Common-mode current calculation method, energy storage system evaluation method and device

Abstract

The invention provides a common-mode current calculation method and an energy storage system evaluation method and device, and the method comprises the steps: carrying out the modeling of a target energy storage system, and obtaining a geometric model of the target energy storage system; calculating stray parameters of the target energy storage system based on the geometric model; and calculating the common-mode current of the target energy storage system according to the stray parameters.

Description

Technical Field

[0001] The present application relates to the field of energy storage safety technology, and more specifically, to a common-mode current calculation method, an energy storage system evaluation method, and an apparatus. Background Art

[0002] As a new type of energy storage system, high-voltage direct-mounted energy storage systems have received relatively little research, resulting in a lack of data basis for their evaluation. Summary of the Invention

[0003] The purpose of this application is to provide a common-mode current calculation method, an energy storage system evaluation method and device, which can provide a common-mode current calculation method to provide a data basis for energy storage system evaluation.

[0004] In a first aspect, the present application provides a common-mode current calculation method, comprising: modeling a target energy storage system to obtain a geometric model of the target energy storage system; calculating stray parameters of the target energy storage system based on the geometric model; and calculating the common-mode current of the target energy storage system according to the stray parameters.

[0005] In the above embodiment, the target energy storage system can be presented in the form of data by modeling the energy storage system, thereby facilitating the calculation of various parameters of the target energy storage system. The stray parameters of the target energy storage system are calculated in combination with the geometric model to determine the parameters that can present the common-mode current that affects the target energy storage system. Finally, based on the processing of the stray parameters, the common-mode current of the energy storage system can be calculated, thereby providing a data basis for the evaluation of the energy storage system.

[0006] In an optional embodiment, calculating the common-mode current of the target energy storage system based on the stray parameters includes: constructing a lumped parameter circuit of the target energy storage system based on the stray parameters and the geometric model; and calculating the common-mode current of the target energy storage system based on the lumped parameter circuit.

[0007] In an optional embodiment, constructing the lumped parameter circuit of the target energy storage system based on the stray parameters and the geometric model includes: determining the parasitic parameters of the target energy storage system based on the geometric model; constructing a main loop circuit of the target energy storage system according to the parasitic parameters; and constructing equivalent devices of the stray parameters in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

[0008] In an optional embodiment, the stray parameters include: stray inductance, stray resistance, and stray capacitance; constructing equivalent devices of the stray parameters in the main loop circuit to form a lumped parameter circuit of the target energy storage system includes: constructing an equivalent device of the stray inductance and an equivalent device of the stray resistance connected in series in the main loop circuit; constructing an equivalent device of the stray capacitance in series between two locations where capacitance is generated in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

[0009] In an optional embodiment, the calculating the common-mode current of the target energy storage system based on the lumped parameter circuit includes: simulating the lumped parameter circuit to obtain the common-mode current of the target energy storage system.

[0010] In an optional embodiment, the calculating the stray parameters of the target energy storage system based on the geometric model includes: dividing the geometric model into multiple geometric units according to a set division strategy; simplifying the structure in the geometric unit to obtain a simplified geometric unit, wherein each simplified geometric unit forms a simplified model of the target energy storage system; and calculating the stray parameters of the target energy storage system based on the simplified model.

[0011] In the above embodiment, the geometric model can be simplified first, which can reduce the difficulty of calculating stray parameters and improve calculation efficiency. Furthermore, the geometric model can be divided into multiple geometric units, which can better determine the parts of the geometric units that need to be simplified, thereby achieving more accurate simplification of the geometric units.

[0012] In an optional embodiment, the simplification process includes: deleting non-circulation components in the geometric unit, wherein the non-circulation components include: one or more of: insulating parts, secondary electrical structures, and mounting accessories.

[0013] In the above embodiment, some analog components that do not affect the value of the common-mode current can be deleted, which can reduce the interference of such components on the calculation, reduce the difficulty of calculating the common-mode current, and improve the efficiency of the common-mode current calculation.

[0014] In an optional embodiment, the simplification process includes: filling the gaps in the charged devices in the geometric unit, wherein the gaps include one or more of hollows and holes.

[0015] In the above embodiment, the gaps in the charged metal device can be filled to reduce the impact of the gaps on the corresponding calculations. The filling of the gaps can also make the simplified geometric unit more integrated, facilitating the calculation of stray parameters in the simplified geometric unit.

[0016] In an optional embodiment, calculating the stray parameters of the target energy storage system based on the simplified model includes: importing the simplified model into a simulation tool; setting conditions required for calculating the stray parameters through the simulation tool; and calculating the stray parameters of the target energy storage system according to the required conditions.

[0017] In the above implementation, the simplified geometric model can be directly imported into the simulation tool, and the tool can be used to calculate the stray parameters more quickly.

[0018] In a second aspect, the present application provides an energy storage system evaluation method, comprising: determining the common-mode current of the energy storage system to be evaluated according to the common-mode current calculation method described in any one of the aforementioned embodiments; and evaluating the electrical stress at each point of the energy storage system to be evaluated based on the common-mode current.

[0019] In the above implementation, by modeling the energy storage system and calculating its stray parameters, the common-mode current of the energy storage system can be calculated based on the model, providing a data basis for evaluating the energy storage system. Furthermore, by evaluating the electrical stress at various points in the energy storage system based on this common-mode current, the system's condition can be understood, enabling better maintenance.

[0020] In a third aspect, the present application provides a common-mode current calculation device, including: a modeling module for modeling a target energy storage system to obtain a geometric model of the target energy storage system; a first calculation module for calculating the stray parameters of the target energy storage system based on the geometric model; and a second calculation module for calculating the common-mode current of the target energy storage system based on the stray parameters.

[0021] In a fourth aspect, the present application provides an energy storage system evaluation device, comprising: a determination module for determining the common-mode current of the energy storage system to be evaluated according to the common-mode current calculation method described in any one of the aforementioned embodiments; and an evaluation module for evaluating the electrical stress at each point of the energy storage system to be evaluated based on the common-mode current.

[0022] In a fifth aspect, the present application provides an electronic device comprising: a processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the machine-readable instructions are executed by the processor to perform the steps of the method described in any of the aforementioned embodiments.

[0023] In a sixth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which executes the steps of the method described in any of the aforementioned embodiments when the computer program is executed by a processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A block diagram of an electronic device provided in an embodiment of the present application;

[0026] Figure 2 A flowchart of a common-mode current calculation method provided in an embodiment of the present application;

[0027] Figure 3 This is a schematic diagram of an MMC type AC direct-mounted energy storage system;

[0028] Figure 4 This is a schematic diagram of a DC direct-hung energy storage system;

[0029] Figure 5 A schematic diagram of a cascaded AC direct-mounted energy storage system;

[0030] Figure 6 A schematic diagram of a lumped parameter circuit formed for an energy storage system in an example;

[0031] Figure 7 A schematic diagram of the functional modules of the common-mode current calculation device provided in an embodiment of the present application;

[0032] Figure 8 A flowchart of the energy storage system evaluation method provided in an embodiment of the present application;

[0033] Figure 9 Schematic diagram of the functional modules of the energy storage system evaluation device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0035] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0036] As a new type of energy storage system, high-voltage direct-mounted energy storage systems are in their infancy in terms of research and implementation. The main difference between high-voltage direct-mounted energy storage systems and traditional low-voltage energy storage systems is that high-voltage energy storage systems use a cascaded structure of energy storage submodules. The voltages of devices in different parts of the system to the ground vary, and the submodule with the highest voltage to the ground can reach tens or even hundreds of kilovolts. If the conductive supports, structural components, and encapsulating shells (hereinafter collectively referred to as "conductive shells") in each submodule were all grounded to the ground, this would far exceed the insulation level of the power modules, batteries, and other main circuit components to the shells, making this impossible. Therefore, certain measures are needed to limit the voltage of the conductive shell of each energy storage submodule to a value close to that of the corresponding position in its main circuit. At this point, technology similar to flexible DC transmission converter valves must be adopted, using insulators to suspend all devices in the air to maintain a high insulation level to the ground and avoid ground faults. This is called an energy storage valve tower. However, because the submodules of a high-voltage energy storage system contain energy storage modules, their combined conductive housing is significantly larger than that of a submodule in flexible DC transmission technology. This creates parasitic capacitance between the main circuit components and the conductive housing, within the housing itself, between the housing and other submodules, and between the housing and the ground. This can cause high-frequency currents to flow between components and the housing that are not normally conductive, potentially damaging insulation at critical locations and increasing electrical stress on components.

[0037] Based on the above research, an embodiment of the present application proposes a common-mode current calculation method to pre-calculate the common-mode current generated by the parasitic capacitance phenomenon in the high-voltage direct-mounted energy storage system. Then, based on the common-mode current, the possible hazards can be evaluated and the design defects can be determined to guide the overall design.

[0038] To facilitate understanding of this embodiment, the electronic device that executes the common-mode current calculation method and energy storage system evaluation method disclosed in the embodiment of the present application is first introduced in detail.

[0039] like Figure 1 , which is a block diagram of an electronic device. The electronic device 100 may include a memory 111, a storage controller 112, a processor 113, a peripheral interface 114, an input and output unit 115, and a display unit 116. It will be understood by those skilled in the art that Figure 1 The structure shown is only for illustration and does not limit the structure of the electronic device 100. For example, the electronic device 100 may further include Figure 1 More or fewer components than shown, or with Figure 1 Different configurations shown.

[0040] The aforementioned memory 111, storage controller 112, processor 113, peripheral interface 114, input / output unit 115, and display unit 116 are electrically connected to each other, directly or indirectly, to enable data transmission or interaction. For example, these components may be electrically connected to each other via one or more communication buses or signal lines. The aforementioned processor 113 is used to execute the executable modules stored in the memory.

[0041] The memory 111 may be, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The memory 111 is used to store programs, and the processor 113 executes the programs after receiving an execution instruction. The method executed by the electronic device 100 defined by the process disclosed in any embodiment of the present application can be applied to the processor 113 or implemented by the processor 113.

[0042] The processor 113 may be an integrated circuit chip with signal processing capabilities. The processor 113 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gates or transistor logic devices, or discrete hardware components. The methods, steps, and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or any conventional processor.

[0043] The peripheral interface 114 couples various input / output devices to the processor 113 and the memory 111. In some embodiments, the peripheral interface 114, the processor 113, and the memory controller 112 can be implemented in a single chip. In other embodiments, they can be implemented in separate chips.

[0044] The input / output unit 115 is used to provide input data to the user and can be, but not limited to, a mouse and a keyboard.

[0045] The display unit 116 provides an interactive interface (e.g., a user operation interface) between the electronic device 100 and the user or is used to display image data for the user's reference. In this embodiment, the display unit can be a liquid crystal display or a touch display. If it is a touch display, it can be a capacitive touch screen or a resistive touch screen that supports single-point and multi-point touch operations. Supporting single-point and multi-point touch operations means that the touch display can sense touch operations generated simultaneously from one or more locations on the touch display, and pass the sensed touch operations to the processor for calculation and processing.

[0046] The display unit 116 provided in this embodiment can be used to display the geometric model, parameter circuit, etc. constructed in the common-mode current calculation method provided in this embodiment.

[0047] The electronic device 100 in this embodiment can be used to execute each step in each method provided in the embodiments of the present application. The following describes in detail the implementation process of the common mode current calculation method and the energy storage system evaluation method through several embodiments.

[0048] See also Figure 2 , is a flow chart of the common mode current calculation method provided in the embodiment of the present application. Figure 2 The specific process shown is explained in detail.

[0049] Step 210 : Modeling the target energy storage system to obtain a geometric model of the target energy storage system.

[0050] The target energy storage system processed in this embodiment may be a high-voltage direct-mounted energy storage system. For example, Figure 3-5 As shown in the figure, the common mode current calculation method provided by the embodiment of the present application can be used to calculate several forms of high-voltage direct-mounted energy storage systems. Among them, Figure 3 A schematic diagram of an MMC type AC direct-mounted energy storage system is shown, which includes multiple submodules SM. Figure 3 The energy storage system shown is merely schematic, and an actual energy storage system may include more components. For example, the energy storage valve branch may include other components such as a current limiting reactor, a current transformer, a high-voltage circuit breaker, and an isolating switch. Figure 4 A schematic diagram of a DC direct-mounted energy storage system is shown, which also includes multiple submodules SM. Figure 4 The energy storage system shown is merely schematic, and an actual energy storage system may include more components. For example, the energy storage valve branch may include other components such as a current limiting reactor, a current transformer, a high-voltage circuit breaker, and an isolating switch. Figure 5 A schematic diagram of a cascaded AC direct-mounted energy storage system is shown, which also includes multiple submodules SM. Figure 5 The energy storage system shown is merely schematic, and an actual energy storage system may include more components. For example, the energy storage valve branch may include other components such as a current limiting reactor, a current transformer, a high-voltage circuit breaker, and an isolating switch.

[0051] The common-mode current calculation method provided in the embodiments of the present application can be used to calculate the common-mode current of a modular multilevel converter (MMC) type AC direct-hung energy storage system, can also be used to calculate the common-mode current of a DC direct-hung energy storage system, and can also be used to calculate the common-mode current of a cascaded AC direct-hung energy storage system.

[0052] Optionally, a physical modeling tool may be used to model the target energy storage system, for example, software such as Solidworks or CATIA.

[0053] Because the distribution and value of stray parameters of an energy storage system depend on its physical structure, these stray parameters can be caused by the physical structure of the energy storage system. These stray parameters can include physical quantities such as stray capacitance, stray inductance, and stray resistance. Based on this, a physical modeling tool can be used to construct a physical geometric model of the target energy storage system. This geometric model can then be used to calculate the stray parameters.

[0054] For example, based on the design scheme and product drawings of the target energy storage system, the dimensions provided by the design scheme and product drawings of the target energy storage system can be used to draw in a physical modeling tool to form a geometric structure.

[0055] Step 220 : Calculate the stray parameters of the target energy storage system based on the geometric model.

[0056] In this embodiment, the geometric model can be imported into a finite element simulation tool, which can perform calculations based on set physical quantities. Optionally, the finite element simulation tool may include: various modules of ANSYS, COMSOL, Altair, etc.

[0057] Exemplarily, when using the finite element simulation tool, a solver may be set based on the stray parameters that need to be calculated, and the solver is used to calculate the stray parameters of the target energy storage system based on the geometric model.

[0058] Different calculation rules can be set based on different parameters. For example, the calculation rules can include parameter calculation formulas, required convergence conditions, etc. Alternatively, different required convergence conditions can be set based on actual needs. For example, higher accuracy can be set for relatively complex geometric models, while lower accuracy can be set for simple geometric models.

[0059] Step 230: Calculate the common-mode current of the target energy storage system according to the stray parameters.

[0060] Optionally, the common-mode current stress flowing in the circuit may be calculated by combining the above-mentioned stray parameters and the circuit structure of the target energy storage system.

[0061] Illustratively, a circuit analysis method, stray parameters, and a circuit structure of the target energy storage system may be used to calculate the common-mode current of the target energy storage system.

[0062] Optionally, a circuit of the target energy storage system may be constructed based on the above-mentioned stray parameters, and each common-mode current may be calculated through the circuit.

[0063] Through the above method embodiment, by physically modeling the target energy storage system, the stray parameters caused by the physical structure can be reflected through the geometric model, so that the stray parameters can be calculated based on the geometric model, and the common-mode current can be further calculated based on the stray parameters.

[0064] In order to make the calculation of the common-mode current more convenient, the circuit of the target energy storage system can be constructed first, and then the calculation of the common-mode current can be realized based on the circuit. Based on this, the above step 230 can include steps 231 and 232.

[0065] Step 231 : constructing a lumped parameter circuit of the target energy storage system according to the stray parameters and the geometric model.

[0066] For example, the geometric model obtained in step 210 can be used to determine the source and composition of the parasitic parameters of the target energy storage system, as well as the magnitude of each parasitic parameter. Based on the parasitic parameters and spurious parameters of the target energy storage system, a lumped parameter circuit of the target energy storage system can be constructed.

[0067] Step 232: Calculate the common-mode current of the target energy storage system based on the lumped parameter circuit.

[0068] Alternatively, a circuit analysis tool can be used to define the lumped parameters and their sources in the lumped parameter circuit, and then the lumped parameter circuit can be simulated to obtain simulation results. Based on the simulation results, the common-mode current of the target energy storage system can be obtained.

[0069] The circuit analysis tool may include software such as matlab, simulink, PSCAD, and TINA.

[0070] Optionally, if the structure contained in the lumped parameter circuit is relatively simple, Kirchhoff's law can also be used to define the parameters of the lumped parameter circuit. Based on the loop equation, the common-mode current flowing through each sub-module and key point of the lumped parameter circuit can be solved.

[0071] By constructing a lumped parameter circuit for the target energy storage system, circuit analysis software can be used to calculate the common-mode current based on the lumped parameter circuit, which can improve the efficiency and accuracy of the calculation.

[0072] In this embodiment, the above-mentioned step 231 may include steps 2311 to 2313.

[0073] Step 2311: Determine the parasitic parameters of the target energy storage system based on the geometric model.

[0074] For example, the parasitic parameters used for analysis in the target energy storage system may include the following:

[0075] The stray inductance and resistance generated by the main circuit components of a single submodule in the target energy storage system (including batteries, power modules, switching devices, current-carrying cables, copper busbars, etc.), the parasitic capacitance of the main circuit components of a single submodule in the target energy storage system to the shell; the parasitic capacitance between the conductive shells of each submodule in the target energy storage system; the parasitic capacitance of the conductive shells of each submodule in the target energy storage system to the nearby ground.

[0076] Step 2312: construct a main loop circuit of the target energy storage system according to the parasitic parameters.

[0077] The parasitic parameters determined in step 2311 can be reflected in the circuit of the target energy storage system. For example, the electrical quantities such as capacitance, inductance, and resistance contained in the target energy storage system are abstracted into an ideal component and connected to the local main circuit of the energy storage system to form the main circuit of the target energy storage system. 。

[0078] Step 2313: construct an equivalent device of the stray parameters in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

[0079] Exemplarily, the stray parameters may include physical parameters such as stray inductance, stray resistance, and stray capacitance.

[0080] The above-mentioned connecting of stray parameters in the main loop circuit to form a lumped parameter circuit of the target energy storage system includes: constructing an equivalent device of stray inductance and an equivalent device of stray resistance connected in series in the main loop circuit; and constructing an equivalent device of stray capacitance connected in series between two locations where capacitance is generated in the main loop circuit to form the lumped parameter circuit of the target energy storage system.

[0081] By reflecting the parasitic parameters and spurious parameters of the target energy storage system in a lumped parameter circuit, circuit analysis software can be used to calculate the common-mode current, which can improve the efficiency and accuracy of the calculation.

[0082] Optionally, the above step 232 may include: simulating the lumped parameter circuit to obtain the common-mode current of the target energy storage system.

[0083] like Figure 6 As shown, the following example describes the lumped parameter circuit formed by the energy storage system: Figure 6 L shown in g 、R g and C g They represent the centralized parameterized inductance, resistance, and capacitance of the metal structure inside a single submodule extracted using the finite element method. Since the two submodules are relatively adjacent in space, although there is no electrical connection, the metal parts of the two submodules induce capacitance in the air medium. The stray capacitance between two spatially adjacent submodules is represented by C t The stray capacitance between two adjacent submodules is expressed as C f ; The stray capacitance of each submodule to ground is C f2g 、C f3g 、C tg ; Its value varies with the distance from the ground space.

[0084] exist Figure 6 In the example shown, two energy storage towers are taken as an example. Each energy storage tower includes three layers of submodules stacked up and down, and a total of six submodules are included as an example.

[0085] In this example, from bottom to top, the first layer submodule, the second layer submodule, and the third layer submodule are shown. The stray capacitance of the first layer submodule to the ground is represented by C tg , the stray capacitance of the second layer submodule is expressed as C f2g , the stray capacitance of the third layer submodule is expressed as C f3gThe stray capacitance between the first layer submodule and the second layer submodule, and between the second layer submodule and the third layer submodule is expressed as C f , the stray capacitance between the submodules on the same layer between the two energy storage towers is expressed as C t . V dc Indicates the rated voltage of a single submodule, and also represents the voltage difference between the two submodule shells; V 10_1 Used to represent the common mode voltage between the first layer submodule and the second layer submodule of the left tower; V 10_2 Used to represent the common mode voltage between the second and third submodules of the left tower; V 10_3 Used to represent the common mode voltage between the third-layer submodule of the left tower and the third-layer submodule of the right tower; V 10_4 Used to represent the common mode voltage between the third layer submodule and the second layer submodule of the right tower, V 10_5 Used to represent the common mode voltage between the first and second submodules of the right tower, V 10_6 Used to represent the common mode voltage of the right tower to ground.

[0086] in, Figure 6 In the example shown, each voltage and current source is the theoretical voltage and current flowing through the main circuit when the system is running.

[0087] After defining the parameters, you can simulate the circuit in circuit analysis software to obtain the voltage and current values at each point. The current flowing through each stray capacitor is the common-mode current between the sub-modules.

[0088] By simulating lumped parameter circuits, the calculation of various parameters in the circuit can be achieved relatively quickly and conveniently.

[0089] Considering that the initially constructed collective model may contain some structures that do not affect the calculation of stray parameters, in order to reduce the complexity of the geometric model, the geometric model of the target energy storage system can be appropriately simplified to reduce the computational complexity. Based on this, step 220 can include steps 221 and 222.

[0090] Step 221 , simplifying the geometric model to obtain a simplified model of the target energy storage system.

[0091] Optionally, the geometric model may be first divided into a plurality of small geometric units, and then the structures in the geometric units may be simplified, thereby obtaining a simplified model of the target energy storage system.

[0092] Optionally, the structure included in the geometric model may be simplified first, and the simplified geometric model may be divided into a plurality of small geometric units, thereby obtaining a simplified model of the target energy storage system.

[0093] Step 222: Calculate the stray parameters of the target energy storage system based on the simplified model.

[0094] In this embodiment, a simulation tool may be used to calculate the geometric model, thereby calculating the stray parameters of the target energy storage system.

[0095] In one embodiment, the geometric model may be divided into a plurality of small geometric units, and then the structure of each small geometric unit may be simplified. Step 221 may include steps 2211 to 2212.

[0096] Step 2211: Divide the geometric model into multiple geometric units according to the set division strategy.

[0097] Alternatively, a finite element analysis (FEA) method may be used to simulate a real physical system, dividing a relatively complex geometric model into smaller regular geometric units in an approximate manner.

[0098] For example, a finite element simulation tool can be used to mesh the geometric model. Meshing can reduce the computational complexity and time of finite element calculations and improve the accuracy of the calculation results.

[0099] Each geometry module to be calculated can contain information such as the material, thickness, and function to be calculated. The number of meshes required for the structure can be determined based on the material thickness and function of the model. Based on this number of meshes, the meshing module of the finite element simulation tool is called to perform the meshing operation.

[0100] Optionally, the meshing strategy may be a meshing algorithm provided in the finite element simulation tool.

[0101] Optionally, parameters in the finite element simulation tool may be set based on the division requirements of the actual geometric model.

[0102] For example, the parameters to be set may include information such as the shape and size of the desired grid. For example, the shape of the grid may be a tetrahedron, a cube, or the like. For another example, the grid size may be limited by limiting the maximum volume or maximum side length of the grid shape.

[0103] Exemplarily, the set parameters may also include the positional limitations of information such as grid interfaces and boundary lines.

[0104] By meshing the geometric model in the above manner, the meshing can be made more convenient for calculation.

[0105] For example, locations with high stress and main structures causing stray parameters can be marked based on the geometric model, and unnecessary details can be deleted or simplified. For example, unnecessary structures such as insulation parts and secondary electrical structures can be deleted.

[0106] Step 2212: For each geometric unit, simplify the structure in the geometric unit to obtain a simplified geometric unit.

[0107] Among them, all simplified geometric units form a simplified model of the target energy storage system.

[0108] In this embodiment, irrelevant devices and structures may be deleted, and the main current-carrying part and the high-voltage part may be retained to achieve the purpose of simplifying the model.

[0109] Since common-mode currents are generated by large-area conductors, electrical components, and structures with metals at different potentials, some components that do not cause common-mode currents can be removed.

[0110] Optionally, the simplification process may include: deleting non-circulation components in the geometric unit to simplify the model, wherein the non-circulation components include: one or more of: insulating components, secondary electrical structures, and mounting accessories.

[0111] The secondary electrical structure may include small wire harnesses, bolts, wire ducts, terminal blocks, etc. The mounting accessories may include chamfers, small protrusions, threaded holes, mounting holes, etc.

[0112] Optionally, the simplification process may include: filling the gaps in the charged devices in the geometric unit to obtain a simplified geometric unit.

[0113] For example, the gap portion may be a portion where a gap is formed by a hollow space, a hole, or the like in a charged device.

[0114] The charged component may be a charged metal part. For example, if the charged metal part has a hollow space or a hole inside, it can be filled to facilitate meshing of the filled geometric units.

[0115] In another embodiment, the structure contained in the geometric model may be simplified first, and then the geometric model may be divided into a plurality of small geometric units. Step 221 may include step 2213 and step 2214.

[0116] Step 2213: Simplify the structure in the geometric model to obtain an initial simplified model.

[0117] Illustratively, the simplification process may include: deleting non-circulating components in the geometric unit, wherein the non-circulating components include: one or more of: insulating parts, secondary electrical structures, and mounting accessories.

[0118] Exemplarily, the simplification process includes: filling the gaps in the charged components in the geometric unit,

[0119] The void area includes one or more of hollow and hole.

[0120] The simplification process of the geometric model may be similar to the simplification process of the geometric unit described above. For details, please refer to the description of the simplification process of the geometric unit described above, which will not be repeated here.

[0121] In step 2214 , the initial simplified model is divided into a plurality of geometric units according to a set division strategy.

[0122] Alternatively, a finite element analysis (FEA) method may be used to simulate the real physical system, dividing a relatively complex initial simplified model into smaller regular geometric units in an approximate manner.

[0123] Through the above processing method, the geometric model can be simplified, and the key points for calculating stray parameters can be highlighted, which facilitates calculation and analysis by finite element simulation software.

[0124] Optionally, step 221 may not first divide the geometric model into small units, but may first simplify the geometric model. The simplification method can be found in the description of step 2212 above and will not be repeated here. Then, step 222 divides the simplified model into multiple geometric units when calculating spurious parameters, and then calculates the spurious parameters based on the divided geometric units.

[0125] The above-mentioned step 222 may include: importing the simplified model into a simulation tool; setting conditions required for calculating stray parameters through the simulation tool; and calculating the stray parameters of the target energy storage system according to the required conditions.

[0126] Optionally, the simulation tool may be finite element calculation software.

[0127] Finite element calculation software will mesh the simplified model according to the preset division strategy, so that complex nonlinear physical quantities can be approximated by piecewise linear approximation.

[0128] Optionally, the simplified model can be divided into cells by receiving a division operation through human-computer interaction. For example, a key area can be selected for finer cell division, such as an area that may cause high stress. For example, the cell division can be limited by limiting the maximum cell width and minimum cell number of the geometric cells.

[0129] Exemplarily, a solver may be set based on stray parameters that need to be calculated in each divided geometric unit, and the solver is used to calculate the stray parameters required by the target energy storage system based on each geometric unit.

[0130] Exemplarily, the stray capacitance, stray inductance, and stray resistance caused by the physical structure of the target energy storage system can be calculated by the above-mentioned solver.

[0131] The common-mode current calculation method provided in the embodiment of the present application can realize the calculation of stray parameters and common-mode current of the high-voltage direct-mounted energy storage system, providing a data basis for the evaluation of the high-voltage direct-mounted energy storage system.

[0132] Based on the same application concept, the embodiment of the present application also provides a common-mode current calculation device corresponding to the common-mode current calculation method. Since the principle of solving the problem by the device in the embodiment of the present application is similar to that of the aforementioned common-mode current calculation method embodiment, the implementation of the device in this embodiment can refer to the description in the embodiment of the above-mentioned method, and the repeated parts will not be repeated.

[0133] See also Figure 7 , is a functional module diagram of the common-mode current calculation device provided in an embodiment of the present application. The various modules in the common-mode current calculation device in this embodiment are used to execute the various steps in the above-mentioned method embodiment. The common-mode current calculation device includes: a modeling module 310, a first calculation module 320, and a second calculation module 330, wherein the contents of each module are as follows: the modeling module 310 is used to model the target energy storage system and obtain a geometric model of the target energy storage system; the first calculation module 320 is used to calculate the stray parameters of the target energy storage system based on the geometric model; the second calculation module 330 is used to calculate the common-mode current of the target energy storage system according to the stray parameters.

[0134] In one possible implementation, the second calculation module 330 includes a circuit construction unit and a current calculation unit; the circuit construction unit is used to construct a lumped parameter circuit of the target energy storage system based on stray parameters and a geometric model; the current calculation unit is used to calculate the common-mode current of the target energy storage system based on the lumped parameter circuit.

[0135] In one possible implementation, a circuit construction unit is configured to determine parasitic parameters of a target energy storage system based on a geometric model; construct a main loop circuit of the target energy storage system according to the parasitic parameters; and construct equivalent devices of the stray parameters in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

[0136] In one possible implementation, the stray parameters include: stray inductance, resistance, and stray capacitance; the circuit construction unit is further configured to construct an equivalent device of the stray inductance and an equivalent device of the stray resistance connected in series in the main loop circuit; and construct an equivalent device of the stray capacitance connected in series between two locations where capacitance is generated in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

[0137] In a possible implementation, the current calculation unit is configured to simulate the lumped parameter circuit to obtain the common-mode current of the target energy storage system.

[0138] In one possible implementation, the first calculation module 320 includes a model simplification unit and a parameter calculation unit; the model simplification unit is used to simplify the geometric model to obtain a simplified model of the target energy storage system; the parameter calculation unit is used to calculate the stray parameters of the target energy storage system based on the simplified model.

[0139] In one possible implementation, a model simplification unit is used to divide the geometric model into multiple geometric units according to a set division strategy; for each geometric unit, the structure in the geometric unit is simplified to obtain a simplified geometric unit; wherein all simplified geometric units form a simplified model of the target energy storage system.

[0140] In a possible implementation, the model simplification unit is used to delete non-circulation components in the geometric unit; wherein the non-circulation components include: one or more of insulating parts, secondary electrical structures, and mounting accessories.

[0141] In a possible implementation, the aforementioned simplified model unit is used to fill a gap in a charged device in a geometric unit, wherein the gap includes one or more of a hollow and a hole.

[0142] In a possible implementation, the parameter calculation unit is configured to import the simplified model into a simulation tool; set conditions required for calculating stray parameters through the simulation tool; and calculate the stray parameters of the target energy storage system based on the required conditions.

[0143] See also Figure 8 , is a flow chart of the energy storage system evaluation method provided in the embodiment of the present application. Figure 8 The specific process shown is explained in detail.

[0144] Step 410 : Determine the common-mode current of the energy storage system to be evaluated according to the common-mode current calculation method.

[0145] The calculation process of the common-mode current of the energy storage system to be evaluated can refer to the description in the above embodiment of the common-mode current calculation method, which will not be repeated here.

[0146] Step 420 : Evaluate the electrical stress at each point of the energy storage system to be evaluated based on the common mode current.

[0147] The calculated common-mode current can be used to assess the electrical stress of the energy storage system's cell insulation film. For example, if the cell insulation film's withstand voltage level is U1 and its high-frequency current level is I1, the calculated common-mode current value can be superimposed on the withstand voltage U0 and current I0 without considering the common-mode current to determine whether it exceeds the tolerance range of U1 and I1.

[0148] Optionally, electrical stress calculations can be performed based on the common-mode current of the energy storage system being evaluated and compared to the insulation level at critical, vulnerable locations. For example, the voltage between the battery cell and the battery box can be calculated; the voltage and current at key locations such as the cell insulation film and battery box can be calculated; and the ground current at each level of the valve tower can be calculated.

[0149] The electrical stress is evaluated by measuring the insulation level at critical and vulnerable locations to assess the losses and current stress at various locations in the energy storage system to be evaluated.

[0150] Based on this common-mode current, the voltage between the battery cell and the battery box can be realized, and the possibility of insulation damage in key locations such as the battery cell insulation blue film and the battery box can be evaluated; the ground current of each layer of the valve tower can be calculated, and the loss and current stress of each part of the energy storage system can be evaluated; further, the stray parameters are extracted and reasonably coupled to form a set of distributed parameter and lumped parameter joint simulation methods to facilitate the overall design of the high-voltage direct-mounted energy storage system.

[0151] Based on the same application concept, an energy storage system evaluation device corresponding to the energy storage system evaluation method is also provided in the embodiment of the present application. Since the principle of solving the problem by the device in the embodiment of the present application is similar to that of the aforementioned energy storage system evaluation method embodiment, the implementation of the device in this embodiment can refer to the description in the embodiment of the above method, and the repeated parts will not be repeated.

[0152] See also Figure 9 , is a functional module diagram of the energy storage system evaluation device provided in an embodiment of the present application. The various modules in the energy storage system evaluation device in this embodiment are used to execute the various steps in the above-mentioned method embodiment. The energy storage system evaluation device includes: a determination module 510 and an evaluation module 520; wherein the contents of each module are as follows: the determination module 510 is used to determine the common-mode current of the energy storage system to be evaluated according to the common-mode current calculation method of any one of the aforementioned embodiments; the evaluation module 520 is used to evaluate the electrical stress of each point of the energy storage system to be evaluated based on the common-mode current.

[0153] In addition, an embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the common-mode current calculation method or the energy storage system evaluation method described in the above method embodiment are executed.

[0154] The computer program products of the common-mode current calculation method and energy storage system evaluation method provided in the embodiments of the present application include a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the steps of the common-mode current calculation method or energy storage system evaluation method described in the above method embodiments. For details, please refer to the above method embodiments and will not be repeated here.

[0155] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to the multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0156] In addition, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0157] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk. It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0158] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

[0159] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A common mode current calculation method, characterized in that: include: Modeling a target energy storage system to obtain a geometric model of the target energy storage system; Calculating stray parameters of the target energy storage system based on the geometric model; The common-mode current of the target energy storage system is calculated according to the stray parameters.

2. The method according to claim 1, characterized in that The calculating the common-mode current of the target energy storage system according to the stray parameters includes: Constructing a lumped parameter circuit of the target energy storage system according to the stray parameters and the geometric model; Calculate the common-mode current of the target energy storage system according to the lumped parameter circuit.

3. The method according to claim 2, characterized in that The step of constructing a lumped parameter circuit of the target energy storage system according to the stray parameters and the geometric model includes: Determining parasitic parameters of the target energy storage system based on the geometric model; Constructing a main loop circuit of the target energy storage system according to the parasitic parameters; An equivalent device of the stray parameters is constructed in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

4. The method according to claim 3, characterized in that The stray parameters include: stray inductance, stray resistance, and stray capacitance; The equivalent device of the stray parameters is constructed in the main loop circuit to form a lumped parameter circuit of the target energy storage system, including: Constructing an equivalent device of the stray inductance and an equivalent device of the stray resistance connected in series in the main loop circuit; An equivalent device of the stray capacitance is constructed in series between two locations where capacitance is generated in the main loop circuit to form a lumped parameter circuit of the target energy storage system.

5. The method according to claim 2, characterized in that Calculating the common-mode current of the target energy storage system according to the lumped parameter circuit includes: The lumped parameter circuit is simulated to obtain the common-mode current of the target energy storage system.

6. The method according to any one of claims 1 to 5, characterized in that The calculating the stray parameters of the target energy storage system based on the geometric model includes: Dividing the geometric model into a plurality of geometric units according to a set division strategy; Simplifying the structure of the geometric unit to obtain a simplified geometric unit, wherein each simplified geometric unit forms a simplified model of the target energy storage system; Based on the simplified model, stray parameters of the target energy storage system are calculated.

7. The method according to claim 6, characterized in that The simplified processing includes: Delete the non-circulation components in the geometric unit, wherein the non-circulation components include: one or more of an insulating part, a secondary electrical structure, and a mounting accessory.

8. The method according to claim 7, characterized in that The simplification process includes: filling the gaps in the charged components in the geometric unit, wherein the gaps include one or more of hollows and holes.

9. The method according to claim 6, characterized in that The calculating the stray parameters of the target energy storage system based on the simplified model includes: Importing the simplified model into a simulation tool; Setting the conditions required for calculating spurious parameters by the simulation tool; The stray parameters of the target energy storage system are calculated according to the required conditions.

10. A method for evaluating an energy storage system, characterized in that: include: The common-mode current calculation method according to any one of claims 1 to 9 is used to determine the common-mode current of the energy storage system to be evaluated; The electrical stress at each point of the energy storage system to be evaluated is evaluated according to the common-mode current.

11. A common mode current calculation device, characterized in that: include: A modeling module, configured to model a target energy storage system and obtain a geometric model of the target energy storage system; A first calculation module, configured to calculate stray parameters of the target energy storage system based on the geometric model; A second calculation module is configured to calculate the common-mode current of the target energy storage system according to the stray parameters.

12. An energy storage system evaluation device, characterized in that: include: a determination module, configured to determine the common-mode current of the energy storage system to be evaluated by the common-mode current calculation method according to any one of claims 1 to 9; An evaluation module is used to evaluate the electrical stress at each point of the energy storage system to be evaluated based on the common-mode current.

13. An electronic device, characterized in that: include: A processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the machine-readable instructions are executed by the processor to perform the steps of the method according to any one of claims 1 to 10.

14. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, executes the steps of the method according to any one of claims 1 to 10.

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