Modeling method and device, computer equipment, storage medium and program product

Abstract

The invention relates to a modeling method and device, computer equipment, a storage medium and a program product. The method comprises the following steps: performing equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system, establishing an electrical state space model of the power grid system based on the system equivalent circuit, establishing a control state space model according to a control link in the power grid system, and establishing a control state space model according to the control link in the power grid system. And establishing a system state space model of the power grid system according to the electrical state space model and the control state space model, so that the influence of the energy storage system on the stability of the power grid system can be analyzed and researched based on the system state space model, and guidance can be provided for system optimization design and controller parameter setting.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage systems, and in particular to a modeling method, apparatus, computer equipment, storage medium and program product. Background Art

[0002] The new power grid system with new energy as the main body is becoming an important choice for sustainable energy development. As an important key link in it, the energy storage system has also begun to develop in the direction of high voltage and large capacity to meet the new power grid needs.

[0003] The DC direct-mounted energy storage system based on the voltage source converter-high voltage direct current (VSC-HVDC) technology combines the VSC valve with the DC energy storage valve, and has the characteristics of a wide range of voltage and capacity adaptability. Compared with other traditional energy storage systems, the operating status of this new energy storage system with this topology will further affect the safe and stable operation of the power grid system due to its high voltage and large capacity. How to evaluate the impact of the new energy storage system on the stability of the power grid system has become an important research issue. Summary of the invention

[0004] Based on this, it is necessary to provide a modeling method, device, computer equipment, storage medium and program product that can evaluate the impact of a new type of energy storage system on the stability of the power grid system in response to the above technical problems.

[0005] In a first aspect, the present application provides a modeling method. The method comprises:

[0006] Performing equivalent processing on the voltage source converter VSC valve and the energy storage valve in the power grid system to obtain a system equivalent circuit of the power grid system;

[0007] Based on the system equivalent circuit, an electrical state space model of the power grid system is established, and a control state space model is established according to the control link in the power grid system;

[0008] A system state space model of the power grid system is established according to the electrical state space model and the control state space model.

[0009] In an embodiment of the present application, by performing equivalent processing on the voltage source converter VSC valve and the energy storage valve in the power grid system, a system equivalent circuit of the power grid system is obtained, and based on the system equivalent circuit, an electrical state space model of the power grid system is established, and a control state space model is established according to the control link in the power grid system. Based on the electrical state space model and the control state space model, a system state space model of the power grid system is established. Therefore, based on the system state space model, the influence of the energy storage system on the stability of the power grid system can be analyzed and studied, which can provide guidance for system optimization design and controller parameter setting.

[0010] In one embodiment, the voltage source converter VSC valve and the energy storage valve in the power grid system are equivalently processed to obtain a system equivalent circuit of the power grid system, including:

[0011] The AC side and the DC side of the VSC valve are respectively processed equivalently to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve;

[0012] Performing equivalent processing on the energy storage valve to obtain an energy storage valve equivalent circuit;

[0013] Based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit, the system equivalent circuit is obtained.

[0014] The method provided in the embodiment of the present application performs equivalent processing on the AC side and the DC side of the VSC valve respectively to obtain the AC side equivalent circuit and the DC side equivalent circuit of the VSC valve, and performs equivalent processing on the energy storage valve to obtain the energy storage valve equivalent circuit, and then obtains the system equivalent circuit based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit, thereby laying a foundation for the subsequent establishment of an electrical state space model and a control state space model of the power grid system.

[0015] In one embodiment, the AC side and the DC side of the VSC valve are respectively processed equivalently to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve, including:

[0016] Based on the average value model and Thevenin theorem, the AC side of the VSC valve is processed equivalently to obtain the equivalent circuit of the AC side.

[0017] Based on the average value model, Thevenin's theorem and the energy conservation theorem, the DC side of the VSC valve is processed equivalently to obtain the DC side equivalent circuit.

[0018] The method provided in the embodiment of the present application performs equivalent processing on the AC side of the VSC valve based on the average value model and the Thevenin theorem to obtain an equivalent circuit on the AC side, and performs equivalent processing on the DC side of the VSC valve based on the average value model, the Thevenin theorem and the law of conservation of energy to obtain an equivalent circuit on the DC side, thereby achieving the equivalent circuit of the VSC valve obtained by performing equivalent processing on the VSC valve, laying the foundation for obtaining the system equivalent circuit of the power grid system.

[0019] In one of the embodiments, the DC side equivalent circuit includes a first inductor, a second inductor, a first resistor, a second resistor, a first controlled DC voltage source, and a VSC valve DC side equivalent capacitor;

[0020] The first end of the first controlled DC voltage source and the first end of the VSC valve DC side equivalent capacitor are both connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the energy storage valve equivalent circuit;

[0021] The second end of the first controlled DC voltage source and the second end of the VSC valve DC side equivalent capacitor are both connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the energy storage valve equivalent circuit.

[0022] The DC side equivalent circuit obtained in the embodiment of the present application not only includes a first inductor, a second inductor, a first resistor, and a second resistor, but also includes a first controlled DC voltage source and a VSC valve DC side equivalent capacitor, thereby achieving equivalence of the capacitor of the VSC valve sub-module in the VSC valve, thereby making the obtained DC side equivalent circuit more accurate, and then the electrical state space model obtained based on the more accurate DC side equivalent circuit is more accurate, thereby improving the simulation accuracy.

[0023] In one of the embodiments, the AC side equivalent circuit includes a third inductor, a third resistor and a controlled AC voltage source;

[0024] The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer in the power grid system, and one end of the controlled AC voltage source is grounded.

[0025] The AC side equivalent circuit obtained in the embodiment of the present application includes a third inductor, a third resistor and a controlled AC voltage source, thereby achieving equivalence of the AC side of the VSC valve, and then achieving an electrical state space model of the VSC valve based on the AC side equivalent circuit, providing a basis for obtaining a system state space model of the power grid system.

[0026] In one embodiment, performing equivalent processing on the energy storage valve to obtain an equivalent circuit of the energy storage valve includes:

[0027] Based on the Thevenin theorem and the average value model, the energy storage submodule of the energy storage valve is equivalently processed to obtain a submodule equivalent circuit of the energy storage submodule;

[0028] Performing a small signal equivalent conversion on the submodule equivalent circuit to obtain a small signal equivalent circuit of the energy storage submodule;

[0029] The energy storage valve equivalent circuit is obtained based on the small signal equivalent circuit, a first number of energy storage submodules put into the energy storage system, and a second number of energy storage submodules involved in switching in the energy storage system.

[0030] In the embodiment of the present application, based on the Thevenin theorem and the average value model, the energy storage submodule of the energy storage valve is equivalently processed to obtain a submodule equivalent circuit of the energy storage submodule, and the submodule equivalent circuit is small-signal equivalently converted to obtain a small-signal equivalent circuit of the energy storage submodule. Based on the small-signal equivalent circuit, a first number of energy storage submodules invested in the energy storage system, and a second number of energy storage submodules involved in switching in the energy storage system, an equivalent circuit of the energy storage valve is obtained, thereby achieving equivalence of the energy storage valve, and laying a foundation for obtaining a system equivalent circuit of the power grid system.

[0031] In one embodiment, the submodule equivalent circuit includes any one of an ohmic resistance equivalent circuit, a first-order RC equivalent circuit obtained based on a battery polarization reaction, and a second-order RC equivalent circuit obtained based on a battery polarization reaction and a concentration difference reaction. This embodiment provides an ohmic resistance equivalent circuit, a first-order RC equivalent circuit, and a second-order RC equivalent circuit to achieve diversity of submodule equivalent circuits of the energy storage submodule, making the method of obtaining the submodule equivalent circuit more flexible.

[0032] In one of the embodiments, the energy storage valve equivalent circuit includes an energy storage valve equivalent resistor and a second controlled DC voltage source;

[0033] The first end of the energy storage valve equivalent resistor is connected to the DC side equivalent circuit, the second end of the energy storage valve equivalent resistor is connected to the first end of the second controlled DC voltage source, and the second end of the second controlled DC voltage source is connected to the DC side equivalent circuit. In the embodiment of the present application, the energy storage valve equivalent circuit of the electrical part of the energy storage valve is established in the embodiment of the present application, so as to achieve the equivalence of the energy storage valve, and lay the foundation for obtaining the system equivalent circuit of the power grid system.

[0034] In one embodiment, the electrical state space model of the power grid system is established based on the system equivalent circuit, including:

[0035] Based on the system equivalent circuit, a first equivalent parameter and a second equivalent parameter are determined; the first equivalent parameter includes a total equivalent inductance on the AC side and a total equivalent resistance on the AC side, the second equivalent parameter includes an equivalent capacitance on the DC side of the VSC valve and a sub-equivalent parameter, the sub-equivalent parameter includes an equivalent inductance on the DC side of the VSC valve, an equivalent resistance on the DC side of the VSC valve, and an equivalent resistance of the energy storage valve;

[0036] Based on the first equivalent parameter, establishing a first electrical state space model of the VSC valve;

[0037] Based on the sub-equivalent parameters, a second electrical state space model of the energy storage valve is established;

[0038] An electrical state space model of the power grid system is established according to the first electrical state space model, the second electrical state space model and the VSC valve DC side equivalent capacitance.

[0039] In the embodiment of the present application, based on the system equivalent circuit, the first equivalent parameter and the second equivalent parameter are determined, and based on the first equivalent parameter, the first electrical state space model of the VSC valve is established, and based on the sub-equivalent parameter, the second electrical state space model of the energy storage valve is established, and then according to the first electrical state space model, the second electrical state space model and the equivalent capacitance of the DC side of the VSC valve, the electrical state space model of the power grid system is established. Since the established system equivalent circuit takes into account the capacitance in the VSC valve submodule in the VSC valve, the system equivalent circuit is more in line with the actual operation of the power grid system. Therefore, the electrical state space model obtained based on the system equivalent circuit is more accurate, which can lay the foundation for analyzing the impact of the energy storage system on the stability of the power grid system and improve the accuracy of the analysis. In addition, in the embodiment of the present application, the electrical parts of the VSC valve and the energy storage valve are independently modeled to achieve modular modeling. The method has clear physical meaning and modular modeling process, and is easy to understand, implement and expand.

[0040] In one embodiment, the first electrical state space model of the VSC valve is established based on the first equivalent parameter, including:

[0041] Establishing a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter and the first output parameter;

[0042] The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system;

[0043] The first state parameter includes the AC grid-side current of the power grid system in the first coordinate system;

[0044] The first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve;

[0045] The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in a second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

[0046] The embodiment of the present application obtains a first electrical state space model based on the parameters in the first coordinate system, the parameters in the second coordinate system, and the first equivalent parameters, so that the first electrical state space model is more accurate, thereby laying a foundation for analyzing the impact of the energy storage system on the stability of the power grid system and improving the accuracy of the analysis.

[0047] In one embodiment, the second electrical state space model of the energy storage valve is established based on the sub-equivalent parameter, including:

[0048] Based on the second coefficient, the second state parameter and the second input parameter, a second electrical state space model of the energy storage valve is established;

[0049] wherein the second coefficient is determined based on the sub-equivalent parameter;

[0050] The second state parameter includes an equivalent direct current of the energy storage valve;

[0051] The second input parameter includes a first controlled DC voltage source of the VSC valve and a second controlled DC voltage source of the energy storage valve.

[0052] The embodiment of the present application obtains a second electrical state space model based on the second coefficient, the second state parameter and the second input parameter, so that the second electrical state space model is more accurate, thereby laying a foundation for analyzing the impact of the energy storage system on the stability of the power grid system and improving the accuracy of the analysis.

[0053] In one embodiment, establishing the electrical state space model of the power grid system according to the first electrical state space model, the second electrical state space model and the VSC valve DC side equivalent capacitance includes:

[0054] Based on the VSC valve DC side equivalent capacitance, a third electrical state space model of the VSC valve is obtained;

[0055] An electrical state space model of the power grid system is established based on the first electrical state space model, the second electrical state space model and the third electrical state space model.

[0056] In an embodiment of the present application, a third electrical state space model of the VSC valve is obtained based on the equivalent capacitance on the DC side of the VSC valve, and an electrical state space model of the power grid system is established based on the first electrical state space model, the second electrical state space model and the third electrical state space model. The obtained electrical state space model is more in line with the actual operation of the power grid system, and the system state space model of the power grid system obtained based on the electrical state space model is more accurate. A more accurate system state space model can improve the accuracy and reliability of analyzing the stability of the power grid system.

[0057] In one embodiment, the control link includes a first control link of the VSC valve and a second control link of the energy storage valve; and establishing a control state space model according to the control link in the power grid system includes:

[0058] Based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter, a first control state space model of the VSC valve is established; wherein the third state parameter includes the control variable of the VSC valve; the third input parameter includes the AC grid-side current of the power grid system in the first coordinate system, the AC grid-side voltage and the AC valve-side current of the power grid system in the second coordinate system, the control reference values ​​of the active power and reactive power of the grid-connected point of the power grid system, and the AC voltage control reference value of the grid-connected point; the second output parameter includes the modulation ratio and the AC grid-side output voltage of the VSC valve in the first coordinate system;

[0059] Based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter, a second control state space model of the energy storage valve is established;

[0060] The fourth coefficient is determined based on the first proportional coefficient of the fixed DC voltage proportional integral link, the first integral coefficient of the fixed DC voltage proportional integral link, the second proportional coefficient of the fixed DC current proportional integral link, the second integral coefficient of the fixed DC current proportional integral link, the DC voltage reference value of the energy storage valve, and the DC current reference value of the energy storage valve;

[0061] The fourth state parameter includes a control variable of a DC voltage integral link of the VSC valve and a control variable of a DC current integral link of the VSC valve;

[0062] The fourth input parameter includes the output DC voltage of the VSC valve, the output DC current of the VSC valve, and a DC voltage control reference value of the VSC valve;

[0063] The third output parameter includes the output voltage of the energy storage valve and the output voltage per unit value of the energy storage valve.

[0064] In the embodiment of the present application, by establishing the first control state space model and the second control state space model, the foundation is laid for obtaining the system state space model of the power grid system, thereby providing a basis for analyzing the impact of the energy storage system on the stability of the power grid system based on the system state space model, and providing guidance for system optimization design and controller parameter setting. In addition, in the embodiment of the present application, the control parts of the VSC valve and the energy storage valve are independently modeled to achieve modular modeling. The method has clear physical meaning and modular modeling process, and is easy to understand, implement and expand.

[0065] In one embodiment, the electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve;

[0066] The system state space model of the power grid system is established according to the electrical state space model and the control state space model, including:

[0067] Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain a sorted first electrical state space model and a sorted third electrical state space model;

[0068] The modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model.

[0069] In an embodiment of the present application, based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain the sorted first electrical state space model and the sorted third electrical state space model, the modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model, thereby providing a basis for analyzing the impact of the energy storage system on the stability of the power grid system based on the system state space model, and providing guidance for system optimization design and controller parameter setting.

[0070] In a second aspect, the present application also provides a modeling device. The device comprises:

[0071] An equivalent processing module is used to perform equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system;

[0072] The first establishing module is used to establish an electrical state space model of the power grid system based on the system equivalent circuit, and to establish a control state space model according to a control link in the power grid system;

[0073] The second establishing module is used to establish a system state space model of the power grid system according to the electrical state space model and the control state space model.

[0074] In a third aspect, the present application further provides a computer device, wherein the computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any of the above methods when executing the computer program.

[0075] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of any of the above methods when executed by a processor.

[0076] In a fifth aspect, the present application further provides a computer program product, wherein the computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0077] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0079] Figure 1 is a schematic diagram of a power grid system provided in an embodiment of the present application;

[0080] Figure 2 It is a flow chart of a modeling method provided in an embodiment of the present application;

[0081] Figure 3a is a schematic diagram of the structure of a VSC valve provided in an embodiment of the present application;

[0082] Figure 3b is a structural schematic diagram of a VSC valve submodule provided in an embodiment of the present application;

[0083] Figure 4ais a schematic structural diagram of an energy storage valve provided in an embodiment of the present application;

[0084] Figure 4b is a schematic diagram of a half-bridge energy storage submodule provided in an embodiment of the present application;

[0085] Figure 4c is a schematic diagram of a full-bridge energy storage submodule provided in an embodiment of the present application;

[0086] Figure 5 It is a flowchart of a method for establishing a system equivalent circuit provided in an embodiment of the present application;

[0087] Figure 6 It is one of the schematic diagrams of the system equivalent circuit provided in the embodiment of the present application;

[0088] Figure 7 This is the second schematic diagram of the system equivalent circuit provided in the embodiment of the present application;

[0089] Figure 8 is a flow chart of a method for obtaining a VSC valve equivalent circuit provided in an embodiment of the present application;

[0090] Fig. 9 It is a flow chart of a method for obtaining an equivalent circuit of an energy storage valve provided in an embodiment of the present application;

[0091] Fig.10a is a schematic diagram of a second-order RC equivalent circuit of an energy storage submodule provided in an embodiment of the present application;

[0092] Fig.10b is a schematic diagram of a first-order RC equivalent circuit of an energy storage submodule provided in an embodiment of the present application;

[0093] Fig.10c is a schematic diagram of an ohmic equivalent circuit of an energy storage submodule provided in an embodiment of the present application;

[0094] Fig.11a is a schematic diagram of a small signal equivalent circuit of a second-order RC equivalent circuit provided in an embodiment of the present application;

[0095] Fig.11b It is a schematic diagram of a small signal equivalent circuit of an energy storage submodule in an engaged state provided by an embodiment of the present application;

[0096] Fig.11c is a schematic diagram of a small signal equivalent circuit of an energy storage submodule in a cut-out state provided in an embodiment of the present application;

[0097] Fig.12 is a schematic diagram of a small signal equivalent circuit of an energy storage valve provided in an embodiment of the present application;

[0098] Fig.13 It is a flowchart of a method for establishing an electrical state space model provided in an embodiment of the present application;

[0099] Fig.14 It is a schematic diagram of a coordinate system provided in an embodiment of the present application;

[0100] Fig.15 It is a flowchart of a method for establishing an electrical state space model provided in an embodiment of the present application;

[0101] Fig.16 It is a flow chart of a method for establishing a control state space model provided in an embodiment of the present application;

[0102] Fig.17 is a schematic diagram of a system control link provided in an embodiment of the present application;

[0103] Fig.18 It is a flowchart of another modeling method provided in an embodiment of the present application;

[0104] Fig.19a It is one of the simulation result schematic diagrams provided in the embodiment of the present application;

[0105] Fig.19b This is the second schematic diagram of the simulation results provided in the embodiment of the present application;

[0106] Fig.19c This is the third simulation result schematic diagram provided in the embodiment of the present application;

[0107] Fig.19d This is the fourth schematic diagram of the simulation results provided in the embodiment of the present application;

[0108] Fig. 20 is a structural block diagram of a modeling device provided in an embodiment of the present application;

[0109] Fig.21 It is a structural block diagram of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0110] 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.

[0111] 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.

[0112] In the description of the embodiments of the present application, the technical terms "first", "second", etc. 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. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0113] 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.

[0114] 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.

[0115] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0116] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0117] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0118] The new power grid system with new energy as the main body is becoming an important choice for sustainable energy development. As an important key link in it, the energy storage system has also begun to develop in the direction of high voltage and large capacity to meet the new power grid needs.

[0119] The DC direct-mounted energy storage system proposed based on VSC-HVDC technology combines the VSC valve with the DC energy storage valve, and has the characteristics of wide voltage and capacity adaptability. Compared with other traditional energy storage systems, the operating status of this new energy storage system with this topology will further affect the safe and stable operation of the power grid system due to its high voltage and large capacity characteristics. Figure 1 As shown, Figure 1 It is a schematic diagram of a power grid system provided in an embodiment of the present application, and the power grid system includes an AC power grid 101, a converter transformer 102, a VSC valve 103, an energy storage valve 104, a first control link 105 of the VSC valve, and a second control link 106 of the energy storage valve. Among them, the energy storage valve 104 is a DC energy storage valve. At present, there is no solution to evaluate the impact of a new type of energy storage system on the stability of the power grid system. How to evaluate the impact of a new type of energy storage system on the stability of the power grid system has become an important research issue. Therefore, it is urgent to establish a small signal model suitable for the power grid system, and analyze the stability of the power grid system based on the small signal model.

[0120] The present application embodiment provides a modeling method, such as Figure 2 As shown, Figure 2 1 is a flow chart of a modeling method provided by an embodiment of the present application. The present application embodiment takes the method applied to a simulation workstation as an example. It can be understood that the simulation workstation can be a terminal, a server, or a system including a terminal and a server. The method can include the following steps:

[0121] S201, performing equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system.

[0122] like Figure 3a As shown, Figure 3a: is a schematic diagram of the structure of the VSC valve provided in the embodiment of the present application. The VSC valve comprises 6 bridge arms in total, each phase of the alternating current is connected to an upper bridge arm and a lower bridge arm, a total of two bridge arms, and one bridge arm comprises n arm VSC valve submodules, among which, Figure 3a In the figure, an SM represents a VSC valve submodule, n arm VSC valve modules are connected in series. Each bridge arm includes n arm A VSC valve module, a resistor R f and an inductor L arm . Figure 3b : is a schematic diagram of a VSC valve submodule provided in an embodiment of the present application. A VSC valve submodule includes a first switch T1, a second switch T2 and a capacitor C sm_vsc .

[0123] like Figure 4a As shown, Figure 4a Schematic diagram of the structure of the energy storage valve provided in the embodiment of the present application. The energy storage valve is a DC energy storage valve, which includes two inductors L dc , two resistors R dc And multiple energy storage submodules connected in series. An energy storage submodule can be a half-bridge energy storage submodule or a full-bridge energy storage submodule. Figure 4b and Figure 4c As shown, Figure 4b is a schematic diagram of a half-bridge energy storage submodule provided in an embodiment of the present application, Figure 4c Schematic diagram of a full-bridge energy storage submodule provided in an embodiment of the present application. The half-bridge energy storage submodule includes a third switch T3, a fourth switch T4, a capacitor C sm The full-bridge submodule has a fifth switch T5 and a sixth switch T6 in addition to the half-bridge submodule.

[0124] In the embodiment of the present application, the Thevenin theorem can be used to perform equivalent processing on the AC side and the DC side of the VSC valve based on the average value model to obtain a VSC valve equivalent circuit of the VSC valve, which is a Thevenin equivalent circuit, and the Thevenin equivalent circuit includes an AC side equivalent circuit and a DC side equivalent circuit, wherein the average value model may include an average value controlled source equivalent model. Based on the Thevenin theorem, the energy storage valve is equivalently processed to obtain an energy storage valve equivalent circuit of the energy storage valve, and based on the VSC valve equivalent circuit and the energy storage valve equivalent circuit, a system equivalent circuit of the power grid system is obtained.

[0125] Alternatively, using the Thevenin theorem, the AC side of the VSC valve is equivalently processed based on the average value model to obtain an AC side equivalent circuit. Based on the average value model and the theorem of conservation of energy, the DC side of the VSC valve is equivalently processed to obtain a DC side equivalent circuit. Based on the Thevenin theorem, the energy storage valve is equivalently processed to obtain the energy storage valve equivalent circuit of the energy storage valve, and based on the VSC valve equivalent circuit and the energy storage valve equivalent circuit, the system equivalent circuit of the power grid system is obtained. Among them, based on the theorem of conservation of energy, the DC side port of the VSC valve is equivalent to the existence of an equivalent capacitor, that is, the first capacitor C in each VSC valve sub-module of the VSC valve can be realized. sm_vsc The equivalent circuit on the DC side is obtained by performing equivalence, thereby improving the accuracy of the obtained equivalent circuit on the DC side and making the equivalent circuit on the DC side more consistent with the operation of the actual power grid system.

[0126] Alternatively, the DC side and AC side of the VSC valve are treated equivalently using Norton's theorem to obtain a DC side equivalent circuit and an AC side equivalent circuit; and the energy storage valve is treated equivalently to obtain an energy storage valve equivalent circuit. Based on the DC side equivalent circuit, the AC side equivalent circuit and the energy storage valve equivalent circuit, the system equivalent circuit of the power grid system is obtained.

[0127] S202, establishing an electrical state space model of the power grid system based on the system equivalent circuit, and establishing a control state space model according to the control link in the power grid system.

[0128] A first electrical state space model of the VSC valve can be established based on the VSC valve equivalent circuit of the VSC valve in the system equivalent circuit. A second electrical state space model of the energy storage valve can be established based on the energy storage valve equivalent circuit of the energy storage valve in the system equivalent circuit, and an electrical state space model of the power grid system can be obtained based on the first electrical state space model and the second electrical state space model.

[0129] In the embodiment of the present application, the AC side equivalent circuit of the VSC valve can be uniformly transformed to the AC grid side based on the setting mode of the converter transformer in the power grid system, and a first electrical state space model is established based on the transformed circuit, wherein the AC grid side refers to the primary side of the converter transformer in the power grid system. Alternatively, the AC grid side circuit of the VSC valve is transformed to the AC valve side, and a first electrical state space model is established based on the transformed circuit, wherein the AC valve side refers to the secondary side of the converter transformer.

[0130] In the embodiment of the present application, it can be based on Figure 1The first control link 105 shown establishes a first control state space model of the VSC valve, and a second control state space model of the energy storage valve is established based on the second control link 106. The control links in the power grid system include the first control link and the second control link. The first control state space model and the second control state space model can be small signal state space models.

[0131] The energy storage valve can use internal and external proportional and integral (PI) links to achieve constant DC voltage control or constant DC current control, thereby establishing a second control state space model.

[0132] S203, establishing a system state space model of the power grid system according to the electrical state space model and the control state space model.

[0133] The control state space model can be substituted into the electrical state space model to obtain an initial small signal state space model of the power grid system, and the initial small signal state space model is used as the system state space model of the power grid system. Alternatively, the initial small signal state space model is corrected by a preset value to obtain a system state space model of the power grid system. For example, the preset value is multiplied by the initial small signal state space model to obtain a small signal state space model, and the small signal state space model is used as the system state space model of the power grid system.

[0134] In an embodiment of the present application, by performing equivalent processing on the voltage source converter VSC valve and the energy storage valve in the power grid system, a system equivalent circuit of the power grid system is obtained, and based on the system equivalent circuit, an electrical state space model of the power grid system is established, and a control state space model is established according to the control link in the power grid system. Based on the electrical state space model and the control state space model, a system state space model of the power grid system is established. Therefore, based on the system state space model, the influence of the energy storage system on the stability of the power grid system can be analyzed and studied, which can provide guidance for system optimization design and controller parameter setting.

[0135] Reference Figure 5 , Figure 5 : is a flow chart of a method for establishing a system equivalent circuit provided in an embodiment of the present application. This embodiment relates to a possible implementation method of how to perform equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system. Based on the above embodiment, the method includes the following steps:

[0136] S501, performing equivalent processing on the AC side and the DC side of the VSC valve respectively to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve.

[0137] like Figure 6 and Figure 7 As shown, Figure 6 and Figure 7 Shown as Figure 3a The VSC valve equivalent circuit of the VSC valve shown is an equivalent circuit obtained based on the Thevenin theorem. Figure 6 is one of the schematic diagrams of the system equivalent circuit provided in the embodiment of the present application, Figure 7 is the second schematic diagram of the system equivalent circuit provided in the embodiment of the present application, Figure 6 for Figure 7 A simplified schematic diagram of . Figure 7 The VSC valve equivalent circuit 701, the converter transformer 705, the inductor L s and resistor R s , the VSC valve equivalent circuit 701 includes an AC side equivalent circuit 702 and a DC side equivalent circuit 703. Considering the port characteristics of the AC and DC networks connected to the VSC valve, the AC side of the VSC valve is equivalent to the AC side equivalent circuit 702, and the DC side of the VSC valve is equivalent to the DC side equivalent circuit 703 using the average value model.

[0138] S502, performing equivalent processing on the energy storage valve to obtain an equivalent circuit of the energy storage valve.

[0139] Figure 7 The energy storage valve equivalent circuit of the energy storage valve is shown in FIG. Figure 3a As shown. Perform Thevenin equivalent on the battery module in the energy storage valve, and then consider the capacitor C in the energy storage submodule in steady state. sm The equivalent impedance can be regarded as infinite, realizing the Thevenin equivalent of the energy storage submodule. Finally, considering that the number of modules put into operation in steady state is unchanged, the Thevenin equivalent of the entire energy storage valve is realized, thus obtaining the energy storage valve equivalent circuit. The Thevenin equivalent circuit can simplify a complex circuit into a series circuit of a voltage source and a resistor, thereby simplifying the analysis of complex circuits.

[0140] S503, obtaining a system equivalent circuit based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit.

[0141] The method provided in the embodiment of the present application performs equivalent processing on the AC side and the DC side of the VSC valve respectively to obtain the AC side equivalent circuit and the DC side equivalent circuit of the VSC valve, and performs equivalent processing on the energy storage valve to obtain the energy storage valve equivalent circuit, and then obtains the system equivalent circuit based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit, thereby laying a foundation for the subsequent establishment of an electrical state space model and a control state space model of the power grid system.

[0142] Reference Figure 8 , Figure 8is a flow chart of a method for obtaining an equivalent circuit of a VSC valve provided in an embodiment of the present application. This embodiment relates to a possible implementation method of how to perform equivalent processing on the AC side and the DC side of the VSC valve respectively to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve. Based on the above embodiment, the above S501 may include the following steps:

[0143] S801, based on the average value model and Thevenin theorem, the AC side of the VSC valve is equivalently processed to obtain an AC side equivalent circuit.

[0144] S802, based on the average value model, Thevenin theorem and the energy conservation theorem, the DC side of the VSC valve is equivalently processed to obtain a DC side equivalent circuit.

[0145] For Figure 3a Considering the port characteristics of the VSC valve and the connected AC / DC network, the DC side of the VSC valve can be equivalent to the following using the average value model: Figure 7 The DC side equivalent circuit 703 shown in FIG. 1 includes a first inductor 7031, a second inductor 7032, a first resistor 7033, a second resistor 7034, a first controlled DC voltage source e dc and VSC valve DC side equivalent capacitance C eq The first inductor 7031 and the second inductor 7032 are both L arm / 3, the first resistor 7033 and the second resistor 7034 are both R f / 3. Wherein, the first controlled DC voltage source is a controlled DC voltage source.

[0146] Based on the average value model, Thevenin theorem and energy conservation theorem, the AC side of the VSC valve can be equivalent to Figure 7 The AC side equivalent circuit 701 shown in FIG. 1 includes a third inductor 7011, a third resistor 7012 and a controlled AC voltage source u c2 , where the size of the third inductor 7011 is L arm / 2, the value of the third resistor 7012 is R f / 2.

[0147] Here, the DC side of the VSC valve is processed equivalently to obtain the first controlled DC voltage source e dc and VSC valve DC side equivalent capacitance C eq The process is introduced as follows: Generally, the VSC valve of MMC structure has no filter capacitor on the DC side, but under normal control, the sum of the number of sub-modules put into operation in the upper and lower bridge arms of each phase remains unchanged, which is the number of bridge arm sub-modules cascaded n arm , assuming that the capacitor voltages of all submodules of the VSC valve are equal, both are u csm_vsc=e dc / n arm , ignoring the bridge arm reactor, the DC side port voltage of the VSC valve is n arm ×u csm_vsc .

[0148] According to the energy conservation theorem, the VSC valve DC side port is equivalent to a VSC valve DC side equivalent capacitor C eq Consider that each phase of the VSC valve has n upper and lower bridge arms. arm sub-modules, then the three phases have a total of 6n arm Each submodule has a capacity of C sm_vsc , then the total energy stored in the submodule is W sum It can be expressed as the following formula (1):

[0149]

[0150] like Figure 7 As shown in the figure, based on formula (1), the capacitance of the VSC valve module can be uniformly equivalent to the DC side and regarded as a voltage of e dc , and the size is Capacitance.

[0151] The method provided in the embodiment of the present application performs equivalent processing on the AC side of the VSC valve based on the average value model and the Thevenin theorem to obtain an equivalent circuit on the AC side, and performs equivalent processing on the DC side of the VSC valve based on the average value model, the Thevenin theorem and the law of conservation of energy to obtain an equivalent circuit on the DC side, thereby achieving the equivalent circuit of the VSC valve obtained by performing equivalent processing on the VSC valve, laying the foundation for obtaining the system equivalent circuit of the power grid system.

[0152] In some embodiments, such as Figure 7 As shown, the DC side equivalent circuit includes a first inductor 7031, a second inductor 7032, a first resistor 7033, a second resistor 7034, a first controlled DC voltage source e dc and VSC valve DC side equivalent capacitance C eq ;

[0153] The first controlled DC voltage source e dc The first end and the VSC valve DC side equivalent capacitance C eq The first end of each of the first inductor 7031 is connected to the first end of the first inductor 7031, the second end of the first inductor 7031 is connected to the first end of the first resistor 7033, and the second end of the first resistor 7033 is connected to the energy storage valve equivalent circuit 704;

[0154] The first controlled DC voltage source e dc The second end and the VSC valve DC side equivalent capacitance C eqThe second ends of the second inductors 7032 are connected to the first ends of the second inductors 7032 , the second ends of the second inductors 7032 are connected to the first ends of the second resistors 7034 , and the second ends of the second resistors 7034 are connected to the energy storage valve equivalent circuit 704 .

[0155] The DC side equivalent circuit obtained in the embodiment of the present application not only includes a first inductor, a second inductor, a first resistor, and a second resistor, but also includes a first controlled DC voltage source and a VSC valve DC side equivalent capacitor, thereby achieving equivalence of the capacitor of the VSC valve sub-module in the VSC valve, thereby making the obtained DC side equivalent circuit more accurate, and then the electrical state space model obtained based on the more accurate DC side equivalent circuit is more accurate, thereby improving the simulation accuracy.

[0156] In some embodiments, such as Figure 7 As shown, the AC side equivalent circuit 702 includes a third inductor 7021, a third resistor 7022 and a controlled AC voltage source;

[0157] The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer 705 in the power grid system, and one end of the controlled AC voltage source is grounded.

[0158] The AC side equivalent circuit obtained in the embodiment of the present application includes a third inductor, a third resistor and a controlled AC voltage source, thereby achieving equivalence of the AC side of the VSC valve, and then achieving an electrical state space model of the VSC valve based on the AC side equivalent circuit, providing a basis for obtaining a system state space model of the power grid system.

[0159] In some embodiments, such as Fig. 9 As shown, Fig. 9 : is a flow chart of a method for obtaining an energy storage valve equivalent circuit provided in an embodiment of the present application. This embodiment relates to a possible implementation method of how to perform equivalent processing on an energy storage valve to obtain an energy storage valve equivalent circuit. Based on the above embodiment, the above S502 may include the following steps:

[0160] S901, based on the Thevenin theorem and the average value model, perform equivalent processing on the energy storage submodule of the energy storage valve to obtain a submodule equivalent circuit of the energy storage submodule.

[0161] like Figure 4a , Figure 4b and Figure 4c As shown, the energy storage valve is composed of multiple energy storage submodules connected in series, each energy storage submodule includes a power module and a battery module, and the power module can be a half-bridge power module or a full-bridge power module, wherein L dc is the inductance of the energy storage valve, R dc is the inductance L dc parasitic resistance.

[0162] by Figure 4b Taking the half-bridge energy storage submodule shown in FIG. 1 as an example, the equivalent circuit of the half-bridge energy storage submodule is as follows: Fig.10a , Fig.10b and Fig.10c As shown, Fig.10a is a schematic diagram of a second-order RC equivalent circuit of an energy storage submodule provided in an embodiment of the present application, Fig.10b is a schematic diagram of a first-order RC equivalent circuit of an energy storage submodule provided in an embodiment of the present application, Fig.10c Schematic diagram of an ohmic equivalent circuit of an energy storage submodule provided in an embodiment of the present application. The battery modules in an energy storage submodule can be equivalent to obtain a submodule equivalent circuit of the energy storage submodule. Fig.10c The figure shows that a battery module is equivalent to an ohmic equivalent circuit consisting of a controlled DC voltage source OCV and an ohmic resistor R0. The battery module can also be equivalent to the following circuit by considering the battery polarization reaction: Fig.10b The first-order RC equivalent circuit shown can also consider the battery polarization reaction and concentration difference reaction at the same time to make the battery module equivalent to Fig.10a The second-order RC equivalent circuit is shown.

[0163] Among them, the equivalent of the battery module can be referred to as follows Fig.10a As shown, a battery module is equivalent to Fig.10a The controlled DC voltage source OCV, ohmic resistor R0, resistor R1, resistor R2, capacitor C1 and capacitor C2. Fig.10b As shown, a battery module is equivalent to Fig.10b The controlled DC voltage source OCV, ohmic resistor R0, resistor R1 and capacitor C1.

[0164] S902, performing small signal equivalent conversion on the submodule equivalent circuit to obtain a small signal equivalent circuit of the energy storage submodule.

[0165] like Figure 4b As shown, the half-bridge power module is composed of two controllable switch devices. The switching signal controls the on and off of the third switch T3 and the fourth switch T4 to realize the input and output of the energy storage submodule. Therefore, the two controlled switches can be equivalent to two controlled variable resistors R T3 and R T4 Taking the upper tube in the energy storage submodule as an example, the upper tube is the third switch T3. When the third switch T3 is turned on, R T3 =R on , R on is the on-resistance of the device, which is very small; when the device is turned off, R T3 =R off , R offThe device is turned off and its resistance is very large, which can be regarded as an open circuit. By controlling the upper tube to be turned on and the lower tube to be turned off, the energy storage submodule is put into the series circuit, and the lower tube is the fourth switch T4; conversely, by controlling the upper tube to be turned off and the lower tube to be turned on, the energy storage submodule is cut out of the series circuit.

[0166] In addition, for the small signal model, it is a system mathematical model that considers small disturbances of the system on the basis of a certain steady state. Therefore, for the DC energy storage valve, under a certain steady state, the number of modules invested is certain and can be regarded as basically unchanged, denoted as n on The total number of energy storage submodules involved in switching the DC energy storage valve is n sm , and the equivalent impedance of the capacitor in the energy storage submodule can be regarded as infinite, then each energy storage submodule is equivalent to a controlled DC voltage source OCV and a battery equivalent resistance R bsm and a switch on-resistance R ob .

[0167] by Fig.10a Taking the second-order RC equivalent circuit of the half-bridge energy storage submodule as an example, the small signal equivalent circuit of the second-order RC equivalent circuit is as follows: Fig.11a , Fig.11b and Fig.11c As shown. Among them, Fig.11a is a schematic diagram of a small signal equivalent circuit of a second-order RC equivalent circuit provided in an embodiment of the present application, Fig.11b is a schematic diagram of a small signal equivalent circuit of an energy storage submodule in an engaged state provided by an embodiment of the present application, Fig.11c is a schematic diagram of a small signal equivalent circuit of an energy storage submodule in a cut-out state provided in an embodiment of the present application. csm is the capacitance C sm The equivalent resistance of Fig.11b and Fig.11c In the figure, the battery equivalent resistance R bsm It includes an ohmic resistor R0, a resistor R1 and a resistor R2.

[0168] S903, obtaining an energy storage valve equivalent circuit based on the small signal equivalent circuit, a first number of energy storage submodules put into the energy storage system, and a second number of energy storage submodules involved in switching in the energy storage system.

[0169] like Fig.11b and Fig.11c As shown, the battery equivalent resistance R bsm =R0+R1+R2. Then, the equivalent circuit of the energy storage valve can be expressed as Fig.12 The form shown, Fig.12 It is a schematic diagram of a small signal equivalent circuit of an energy storage valve provided in an embodiment of the present application. Fig.12FIG. 1 shows a first equivalent circuit 1201 of an energy storage submodule put into an energy storage valve and a second equivalent circuit 1202 of an energy storage submodule cut out. Based on the first equivalent circuit 1201 and the second equivalent circuit 1202, R eq =n sm R ton +n on R bsm ,u dc =n on ×OCV, which can be achieved by controlling the number of energy storage submodules n on Realize the modulation of DC voltage.

[0170] In an embodiment of the present application, based on the Thevenin theorem and the average value model, the energy storage submodule of the energy storage valve is equivalently processed to obtain a submodule equivalent circuit of the energy storage submodule, and the submodule equivalent circuit is small-signal equivalently converted to obtain a small-signal equivalent circuit of the energy storage submodule. Based on the small-signal equivalent circuit, a first number of energy storage submodules invested in the energy storage system, and a second number of energy storage submodules involved in switching in the energy storage system, an equivalent circuit of the energy storage valve is obtained, thereby achieving equivalence of the energy storage valve, and laying a foundation for obtaining a system equivalent circuit of the power grid system.

[0171] In some embodiments, such as Figure 7 As shown, the energy storage valve equivalent circuit includes the energy storage valve equivalent resistance R eq and a second controlled DC voltage source u dc ;

[0172] Energy storage valve equivalent resistance R eq The first end is connected to the DC side equivalent circuit 701, and the energy storage valve equivalent resistor R eq The second end of the second controlled DC voltage source u dc The first end is connected to the second controlled DC voltage source u dc The second end is connected to the DC side equivalent circuit 701.

[0173] In the embodiment of the present application, an energy storage valve equivalent circuit of the electrical part of the energy storage valve is established in the embodiment of the present application, thereby achieving equivalence of the energy storage valve and laying a foundation for obtaining a system equivalent circuit of the power grid system.

[0174] In some embodiments, Fig.13 As shown, Fig.13 1 is a flow chart of a method for establishing an electrical state space model provided in an embodiment of the present application. This embodiment relates to a possible implementation method of how to establish an electrical state space model of a power grid system based on a system equivalent circuit. Based on the above embodiment, the method includes the following steps:

[0175] S1301, determining a first equivalent parameter and a second equivalent parameter based on a system equivalent circuit.

[0176] Among them, the first equivalent parameter includes the total equivalent inductance on the AC side and the total equivalent resistance on the AC side, the second equivalent parameter includes the equivalent capacitance on the DC side of the VSC valve and the sub-equivalent parameters, and the sub-equivalent parameters include the equivalent inductance on the DC side of the VSC valve, the equivalent resistance on the DC side of the VSC valve and the equivalent resistance of the energy storage valve.

[0177] like Figure 7 The system equivalent circuit shown in FIG. 1 considers the setting mode of the converter transformer 705. In this embodiment, the AC side equivalent circuit of the VSC valve is uniformly transformed to the primary side of the converter transformer 705 as an example, so there are the equivalent relationship of each AC side parameter as shown in Table 1, and the equivalent relationship of each DC side parameter as shown in Table 2. Among them, Table 1 includes the first equivalent parameters, and Table 2 includes the second equivalent parameters.

[0178] Table 1

[0179]

[0180] Table 2

[0181]

[0182] Optionally, the configuration of the converter transformer 705 may be considered, and the primary side of the converter transformer 705 may be uniformly transformed to the AC valve side of the converter transformer 705, that is, transformed to the secondary side of the converter transformer 705. When transformed to the secondary side of the converter transformer 705, the total equivalent inductance of the AC side is equal to L link2 With L s2 The sum of L s2 equal The total equivalent resistance on the AC side can also be determined.

[0183] S1302: Establish a first electrical state space model of the VSC valve based on the first equivalent parameter.

[0184] Coefficients of a first electrical state space model may be determined based on the first equivalent parameters, and the first electrical state space model may be established based on the determined coefficients, state parameters of the VSC valve, input parameters, and output parameters.

[0185] S1303: Establish a second electrical state space model of the energy storage valve based on the sub-equivalent parameters.

[0186] The coefficients of the second electrical state space model can be determined based on the sub-equivalent parameters, and the second electrical state space model can be established based on the determined coefficients, the DC current on the DC line in the system equivalent circuit, and the input parameters.

[0187] S1304: Establish an electrical state space model of the power grid system according to the first electrical state space model, the second electrical state space model, and the VSC valve DC side equivalent capacitance.

[0188] The equivalent capacitance C of the VSC valve DC side can be used eq The first electrical state space model and the second electrical state space model are connected to obtain an electrical state space model of the power grid system.

[0189] In the embodiment of the present application, based on the system equivalent circuit, the first equivalent parameter and the second equivalent parameter are determined, and based on the first equivalent parameter, the first electrical state space model of the VSC valve is established, and based on the sub-equivalent parameter, the second electrical state space model of the energy storage valve is established, and then according to the first electrical state space model, the second electrical state space model and the equivalent capacitance of the DC side of the VSC valve, the electrical state space model of the power grid system is established. Since the established system equivalent circuit takes into account the capacitance in the VSC valve submodule in the VSC valve, the system equivalent circuit is more in line with the actual operation of the power grid system. Therefore, the electrical state space model obtained based on the system equivalent circuit is more accurate, which can lay the foundation for analyzing the impact of the energy storage system on the stability of the power grid system and improve the accuracy of the analysis. In addition, in the embodiment of the present application, the electrical parts of the VSC valve and the energy storage valve are independently modeled to achieve modular modeling. The method has clear physical meaning and modular modeling process, and is easy to understand, implement and expand.

[0190] In some embodiments, the above S1302, based on the first equivalent parameter, establishing the first electrical state space model of the VSC valve can be implemented in the following manner:

[0191] Establishing a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter, and the first output parameter;

[0192] The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system;

[0193] The first state parameter includes the AC grid-side current of the power grid system in the first coordinate system; the first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve;

[0194] The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in the second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

[0195] The first coordinate system and the second coordinate system are Fig.14 As shown, Fig.14 1 is a schematic diagram of a coordinate system provided in an embodiment of the present application. A first coordinate system is established with an x-axis and a y-axis, and a second coordinate system is established with a d-axis and a q-axis. The first coordinate system and the second coordinate system are rotating coordinate systems.

[0196] The first coefficient can be obtained by combining the first equivalent parameter shown in Table 1. Based on the first coefficient, the first state parameter, the first input parameter and the first output parameter, a first electrical state space model of the VSC valve is established. The first electrical state space model of the VSC valve can be expressed as shown in the following formulas (2), (3) and (4):

[0197]

[0198]

[0199]

[0200] The first electrical state space model of the above VSC valve can be simplified as shown in the following formulas (5), (6) and (7):

[0201]

[0202] Δi dq1 =C xele,idq Δi xy +C xvsc,idq Δx ctrl,vsc -------(6)

[0203] Δi dq2 =K t Δi dq1 -------(7)

[0204] Among them, ω n The rated angular frequency of the power grid system, θ0 is the voltage phase angle of the power grid system in steady state, i xy0 is the AC grid-side current of the power grid system in steady state, K t is the transformer ratio of the converter transformer 705 in the power grid system, i x0 for i xy0 The component in the x direction, i y0 for i xy0 Component in the y direction.

[0205] The first state parameter includes Δi xy , Δi xy is the AC grid-side current of the power grid system in the first coordinate system.

[0206] The first input parameter includes Δu cxy and Δx ctrl,vsc , Δu cxy is the AC grid-side output voltage of the VSC valve, Δx ctrl,vsc is the control state quantity of the VSC valve control state space model of the VSC valve. The first output parameter includes the AC grid side current Δi of the power grid system in the second coordinate system dq1 and AC valve side current Δi dq2 .

[0207] The embodiment of the present application obtains a first electrical state space model based on the parameters in the first coordinate system, the parameters in the second coordinate system, and the first equivalent parameters, so that the first electrical state space model is more accurate, thereby laying a foundation for analyzing the impact of the energy storage system on the stability of the power grid system and improving the accuracy of the analysis.

[0208] In some embodiments, the above S1303, based on the sub-equivalent parameters, establishing the second electrical state space model of the energy storage valve can be implemented in the following manner:

[0209] Establishing a second electrical state space model of the energy storage valve based on the second coefficient, the second state parameter and the second input parameter;

[0210] Wherein, the second coefficient is determined based on the sub-equivalent parameter; the second state parameter includes the equivalent DC current of the energy storage valve; the second input parameter includes the first controlled DC voltage source of the VSC valve and the second controlled DC voltage source of the energy storage valve. The second electrical state space model of the energy storage valve is shown in the following formula (8):

[0211]

[0212] The second state parameter includes the equivalent DC current Δi of the energy storage valve dclink The second input parameter includes the first controlled DC voltage source Δe of the VSC valve dc and the second controlled DC voltage source Δu of the energy storage valve dc .

[0213] The embodiment of the present application obtains a second electrical state space model based on the second coefficient, the second state parameter and the second input parameter, so that the second electrical state space model is more accurate, thereby laying a foundation for analyzing the impact of the energy storage system on the stability of the power grid system and improving the accuracy of the analysis.

[0214] In some embodiments, Fig.15 As shown, Fig.151 is a flow chart of a method for establishing an electrical state space model provided in an embodiment of the present application. This embodiment relates to a possible implementation method of how to establish an electrical state space model of a power grid system based on a first electrical state space model, a second electrical state space model and a VSC valve DC side equivalent capacitance. Based on the above embodiment, the above S1304 may include the following steps:

[0215] S1501: Based on the equivalent capacitance of the VSC valve DC side, a third electrical state space model of the VSC valve is obtained.

[0216] Based on the equivalent capacitance C of the VSC valve DC side eq , the third electrical state space model of the VSC valve is obtained, and the third electrical state space model can realize the DC side electrical connection between the VSC valve and the energy storage valve. The third electrical state space model is shown in the following formula (9):

[0217]

[0218] S1502: Establish an electrical state space model of the power grid system based on the first electrical state space model, the second electrical state space model, and the third electrical state space model.

[0219] The electrical state space model of the power grid system is obtained by combining the first electrical state space model, the second electrical state space model and the third state space model.

[0220] In an embodiment of the present application, a third electrical state space model of the VSC valve is obtained based on the equivalent capacitance on the DC side of the VSC valve, and an electrical state space model of the power grid system is established based on the first electrical state space model, the second electrical state space model and the third electrical state space model. The obtained electrical state space model is more in line with the actual operation of the power grid system, and the system state space model of the power grid system obtained based on the electrical state space model is more accurate. A more accurate system state space model can improve the accuracy and reliability of analyzing the stability of the power grid system.

[0221] In some embodiments, Fig.16 As shown, Fig.16 1 is a flow chart of a method for establishing a control state space model provided in an embodiment of the present application. This embodiment relates to a possible implementation method of how to establish a control state space model based on a control link in a power grid system. In this embodiment, the control link includes a first control link of a VSC valve and a second control link of an energy storage valve. Based on the above embodiment, the method includes the following steps:

[0222] S1601, establishing a first control state space model of the VSC valve based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter.

[0223] like Fig.17 The system control link shown, Fig.17 1701 is a schematic diagram of a system control link provided in an embodiment of the present application. The system control link includes a first control link 1701 and a second control link 1702. The parameters in the system control link are shown in Tables 3, 4 and 5 below:

[0224] Table 3

[0225]

[0226] Table 4

[0227]

[0228] Table 5

[0229]

[0230] The system control link includes a first control link and a second control link. The expression of the first control state space model is shown in the following formulas (10), (11) and (12):

[0231]

[0232] Δu cxy =K xvsc,ucxy Δx ctrl,vsc +K udq,ucxy Δu dq1 +K idq,ucxy Δi dq2 -------(11)

[0233] ΔM xy =K Mxy,xvsc Δx ctrl,vsc +K Mxy,udq1 Δu dq1 +K Mxy,ixy Δi xy +K Mxy,edc Δe dc ----(12)

[0234] The third state parameter includes the control variable Δx of the VSC valve. ctrl,vsc ; The third input parameter includes the AC grid-side current Δi of the power grid system in the first coordinate system xy , AC grid side voltage Δu of the power grid system in the second coordinate system dq1 and AC valve side current Δi dq2, the control reference value ΔPQ of active power and reactive power at the grid connection point of the power grid system ref,pu And the AC voltage control reference value Δu of the grid connection point ref,pu ; The second output parameter includes the modulation ratio ΔM xy and the AC grid-side output voltage Δu of the VSC valve in the first coordinate system cxy .

[0235] S1602: Establish a second control state space model of the energy storage valve based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter.

[0236] The control state space model includes a first control state space model and a second control state space model.

[0237] The energy storage valve generally adopts internal and external PI (proportional and integral) links to realize constant DC voltage and constant DC current control. Taking constant DC voltage control as an example, the second control state space model of the energy storage valve is established with the fourth state parameter as the control object. The second control state space model is shown in the following formulas (13), (14) and (15):

[0238]

[0239]

[0240] Δu dc =U dc,base Δu dcm,pu -------(15)

[0241] Among them, the fourth coefficient is based on the first proportional coefficient K of the fixed DC voltage proportional integral link p,udc , the first integral coefficient K of the DC voltage proportional integral link i,udc , the second proportional coefficient K of the DC current proportional integral link p,idc , the second integral coefficient K of the DC current proportional integral link i,idc , DC voltage reference value U of energy storage valve dc,base , DC current reference value I of energy storage valve dc,base Sure;

[0242] The fourth state parameter includes the control variable Δx of the DC voltage integral link of the VSC valve edc,pu , the control variable Δx of the DC current integral link of the VSC valve idc,pu ;

[0243] The fourth input parameter includes the output DC voltage Δe of the VSC valve dc , VSC valve output DC current Δidc , VSC valve DC voltage control reference value Δe dcref ;

[0244] The third output parameter includes the output voltage Δu of the energy storage valve dc , the output voltage per unit value of the energy storage valve Δu dcm,pu .

[0245] The second control state space model can be simplified as shown in the following formulas (16) and (17):

[0246]

[0247] Δu dc =K udc,xctrldc Δx ctrl,dc +K udc,edc Δe dc +K udc,edcref Δe dcref +K udc,idc Δi dc ----(17)

[0248] Where Δx ctrl,dc is the control variable of the DC energy storage valve.

[0249] In the embodiment of the present application, by establishing the first control state space model and the second control state space model, the foundation is laid for obtaining the system state space model of the power grid system, thereby providing a basis for analyzing the impact of the energy storage system on the stability of the power grid system based on the system state space model, and providing guidance for system optimization design and controller parameter setting. In addition, in the embodiment of the present application, the control parts of the VSC valve and the energy storage valve are independently modeled to achieve modular modeling. The method has clear physical meaning and modular modeling process, and is easy to understand, implement and expand.

[0250] In some embodiments, the electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve; the above S203, according to the electrical state space model and the control state space model, establishes a system state space model of the power grid system, which can be implemented in the following manner:

[0251] Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain the sorted first electrical state space model and the sorted third electrical state space model; the modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model.

[0252] Exemplarily, the AC / DC link relationship of the power grid system is shown in the following formulas (18) and (19), where Δi in formula (20) is dc Substitute the third electrical state space model shown in formula (9) to obtain the sorted third electrical state space model; replace Δu in formula (21) cxy Substitute the first electrical state space model into the above model to obtain the first electrical state space model. Then, the second output parameter formula (12) ΔM of the first control state space model is xy Substitute the expression into the first electrical state space model and the third electrical state space model, and change the third output parameter formula (17) Δu of the second control state space model dc Substitute the expression into the second electrical state space model to obtain the system state space model of the power grid system.

[0253]

[0254]

[0255] Among them, i x0 for i xy0 The component in the x direction, i y0 for i xy0 The component in the y direction. M x0 and M y0 are the components of the AC / DC modulation ratio of the power grid system in a certain steady state in the x-direction and y-direction respectively, e dc0 is the output DC voltage of the VSC valve in a certain steady state of the power grid system. The AC-DC link relationship of the above power grid system can be simplified as shown in formulas (20) and (21):

[0256] Δi dc =K idc,Mxy ΔM xy +K idc,ixy Δi xy -------(20)

[0257] Δu cxy =K ucxy,Mxy ΔMxy +K ucxy,edc Δe dc -------(twenty one)

[0258] After sorting and simplifying, the final system state space model can be expressed as shown in the following formula (22):

[0259]

[0260] In an embodiment of the present application, based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain the sorted first electrical state space model and the sorted third electrical state space model, the modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model, thereby providing a basis for analyzing the impact of the energy storage system on the stability of the power grid system based on the system state space model, and providing guidance for system optimization design and controller parameter setting.

[0261] Reference Fig.18 , Fig.18 : is a flow chart of another modeling method provided in an embodiment of the present application, the method comprising:

[0262] S1801, perform equivalent processing on the voltage source converter VSC valve and the energy storage valve in the power grid system to obtain a system equivalent circuit of the power grid system.

[0263] S1802, establishing a first coordinate system and a second coordinate system.

[0264] S1803: Based on the first coordinate system, the second coordinate system and the system equivalent circuit, a first electrical state space model of the VSC valve and a second electrical state space model of the energy storage valve are established.

[0265] S1804, using the equivalent capacitance on the DC side of the VSC valve as a medium, connect the first electrical state space model and the second electrical state space model to obtain a third electrical state space model of the VSC valve, and combine the first electrical state space model, the second electrical state space model and the third electrical state space model to obtain an electrical state space model of the power grid system.

[0266] S1805: Based on the first coordinate system and the second coordinate system, establish a first control state space model of the VSC valve and a second control state space model of the energy storage valve.

[0267] S1806, using the AC / DC link relationship of the power grid system, the output parameters of the first control state space model and the second control state space model as the medium, the electrical state space model of the power grid system is connected with the control state space model to obtain the system state space model of the power grid system.

[0268] Reference Fig.19a , Fig.19b , Fig.19c , Fig.19d , Fig.19a is one of the simulation result schematic diagrams provided in the embodiment of the present application, Fig.19b This is the second schematic diagram of the simulation results provided in the embodiment of the present application. Fig.19c This is the third simulation result schematic diagram provided in the embodiment of the present application. Fig.19d This is the fourth schematic diagram of the simulation results provided in the embodiment of the present application. Fig.19a , Fig.19b , Fig.19c , Fig.19d The black waveform in the figure is the actual operation result of the power grid system, and the gray waveform is the waveform of the simulation result obtained based on the state space model of the power grid system. Fig.19a The AC current Δi x The waveform of the simulation result is Fig.19b The AC current Δi y The waveform of the simulation result is Fig.19c The DC voltage Δe is shown dc The waveform of the simulation result is Fig.19d The DC current Δi is shown dclink The waveform of the simulation results.

[0269] Depend on Fig.19a , Fig.19b , Fig.19c , Fig.19d It can be seen from the simulation results shown that the actual operation results of the power grid system have a high degree of waveform matching with the simulation results obtained based on the state-space model of the power grid system, thereby verifying that the state-space model of the power grid system has a high accuracy.

[0270] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0271] Based on the same inventive concept, the embodiment of the present application also provides a modeling device for implementing the modeling method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more modeling device embodiments provided below can refer to the limitations on the modeling method above, and will not be repeated here.

[0272] In one embodiment, Fig. 20 As shown, Fig. 20 2000 is a structural block diagram of a modeling device provided in an embodiment of the present application, and the device 2000 includes:

[0273] An equivalent processing module 2001 is used to perform equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system;

[0274] The first establishing module 2002 is used to establish an electrical state space model of the power grid system based on the system equivalent circuit, and to establish a control state space model according to the control link in the power grid system;

[0275] The second establishing module 2003 is used to establish a system state space model of the power grid system according to the electrical state space model and the control state space model.

[0276] In one embodiment, the equivalent processing module 2001 includes:

[0277] A first equivalent processing unit is used to perform equivalent processing on the AC side and the DC side of the VSC valve respectively to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve;

[0278] A second equivalent processing unit is used to perform equivalent processing on the energy storage valve to obtain an equivalent circuit of the energy storage valve;

[0279] The acquisition unit is used to obtain a system equivalent circuit based on an AC side equivalent circuit, a DC side equivalent circuit and an energy storage valve equivalent circuit.

[0280] In one of the embodiments, the first equivalent processing unit is specifically used to perform equivalent processing on the AC side of the VSC valve based on the average value model and the Thevenin theorem to obtain an AC side equivalent circuit; based on the average value model, the Thevenin theorem and the law of conservation of energy, perform equivalent processing on the DC side of the VSC valve to obtain a DC side equivalent circuit.

[0281] In one embodiment, the DC side equivalent circuit includes a first inductor, a second inductor, a first resistor, a second resistor, a first controlled DC voltage source and a VSC valve DC side equivalent capacitor; the first end of the first controlled DC voltage source and the first end of the VSC valve DC side equivalent capacitor are both connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the energy storage valve equivalent circuit; the second end of the first controlled DC voltage source and the second end of the VSC valve DC side equivalent capacitor are both connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the energy storage valve equivalent circuit.

[0282] In one of the embodiments, the AC side equivalent circuit includes a third inductor, a third resistor and a controlled AC voltage source;

[0283] The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer in the power grid system, and one end of the controlled AC voltage source is grounded.

[0284] In one of the embodiments, the second equivalent processing unit is specifically used to perform equivalent processing on the energy storage submodule of the energy storage valve based on the Thevenin theorem and the average value model to obtain a submodule equivalent circuit of the energy storage submodule; perform small signal equivalent conversion on the submodule equivalent circuit to obtain a small signal equivalent circuit of the energy storage submodule; and obtain the energy storage valve equivalent circuit based on the small signal equivalent circuit, a first number of energy storage submodules put into the energy storage system, and a second number of energy storage submodules involved in switching in the energy storage system.

[0285] In one embodiment, the submodule equivalent circuit includes any one of an ohmic resistance equivalent circuit, a first-order RC equivalent circuit obtained based on a battery polarization reaction, and a second-order RC equivalent circuit obtained based on a battery polarization reaction and a concentration difference reaction.

[0286] In one of the embodiments, the energy storage valve equivalent circuit includes an energy storage valve equivalent resistor and a second controlled DC voltage source;

[0287] The first end of the energy storage valve equivalent resistor is connected to the DC side equivalent circuit, the second end of the energy storage valve equivalent resistor is connected to the first end of the second controlled DC voltage source, and the second end of the second controlled DC voltage source is connected to the DC side equivalent circuit.

[0288] In one embodiment, the first establishing module 2002 includes:

[0289] A determination unit, configured to determine a first equivalent parameter and a second equivalent parameter based on a system equivalent circuit; the first equivalent parameter includes a total equivalent inductance of the AC side and a total equivalent resistance of the AC side, and the second equivalent parameter includes an equivalent capacitance of the VSC valve DC side and a sub-equivalent parameter, wherein the sub-equivalent parameter includes an equivalent inductance of the VSC valve DC side, an equivalent resistance of the VSC valve DC side, and an equivalent resistance of the energy storage valve;

[0290] A first establishing unit, configured to establish a first electrical state space model of the VSC valve based on a first equivalent parameter;

[0291] A second establishing unit is used to establish a second electrical state space model of the energy storage valve based on the sub-equivalent parameters;

[0292] The third establishing unit is used to establish an electrical state space model of the power grid system according to the first electrical state space model, the second electrical state space model and the equivalent capacitance of the DC side of the VSC valve.

[0293] In one of the embodiments, the first establishing unit is specifically configured to establish a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter, and the first output parameter;

[0294] The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system;

[0295] The first state parameter includes the AC grid-side current of the power grid system in the first coordinate system; the first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve;

[0296] The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in the second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

[0297] In one of the embodiments, the second establishing unit is specifically used to establish a second electrical state space model of the energy storage valve based on the second coefficient, the second state parameter and the second input parameter;

[0298] wherein the second coefficient is determined based on the sub-equivalent parameter;

[0299] The second state parameter includes an equivalent DC current of the energy storage valve;

[0300] The second input parameter includes a first controlled DC voltage source of the VSC valve and a second controlled DC voltage source of the energy storage valve. In one embodiment, the third establishing unit is specifically used to obtain a third electrical state space model of the VSC valve based on the VSC valve DC side equivalent capacitance; and to establish an electrical state space model of the power grid system based on the first electrical state space model, the second electrical state space model and the third electrical state space model.

[0301] In one embodiment, the control link includes a first control link of the VSC valve and a second control link of the energy storage valve; the first establishment module is specifically used to establish a first control state space model of the VSC valve based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter; wherein the third state parameter includes the control variable of the VSC valve; the third input parameter includes the AC grid side current of the power grid system in the first coordinate system, the AC grid side voltage and the AC valve side current of the power grid system in the second coordinate system, the control reference value of the active power and reactive power of the grid connection point of the power grid system, and the AC voltage control reference value of the grid connection point; the second output parameter includes the modulation ratio and the AC grid side output voltage of the VSC valve in the first coordinate system;

[0302] A second control state space model of the energy storage valve is established based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter;

[0303] The fourth coefficient is determined based on the first proportional coefficient of the fixed DC voltage proportional integral link, the first integral coefficient of the fixed DC voltage proportional integral link, the second proportional coefficient of the fixed DC current proportional integral link, the second integral coefficient of the fixed DC current proportional integral link, the DC voltage reference value of the energy storage valve, and the DC current reference value of the energy storage valve;

[0304] The fourth state parameter includes a control variable of a DC voltage integral link of the VSC valve and a control variable of a DC current integral link of the VSC valve;

[0305] The fourth input parameter includes an output DC voltage of the VSC valve, an output DC current of the VSC valve, and a DC voltage control reference value of the VSC valve;

[0306] The third output parameter includes the output voltage of the energy storage valve and the output voltage per unit value of the energy storage valve.

[0307] In one embodiment, the electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve;

[0308] The step of establishing a system state space model of the power grid system according to the electrical state space model and the control state space model comprises:

[0309] Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain a sorted first electrical state space model and a sorted third electrical state space model;

[0310] The modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model.

[0311] Each module in the above modeling device can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0312] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Fig.21 As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store XX data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a modeling method is implemented.

[0313] Those skilled in the art will understand that Fig.21 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0314] In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0315] Perform equivalent processing on the voltage source converter VSC valve and energy storage valve in the power grid system to obtain a system equivalent circuit of the power grid system;

[0316] An electrical state space model of the power grid system is established based on the system equivalent circuit, and a control state space model is established according to the control link in the power grid system;

[0317] A system state space model of the power grid system is established based on the electrical state space model and the control state space model.

[0318] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0319] The AC side and DC side of the VSC valve are processed equivalently respectively to obtain the AC side equivalent circuit and DC side equivalent circuit of the VSC valve; the energy storage valve is processed equivalently to obtain the energy storage valve equivalent circuit; based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit, the system equivalent circuit is obtained.

[0320] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0321] Based on the average value model and Thevenin's theorem, the AC side of the VSC valve is treated equivalently to obtain the AC side equivalent circuit; based on the average value model, Thevenin's theorem and the energy conservation theorem, the DC side of the VSC valve is treated equivalently to obtain the DC side equivalent circuit.

[0322] In one embodiment, the DC side equivalent circuit includes a first inductor, a second inductor, a first resistor, a second resistor, a first controlled DC voltage source, and a VSC valve DC side equivalent capacitor;

[0323] The first end of the first controlled DC voltage source and the first end of the equivalent capacitor on the DC side of the VSC valve are both connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the energy storage valve equivalent circuit;

[0324] The second end of the first controlled DC voltage source and the second end of the VSC valve DC side equivalent capacitor are both connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the energy storage valve equivalent circuit.

[0325] In one embodiment, the AC side equivalent circuit includes a third inductor, a third resistor and a controlled AC voltage source;

[0326] The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer in the power grid system, and one end of the controlled AC voltage source is grounded.

[0327] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0328] Based on the Thevenin theorem and the average value model, the energy storage submodule of the energy storage valve is equivalently processed to obtain the submodule equivalent circuit of the energy storage submodule; the submodule equivalent circuit is converted into a small signal equivalent circuit to obtain the small signal equivalent circuit of the energy storage submodule; based on the small signal equivalent circuit, the first number of energy storage submodules put into the energy storage system, and the second number of energy storage submodules involved in switching in the energy storage system, the energy storage valve equivalent circuit is obtained.

[0329] In one embodiment, the submodule equivalent circuit includes any one of an ohmic resistance equivalent circuit, a first-order RC equivalent circuit obtained based on a battery polarization reaction, and a second-order RC equivalent circuit obtained based on a battery polarization reaction and a concentration difference reaction.

[0330] In one embodiment, the energy storage valve equivalent circuit includes an energy storage valve equivalent resistor and a second controlled DC voltage source;

[0331] The first end of the energy storage valve equivalent resistor is connected to the DC side equivalent circuit, the second end of the energy storage valve equivalent resistor is connected to the first end of the second controlled DC voltage source, and the second end of the second controlled DC voltage source is connected to the DC side equivalent circuit.

[0332] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0333] Based on the system equivalent circuit, the first equivalent parameter and the second equivalent parameter are determined; the first equivalent parameter includes the total equivalent inductance on the AC side and the total equivalent resistance on the AC side, the second equivalent parameter includes the equivalent capacitance on the DC side of the VSC valve and the sub-equivalent parameters, the sub-equivalent parameters include the equivalent inductance on the DC side of the VSC valve, the equivalent resistance on the DC side of the VSC valve and the equivalent resistance of the energy storage valve; based on the first equivalent parameter, a first electrical state space model of the VSC valve is established; based on the sub-equivalent parameter, a second electrical state space model of the energy storage valve is established; according to the first electrical state space model, the second electrical state space model and the equivalent capacitance on the DC side of the VSC valve, an electrical state space model of the power grid system is established.

[0334] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0335] Establishing a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter, and the first output parameter;

[0336] The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system;

[0337] The first state parameter includes an AC grid-side current of the power grid system in a first coordinate system;

[0338] The first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve;

[0339] The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in the second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

[0340] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0341] Establishing a second electrical state space model of the energy storage valve based on the second coefficient, the second state parameter and the second input parameter;

[0342] wherein the second coefficient is determined based on the sub-equivalent parameter;

[0343] The second state parameter includes an equivalent DC current of the energy storage valve;

[0344] The second input parameter includes a first controlled DC voltage source for the VSC valve and a second controlled DC voltage source for the energy storage valve.

[0345] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0346] Based on the equivalent capacitance of the VSC valve DC side, a third electrical state space model of the VSC valve is obtained; based on the first electrical state space model, the second electrical state space model and the third electrical state space model, an electrical state space model of the power grid system is established.

[0347] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0348] A first control state space model of the VSC valve is established based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter; wherein the third state parameter includes the control variable of the VSC valve; the third input parameter includes the AC grid-side current of the power grid system in the first coordinate system, the AC grid-side voltage and the AC valve-side current of the power grid system in the second coordinate system, the control reference values ​​of the active power and reactive power of the grid-connected point of the power grid system, and the AC voltage control reference value of the grid-connected point; the second output parameter includes the modulation ratio and the AC grid-side output voltage of the VSC valve in the first coordinate system;

[0349] A second control state space model of the energy storage valve is established based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter;

[0350] The fourth coefficient is determined based on the first proportional coefficient of the fixed DC voltage proportional integral link, the first integral coefficient of the fixed DC voltage proportional integral link, the second proportional coefficient of the fixed DC current proportional integral link, the second integral coefficient of the fixed DC current proportional integral link, the DC voltage reference value of the energy storage valve, and the DC current reference value of the energy storage valve;

[0351] The fourth state parameter includes a control variable of a DC voltage integral link of the VSC valve and a control variable of a DC current integral link of the VSC valve;

[0352] The fourth input parameter includes an output DC voltage of the VSC valve, an output DC current of the VSC valve, and a DC voltage control reference value of the VSC valve;

[0353] The third output parameter includes the output voltage of the energy storage valve and the output voltage per unit value of the energy storage valve.

[0354] In one embodiment, the electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve; when the processor executes the computer program, the following steps are also implemented:

[0355] Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain a sorted first electrical state space model and a sorted third electrical state space model; the modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain a system state space model.

[0356] In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0357] Perform equivalent processing on the voltage source converter VSC valve and energy storage valve in the power grid system to obtain a system equivalent circuit of the power grid system;

[0358] An electrical state space model of the power grid system is established based on the system equivalent circuit, and a control state space model is established according to the control link in the power grid system;

[0359] A system state space model of the power grid system is established based on the electrical state space model and the control state space model.

[0360] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0361] The AC side and DC side of the VSC valve are processed equivalently respectively to obtain the AC side equivalent circuit and DC side equivalent circuit of the VSC valve; the energy storage valve is processed equivalently to obtain the energy storage valve equivalent circuit; based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit, the system equivalent circuit is obtained.

[0362] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0363] Based on the average value model and Thevenin's theorem, the AC side of the VSC valve is treated equivalently to obtain the AC side equivalent circuit; based on the average value model, Thevenin's theorem and the energy conservation theorem, the DC side of the VSC valve is treated equivalently to obtain the DC side equivalent circuit.

[0364] In one embodiment, the DC side equivalent circuit includes a first inductor, a second inductor, a first resistor, a second resistor, a first controlled DC voltage source, and a VSC valve DC side equivalent capacitor;

[0365] The first end of the first controlled DC voltage source and the first end of the equivalent capacitor on the DC side of the VSC valve are both connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the energy storage valve equivalent circuit;

[0366] The second end of the first controlled DC voltage source and the second end of the VSC valve DC side equivalent capacitor are both connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the energy storage valve equivalent circuit.

[0367] In one embodiment, the AC side equivalent circuit includes a third inductor, a third resistor and a controlled AC voltage source;

[0368] The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer in the power grid system, and one end of the controlled AC voltage source is grounded.

[0369] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0370] Based on the Thevenin theorem and the average value model, the energy storage submodule of the energy storage valve is equivalently processed to obtain the submodule equivalent circuit of the energy storage submodule; the submodule equivalent circuit is converted into a small signal equivalent circuit to obtain the small signal equivalent circuit of the energy storage submodule; based on the small signal equivalent circuit, the first number of energy storage submodules put into the energy storage system, and the second number of energy storage submodules involved in switching in the energy storage system, the energy storage valve equivalent circuit is obtained.

[0371] In one embodiment, the submodule equivalent circuit includes any one of an ohmic resistance equivalent circuit, a first-order RC equivalent circuit obtained based on a battery polarization reaction, and a second-order RC equivalent circuit obtained based on a battery polarization reaction and a concentration difference reaction.

[0372] In one embodiment, the energy storage valve equivalent circuit includes an energy storage valve equivalent resistor and a second controlled DC voltage source;

[0373] The first end of the energy storage valve equivalent resistor is connected to the DC side equivalent circuit, the second end of the energy storage valve equivalent resistor is connected to the first end of the second controlled DC voltage source, and the second end of the second controlled DC voltage source is connected to the DC side equivalent circuit.

[0374] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0375] Based on the system equivalent circuit, the first equivalent parameter and the second equivalent parameter are determined; the first equivalent parameter includes the total equivalent inductance on the AC side and the total equivalent resistance on the AC side, the second equivalent parameter includes the equivalent capacitance on the DC side of the VSC valve and the sub-equivalent parameters, the sub-equivalent parameters include the equivalent inductance on the DC side of the VSC valve, the equivalent resistance on the DC side of the VSC valve and the equivalent resistance of the energy storage valve; based on the first equivalent parameter, a first electrical state space model of the VSC valve is established; based on the sub-equivalent parameter, a second electrical state space model of the energy storage valve is established; according to the first electrical state space model, the second electrical state space model and the equivalent capacitance on the DC side of the VSC valve, an electrical state space model of the power grid system is established.

[0376] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0377] Establishing a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter, and the first output parameter;

[0378] The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system;

[0379] The first state parameter includes an AC grid-side current of the power grid system in a first coordinate system;

[0380] The first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve;

[0381] The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in the second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

[0382] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0383] Establishing a second electrical state space model of the energy storage valve based on the second coefficient, the second state parameter and the second input parameter;

[0384] wherein the second coefficient is determined based on the sub-equivalent parameter;

[0385] The second state parameter includes an equivalent DC current of the energy storage valve;

[0386] The second input parameter includes a first controlled DC voltage source for the VSC valve and a second controlled DC voltage source for the energy storage valve.

[0387] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0388] Based on the equivalent capacitance of the VSC valve DC side, a third electrical state space model of the VSC valve is obtained; based on the first electrical state space model, the second electrical state space model and the third electrical state space model, an electrical state space model of the power grid system is established.

[0389] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0390] A first control state space model of the VSC valve is established based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter; wherein the third state parameter includes the control variable of the VSC valve; the third input parameter includes the AC grid-side current of the power grid system in the first coordinate system, the AC grid-side voltage and the AC valve-side current of the power grid system in the second coordinate system, the control reference values ​​of the active power and reactive power of the grid-connected point of the power grid system, and the AC voltage control reference value of the grid-connected point; the second output parameter includes the modulation ratio and the AC grid-side output voltage of the VSC valve in the first coordinate system;

[0391] A second control state space model of the energy storage valve is established based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter;

[0392] The fourth coefficient is determined based on the first proportional coefficient of the fixed DC voltage proportional integral link, the first integral coefficient of the fixed DC voltage proportional integral link, the second proportional coefficient of the fixed DC current proportional integral link, the second integral coefficient of the fixed DC current proportional integral link, the DC voltage reference value of the energy storage valve, and the DC current reference value of the energy storage valve;

[0393] The fourth state parameter includes a control variable of a DC voltage integral link of the VSC valve and a control variable of a DC current integral link of the VSC valve;

[0394] The fourth input parameter includes an output DC voltage of the VSC valve, an output DC current of the VSC valve, and a DC voltage control reference value of the VSC valve;

[0395] The third output parameter includes the output voltage of the energy storage valve and the output voltage per unit value of the energy storage valve.

[0396] In one embodiment, the electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve; when the computer program is executed by the processor, the following steps are also implemented:

[0397] Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain a sorted first electrical state space model and a sorted third electrical state space model;

[0398] The modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model.

[0399] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0400] Perform equivalent processing on the voltage source converter VSC valve and energy storage valve in the power grid system to obtain a system equivalent circuit of the power grid system;

[0401] An electrical state space model of the power grid system is established based on the system equivalent circuit, and a control state space model is established according to the control link in the power grid system;

[0402] A system state space model of the power grid system is established based on the electrical state space model and the control state space model.

[0403] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0404] The AC side and DC side of the VSC valve are processed equivalently respectively to obtain the AC side equivalent circuit and DC side equivalent circuit of the VSC valve; the energy storage valve is processed equivalently to obtain the energy storage valve equivalent circuit; based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit, the system equivalent circuit is obtained.

[0405] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0406] Based on the average value model and Thevenin's theorem, the AC side of the VSC valve is treated equivalently to obtain the AC side equivalent circuit; based on the average value model, Thevenin's theorem and the energy conservation theorem, the DC side of the VSC valve is treated equivalently to obtain the DC side equivalent circuit.

[0407] In one embodiment, the DC side equivalent circuit includes a first inductor, a second inductor, a first resistor, a second resistor, a first controlled DC voltage source, and a VSC valve DC side equivalent capacitor;

[0408] The first end of the first controlled DC voltage source and the first end of the equivalent capacitor on the DC side of the VSC valve are both connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the energy storage valve equivalent circuit;

[0409] The second end of the first controlled DC voltage source and the second end of the VSC valve DC side equivalent capacitor are both connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the energy storage valve equivalent circuit.

[0410] In one embodiment, the AC side equivalent circuit includes a third inductor, a third resistor and a controlled AC voltage source;

[0411] The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer in the power grid system, and one end of the controlled AC voltage source is grounded.

[0412] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0413] Based on the Thevenin theorem and the average value model, the energy storage submodule of the energy storage valve is equivalently processed to obtain the submodule equivalent circuit of the energy storage submodule; the submodule equivalent circuit is converted into a small signal equivalent circuit to obtain the small signal equivalent circuit of the energy storage submodule; based on the small signal equivalent circuit, the first number of energy storage submodules put into the energy storage system, and the second number of energy storage submodules involved in switching in the energy storage system, the energy storage valve equivalent circuit is obtained.

[0414] In one embodiment, the submodule equivalent circuit includes any one of an ohmic resistance equivalent circuit, a first-order RC equivalent circuit obtained based on a battery polarization reaction, and a second-order RC equivalent circuit obtained based on a battery polarization reaction and a concentration difference reaction.

[0415] In one embodiment, the energy storage valve equivalent circuit includes an energy storage valve equivalent resistor and a second controlled DC voltage source;

[0416] The first end of the energy storage valve equivalent resistor is connected to the DC side equivalent circuit, the second end of the energy storage valve equivalent resistor is connected to the first end of the second controlled DC voltage source, and the second end of the second controlled DC voltage source is connected to the DC side equivalent circuit.

[0417] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0418] Based on the system equivalent circuit, the first equivalent parameter and the second equivalent parameter are determined; the first equivalent parameter includes the total equivalent inductance on the AC side and the total equivalent resistance on the AC side, the second equivalent parameter includes the equivalent capacitance on the DC side of the VSC valve and the sub-equivalent parameters, the sub-equivalent parameters include the equivalent inductance on the DC side of the VSC valve, the equivalent resistance on the DC side of the VSC valve and the equivalent resistance of the energy storage valve; based on the first equivalent parameter, a first electrical state space model of the VSC valve is established; based on the sub-equivalent parameter, a second electrical state space model of the energy storage valve is established; according to the first electrical state space model, the second electrical state space model and the equivalent capacitance on the DC side of the VSC valve, an electrical state space model of the power grid system is established.

[0419] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0420] Establishing a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter, and the first output parameter;

[0421] The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system;

[0422] The first state parameter includes an AC grid-side current of the power grid system in a first coordinate system;

[0423] The first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve;

[0424] The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in the second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

[0425] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0426] Establishing a second electrical state space model of the energy storage valve based on the second coefficient, the second state parameter and the second input parameter;

[0427] wherein the second coefficient is determined based on the sub-equivalent parameter;

[0428] The second state parameter includes an equivalent DC current of the energy storage valve;

[0429] The second input parameter includes a first controlled DC voltage source for the VSC valve and a second controlled DC voltage source for the energy storage valve.

[0430] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0431] Based on the equivalent capacitance of the VSC valve DC side, a third electrical state space model of the VSC valve is obtained; based on the first electrical state space model, the second electrical state space model and the third electrical state space model, an electrical state space model of the power grid system is established.

[0432] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0433] A first control state space model of the VSC valve is established based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter; wherein the third state parameter includes the control variable of the VSC valve; the third input parameter includes the AC grid-side current of the power grid system in the first coordinate system, the AC grid-side voltage and the AC valve-side current of the power grid system in the second coordinate system, the control reference values ​​of the active power and reactive power of the grid-connected point of the power grid system, and the AC voltage control reference value of the grid-connected point; the second output parameter includes the modulation ratio and the AC grid-side output voltage of the VSC valve in the first coordinate system;

[0434] A second control state space model of the energy storage valve is established based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter;

[0435] The fourth coefficient is determined based on the first proportional coefficient of the fixed DC voltage proportional integral link, the first integral coefficient of the fixed DC voltage proportional integral link, the second proportional coefficient of the fixed DC current proportional integral link, the second integral coefficient of the fixed DC current proportional integral link, the DC voltage reference value of the energy storage valve, and the DC current reference value of the energy storage valve;

[0436] The fourth state parameter includes a control variable of a DC voltage integral link of the VSC valve and a control variable of a DC current integral link of the VSC valve;

[0437] The fourth input parameter includes an output DC voltage of the VSC valve, an output DC current of the VSC valve, and a DC voltage control reference value of the VSC valve;

[0438] The third output parameter includes the output voltage of the energy storage valve and the output voltage per unit value of the energy storage valve.

[0439] In one embodiment, the electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve; when the computer program is executed by the processor, the following steps are also implemented:

[0440] Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain a sorted first electrical state space model and a sorted third electrical state space model;

[0441] The modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model.

[0442] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0443] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0444] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0445] Finally, it should be noted that 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A modeling method, characterized in that: The method comprises: Performing equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system; Based on the system equivalent circuit, an electrical state space model of the power grid system is established, and a control state space model is established according to the control links in the power grid system; A system state space model of the power grid system is established according to the electrical state space model and the control state space model.

2. The method according to claim 1, characterized in that The equivalent processing of the voltage source converter VSC valve and the energy storage valve in the power grid system to obtain the system equivalent circuit of the power grid system includes: Performing equivalent processing on the AC side and the DC side of the VSC valve respectively to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve; Performing equivalent processing on the energy storage valve to obtain an energy storage valve equivalent circuit; The system equivalent circuit is obtained based on the AC side equivalent circuit, the DC side equivalent circuit and the energy storage valve equivalent circuit.

3. The method according to claim 2, characterized in that The equivalent processing is performed on the AC side and the DC side of the VSC valve respectively to obtain an AC side equivalent circuit and a DC side equivalent circuit of the VSC valve, including: Based on the average value model and the Thevenin theorem, equivalent processing is performed on the AC side of the VSC valve to obtain the AC side equivalent circuit; Based on the average value model, Thevenin's theorem and the energy conservation theorem, equivalent processing is performed on the DC side of the VSC valve to obtain the DC side equivalent circuit.

4. The method according to claim 2 or 3, characterized in that: The DC side equivalent circuit includes a first inductor, a second inductor, a first resistor, a second resistor, a first controlled DC voltage source and a VSC valve DC side equivalent capacitor; The first end of the first controlled DC voltage source and the first end of the VSC valve DC side equivalent capacitor are both connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the energy storage valve equivalent circuit; The second end of the first controlled DC voltage source and the second end of the VSC valve DC side equivalent capacitor are both connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the energy storage valve equivalent circuit.

5. The method according to claim 2 or 3, characterized in that: The AC side equivalent circuit includes a third inductor, a third resistor and a controlled AC voltage source; The third resistor is arranged between the third inductor and the controlled AC voltage source, one end of the third inductor is connected to one end of the converter transformer in the power grid system, and one end of the controlled AC voltage source is grounded.

6. The method according to claim 2 or 3, characterized in that: The performing equivalent processing on the energy storage valve to obtain the energy storage valve equivalent circuit comprises: Based on the Thevenin theorem and the average value model, an energy storage submodule of the energy storage valve is equivalently processed to obtain a submodule equivalent circuit of the energy storage submodule; Performing small signal equivalent conversion on the submodule equivalent circuit to obtain a small signal equivalent circuit of the energy storage submodule; The energy storage valve equivalent circuit is obtained based on the small signal equivalent circuit, a first number of energy storage submodules put into the energy storage system, and a second number of energy storage submodules involved in switching in the energy storage system.

7. The method according to claim 6, characterized in that The submodule equivalent circuit includes any one of an ohmic resistance equivalent circuit, a first-order RC equivalent circuit obtained based on a battery polarization reaction, and a second-order RC equivalent circuit obtained based on a battery polarization reaction and a concentration difference reaction.

8. The method according to claim 6, characterized in that The energy storage valve equivalent circuit includes an energy storage valve equivalent resistor and a second controlled DC voltage source; The first end of the energy storage valve equivalent resistor is connected to the DC side equivalent circuit, the second end of the energy storage valve equivalent resistor is connected to the first end of the second controlled DC voltage source, and the second end of the second controlled DC voltage source is connected to the DC side equivalent circuit.

9. The method according to claim 4, characterized in that The step of establishing an electrical state space model of the power grid system based on the system equivalent circuit comprises: Based on the system equivalent circuit, determining a first equivalent parameter and a second equivalent parameter; the first equivalent parameter includes a total equivalent inductance of the AC side and a total equivalent resistance of the AC side, and the second equivalent parameter includes an equivalent capacitance of the VSC valve DC side and a sub-equivalent parameter, and the sub-equivalent parameter includes an equivalent inductance of the VSC valve DC side, an equivalent resistance of the VSC valve DC side, and an equivalent resistance of the energy storage valve; Based on the first equivalent parameters, establishing a first electrical state space model of the VSC valve; Based on the sub-equivalent parameters, establishing a second electrical state space model of the energy storage valve; An electrical state space model of the power grid system is established according to the first electrical state space model, the second electrical state space model and the VSC valve DC side equivalent capacitance.

10. The method according to claim 9, characterized in that The establishing of a first electrical state space model of the VSC valve based on the first equivalent parameter includes: Establishing a first electrical state space model of the VSC valve based on the first coefficient, the first state parameter, the first input parameter and the first output parameter; The first coefficient is determined based on the first equivalent parameter, the rated angular frequency of the power grid system, the voltage phase angle of the power grid system in a steady state, the AC grid-side current of the power grid system in a steady state, and the transformer ratio of the converter transformer in the power grid system; The first state parameter includes the AC grid-side current of the power grid system in the first coordinate system; The first input parameter includes the AC grid-side output voltage of the VSC valve and the control state quantity of the VSC valve; The first output parameter includes the AC grid side current and the AC valve side current of the power grid system in a second coordinate system. The first coordinate system is a coordinate system established based on the phase of the A-phase AC voltage of the AC grid in the power grid system, and the second coordinate system is a coordinate system established based on the phase of the output voltage of the phase-locked loop.

11. The method according to claim 10, characterized in that The step of establishing a second electrical state space model of the energy storage valve based on the sub-equivalent parameters comprises: Establishing a second electrical state space model of the energy storage valve based on the second coefficient, the second state parameter and the second input parameter; wherein the second coefficient is determined based on the sub-equivalent parameter; The second state parameter includes an equivalent direct current of the energy storage valve; The second input parameter includes a first controlled DC voltage source of the VSC valve and a second controlled DC voltage source of the energy storage valve.

12. The method according to any one of claims 9 to 11, characterized in that: The step of establishing the electrical state space model of the power grid system according to the first electrical state space model, the second electrical state space model and the VSC valve DC side equivalent capacitance includes: Based on the VSC valve DC side equivalent capacitance, a third electrical state space model of the VSC valve is obtained; An electrical state space model of the power grid system is established based on the first electrical state space model, the second electrical state space model and the third electrical state space model.

13. The method according to claim 12, characterized in that The control link includes a first control link of the VSC valve and a second control link of the energy storage valve; and establishing a control state space model according to the control link in the power grid system includes: Based on the first control link, the third coefficient, the third state parameter, the third input parameter, and the second output parameter, a first control state space model of the VSC valve is established; wherein the third state parameter includes the control variable of the VSC valve; the third input parameter includes the AC grid-side current of the power grid system in the first coordinate system, the AC grid-side voltage and the AC valve-side current of the power grid system in the second coordinate system, the control reference values ​​of the active power and reactive power of the grid-connected point of the power grid system, and the AC voltage control reference value of the grid-connected point; the second output parameter includes the modulation ratio and the AC grid-side output voltage of the VSC valve in the first coordinate system; Based on the second control link, the fourth coefficient, the fourth state parameter, the fourth input parameter, and the third output parameter, a second control state space model of the energy storage valve is established; The fourth coefficient is determined based on the first proportional coefficient of the fixed DC voltage proportional integral link, the first integral coefficient of the fixed DC voltage proportional integral link, the second proportional coefficient of the fixed DC current proportional integral link, the second integral coefficient of the fixed DC current proportional integral link, the DC voltage reference value of the energy storage valve, and the DC current reference value of the energy storage valve; The fourth state parameter includes a control variable of a DC voltage integral link of the VSC valve and a control variable of a DC current integral link of the VSC valve; The fourth input parameter includes the output DC voltage of the VSC valve, the output DC current of the VSC valve, and a DC voltage control reference value of the VSC valve; The third output parameter includes the output voltage of the energy storage valve and the output voltage per unit value of the energy storage valve.

14. The method according to claim 13, characterized in that The electrical state space model includes a first electrical state space model of the VSC valve, a second electrical state space model of the energy storage valve, and a third electrical state space model, and the control state space model includes a first control state space model of the VSC valve and a second control state space model of the energy storage valve; The step of establishing a system state space model of the power grid system according to the electrical state space model and the control state space model comprises: Based on the AC / DC link relationship of the power grid system, the first electrical state space model and the third electrical state space model are sorted to obtain a sorted first electrical state space model and a sorted third electrical state space model; The modulation ratio in the second output parameter is substituted into the sorted first electrical state space model and the sorted third electrical state space model, and the output voltage of the energy storage valve in the third output parameter is substituted into the second electrical state space model to obtain the system state space model.

15. A modeling device, characterized in that: The device comprises: An equivalent processing module, used for performing equivalent processing on a voltage source converter VSC valve and an energy storage valve in a power grid system to obtain a system equivalent circuit of the power grid system; A first establishing module is used to establish an electrical state space model of the power grid system based on the system equivalent circuit, and to establish a control state space model according to a control link in the power grid system; The second establishing module is used to establish a system state space model of the power grid system according to the electrical state space model and the control state space model.

16. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 14 are implemented.

17. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 14 are implemented.

18. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 14 are implemented.

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