first aspect, adjusting the control parameters of the control part to obtain a DC impedance curve of the energy storage system in the second adjustment state includes:

[0045] The control parameters of the inner loop controller are adjusted to obtain the DC impedance curve under different inner loop control parameters.

[0046] In some implementations of the first aspect, adjusting the control parameters of the inner loop controller to obtain a DC impedance curve under different inner loop control parameters includes:

[0047] Adjust the proportional adjustment coefficient of the inner loop controller to obtain the DC impedance curve under different proportional adjustment coefficients; or,

[0048] The integral regulation coefficient of the inner loop controller is adjusted to obtain the DC impedance curves under different integral regulation coefficients.

[0049] In a second aspect, the present application provides a stability analysis device for an energy storage system, comprising:

[0050] A first building block is used to build an equivalent circuit model of the energy storage system;

[0051] The second model building is used to build a time domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system;

[0052] A small signal processing model is used to perform small signal linearization processing on the above-mentioned time domain nonlinear model under steady-state conditions to obtain a time domain linear small signal model;

[0053] A conversion module, used to obtain a DC side small signal impedance model according to the above time domain linear small signal model;

[0054] The analysis module is used to perform stability analysis based on the DC side small signal impedance model to obtain the stability analysis result of the energy storage system.

[0055] In a third aspect, the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method provided in any one of the implementations in the first aspect when executing the computer program.

[0056] In a fourth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method provided in any implementation manner in the first aspect is implemented.

[0057] In a fifth aspect, the present application provides a computer program product, which includes a computer program. When the computer program is executed by one or more processors, it implements the method provided in any implementation manner in the first aspect.

[0058] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0060] Figure 1 It is a schematic diagram of the implementation flow of a stability analysis method for an energy storage system provided in an embodiment of the present application;

[0061] Figure 2 It is a circuit structure diagram of a cascade type direct current direct-mounted energy storage system provided in an embodiment of the present application;

[0062] Figure 3 Schematic diagram of the circuit structure of a half-bridge energy storage valve submodule provided in an embodiment of the present application;

[0063] Figure 4 Schematic diagram of the circuit structure of a full-bridge energy storage valve submodule provided in an embodiment of the present application;

[0064] Figure 5 It is a schematic diagram of the implementation flow of S101 in a stability analysis method for an energy storage system provided in an embodiment of the present application;

[0065] Figure 6 It is a structural schematic diagram of a simplified energy storage system topology provided in an embodiment of the present application;

[0066] Figure 7 is a schematic diagram of the circuit structure of an equivalent circuit of a battery module provided in an embodiment of the present application;

[0067] Figure 8 It is a structural schematic diagram of an equivalent circuit model constructed by a stability analysis method of an energy storage system provided in an embodiment of the present application;

[0068] Fig. 9 is a schematic diagram of a DC current response of a first time domain simulation model and a DC current response of a second time domain simulation model;

[0069] Fig.10 It is a schematic diagram of the implementation process of S102 in the stability analysis method of the energy storage system provided in the embodiment of the present application;

[0070] Fig.11 It is a schematic diagram of the theoretical impedance curve provided in the embodiment of the present application and the frequency sweep characteristic points obtained by the simulation system;

[0071] Fig.12 It is a schematic diagram of the implementation process of S105 in the stability analysis method of the energy storage system provided in the embodiment of the present application;

[0072] Fig.13 The schematic diagram of the DC impedance curve of the energy storage system obtained by adjusting the line equivalent resistance to the resistance reference value of 0.5pu, 1pu and 2pu is shown;

[0073] Fig.14 is a schematic diagram of a DC impedance curve of an energy storage system obtained by adjusting the line equivalent inductance to 0.5pu, 1pu and 2pu of the inductance reference value;

[0074] Fig.15 It is a schematic diagram of the DC impedance curve of the energy storage system obtained by adjusting the equivalent capacitance of all energy storage valve submodules to 0.5pu, 1pu and 2pu of the capacitance reference value;

[0075] Fig.16is a schematic diagram of a DC impedance curve of an energy storage system obtained by adjusting the proportional adjustment coefficient of an outer loop controller to corresponding reference values ​​of 0.5pu, 1pu and 2pu;

[0076] Fig.17 is a schematic diagram of a DC impedance curve of an energy storage system obtained by adjusting the integral adjustment coefficient of the outer loop controller to 0.5pu, 1pu and 2pu corresponding to the reference value;

[0077] Fig.18 is a schematic diagram of a DC impedance curve of an energy storage system obtained by adjusting the proportional adjustment coefficient of the inner loop controller to 0.5pu, 1pu and 2pu corresponding to the reference value;

[0078] Fig.19 A schematic diagram of a DC impedance curve of an energy storage system obtained by adjusting the integral adjustment coefficient of the inner loop controller to 0.5 pu, 1 pu and 2 pu corresponding to the reference value;

[0079] Fig. 20 It is a structural schematic diagram of a stability analysis device for an energy storage system provided in an embodiment of the present application;

[0080] Fig.21 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0081] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0083] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0084] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0085] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0086] In the description of the embodiments of the present application, the term "plurality" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0087] Renewable energy generation methods represented by wind power generation and photovoltaic power generation are effective means to ease energy supply and adjust the energy structure. However, due to the randomness and intermittency of renewable energy generation, the power system's own absorption capacity is insufficient, and phenomena such as "abandoning wind" and "abandoning solar" occur from time to time, resulting in the power system showing a "double high" trend. How to solve the problems of power system stability and large-scale power transmission of renewable energy generation are issues that need to be solved urgently.

[0088] Energy storage refers to the process of storing energy through a medium or device and releasing it when needed. Energy storage is an important technology to adapt to the new energy power generation system. In the field of energy storage, energy storage systems such as cascade energy storage systems and DC direct-mounted energy storage systems have stronger regulation capabilities of flexible DC transmission systems than traditional energy storage systems, are more suitable for application scenarios of offshore wind power output via flexible DC, have lower system network losses, higher economic benefits and higher operational reliability, etc.

[0089] Among them, the DC direct-mounted energy storage system refers to an energy storage system directly connected to the DC bus. The energy storage valve submodule of the DC direct-mounted energy storage system is based on the modular multi-level converter technology. It is obtained by connecting the energy storage unit in parallel on the basis of the converter valve submodule of the original modular multi-level converter. For this energy storage system composed of complex power electronic devices, how to improve its operation stability is a very important topic. Therefore, it is necessary to analyze the system stability and the key factors affecting the system stability.

[0090] At present, the research on converter valves of flexible DC transmission systems has been relatively mature. However, the research on energy storage systems with multiple cascaded energy storage valve submodules has just started. The industry still lacks stability analysis solutions for complex energy storage systems such as DC direct-mounted energy storage systems and cascaded energy storage systems.

[0091] Based on this, an embodiment of the present application provides a stability analysis method for an energy storage system, which establishes an equivalent circuit model of the energy storage system, and derives a time domain nonlinear model from the equivalent circuit model and the control loop of the energy storage system. Through small signal linearization processing, the dynamic characteristic equations of various variables inside the energy storage system are derived and analyzed, thereby obtaining a DC side small signal impedance model corresponding to the energy storage system, thereby providing a basis for the stability analysis of the energy storage system, and can be effectively applied to the stability analysis of complex energy storage systems such as DC direct-mounted energy storage systems and cascaded energy storage systems.

[0092] In order to illustrate the technical solution proposed in the embodiments of the present application, a specific embodiment is provided below for illustration.

[0093] The following is a description of a stability analysis method for an energy storage system provided in an embodiment of the present application from a technical perspective. The stability analysis method for the energy storage system can be applied to a direct-mounted DC energy storage system, that is, a stability analysis of the DC side can be performed on a direct-mounted DC energy storage system. Since the stability of the DC side is closely related to the DC impedance characteristics of the energy storage system, a stability analysis can be performed based on the impedance model of the DC side of the energy storage system, thereby determining the impedance negative damping interval of the energy storage system and the key influencing factors affecting the stability of the system. It should be noted that the embodiment of the present application only uses a direct-mounted DC energy storage system as an example to exemplify the stability analysis method for the energy storage system. The stability analysis method for the energy storage system provided in the embodiment of the present application can also be applied to the stability analysis of complex energy storage systems such as cascade energy storage systems.

[0094] The execution subject of the stability analysis method provided in the embodiment of the present application may be an electronic device with data processing functions (i.e., capable of performing data processing functions such as model construction, model simulation, parameter calculation, parameter extraction, etc.). The electronic device includes but is not limited to computers, mobile phones, servers, etc. Here, taking a cascaded DC direct-mounted energy storage system as an example, the stability analysis method of the energy storage system provided in the embodiment of the present application is exemplarily described. It can be understood that the stability analysis method of the energy storage system provided in the embodiment of the present application can also be applied to the stability analysis of other types of energy storage systems, for example, it can be used for the stability analysis of a cascaded energy storage system.

[0095] See also Figure 1 , Figure 1The schematic diagram of the implementation process of the stability analysis method of the energy storage system provided in the embodiment of the present application is shown. Figure 1 As shown, the stability analysis method of the energy storage system in the embodiment of the present application may include:

[0096] S101, construct an equivalent circuit model of the energy storage system.

[0097] See also Figure 2 , Figure 2 The figure shows a circuit structure diagram of a cascade type DC direct-mounted energy storage system. Figure 2 It can be seen that the DC direct-mounted energy storage system usually includes multiple energy storage valve submodules (represented by SM in the figure), for example Figure 2 It includes N energy storage valve submodules SM (SM1 to SM N ), N energy storage valve sub-modules SM are connected in series.

[0098] In the embodiment of the present application, the energy storage valve submodule may include a battery module and a power module, wherein the power module may be used as follows: Figure 3 The half-bridge energy storage valve submodule shown in FIG. Figure 4 The full-bridge energy storage valve submodule shown.

[0099] The power module may include an IGBT, for example Figure 3 The power module in the half-bridge energy storage valve submodule shown includes two controllable switch devices, namely IGBT1 and IGBT2. By controlling the on and off of IGBT1 and IGBT2, the energy storage valve submodule can be switched on and off. Figure 4 The power module in the full-bridge energy storage valve submodule shown includes four controllable switch devices, namely IGBT3, IGBT4, IGBT5 and IGBT6. By controlling the on and off of IGBT3, IGBT4, IGBT5 and IGBT6, the energy storage valve submodule is switched on and off.

[0100] The above-mentioned construction of the equivalent circuit model of the energy storage system may specifically be to establish the equivalent circuit model of the energy storage system according to the electrical characteristics of each device in the above-mentioned energy storage system, or may be to first simplify the above-mentioned energy storage system and then construct a corresponding equivalent circuit model for the simplified energy storage system.

[0101] In specific applications, the above-mentioned equivalent circuit model can equate the energy storage valve sub-module invested in the energy storage system to the corresponding equivalent resistance, equivalent capacitance, equivalent inductance, etc., and determine the corresponding equivalent circuit based on the connection relationship of the energy storage valve sub-module in the energy storage system, that is, obtain the equivalent circuit model.

[0102] It should be noted that different types of energy storage systems have different hardware architectures, and therefore the equivalent circuit models constructed are also different. This embodiment is only an illustrative description using a DC direct-mounted energy storage system as an example, and cannot be considered as a limitation on the equivalent circuit model.

[0103] S102, constructing a time domain nonlinear model according to the equivalent circuit model.

[0104] In a specific application, after obtaining the equivalent circuit model, the data model is constructed in the time domain based on the internal control relationship and circuit relationship of the energy storage system, and the above-mentioned time domain nonlinear model can be obtained. For example, based on the network topology of the equivalent circuit model obtained in S101 above, the time domain nonlinear model corresponding to the equivalent circuit model is derived using Kirchhoff's voltage law and Kirchhoff's current law.

[0105] S103, under steady-state conditions, performing small signal linearization processing on the time-domain nonlinear model to obtain a time-domain linear small signal model.

[0106] Steady-state operating conditions refer to the operating condition where the energy storage system is in a constant DC voltage output.

[0107] Small signal linearization of a time-domain nonlinear model refers to linearizing the data model of the nonlinear model under steady-state conditions to obtain a linearized model that can be used to calculate the response generated by small signal excitation, that is, a time-domain linear small signal model.

[0108] S104, obtaining a DC side small signal impedance model according to the time domain linear small signal model.

[0109] In a specific application, the above-mentioned time-domain linear small signal model is converted into the frequency domain, so as to obtain the above-mentioned DC side small signal impedance model.

[0110] S105, performing stability analysis based on the DC side small signal impedance model to obtain a stability analysis result of the energy storage system.

[0111] In specific applications, after obtaining the small signal impedance model of the DC side, the impedance-based stability analysis method can analyze the stability of the energy storage system.

[0112] It should be noted that after obtaining the impedance model, the stability boundary of the energy storage system can be determined by calculating the frequency response of the equivalent impedance. When the amplitude and phase of the equivalent impedance meet the stability conditions, it means that the energy storage system is stable. Otherwise, it is considered that the energy storage system is unstable.

[0113] The impedance model can be analyzed for stability using the swept frequency analysis method. Of course, other existing stability analysis methods can also be used for stability analysis.

[0114] In specific applications, after obtaining the DC side small signal impedance model, the influence of the main circuit and control parameters of the energy storage system on the broadband impedance can be specifically analyzed based on the DC side small signal impedance model, and the negative impedance damping interval and key influencing factors of the small signal stability of the energy storage system can be determined. Among them, the negative impedance damping interval is the part of the energy storage system that is prone to instability.

[0115] It can be seen from the above that the embodiment of the present application establishes an equivalent circuit model of the energy storage system, and derives and analyzes the dynamic characteristic equations of various variables inside the energy storage system through small signal linearization processing based on the time domain nonlinear model derived from the equivalent circuit model and the control loop of the energy storage system, thereby obtaining a DC side small signal impedance model corresponding to the energy storage system, thereby providing a basis for the stability analysis of the energy storage system, and can be effectively applied to the stability analysis of complex energy storage systems such as DC direct-mounted energy storage systems.

[0116] In some embodiments, in order to reduce the difficulty of building the impedance model, the DC direct-mounted energy storage system can be simplified. The above equivalent circuit model can construct equivalent circuits for the power module and the battery module respectively, that is, the equivalent circuit of the battery module and the equivalent circuit of the power module can be constructed separately under steady-state conditions. Based on this, please refer to Figure 5 , Figure 5 A schematic diagram of the implementation flow of S101 in the stability analysis method of the energy storage system provided in the embodiment of the present application is shown in FIG. Figure 5 As shown, the above S101 may specifically include the following steps:

[0117] S1011, simplifying the energy storage system to obtain a simplified energy storage system topology.

[0118] In specific applications, the energy storage system can be simplified by ignoring the adjustment link in the operation of the above energy storage system and only considering the electrical part and the control part. dc To represent the inductance in the energy storage system line, the DC series inductor parasitic resistance R dc To represent the resistance in the energy storage system circuit, the simplified energy storage system topology is as follows: Figure 6 shown.

[0119] S1012, constructing an equivalent circuit of the battery module in the simplified energy storage system topology.

[0120] In specific applications, the battery module in each energy storage valve submodule can be equivalent to an equivalent circuit consisting of a controlled DC power supply OCV and an ohmic resistor R0. The polarization reaction of the battery can also be considered, and the battery module can be equivalent to a first-order RC equivalent circuit. The battery polarization reaction and concentration difference reaction can also be considered at the same time, and the battery module can be equivalent to a second-order RC equivalent circuit. Of course, other types of equivalent circuits can also be constructed by considering other reaction characteristics of the battery. For example, the equivalent circuit of the battery module is as follows Figure 7 shown.

[0121] S1013, constructing an equivalent circuit of a power module in a simplified energy storage system topology.

[0122] In specific applications, the power module includes switching devices, such as Figure 3 IGBT1 and IGBT2 in the half-bridge energy storage valve submodule described in the above. The switch device can be equivalent to two controlled variable resistors, that is, IGBT1 is equivalent to a variable resistor R T1 , IGBT2 is equivalent to a variable resistor R T2 When IGBT1 is turned on, R T1 =R on , R on is the on-resistance of IGBT1, which is very small and can be regarded as 0; when IGBT1 is turned off, R T1 =R off , R off is the off resistance of IGBT1, which is very large and can be regarded as infinite. When IGBT2 is turned on, R T2 =R on , R on is the on-resistance of IGBT2, which is very small and can be regarded as 0; when IGBT2 is turned off, R T2 =R off , R off is the off resistance of IGBT2, which is very large and can be regarded as infinite. When the energy storage valve submodule needs to be put into the energy storage system, the energy storage valve submodule can be put into the energy storage system in which multiple energy storage valve submodules are connected in series by controlling IGBT1 to turn on and IGBT2 to turn off. On the contrary, by controlling IGBT1 to turn off and IGBT2 to turn on, the energy storage valve submodule can be cut out of the energy storage system.

[0123] S1014, constructing an equivalent circuit model of the energy storage system according to the number of energy storage valve submodules put into the energy storage system under stable working conditions, the equivalent circuit of the battery module and the equivalent circuit of the power module.

[0124] In a certain stable working condition, in order to output a fixed voltage DC voltage, the number of energy storage valve submodules put into the energy storage system is fixed (denoted as non ), assuming that the number of all energy storage valve submodules involved in switching in the energy storage system is n sm Since multiple energy storage valve modules are connected in series in the DC direct-mounted energy storage system, the equivalent capacitance of the energy storage valve module in the energy storage system under steady-state conditions is C eq =C / n on , where C is the equivalent capacitance of a single energy storage valve submodule. Assume that the battery module in each energy storage valve submodule is equivalent to a controlled DC voltage source OCV and a battery equivalent resistance R bsm Taking the power module as a half-bridge energy storage valve submodule as an example, pulses are generated by controlling the DC voltage of the external loop and the DC current of the internal loop to control the number of energy storage valve submodules n put into operation in each operation cycle. on , in order to achieve the modulation of DC voltage.

[0125] Based on the above analysis, an equivalent circuit model of the energy storage system under steady-state conditions can be constructed. For example, see Figure 8 , Figure 8 The structural diagram of the equivalent circuit model constructed by the stability analysis method provided in the embodiment of the present application is shown. bsmeq =n on ×R bsm ; Line equivalent resistance R eq =2R dc ; Line equivalent inductance L eq =2L dc , energy storage valve DC voltage u dc =R bsmeq ×i dcbsm +u bsm ,u bsm is the equivalent battery voltage.

[0126] In order to verify the accuracy of the simplified equivalent circuit model, a time domain simulation model of the simplified equivalent circuit model (hereinafter referred to as the first time domain simulation model) and a time domain simulation model corresponding to the complete energy storage system (hereinafter referred to as the second time domain simulation model) can be established through simulation software, and simulation tests are performed. The simulation test process is: the power is stepped from 1pu to 0.8pu at 2S, and the DC current response of the two simulation models is tested. The simulation test results are shown in FIG. Fig. 9 As shown. Fig. 9 It can be seen that the DC current response of the first time domain simulation model is basically consistent with the DC current response of the second time domain simulation model. Therefore, it can be determined that the simplified equivalent circuit model of the energy storage system provided in the embodiment of the present application can also be used to construct an impedance model of the energy storage system with a certain accuracy.

[0127] It should be noted that the above-mentioned simulation software includes but is not limited to MATLAB simulation software, Simulink simulation software, etc.

[0128] It can be seen from the above that simplifying the network topology of the energy storage system can effectively reduce the difficulty of constructing the equivalent circuit model and improve the efficiency of establishing the impedance model of the energy storage system.

[0129] In some embodiments, in order to more accurately determine the factors affecting system stability, when deriving the dynamic change equations of each variable in the energy storage system, a nonlinear analytical model of the electrical part and a nonlinear analytical model of the control part can be established for the energy storage system. The electrical part refers to the main circuit in the equivalent circuit model corresponding to the energy storage system, and the control part refers to the control parameters corresponding to the modulation control system of the energy storage system, such as the voltage outer loop controller and the current inner loop controller. Based on this, please refer to Fig.10 , Fig.10 The implementation process of S102 in the stability analysis method of the energy storage system provided in one embodiment of the present application is shown. Fig.10 As shown, the above S102 may include the following steps:

[0130] S1021: Based on the equivalent circuit model, construct a nonlinear analytical model of the electrical part of the energy storage system.

[0131] In specific applications, the voltage parameters and current parameters in the equivalent circuit model are derived based on Kirchhoff's voltage law and Kirchhoff's current law, and the nonlinear analytical model of the electrical part can be obtained.

[0132] For example, Figure 8 The electrical parameters and current parameters are derived from the equivalent circuit model shown in the figure, and the nonlinear analytical model of the electrical part can be obtained as follows:

[0133]

[0134] Among them, L eq is the equivalent inductance of the line, e dc is the DC side equivalent u dc,pu The voltage across the current source, R eq is the line equivalent resistance, u dc is the DC voltage of the energy storage system, C eq is the equivalent capacitance of all energy storage valve submodules, i dc is the current in the line, i dcbsm is the current on the DC side, R bsmeq is the battery equivalent resistance, u bsm is the equivalent battery voltage.

[0135] S1022: Construct a nonlinear analytical model of the control part of the energy storage system according to the control parameters of the control loop of the energy storage system.

[0136] In a specific application, the control parameters of the energy storage system may include a transfer function of an outer loop voltage controller and a transfer function of an inner loop current controller.

[0137] For example, Figure 8 The nonlinear analytical model of the control part constructed by the control parameters in the equivalent circuit model shown is:

[0138]

[0139] Among them, G udc is the transfer function of the outer loop voltage controller of the DC direct-mounted energy storage valve, Among them, K p,udc is the proportional adjustment coefficient of the outer loop voltage controller, K i,udc is the integral adjustment coefficient of the outer loop voltage controller, G idc is the transfer function of the inner loop current controller of the DC direct-mounted energy storage valve, Among them, K p,idc is the proportional adjustment coefficient of the inner loop current controller, K i,idv is the integral adjustment coefficient of the inner loop current controller, e dc,pu is the per unit value of the voltage across the equivalent current source on the DC side, e dcref,pu is the per unit value of the reference voltage of the energy storage system, i dc,pu is the per unit value of the current on the DC side, i dcref,pu is the per unit value of the reference current of the energy storage system, U dc,base is the voltage reference value of the energy storage system, I dc,base It is the current reference value of the energy storage system.

[0140] In some embodiments, by performing small signal linearization processing on the nonlinear analytical model of the electrical part (the model corresponding to formula (1)), the time domain linear small signal model of the electrical part can be obtained. The time domain linear small signal model of the electrical part is as follows:

[0141]

[0142] By performing small signal linearization processing on the nonlinear analytical model of the control part (the model corresponding to formula (2)), the time domain linear small signal model of the control part can be obtained. The time domain linear small signal model of the control part is as follows:

[0143]

[0144] In some embodiments, the above S104 may specifically be to convert the time domain linear small signal model into the frequency domain, so as to obtain the DC side small signal impedance model.

[0145] In specific applications, Figure 8 Taking the time domain linear small signal model corresponding to the equivalent circuit model shown in FIG. 1 as an example, substituting formula (4) into formula (3) and simplifying it in the frequency domain, we can obtain:

[0146]

[0147] B=G idc G udc (6);

[0148] Δu dc =R bsmeq Δi dcbsm +AΔi dc -BΔe dc (7);

[0149] (R eq +R bsmeq +sL eq +A)Δi dc =(1+sC eq Δu dc +B)Δe dc (8);

[0150] Let C = R eq +R bsmeq +sL eq +A,D=1+sC eq Δu dc +B, so the DC side small signal impedance model is as follows:

[0151]

[0152] After obtaining the DC side small signal impedance model, in order to verify the accuracy of the impedance model constructed by the method provided in the present application, the energy storage system simulation system is established using simulation software, and a broadband disturbance signal is injected into the DC bus of the energy storage system simulation system, so as to obtain the accurate impedance sweep frequency characteristic points of the energy storage system within a certain frequency range. The theoretical impedance curve is determined according to the constructed DC side small signal impedance model, and the scan frequency characteristic points obtained by simulation are analyzed for the degree of fit with the impedance curve. The analysis results are as follows: Fig.11 As shown. Fig.11 It can be seen that the frequency sweep feature points obtained by the simulation system are basically consistent with the theoretical impedance curve obtained by the DC side small signal impedance model established in the embodiment of the present application, which shows that the DC side small signal impedance model obtained by the stability analysis method provided in the embodiment of the present application is relatively accurate.

[0153] In a specific application, the above-mentioned injection of a wide-band disturbance signal at the DC bus of the simulation system can be based on 200Hz as the dividing point, injecting a DC disturbance current every 10Hz in the range of 1-200Hz, and injecting a DC disturbance current every 50Hz in the range of 200-1000Hz, and measuring the DC disturbance voltage component at the corresponding frequency, so as to calculate the DC side impedance (the DC side impedance is the ratio of the measured DC disturbance voltage component to the injected DC disturbance current).

[0154] It can be seen from the above that the stability analysis method provided in the embodiment of the present application constructs time domain small signal models of the electrical part and the control part respectively for the simplified equivalent circuit model of the energy storage system, and obtains the DC side small signal impedance model of the energy storage system based on this construction, which can simplify the establishment process of the DC side small signal impedance model while ensuring the accuracy of the model.

[0155] In some embodiments, in order to determine the key factors affecting the stability of the energy storage system, such as Fig.12 As shown, the above S105 may include the following steps:

[0156] S1051, adjusting electrical parameters of a circuit part to obtain a DC impedance curve of the energy storage system in a first adjustment state.

[0157] In specific applications, the electrical parameters that can be adjusted in the electrical part include the line equivalent resistance R eq , Line equivalent inductance L eq And the equivalent capacitance C in the energy storage valve submodule put into the energy storage system eq .

[0158] The above S1051 can specifically be to adjust the circuit equivalent resistance R eq , get the equivalent resistance R of different lines eq For example, the line equivalent resistance R eq Adjusted to the resistance reference value of 0.5pu, 1pu and 2pu, the DC impedance curve of the energy storage system is as follows Fig.13 shown.

[0159] The above S1051 can also be used to adjust the line equivalent inductance L eq , obtain the equivalent inductance L of different lines eq For example, the line equivalent inductance L eq Adjusted to the inductance base value of 0.5pu, 1pu and 2pu, the DC impedance curve of the energy storage system is as follows Fig.14 shown.

[0160] The above S1051 may also specifically adjust the equivalent capacitance C of the energy storage valve submodule put into the energy storage system. eq , get different equivalent capacitance C eq For example, all equivalent capacitors C in the energy storage valve submodule are respectively eq Adjusted to the capacitance reference value of 0.5pu, 1pu and 2pu, the DC impedance curve of the energy storage system is as follows Fig.15 shown.

[0161] It is understandable that the electrical parameters may also be adjusted to other per-unit values ​​corresponding to the reference values, and the above 0.5 pu, 1 pu and 2 pu are only exemplary implementations.

[0162] S1052, adjusting the control parameters of the control part to obtain a DC impedance curve of the energy storage system in a second adjustment state.

[0163] In specific applications, the control parameters of the above-mentioned control part may include voltage outer loop control parameters and current inner loop control parameters. Therefore, the above-mentioned voltage outer loop control parameters can be adjusted to obtain a DC impedance curve under different voltage outer loop control parameters, and the above-mentioned current inner loop control parameters can also be adjusted to obtain a DC impedance curve under different inner loop current control parameters.

[0164] In a specific application, the above S1052 can specifically adjust the control parameters of the outer loop controller to obtain the DC impedance curve under different outer loop control parameters. For example, adjust the proportional adjustment coefficient K of the outer loop controller p,udc The DC impedance curve of the energy storage system is obtained as follows: Fig.16 As shown. For example, adjusting the integral adjustment coefficient K of the outer loop controller i,udc They are 0.5pu, 1pu and 2pu corresponding to the benchmark values ​​respectively. The DC impedance curve of the energy storage system is as follows: Fig.17 shown.

[0165] The above S1052 can also be to adjust the control parameters of the inner loop controller to obtain the DC impedance curve under different inner loop control parameters. For example, adjust the proportional adjustment coefficient K of the inner loop controller p,idc The DC impedance curve of the energy storage system is obtained as follows: Fig.18 As shown. For example, adjusting the integral adjustment coefficient K of the inner loop controller i,idc They are 0.5pu, 1pu and 2pu corresponding to the benchmark values ​​respectively. The DC impedance curve of the energy storage system is as follows: Fig.19 shown.

[0166] It is understandable that the control parameter may also be adjusted to other per-unit values ​​corresponding to the reference value, and the above 0.5 pu, 1 pu and 2 pu are only exemplary implementations.

[0167] S1053: Determine key influencing factors affecting the stability of the energy storage system according to the DC impedance curve of the energy storage system in the first adjustment state and the DC impedance curve of the energy storage system in the second adjustment state.

[0168] In specific applications, Fig.13 It can be seen that the line equivalent resistance R eq The change of has little impact on the overall DC impedance characteristics and negative damping range. Fig.14 It can be seen that the line equivalent inductance L eq The change of mainly affects the medium and high frequency (frequency above 100Hz) characteristics of DC impedance. eq As the impedance increases, the inductance of the impedance increases, the impedance amplitude in the medium and high frequency bands increases, and the negative damping range of the impedance phase gradually moves toward the low frequency. Fig.15 It can be seen that the equivalent capacitance C of all the energy storage valve submodules eq The phase characteristics of the medium and high frequencies (frequency above 100 Hz) that mainly affect the DC impedance, with the increase of the equivalent capacitance Ceq in all energy storage valve submodules, the negative damping range of the impedance phase gradually moves to the low frequency.

[0169] Depend on Fig.16 It can be seen that the proportional adjustment coefficient K of the DC voltage outer loop controller is p,udc The change of the DC impedance amplitude has little effect on the overall value. p,udc As the impedance increases, the impedance amplitude decreases slightly, the impedance phase becomes less perceptual in the low frequency band (frequency is 100Hz and below), the perceptual in the mid-high frequency band increases, and the negative damping range of the impedance phase gradually moves toward the low frequency. Fig.17 It can be seen that the integral regulation integral K of the DC voltage outer loop controller i,udc The phase characteristics of the low-frequency band that mainly affects the DC impedance are adjusted with the integral K i,udc As the impedance increases, the inductance of the low-frequency band gradually increases.

[0170] Depend on Fig.18 It can be seen that the proportional adjustment coefficient K of the DC current inner loop controller is p,idc The change of the DC impedance amplitude has little effect on the overall value. p,idc With the increase of impedance, the impedance amplitude decreases slightly, and the influence of impedance phase is nonlinear. The inductance in the low frequency band first weakens and then increases, and the overall change of the negative damping range of impedance phase is small. Fig.19 It can be seen that the integral adjustment coefficient K of the DC current inner loop controller isi,idc The change in has little effect on the overall DC impedance.

[0171] It can be seen from the above that the embodiment of the present application analyzes the key influencing factors affecting the stability of the energy storage system through the impedance model, which can provide an analysis basis for the stable operation of the energy storage system.

[0172] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0173] Corresponding to the above, the present application embodiment also provides a stability analysis device for an energy storage system. Fig. 20 The stability analysis device 20 of the energy storage system in the embodiment of the present application includes: a first construction module 101, a second construction model 102, a small signal processing model 103, a conversion module 104 and an analysis module 105.

[0174] The first building module 101 is used to build an equivalent circuit model of the energy storage system.

[0175] The second constructed model 102 is used to construct a time-domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system.

[0176] The small signal processing model 103 is used to perform small signal linearization processing on the time domain nonlinear model under steady-state conditions to obtain a time domain linear small signal model.

[0177] The conversion module 104 is used to obtain a DC side small signal impedance model according to the time domain linear small signal model.

[0178] The analysis module 105 is used to perform stability analysis based on the DC side small signal impedance model to obtain a stability analysis result of the energy storage system.

[0179] As can be seen from the above, in the embodiments of the present application, by establishing an equivalent circuit model of the energy storage system, the time domain nonlinear model derived from the equivalent circuit model and the control loop of the energy storage system is used, and the dynamic characteristic equations of each variable inside the energy storage system are derived and analyzed through small signal linearization processing, thereby obtaining a DC side small signal impedance model corresponding to the energy storage system, thereby providing a basis for the stability analysis of the energy storage system, and can be effectively applied to the stability analysis of complex energy storage systems such as DC direct-mounted energy storage systems.

[0180] In some embodiments, the first building block 101 includes: a simplification unit, a first building unit, a second building unit, and a third building unit.

[0181] The simplification unit is used to simplify the above energy storage system to obtain a simplified energy storage system topology.

[0182] The first construction unit is used to construct an equivalent circuit of the battery module in the simplified energy storage system topology.

[0183] The second construction unit is used to construct an equivalent circuit of the power module in the simplified energy storage system topology.

[0184] The third construction unit is used to construct an equivalent circuit model of the energy storage system according to the number of energy storage valve submodules put into the energy storage system under stable working conditions, the equivalent circuit of the battery module and the equivalent circuit of the power module.

[0185] As can be seen from the above, in the embodiments of the present application, simplifying the network topology of the energy storage system can effectively reduce the difficulty of constructing the equivalent circuit model and improve the efficiency of establishing the impedance model of the energy storage system.

[0186] In some embodiments, the second building block 102 includes a fourth building unit and a fifth building unit.

[0187] The fourth construction unit is used to construct a nonlinear analytical model of the electrical part of the energy storage system based on the equivalent circuit model.

[0188] The fifth construction unit is used to construct a nonlinear analytical model of the control part of the energy storage system according to the control parameters of the control loop of the energy storage system.

[0189] In some embodiments, the small signal processing model 103 includes a first small signal processing unit and a second small signal processing unit.

[0190] The first small signal processing unit is used to perform small signal linearization processing on the nonlinear analytical model of the electrical part to obtain a time domain linear small signal model corresponding to the electrical part.

[0191] The second small signal processing unit is used to perform small signal linearization processing on the nonlinear analytical model of the control part to obtain a time domain linear small signal model corresponding to the control part.

[0192] In some embodiments, the conversion module 104 is specifically used to convert the time-domain linear small signal model into the frequency domain to obtain the above-mentioned DC side small signal impedance model.

[0193] As can be seen from the above, in the embodiment of the present application, the time domain small signal models of the electrical part and the control part are respectively constructed for the simplified equivalent circuit model of the energy storage system, and the DC side small signal impedance model of the energy storage system is obtained based on this construction, which can simplify the establishment process of the DC side small signal impedance model while ensuring the accuracy of the model.

[0194] In some embodiments, the analysis module 105 includes an electrical parameter adjustment unit, a control parameter adjustment unit and an analysis unit.

[0195] The electrical parameter adjustment unit is used to adjust the electrical parameters of the circuit part and obtain the DC impedance curve of the energy storage system in the first adjustment state.

[0196] The control parameter adjustment unit is used to adjust the control parameters of the control part to obtain the DC impedance curve of the energy storage system in the second adjustment state.

[0197] The analyzing unit is used to determine key influencing factors affecting the stability of the energy storage system according to the DC impedance curve of the energy storage system in the first adjustment state and the DC impedance curve of the energy storage system in the second adjustment state.

[0198] In some embodiments, the electrical parameter adjustment unit is specifically used to adjust the line equivalent resistance and obtain a DC impedance curve under different line equivalent resistances.

[0199] In other embodiments, the electrical parameter adjustment unit is specifically used to adjust the line equivalent inductance and obtain a DC impedance curve under different line equivalent inductances.

[0200] In other embodiments, the electrical parameter adjustment unit is specifically used to adjust the equivalent capacitance in the energy storage valve submodule put into the energy storage system to obtain DC impedance curves under different equivalent capacitances.

[0201] In some embodiments, the control parameter adjustment unit is specifically used to adjust the control parameters of the outer loop controller to obtain the DC impedance curve under different outer loop control parameters. The control parameter adjustment unit can be used to adjust the proportional adjustment coefficient of the outer loop controller to obtain the DC impedance curve under different proportional adjustment coefficients; or adjust the integral adjustment coefficient of the outer loop controller to obtain the DC impedance curve under different integral adjustment coefficients.

[0202] In other embodiments, the control parameter adjustment unit is specifically used to adjust the control parameters of the inner loop controller to obtain the DC impedance curve under different inner loop control parameters. The control parameter adjustment unit can be used to adjust the proportional adjustment coefficient of the inner loop controller to obtain the DC impedance curve under different proportional adjustment coefficients; or adjust the integral adjustment coefficient of the inner loop controller to obtain the DC impedance curve under different integral adjustment coefficients.

[0203] As can be seen from the above, in the embodiment of the present application, by adjusting the electrical parameters of the circuit part and the control parameters of the control part respectively, the DC impedance curve of the energy storage system under different adjustment states is obtained, and the influence of the change of each electrical parameter and control parameter on the impedance characteristics and negative damping range of the energy storage system can be accurately determined, which provides a basis for analyzing the stability of the energy storage system.

[0204] Corresponding to the stability analysis method of the energy storage system provided above, the embodiment of the present application further provides an electronic device. Fig.21 The electronic device 21 in the embodiment of the present application includes: a memory 211, one or more processors 212 ( Fig.21 Only one is shown) and a computer program stored in the memory 211 and executable on the processor. Among them: the memory 211 is used to store software programs and modules, and the processor 212 executes various functional applications and data processing by running the software programs and units stored in the memory 211. Specifically, the processor 212 implements the specific steps of each embodiment of the stability analysis method of the energy storage system provided in the embodiment of the present application by running the above-mentioned computer program stored in the memory 211.

[0205] It should be understood that in the embodiment of the present application, the processor 212 may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0206] The memory 211 may include a read-only memory and a random access memory, and provides instructions and data to the processor 212. A part or all of the memory 211 may also include a nonvolatile random access memory.

[0207] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0208] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0209] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of external device software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0210] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the system embodiments described above are merely schematic. For example, the division of the above modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units 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 an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0211] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0212] If the above-mentioned integrated unit 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 present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the associated hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The above-mentioned computer-readable storage medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer-readable memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media does not include electrical carrier signals and telecommunication signals.

[0213] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A stability analysis method for an energy storage system, characterized in that: include: Construct an equivalent circuit model of the energy storage system; Constructing a time-domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system; Under steady-state conditions, small-signal linearization is performed on the time-domain nonlinear model to obtain a time-domain linear small-signal model; Obtaining a DC side small signal impedance model according to the time domain linear small signal model; A stability analysis is performed based on the DC side small signal impedance model to obtain a stability analysis result of the energy storage system.

2. The method according to claim 1, characterized in that The equivalent circuit model of the energy storage system is constructed as follows: Simplifying the energy storage system to obtain a simplified energy storage system topology; Constructing an equivalent circuit of a battery module in the simplified energy storage system topology; Constructing an equivalent circuit of a power module in the simplified energy storage system topology; An equivalent circuit model of the energy storage system is constructed according to the number of energy storage valve submodules put into the energy storage system under stable working conditions, the equivalent circuit of the battery module and the equivalent circuit of the power module.

3. The method according to claim 1, characterized in that The constructing of a time-domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system includes: Based on the equivalent circuit model, construct a nonlinear analytical model of the electrical part of the energy storage system; According to the control parameters of the control loop of the energy storage system, a nonlinear analytical model of the control part of the energy storage system is constructed.

4. The method according to claim 3, characterized in that Under the steady-state condition, the time-domain nonlinear model is subjected to small signal linearization processing to obtain a time-domain linear small signal model, including: Performing small signal linearization processing on the nonlinear analytical model of the electrical part to obtain a time domain linear small signal model corresponding to the electrical part; The nonlinear analytical model of the control part is subjected to small signal linearization processing to obtain a time domain linear small signal model corresponding to the control part.

5. The method according to claim 1, characterized in that The step of obtaining a DC side small signal impedance model according to the time domain linear small signal model includes: The time domain linear small signal model is converted to the frequency domain to obtain the DC side small signal impedance model.

6. The method according to any one of claims 1 to 5, characterized in that: The stability analysis is performed based on the DC side small signal impedance model to obtain the stability analysis result of the energy storage system, including: Adjusting electrical parameters of a circuit portion to obtain a DC impedance curve of the energy storage system in a first adjustment state; Adjusting the control parameters of the control part to obtain a DC impedance curve of the energy storage system in a second adjustment state; According to the DC impedance curve of the energy storage system in the first adjustment state and the DC impedance curve of the energy storage system in the second adjustment state, key influencing factors affecting the stability of the energy storage system are determined.

7. The method according to claim 6, characterized in that The step of adjusting the electrical parameters of the circuit part to obtain a DC impedance curve of the energy storage system in a first adjustment state includes: Adjust the line equivalent resistance to obtain the DC impedance curve under different line equivalent resistances.

8. The method according to claim 6, characterized in that The step of adjusting the electrical parameters of the circuit part to obtain a DC impedance curve of the energy storage system in a first adjustment state includes: Adjust the line equivalent inductance to obtain the DC impedance curve under different line equivalent inductances.

9. The method according to claim 6, characterized in that The step of adjusting the electrical parameters of the circuit part to obtain a DC impedance curve of the energy storage system in a first adjustment state includes: The equivalent capacitance of the energy storage valve submodule in the energy storage system is adjusted to obtain DC impedance curves under different equivalent capacitances.

10. The method according to claim 6, characterized in that The adjusting control parameters of the control part to obtain a DC impedance curve of the energy storage system in a second adjustment state includes: The control parameters of the outer loop controller are adjusted to obtain the DC impedance curve under different outer loop control parameters.

11. The method according to claim 10, characterized in that The step of adjusting the control parameters of the outer loop controller to obtain a DC impedance curve under different outer loop control parameters includes: Adjust the proportional adjustment coefficient of the outer loop controller to obtain the DC impedance curve under different proportional adjustment coefficients; or, The integral adjustment coefficient of the outer loop controller is adjusted to obtain the DC impedance curve under different integral adjustment coefficients.

12. The method according to claim 6, characterized in that The adjusting control parameters of the control part to obtain a DC impedance curve of the energy storage system in a second adjustment state includes: The control parameters of the inner loop controller are adjusted to obtain the DC impedance curve under different inner loop control parameters.

13. The method according to claim 12, characterized in that The step of adjusting the control parameters of the inner loop controller to obtain a DC impedance curve under different inner loop control parameters includes: Adjust the proportional adjustment coefficient of the inner loop controller to obtain the DC impedance curve under different proportional adjustment coefficients; or, The integral regulation coefficient of the inner loop controller is adjusted to obtain the DC impedance curves under different integral regulation coefficients.

14. A stability analysis device for an energy storage system, characterized in that: include: A first building block is used to build an equivalent circuit model of the energy storage system; A second model building, for building a time domain nonlinear model based on the equivalent circuit model and the control loop of the energy storage system; A small signal processing model is used to perform small signal linearization processing on the time domain nonlinear model under steady-state conditions to obtain a time domain linear small signal model; A conversion module, used for obtaining a DC side small signal impedance model according to the time domain linear small signal model; The analysis module is used to perform stability analysis based on the DC side small signal impedance model to obtain a stability analysis result of the energy storage system.

15. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 13 is implemented.

16. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 13 is implemented.

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