Power grid short-circuit current calculation method and related equipment

Abstract

The invention discloses a power grid short-circuit current calculation method and related equipment, and provides an effective solution for solving the problem of short-circuit current calculation of a power grid containing network construction type energy storage equipment. Based on a power grid topology, a synchronous generator, a power transmission network and a load are equivalent, a predefined three-sequence discrete equivalent model is adopted to process a network-constructing energy storage device, a power grid node impedance matrix is constructed, complex operation characteristics of the device are converted into computable parameters, and the blank of the power grid short-circuit current calculation method is filled. And meanwhile, through an iterative calculation mechanism, according to a grid-connected node voltage difference value, a compensation current source value and equipment equivalent impedance of the grid-forming type energy storage equipment, parameters are continuously updated, and characteristics of dynamic adjustment output of the equipment according to a power grid state during short circuit are accurately simulated. And when the iteration meets the condition, determining the final short-circuit current.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric power data processing, and more particularly to a power grid short-circuit current calculation method and related equipment. BACKGROUND

[0002] In the design and operation process of a power system, short-circuit current calculation is an indispensable basic calculation for solving many technical problems, such as providing a basis for selecting types of electrical equipment such as circuit breakers, transformers, busbars, and cables, checking the stability of the equipment power by calculating the impact current, checking the thermal stability by calculating the short-circuit current periodic component, and checking the breaking capacity of the circuit breaker by calculating the short-circuit current effective value. At present, for traditional alternating current power grids and power grids containing grid-connected devices, a relatively mature short-circuit current calculation method has been formed. The traditional method equivalent synchronous generators as a parallel combination of constant current sources and admittances, equivalent transmission networks as a combination of resistance and reactance, and equivalent loads as ground branches represented by constant impedance, which can accurately calculate the short-circuit current and meet the design and operation analysis needs of the corresponding power grid.

[0003] However, with the wide application of grid-connected energy storage devices in power grids, the above traditional calculation method has obvious limitations, and it cannot be directly applied to power grids containing grid-connected energy storage devices. Grid-connected energy storage devices have the ability to actively support the voltage and frequency of the power grid and dynamically adjust the output characteristics. The transient behavior of grid-connected energy storage devices during short-circuit faults is significantly different from that of traditional devices. The equivalent method of synchronous generators, transmission networks, and loads in the traditional calculation method does not consider the impact of grid-connected energy storage devices on the topology and electrical parameters of the power grid, and cannot reflect the flexible and variable output characteristics of grid-connected energy storage devices and their unique control strategies and operating modes. Therefore, when calculating the short-circuit current of a power grid containing grid-connected energy storage devices, the traditional method cannot accurately simulate the influence of grid-connected energy storage devices on the size, phase, and duration of the short-circuit current, and cannot obtain reliable calculation results. And up to now, there is no mature and referenceable short-circuit current calculation method for power grids containing grid-connected energy storage devices, which makes the design, equipment selection, and operation and maintenance of related power grids lack effective basis, seriously restricting the safe and stable operation of the power grid.

[0004] Therefore, there is an urgent need for a short-circuit current calculation method for power grids containing grid-connected energy storage devices. SUMMARY

[0005] The present application provides a power grid short-circuit current calculation method and related equipment, which converts the complex characteristics of devices into a calculable model by constructing a power grid node impedance matrix containing grid-connected energy storage devices and combining iterative calculation, simulates the dynamic output, and accurately calculates the short-circuit current of a power grid containing grid-connected energy storage devices.

[0006] A power grid short-circuit current calculation method, comprising:

[0007] Based on the power grid topology, the synchronous generator is equivalent to a current source in parallel with an admittance, the power transmission network is equivalent to an impedance combination, the load is equivalent to a grounding impedance, and the grid-forming energy storage device accesses the node using a predefined three-sequence discrete equivalent model to construct a power grid node impedance matrix;

[0008] According to the voltage before the short circuit at the fault point, the power grid node impedance matrix, and the compensation current source value determined based on the equivalent model of each grid-forming energy storage device, the short circuit current at the fault point and the grid-connected node voltage of each grid-forming energy storage device are calculated;

[0009] If the difference between the grid-connected node voltages obtained by the iterative calculation of any grid-forming energy storage device in the current round and the previous round exceeds a threshold value, or the current round is the initial round, then the injected short circuit current of the grid-forming energy storage device to the power grid is calculated according to the grid-connected node voltage, the compensation current source value, and the device equivalent impedance;

[0010] The active and reactive components of the injected short circuit current are analyzed, and the compensation current source value is updated in combination with the preset current limiting condition, and the process of calculating the short circuit current at the fault point is returned to execute;

[0011] If the difference between the grid-connected node voltages obtained by the iterative calculation of any grid-forming energy storage device in the current round and the previous round does not exceed a threshold value, and the current round is not the initial round, then the short circuit current at the fault point is determined as the short circuit current of the power grid.

[0012] Optionally, the calculation formula of the short circuit current at the fault point is:

[0013]

[0014] wherein, is the short circuit current at the fault point, is the voltage before the short circuit at the fault point, is the transfer impedance between the fault point and the node of the kth grid-forming energy storage device, is the compensation current source value of the kth device, is the self-impedance of the fault point, is the set of grid-forming energy storage devices.

[0015] Optionally, the calculation formula of the grid-connected node voltage of the grid-forming energy storage device is:

[0016]

[0017] wherein, is the grid-connected node voltage of the grid-forming energy storage device, is the voltage before the short circuit at node m, is the transfer impedance between node m and the fault point, is the short circuit current at the fault point, a compensation current source value for the kth device, a transfer impedance between the node m and the kth grid-forming energy storage device node, a set of grid-forming energy storage devices.

[0018] Optionally, the calculation formula of the short-circuit current injected by the grid-forming energy storage device into the power grid is:

[0019]

[0020] wherein, a short-circuit current injected by the grid-forming energy storage device into the power grid, a grid-connected node voltage of the grid-forming energy storage device, a compensation current source value, an equivalent impedance of the device.

[0021] Optionally, the active component and the reactive component of the short-circuit current are analyzed, and the compensation current source value is updated in combination with a preset current limiting condition, including:

[0022] The short-circuit current is decomposed into an active component and a reactive component in a rotating coordinate system, and a current vector modulus value is calculated;

[0023] It is judged whether the active component exceeds a preset active limiting value, whether the reactive component exceeds a preset reactive limiting value, and whether the current vector modulus value exceeds a total limiting value;

[0024] According to the judgment result and the limiting control strategy type of the grid-forming energy storage device, a corresponding compensation current calculation rule is selected to update the compensation current source value.

[0025] Optionally, according to the judgment result and the limiting control strategy type of the grid-forming energy storage device, a corresponding compensation current calculation rule is selected to update the compensation current source value, including:

[0026] When the current vector modulus value is not over-limited, the active current component is not over-limited, and the reactive current component is not over-limited, the compensation current source value is determined to be zero;

[0027] When the current vector modulus value is not over-limited, the active current component is over-limited, and the reactive current component is not over-limited, the compensation current calculation formula is:

[0028]

[0029] When the current vector modulus value is not over-limited, the active current component is not over-limited, and the reactive current component is over-limited, the compensation current calculation formula is:

[0030]

[0031] When the current vector modulus value is not over-limit, the active current component is over-limit, and the reactive current component is over-limit, the compensation current calculation formula is:

[0032]

[0033] When the current vector modulus value is over-limit, the active current component is not over-limit, the reactive current component is not over-limit, and the grid-forming energy storage device adopts an active priority control strategy, the compensation current calculation formula is:

[0034]

[0035] When the current vector modulus value is over-limit, the active current component is not over-limit, the reactive current component is not over-limit, and the grid-forming energy storage device adopts a reactive priority control strategy, the compensation current calculation formula is:

[0036]

[0037] wherein, is a compensation current source value, , is an active component and a reactive component respectively, , is an active amplitude limit value and a reactive amplitude limit value respectively, is a total amplitude limit value, and j is an imaginary unit.

[0038] A power grid short-circuit current calculation device, comprising:

[0039] An equivalent construction unit, configured to: based on a power grid topology structure, equivalent a synchronous generator to a current source in parallel with an admittance, equivalent a power transmission network to an impedance combination, equivalent a load to a grounding impedance, and equivalent a grid-forming energy storage device to access a node by using a predefined three-sequence discrete equivalent model, to construct a power grid node impedance matrix;

[0040] A compensation calculation unit, configured to: according to a fault point pre-fault voltage, the power grid node impedance matrix, and a compensation current source value determined based on an equivalent model of each grid-forming energy storage device, calculate a fault point short-circuit current and a grid-connected node voltage of each grid-forming energy storage device;

[0041] An iterative calculation unit, configured to: in a case where a difference between a grid-connected node voltage obtained in a current iteration and a grid-connected node voltage obtained in a previous iteration of any grid-forming energy storage device exceeds a threshold value, or in a case where the current iteration is an initial iteration, calculate an injected short-circuit current of the grid-forming energy storage device to the power grid according to the grid-connected node voltage, the compensation current source value, and a device equivalent impedance;

[0042] A compensation updating unit, configured to: analyze an active component and a reactive component of the injected short-circuit current, and update the compensation current source value in combination with a preset current amplitude limit condition, and return to execute a process of calculating a fault point short-circuit current.

[0043] a current determination unit configured to determine the fault point short-circuit current as the power grid short-circuit current in a case where the difference between the grid-connected node voltage obtained in the current iteration and the grid-connected node voltage obtained in the previous iteration of any of the network-constructed energy storage devices does not exceed a threshold value and the current iteration is a non-initial iteration.

[0044] A power grid short-circuit current calculation device, comprising a memory and a processor;

[0045] The memory is configured to store a program.

[0046] The processor is configured to execute the program to implement the steps of the power grid short-circuit current calculation method according to any of the preceding embodiments.

[0047] A readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of the power grid short-circuit current calculation method according to any of the preceding embodiments.

[0048] A computer program product comprising a computer program, the computer program being executed by a processor to implement the steps of the power grid short-circuit current calculation method according to any of the preceding embodiments.

[0049] As can be seen from the above technical solutions, the power grid short-circuit current calculation method and related device provided by the embodiments of the present application provide a feasible solution for the short-circuit current calculation of a power grid containing network-constructed energy storage devices by constructing a power grid node impedance matrix containing network-constructed energy storage devices and obtaining accurate results through iterative calculation. The embodiments of the present application first construct a power grid node impedance matrix by connecting network-constructed energy storage devices to nodes using a predefined three-sequence discrete equivalent model. Compared with the traditional calculation method which does not consider the characteristics of network-constructed energy storage devices, this operation converts the complex characteristics of network-constructed energy storage devices into a calculable equivalent model and integrates them into the overall calculation system of the power grid, thereby accurately calculating the fault point short-circuit current and the grid-connected node voltage of each network-constructed energy storage device, and solving the problem of the lack of a power grid short-circuit current calculation method containing network-constructed energy storage devices.

[0050] Secondly, an iterative calculation mechanism is introduced, which updates the compensation current source value by judging the difference between the grid-connected node voltage obtained in the current iteration and the grid-connected node voltage obtained in the previous iteration of the network-constructed energy storage device, and combining the preset current limiting condition. This mechanism can simulate the characteristics of the network-constructed energy storage device dynamically adjusting the output according to the state of the power grid. Because the output of the network-constructed energy storage device is not constant when the power grid is short-circuited, it will be adjusted according to its own control strategy and changes in the voltage and frequency of the power grid. By continuously updating the parameters such as the compensation current source value, this solution can accurately capture this dynamic change, thereby more accurately simulating the behavior of the network-constructed energy storage device when the power grid is short-circuited.

[0051] When the grid-connected node voltage difference of the arbitrary network-constructed energy storage device in the current iteration and the previous iteration does not exceed the threshold value, and the current iteration is not the initial round, the short-circuit current at the fault point at this time is determined as the grid short-circuit current. In this way, the final short-circuit current calculation result can truly reflect the actual situation of the grid containing the network-constructed energy storage device under short-circuit fault. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0053] Figure 1 A flowchart of a grid short-circuit current calculation method disclosed by an embodiment of the present application;

[0054] Figure 2 A schematic diagram of an equivalent circuit model of a network-constructed energy storage device disclosed by an embodiment of the present application;

[0055] Figure 3 A schematic diagram of a grid short-circuit current calculation device disclosed by an embodiment of the present application;

[0056] Figure 4 A hardware structure block diagram of a grid short-circuit current calculation device disclosed by an embodiment of the present application. DETAILED DESCRIPTION

[0057] The technical solutions of the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0058] The present application can be used in many general or special-purpose computing device environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, multi-processor devices, distributed computing environments including any of the above devices or devices, etc.

[0059] Next, the technical solutions of the present application are introduced. The present application proposes the following technical solutions, which are described in detail below.

[0060] Figure 1 A flowchart of a grid short-circuit current calculation method disclosed by an embodiment of the present application;

[0061] AsFigure 1 As shown, the method can comprise:

[0062] Step S1, based on the power grid topology, the synchronous generator is equivalent to a current source in parallel with an admittance, the power transmission network is equivalent to an impedance combination, the load is equivalent to a grounding impedance, the grid-forming energy storage device accesses the node using a predefined three-sequence discrete equivalent model, and a power grid node impedance matrix is constructed.

[0063] Specifically, the power grid topology reflects the connection relationship and layout of each element in the power grid, and is the basic framework for short-circuit current calculation. In this step, for the synchronous generator, according to its electrical characteristics and operating principle, it is equivalent to a current source in parallel with an admittance. This equivalent method can simplify the mathematical model of the generator in the power grid, facilitating subsequent calculation. The power transmission network includes transmission lines and transformers and other elements, which are equivalent to an impedance combination. Through the integration of line resistance, reactance, and transformer ratio and other parameters, the influence of the power transmission network on current transmission is accurately simulated. The load consumes power in the power grid, which is equivalent to a grounding impedance to reflect the effect of the load on the voltage and current of the power grid. For the grid-forming energy storage device, since it has the function of actively supporting the voltage and frequency of the power grid and dynamically adjusting the output characteristics, a predefined three-sequence discrete equivalent model is used to access the node. For example, as shown in the equivalent circuit model of the grid-forming energy storage device, it includes Figure 2 the positive sequence equivalent circuit of (a), Figure 2 the negative sequence equivalent circuit of (b), and Figure 2 the zero sequence equivalent circuit of (c). This model fully considers the different electrical characteristics of the device in the positive sequence, negative sequence and zero sequence states, and converts the complex operating characteristics into calculable parameters. After the equivalence of various elements is completed, according to the node analysis method in circuit theory, the equivalent parameters of each element and the node connection relationship are combined through matrix operation, and a power grid node impedance matrix is constructed. This matrix completely describes the electrical relationship between each node in the power grid, and lays the foundation for subsequent short-circuit current calculation. Figure 2 Step S2, according to the voltage before the fault point short-circuit, the power grid node impedance matrix and the compensation current source value determined based on the equivalent model of each grid-forming energy storage device, the fault point short-circuit current and the grid-connected node voltage of each grid-forming energy storage device are calculated.

[0064]

[0065] ​In particular, the pre-fault voltage of the fault point reflects the voltage level of the point in the normal operation state of the power grid, which can be obtained through power grid operation monitoring data. The power grid node impedance matrix has been constructed in step S1, which contains the electrical parameter information of each node of the power grid. The compensation current source value determined based on the equivalent model of each grid-connected energy storage device is calculated according to the control strategy, operating state and equivalent model parameters of the device, and is used to simulate the current injection of the grid-connected energy storage device to the power grid during the short circuit process. In the calculation, according to the short circuit current calculation principle in circuit theory, the pre-fault voltage of the fault point is taken as the excitation source, the electrical characteristics of the power grid described by the power grid node impedance matrix are combined, and the fault point short circuit current is solved by matrix operation. At the same time, in the process of calculating the fault point short circuit current, the influence of the equivalent model of each grid-connected energy storage device and the compensation current source value on the voltage of the power grid node is considered, and the grid-connected node voltage of each grid-connected energy storage device is solved by using the circuit equation. This step realizes the preliminary calculation of the fault point short circuit current and the device grid-connected node voltage by comprehensively using the power grid operation data, the power grid node impedance matrix and the equivalent parameters of the grid-connected energy storage device.

[0066] In the calculation of the fault point short circuit current, the pre-fault voltage of the fault point needs to be obtained, which reflects the steady-state operation state of the power grid before the fault. At the same time, the transfer impedance between the fault point and the nodes of each grid-connected energy storage device, the self-impedance of the fault point, and the compensation current source value of each grid-connected energy storage device are determined. By subtracting the current influence of each grid-connected energy storage device node on the fault point (obtained by summing the product of the transfer impedance and the compensation current source value) from the pre-fault voltage of the fault point, and then dividing by the self-impedance of the fault point, the fault point short circuit current can be obtained. This current reflects the current intensity of the fault point at the moment of the fault, and provides a key parameter for power grid fault analysis and protection design.

[0067] The calculation formula of the fault point short circuit current is:

[0068]

[0069] wherein, is the fault point short circuit current, is the pre-fault voltage of the fault point, is the transfer impedance between the fault point and the node of the kth grid-connected energy storage device, is the compensation current source value of the kth device, is the self-impedance of the fault point, is the set of grid-connected energy storage devices.

[0070] The voltage of the grid-connected node of the grid-forming energy storage device during the fault is calculated by using the voltage before the short-circuit of the node, the transfer impedance between the node and the fault point and the nodes of each grid-forming energy storage device, the short-circuit current of the fault point and the compensation current source values of each device. The voltage of the grid-connected node is obtained by subtracting the voltage before the short-circuit of the node from the voltage before the short-circuit of the node and the voltage before the short-circuit of the node, which reflects the voltage state of the device grid-connected node and helps to analyze the operation characteristics of the device during the fault and the support of the device to the power grid.

[0071] The calculation formula of the grid-connected node voltage of the grid-forming energy storage device is:

[0072]

[0073] wherein, is the grid-connected node voltage of the grid-forming energy storage device, is the voltage before the short-circuit of the node m, is the transfer impedance between the node m and the fault point, is the short-circuit current of the fault point, is the compensation current source value of the kth device, is the transfer impedance between the node m and the node of the kth grid-forming energy storage device, is the set of grid-forming energy storage devices.

[0074] In step S3, if the difference between the grid-connected node voltages obtained by the iteration calculation in the current round and the previous round of any grid-forming energy storage device exceeds the threshold value, or the current round is the initial round, the injection short-circuit current of the grid-forming energy storage device to the power grid is calculated according to the grid-connected node voltage, the compensation current source value and the equivalent impedance of the device.

[0075] Specifically, in the iteration process of the power grid short-circuit current calculation, when one of the following two conditions occurs, the calculation of the injection short-circuit current of the grid-forming energy storage device to the power grid needs to be performed: one is that the difference between the grid-connected node voltages obtained by the iteration in the current round and the previous round of any grid-forming energy storage device exceeds the set threshold value, indicating that the device operating state is not stable; the second is that the current round is the initial round of iteration, because there is no previous round data for reference. In the calculation, the current grid-connected node voltage, the compensation current source value and the equivalent impedance which can reflect the electrical characteristics of the device itself are combined, and the circuit equation is constructed and solved to obtain the injection short-circuit current of the grid-forming energy storage device to the power grid. The current can reflect the contribution of the device to the power grid short-circuit current, which provides a basis for parameter updating in the subsequent iteration.

[0076] In the iterative calculation process, the grid-connected node voltage of each grid-forming energy storage device is obtained in each round of calculation. The difference between the grid-connected node voltage obtained in this round of calculation and the result of the last round is calculated. The threshold is set to determine whether the operating state of the grid-forming energy storage device tends to be stable. If the grid-connected node voltage difference of any grid-forming energy storage device exceeds the threshold, it indicates that the device operating state is still changing, and further adjustment of the calculation parameters is needed. If this round is the initial round, since there is no last round calculation result as a reference, subsequent calculation is also needed. When the above conditions are met, according to Ohm's law and Kirchhoff's law in circuit theory, combined with the current grid-connected node voltage, the compensation current source value and the device equivalent impedance, the injection short-circuit current of the grid-forming energy storage device to the grid is calculated through the circuit equation. The current reflects the contribution of the grid-forming energy storage device to the grid short-circuit current under the current operating state, and provides a basis for subsequent parameter updating.

[0077] The calculation formula of the injection short-circuit current of the grid-forming energy storage device to the grid is:

[0078]

[0079] Among them, is the injection short-circuit current of the grid-forming energy storage device to the grid, is the grid-connected node voltage of the grid-forming energy storage device, is the compensation current source value, is the device equivalent impedance.

[0080] Step S4, analyze the active component and the reactive component of the injection short-circuit current, and update the compensation current source value combined with the preset current limiting condition, and return to execute the process of calculating the fault point short-circuit current.

[0081] Specifically, after obtaining the injection short-circuit current of the grid-forming energy storage device to the grid, according to the trigonometric function relationship and power theory, the current is analyzed to separate the active component and the reactive component. The active component is related to the actual active power consumed or generated by the device, and the reactive component is related to the voltage regulation capability of the device to the grid. The preset current limiting condition is set according to the rated parameters and safe operation requirements of the grid-forming energy storage device, which is used to limit the device output current within a reasonable range and ensure the safe and stable operation of the device. Combined with the active component, the reactive component obtained by analysis and the preset current limiting condition, the compensation current source value is updated. In the updating process, the control strategy, operating state of the device and the actual demand of the grid are comprehensively considered, and the size and phase of the compensation current source value are adjusted through the algorithm. After completing the update of the compensation current source value, return to step S2 to recalculate the fault point short-circuit current and the grid-connected node voltage of each grid-forming energy storage device using the updated parameters, and perform the next round of iterative calculation until the iteration termination condition is met.

[0082] Step S5, if the grid-connected node voltage difference of any network-constructed energy storage device in the current iteration and the previous iteration does not exceed the threshold value, and the current iteration is not the initial round, the fault point short-circuit current is determined as the grid short-circuit current.

[0083] Specifically, in the iterative calculation process, the grid-connected node voltage difference of each network-constructed energy storage device in the current iteration and the previous iteration is continuously monitored. When the grid-connected node voltage difference of all network-constructed energy storage devices does not exceed the set threshold value, and the current calculation is not the initial round, it is indicated that after multiple rounds of iterative calculation, the operating state of each network-constructed energy storage device has stabilized, and its influence on the grid short-circuit current has also reached a stable state. At this time, the fault point short-circuit current calculated at the current time is determined as the grid short-circuit current. The short-circuit current result truly reflects the actual current size of the grid containing network-constructed energy storage devices under short-circuit fault, and provides a reliable basis for subsequent electrical equipment selection, relay protection configuration, etc., to ensure that the grid can operate safely and stably when a short-circuit fault occurs.

[0084] As can be seen from the above technical solutions, the grid short-circuit current calculation method and related equipment provided by the embodiments of the present application construct the grid node impedance matrix containing network-constructed energy storage devices, and obtain accurate results by combining iterative calculation, thereby providing a practical solution for the short-circuit current calculation of the grid containing network-constructed energy storage devices. The present application first constructs the grid node impedance matrix by connecting the network-constructed energy storage devices to the nodes using the pre-defined three-sequence discrete equivalent model. Compared with the traditional calculation method which does not consider the characteristics of network-constructed energy storage devices, this operation converts the complex characteristics of network-constructed energy storage devices into a calculable equivalent model and integrates them into the overall grid calculation system, thereby accurately calculating the fault point short-circuit current and the grid-connected node voltage of each network-constructed energy storage device, and solving the problem of lack of grid short-circuit current calculation method for the grid containing network-constructed energy storage devices.

[0085] Secondly, an iterative calculation mechanism is introduced, which judges the grid-connected node voltage difference of network-constructed energy storage devices in the current iteration and the previous iteration, and updates the compensation current source value in combination with the pre-set current limiting condition. This mechanism can simulate the characteristics of network-constructed energy storage devices dynamically adjusting the output according to the grid state. Because the output of network-constructed energy storage devices is not constant when a short-circuit occurs, it will be adjusted according to its own control strategy and changes in grid voltage, frequency, etc., and the present solution can accurately capture this dynamic change by continuously updating parameters such as compensation current source value, thereby more accurately simulating the behavior of network-constructed energy storage devices when the grid is short-circuited.

[0086] When the difference between the grid-connected node voltage of the arbitrary network-constructed energy storage device in the current iteration and the grid-connected node voltage in the previous iteration does not exceed the threshold value, and the current iteration is not the initial round, the short-circuit current at the fault point at this time is determined as the grid short-circuit current. In this way, the final short-circuit current calculation result can truly reflect the actual situation of the power grid containing the network-constructed energy storage device under short-circuit fault.

[0087] In some embodiments of the present application, the process of updating the compensation current source value by resolving the active component and the reactive component of the injected short-circuit current in step S4 and combining the preset current limiting condition is introduced, which can specifically include:

[0088] Step S41, decompose the injected short-circuit current into an active component and a reactive component in a rotating coordinate system, and calculate the current vector modulus value;

[0089] Step S42, determine whether the active component exceeds the preset active limiting value, whether the reactive component exceeds the preset reactive limiting value, and whether the current vector modulus value exceeds the total limiting value;

[0090] Step S43, according to the judgment result and the limiting control strategy type of the network-constructed energy storage device, select the corresponding compensation current calculation rule to update the compensation current source value.

[0091] Specifically, in power system analysis, the injected short-circuit current is converted from the natural coordinate system to the rotating coordinate system through coordinate transformation, and the current is decomposed into an active component and a reactive component by using the trigonometric function relationship and power theory. The active component reflects the actual energy exchange between the network-constructed energy storage device and the power grid, and is related to the active power consumed or generated by the device; the reactive component reflects the voltage regulation capability of the device to the power grid. At the same time, according to the vector operation principle, the modulus value of the current vector is calculated, which represents the size of the injected short-circuit current and is used for subsequent comparison with the total limiting value. This step provides basic data for subsequent limiting judgment and compensation current source value updating.

[0092] The preset active limiting value, the preset reactive limiting value, and the total limiting value are set according to the rated parameters of the network-constructed energy storage device, the safety operation requirements, and the power grid operation specifications, aiming to ensure the safe operation of the device during short-circuit fault and avoid damage to the device due to excessive current. By comparing the calculated active component, reactive component, and current vector modulus value with the corresponding limiting value, it is determined whether it exceeds the safe range, so as to determine whether the current operation state of the device needs to be adjusted, and to provide a judgment basis for the updating of the compensation current source value in the next step.

[0093] The grid-forming energy storage device usually has multiple types of limiting control strategies, such as a strategy for preferentially guaranteeing active output, a reactive compensation strategy for preferentially stabilizing grid voltage, or a balanced strategy considering active and reactive power. When the judgment result shows that one or more current components exceed the limiting value, the compensation current calculation rule matched with the limiting control strategy adopted by the device is selected according to the type of the limiting control strategy. These calculation rules are formulated based on circuit theory, device control principles, and grid operation requirements, and the size and phase of the compensation current source value are adjusted through specific algorithms and formulas. For example, if the strategy for preferentially guaranteeing active output is adopted and the active component exceeds the limiting value, the calculation rule may appropriately adjust the reactive component to reduce the total current under the premise of guaranteeing the active output; if the reactive compensation strategy for preferentially stabilizing the grid voltage is adopted and the reactive component exceeds the limiting value, the reactive component is preferentially adjusted, and the active component and the total current are also considered. In this way, the compensation current source value is accurately updated, ensuring that the grid-forming energy storage device can meet the operation requirements of the grid and ensure its safe and stable operation during short-circuit faults.

[0094] When updating the compensation current source value, the current vector modulus, the over-limit situation of active and reactive current components, and the control strategy of the grid-forming energy storage device need to be considered, and the specific processing can be divided into six scenarios:

[0095] First, when the current vector modulus is not over-limited, the active current component is not over-limited, and the reactive current component is not over-limited, the compensation current source value is determined to be zero.

[0096] When the current vector modulus, the active current component, and the reactive current component are all not over-limited, it indicates that the grid-forming energy storage device is currently outputting to adapt to the grid state, and no additional compensation is needed, so the compensation current source value is set to zero.

[0097] Second, when the current vector modulus is not over-limited, the active current component is over-limited, and the reactive current component is not over-limited, the compensation current calculation formula is:

[0098]

[0099] If the current vector modulus is not over-limited, only the active current component is over-limited, and the reactive component is not over-limited, it indicates that the active output exceeds the range that the device or the grid can bear. At this time, the compensation current source value is obtained by subtracting the active limiting value from the current active component, so as to limit the active output and make it return to a reasonable range.

[0100] Third, when the current vector modulus is not over-limited, the active current component is not over-limited, and the reactive current component is over-limited, the compensation current calculation formula is:

[0101]

[0102] When the current vector modulus is not exceeded, only the reactive current component is exceeded, and the active is not exceeded, it means that the reactive regulation is excessive. The compensation current source value is calculated by subtracting the reactive limit value from the current reactive component (combined with the imaginary unit to reflect the reactive characteristic), and the reactive output is constrained.

[0103] Fourthly, when the current vector modulus is not exceeded, the active current component is exceeded, and the reactive current component is exceeded, the compensation current calculation formula is:

[0104]

[0105] If the current vector modulus is not exceeded, but the active and reactive current components are both exceeded, both need to be limited. The active component is subtracted from the active limit value, the reactive component is subtracted from the reactive limit value (the reactive term has a virtual number), and the results are combined to obtain the compensation current source value, and the active and reactive outputs are simultaneously regulated.

[0106] Fifthly, when the current vector modulus is exceeded, the active current component is not exceeded, the reactive current component is not exceeded, and the grid-type energy storage device adopts an active priority control strategy, the compensation current calculation formula is:

[0107]

[0108] When the current vector modulus is exceeded, and the active and reactive components are individually not exceeded, and the device adopts an active priority control strategy, the active output is prioritized. The total limit value and the active component are used to calculate the compensation current source value, and the reactive is reduced to reduce the total current modulus without affecting the active.

[0109] Sixthly, when the current vector modulus is exceeded, the active current component is not exceeded, the reactive current component is not exceeded, and the grid-type energy storage device adopts a reactive priority control strategy, the compensation current calculation formula is:

[0110]

[0111] wherein, is the compensation current source value, , is the active component and the reactive component, respectively, , is the active limit value and the reactive limit value, respectively, is the total limit value, and j is the imaginary unit.

[0112] If the current vector modulus is exceeded, the active and reactive components are individually not exceeded, and the device adopts a reactive priority control strategy, the reactive is prioritized. The total limit value and the reactive component are used to calculate the compensation current source value, and the active is reduced to control the total current modulus while ensuring the reactive.

[0113] The above six cases cover different over-limit combinations of current components and modulus in the operation of the device, and different control strategy requirements. By operating the compensation current source value through the corresponding formula, the output of the grid-connected energy storage device can be accurately adjusted to adapt to the short-circuit operating condition of the power grid, meet the current support demand under fault, avoid overloading of the device, and ensure safe and stable operation of the power grid and the device.

[0114] Next, a power grid short-circuit current calculation device provided by an embodiment of the present application is described. The power grid short-circuit current calculation device described below can be correspondingly referred to the power grid short-circuit current calculation method described above.

[0115] Referring to Figure 3 , Figure 3 FIG. 1 is a schematic diagram of a power grid short-circuit current calculation device disclosed by an embodiment of the present application.

[0116] As shown in Figure 3 , the power grid short-circuit current calculation device can include:

[0117] An equivalent construction unit 110 is configured to equivalently construct a synchronous generator as a current source and a shunt admittance, equivalently construct a power transmission network as an impedance combination, equivalently construct a load as a grounding impedance, and equivalently construct a grid-connected energy storage device as a pre-defined three-sequence discrete equivalent model connected to a node, to obtain a power grid node impedance matrix;

[0118] A compensation calculation unit 120 is configured to calculate a fault point short-circuit current and a grid-connected node voltage of each grid-connected energy storage device according to a voltage before short-circuit at the fault point, the power grid node impedance matrix, and a compensation current source value determined based on an equivalent model of each grid-connected energy storage device;

[0119] An iterative calculation unit 130 is configured to calculate an injected short-circuit current of the grid-connected energy storage device to the power grid according to the grid-connected node voltage, the compensation current source value, and a device equivalent impedance, in a case where a difference between the grid-connected node voltage obtained by the iterative calculation in the current round and the previous round exceeds a threshold value, or in a case where the current round is an initial round;

[0120] A compensation updating unit 140 is configured to analyze an active component and a reactive component of the injected short-circuit current, and update the compensation current source value in combination with a preset current limiting condition, and return to execute the process of calculating the fault point short-circuit current;

[0121] A current determination unit 150 is configured to determine the fault point short-circuit current as a power grid short-circuit current in a case where a difference between the grid-connected node voltage obtained by the iterative calculation in the current round and the previous round does not exceed a threshold value, and the current round is not an initial round.

[0122] It can be seen from the technical solution that the power grid short-circuit current calculation method and related equipment provided by the embodiment of the application can provide an accurate solution for the short-circuit current calculation of the power grid containing the grid-connected energy storage device by constructing the power grid node impedance matrix containing the grid-connected energy storage device and combining the iterative calculation to obtain accurate results. First, the grid-connected energy storage device is connected to the node by using the pre-defined three-sequence discrete equivalent model to construct the power grid node impedance matrix. Compared with the traditional calculation method which does not consider the characteristics of the grid-connected energy storage device, this operation converts the complex characteristics of the grid-connected energy storage device into a calculable equivalent model and integrates it into the overall calculation system of the power grid, thereby accurately calculating the fault point short-circuit current and the grid-connected node voltage of each grid-connected energy storage device, and solving the problem of lack of short-circuit current calculation method for the power grid containing the grid-connected energy storage device.

[0123] Secondly, the iterative calculation mechanism is introduced, which updates the compensation current source value by judging the difference between the grid-connected node voltage obtained by the current iteration and the previous iteration, and combining the preset current limiting condition. This mechanism can simulate the characteristics of the grid-connected energy storage device dynamically adjusting the output according to the state of the power grid. Because the output of the grid-connected energy storage device is not constant when the short circuit occurs, it will be adjusted according to the control strategy, voltage, frequency and other changes of the power grid. By continuously updating the parameters such as compensation current source value, this scheme can accurately capture the dynamic changes, thereby more accurately simulating the behavior of the grid-connected energy storage device when the power grid is short-circuited.

[0124] When the difference between the grid-connected node voltage obtained by the current iteration and the previous iteration of any grid-connected energy storage device does not exceed the threshold value, and the current iteration is not the initial round, the fault point short-circuit current at this time is determined as the power grid short-circuit current. In this way, the final short-circuit current calculation result can truly reflect the actual situation of the power grid containing the grid-connected energy storage device under short-circuit fault.

[0125] Optionally, the calculation formula of the fault point short-circuit current is:

[0126]

[0127] Wherein, is the fault point short-circuit current, is the voltage before the fault point short-circuit, is the transfer impedance between the fault point and the node of the kth grid-connected energy storage device, is the compensation current source value of the kth device, is the self-impedance of the fault point, is the set of grid-connected energy storage devices.

[0128] Optionally, the calculation formula of the grid-connected node voltage of the grid-connected energy storage device is:

[0129]

[0130] in, is the grid-connected node voltage of the grid-type energy storage device, is the voltage before node m is short-circuited, is the transfer impedance between node m and the fault point, is the short-circuit current at the fault point, is the compensation current source value of the kth device, is the transfer impedance between node m and the kth grid-type energy storage device node, It is a collection of grid-type energy storage devices.

[0131] Optionally, the calculation formula for the short-circuit current injected into the grid by the grid-connected energy storage device is:

[0132]

[0133] in, To inject short-circuit current into the grid for grid-type energy storage equipment, is the grid-connected node voltage of the grid-type energy storage device, is the compensation current source value, is the equivalent impedance of the device.

[0134] Optionally, analyzing the active component and reactive component of the injected short-circuit current and updating the compensation current source value in combination with a preset current limiting condition includes:

[0135] Decomposing the injected short-circuit current into an active component and a reactive component in a rotating coordinate system, and calculating a current vector modulus;

[0136] Determining whether the active component exceeds a preset active limit value, whether the reactive component exceeds a preset reactive limit value, and whether the current vector modulus exceeds a total limit value;

[0137] According to the judgment result and the type of limiting control strategy of the grid-type energy storage device, the corresponding compensation current calculation rule is selected to update the compensation current source value.

[0138] Optionally, according to the judgment result and the type of the limiting control strategy of the grid-type energy storage device, a corresponding compensation current calculation rule is selected to update the compensation current source value, including:

[0139] When the current vector modulus value does not exceed the limit, the active current component does not exceed the limit, and the reactive current component does not exceed the limit, the compensation current source value is determined to be zero;

[0140] When the current vector modulus is within the limit, the active current component is within the limit, and the reactive current component is within the limit, the compensation current calculation formula is:

[0141]

[0142] When the current vector modulus is not over-limited, the active current component is not over-limited, and the reactive current component is over-limited, the compensation current calculation formula is:

[0143]

[0144] When the current vector modulus is not over-limited, the active current component is over-limited, and the reactive current component is over-limited, the compensation current calculation formula is:

[0145]

[0146] When the current vector modulus is over-limited, the active current component is not over-limited, the reactive current component is not over-limited, and the grid-forming energy storage device adopts an active priority control strategy, the compensation current calculation formula is:

[0147]

[0148] When the current vector modulus is over-limited, the active current component is not over-limited, the reactive current component is not over-limited, and the grid-forming energy storage device adopts a reactive priority control strategy, the compensation current calculation formula is:

[0149]

[0150] wherein, is a compensation current source value, , are active and reactive components, respectively, , are active and reactive limiting values, respectively, is a total limiting value, and j is an imaginary unit.

[0151] The power grid short-circuit current calculation device provided by the embodiment of the application can be applied to a power grid short-circuit current calculation device. Figure 4 A hardware structure block diagram of the power grid short-circuit current calculation device is shown, referring to Figure 4 The hardware structure of the power grid short-circuit current calculation device can include at least one processor 1, at least one communication interface 2, at least one memory 3, and at least one communication bus 4.

[0152] In the embodiment of the application, the number of the processor 1, the communication interface 2, the memory 3, and the communication bus 4 is at least one, and the processor 1, the communication interface 2, and the memory 3 complete mutual communication through the communication bus 4.

[0153] The processor 1 can be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present application, etc.

[0154] The memory 3 can include a high-speed RAM memory and can also include a non-volatile memory such as at least one disk memory, etc.

[0155] The memory stores a program, and the processor can invoke the program stored in the memory, and the program is used for:

[0156] Based on the power grid topology, the synchronous generator is equivalent to a current source and a shunt admittance, the power transmission network is equivalent to an impedance combination, the load is equivalent to a grounding impedance, and the grid-forming energy storage device is connected to a node by using a predefined three-sequence discrete equivalent model, and a power grid node impedance matrix is constructed.

[0157] According to the voltage before short-circuit at the fault point, the power grid node impedance matrix, and the compensation current source value determined based on the equivalent model of each grid-forming energy storage device, the short-circuit current at the fault point and the grid-connected node voltage of each grid-forming energy storage device are calculated.

[0158] If the difference between the grid-connected node voltage calculated in the current iteration and the grid-connected node voltage calculated in the previous iteration of any grid-forming energy storage device exceeds a threshold value, or the current iteration is the initial iteration, then the injection short-circuit current of the grid-forming energy storage device to the power grid is calculated according to the grid-connected node voltage, the compensation current source value, and the device equivalent impedance.

[0159] The active component and the reactive component of the injection short-circuit current are analyzed, and the compensation current source value is updated in combination with a preset current amplitude limiting condition, and the process of calculating the short-circuit current at the fault point is returned to be executed.

[0160] If the difference between the grid-connected node voltage calculated in the current iteration and the grid-connected node voltage calculated in the previous iteration of any grid-forming energy storage device does not exceed a threshold value, and the current iteration is not the initial iteration, then the short-circuit current at the fault point is determined as the short-circuit current of the power grid.

[0161] Optionally, the detailed functions and extended functions of the program can refer to the description above.

[0162] Embodiments of the present application also provide a readable storage medium which can store a program suitable for execution by a processor, and the program is used for:

[0163] Based on the power grid topology, the synchronous generator is equivalent to a current source and an admittance in parallel, the power transmission network is equivalent to an impedance combination, the load is equivalent to a grounding impedance, the grid-forming energy storage device accesses a node using a predefined three-sequence discrete equivalent model, and a power grid node impedance matrix is constructed;

[0164] According to the pre-fault voltage of the fault point, the power grid node impedance matrix, and the compensation current source value determined based on the equivalent model of each grid-forming energy storage device, the fault point short-circuit current and the grid-connected node voltage of each grid-forming energy storage device are calculated.

[0165] If the difference between the grid-connected node voltages obtained by the iterative calculation in the current round and the previous round of any grid-forming energy storage device exceeds a threshold value, or the current round is the initial round, the injected short-circuit current of the grid-forming energy storage device to the power grid is calculated according to the grid-connected node voltage, the compensation current source value, and the device equivalent impedance.

[0166] The active and reactive components of the injected short-circuit current are analyzed, and the compensation current source value is updated in combination with a preset current amplitude limiting condition, and the process of calculating the fault point short-circuit current is returned to execute.

[0167] If the difference between the grid-connected node voltages obtained by the iterative calculation in the current round and the previous round of any grid-forming energy storage device does not exceed a threshold value, and the current round is not the initial round, the fault point short-circuit current is determined as the power grid short-circuit current.

[0168] Optionally, the refinement function and the expansion function of the program can refer to the description above.

[0169] The embodiments of the present application also provide a computer program product comprising a computer program, which, when executed by a processor, performs the method.

[0170] Based on the power grid topology, the synchronous generator is equivalent to a current source and an admittance in parallel, the power transmission network is equivalent to an impedance combination, the load is equivalent to a grounding impedance, the grid-forming energy storage device accesses a node using a predefined three-sequence discrete equivalent model, and a power grid node impedance matrix is constructed;

[0171] According to the pre-fault voltage of the fault point, the power grid node impedance matrix, and the compensation current source value determined based on the equivalent model of each grid-forming energy storage device, the fault point short-circuit current and the grid-connected node voltage of each grid-forming energy storage device are calculated.

[0172] If the difference between the grid-connected node voltages obtained by the iterative calculation in the current round and the previous round of any grid-forming energy storage device exceeds a threshold value, or the current round is the initial round, the injected short-circuit current of the grid-forming energy storage device to the power grid is calculated according to the grid-connected node voltage, the compensation current source value, and the device equivalent impedance.

[0173] The active component and the reactive component of the injected short-circuit current are analyzed, and the compensation current source value is updated in combination with a preset current limiting condition, and the process of calculating the fault point short-circuit current is returned to execute.

[0174] If the difference between the grid-connected node voltages obtained by the iteration calculation in the current round and the previous round does not exceed the threshold value, and the current round is not the initial round, the fault point short-circuit current is determined as the grid short-circuit current.

[0175] Optionally, the refinement function and the extension function of the program can refer to the description above.

[0176] Finally, it should be noted that in this document, the terms such as first and second are used only 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 "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0177] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between various embodiments can be referred to each other.

[0178] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating short-circuit current of a power grid, characterized in that: include: Based on the grid topology, the synchronous generator is equivalent to a current source in parallel with an admittance, the transmission network is equivalent to an impedance combination, the load is equivalent to the ground impedance, and the grid-type energy storage device is connected to the node using a predefined three-sequence discrete equivalent model to construct the grid node impedance matrix. Calculating the short-circuit current at the fault point and the grid-connected node voltage of each grid-connected energy storage device based on the voltage before the short circuit at the fault point, the grid node impedance matrix, and the compensation current source value determined based on the equivalent model of each grid-connected energy storage device; If the grid-connected node voltage difference between the current and previous iterative calculations of any of the grid-connected energy storage devices exceeds a threshold, or if this round is the initial round, the short-circuit current injected by the grid-connected energy storage device into the power grid is calculated based on the grid-connected node voltage, the compensation current source value, and the device equivalent impedance; Analyze the active component and reactive component of the injected short-circuit current, update the compensation current source value in combination with the preset current limiting condition, and return to the process of calculating the short-circuit current at the fault point; If the grid-connected node voltage difference between the current and previous iterative calculations of any of the grid-connected energy storage devices does not exceed a threshold, and the current round is not an initial round, the fault point short-circuit current is determined as the grid short-circuit current.

2. The method according to claim 1, characterized in that The calculation formula of the short-circuit current at the fault point is: in, is the short-circuit current at the fault point, is the voltage before the fault point is short-circuited, is the transfer impedance between the fault point and the kth grid-connected energy storage device node, is the compensation current source value of the kth device, is the fault point self-impedance, It is a collection of grid-type energy storage devices.

3. The method according to claim 1, characterized in that The calculation formula for the grid-connected node voltage of the grid-connected energy storage device is: in, is the grid-connected node voltage of the grid-type energy storage device, is the voltage before node m is short-circuited, is the transfer impedance between node m and the fault point, is the short-circuit current at the fault point, is the compensation current source value of the kth device, is the transfer impedance between node m and the kth grid-type energy storage device node, It is a collection of grid-type energy storage devices.

4. The method according to claim 1, wherein The calculation formula for the short-circuit current injected into the grid by the grid-connected energy storage device is: in, To inject short-circuit current into the grid for grid-type energy storage equipment, is the grid-connected node voltage of the grid-type energy storage device, is the compensation current source value, is the equivalent impedance of the device.

5. The method according to claim 1, wherein Analyzing the active component and reactive component of the injected short-circuit current and updating the compensation current source value in combination with a preset current limiting condition, including: Decomposing the injected short-circuit current into an active component and a reactive component in a rotating coordinate system, and calculating a current vector modulus; Determining whether the active component exceeds a preset active limit value, whether the reactive component exceeds a preset reactive limit value, and whether the current vector modulus exceeds a total limit value; According to the judgment result and the type of limiting control strategy of the grid-type energy storage device, the corresponding compensation current calculation rule is selected to update the compensation current source value.

6. The method according to claim 5, characterized in that According to the judgment result and the type of limiting control strategy of the grid-type energy storage device, the corresponding compensation current calculation rule is selected to update the compensation current source value, including: When the current vector modulus value does not exceed the limit, the active current component does not exceed the limit, and the reactive current component does not exceed the limit, the compensation current source value is determined to be zero; When the current vector modulus is within the limit, the active current component is within the limit, and the reactive current component is within the limit, the compensation current calculation formula is: When the current vector modulus is within the limit, the active current component is within the limit, and the reactive current component is within the limit, the compensation current calculation formula is: When the current vector modulus is within the limit, the active current component is exceeded, and the reactive current component is exceeded, the compensation current calculation formula is: When the current vector modulus exceeds the limit, the active current component does not exceed the limit, the reactive current component does not exceed the limit, and the grid-type energy storage device adopts the active power priority control strategy, the compensation current calculation formula is: When the current vector modulus exceeds the limit, the active current component does not exceed the limit, the reactive current component does not exceed the limit, and the grid-type energy storage device adopts the reactive power priority control strategy, the compensation current calculation formula is: in, is the compensation current source value, 、 are active and reactive components respectively, 、 are active power limit value and reactive power limit value respectively, is the total limit value, and j is the imaginary unit.

7. A power grid short-circuit current calculation device, characterized in that: include: The equivalent construction unit is used to construct the grid node impedance matrix based on the grid topology by equating the synchronous generator to a current source in parallel with an admittance, the transmission network to an impedance combination, the load to a ground impedance, and the grid-type energy storage device to a node using a predefined three-sequence discrete equivalent model; A compensation calculation unit, configured to calculate the short-circuit current at the fault point and the grid-connected node voltage of each of the grid-connected energy storage devices based on the voltage before the short circuit at the fault point, the grid node impedance matrix, and a compensation current source value determined based on an equivalent model of each grid-connected energy storage device; an iterative calculation unit, configured to calculate, when a difference between the grid-connected node voltages of any of the grid-connected energy storage devices obtained by iterative calculation in the current round and the previous round exceeds a threshold, or when the current round is an initial round, calculate the short-circuit current injected by the grid-connected energy storage device into the power grid based on the grid-connected node voltage, the compensation current source value, and the device equivalent impedance; a compensation updating unit, configured to analyze the active component and reactive component of the injected short-circuit current, update the compensation current source value in combination with a preset current limiting condition, and return to the process of calculating the short-circuit current at the fault point; The current determination unit is configured to determine the fault point short-circuit current as the grid short-circuit current when the grid-connected node voltage difference between the current and previous iterative calculations of any of the grid-connected energy storage devices does not exceed a threshold value and the current round is not an initial round.

8. A power grid short-circuit current calculation device, characterized in that: including memory and processor; The memory is used to store programs; The processor is configured to execute the program to implement each step of the method for calculating the short-circuit current of a power grid according to any one of claims 1 to 6.

9. A readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, each step of the method for calculating the short-circuit current of a power grid according to any one of claims 1 to 6 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, each step of the method for calculating the short-circuit current of a power grid as claimed in any one of claims 1 to 6 is executed.

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