Power grid fault voltage distribution fast calculation method and system under new energy access

Abstract

The application discloses a new energy access under power grid fault voltage distribution fast calculation method and system, including: establishing a new energy controlled voltage source model, determining a network node admittance matrix Y; calculating the fault current injected by each node after the power grid fails; when the node is an active node and the connected power source is a new energy unit, ignoring the phase change of the terminal voltage of the new energy grid connection point before and after the fault, calculating the fault current injected by the power source into the node; based on the location of the fault point, correcting the node admittance matrix Y; using the corrected node admittance matrix and the fault current injected by each node, the fault voltage of each node is calculated. When calculating the injected fault current of the active node connected with the new energy unit, the phase of the equivalent electromotive force of the new energy is determined by using the terminal voltage phase before the fault, thereby avoiding nonlinear iterative calculation, reducing the calculation complexity and improving the calculation speed.

Description

Technical Field

[0001] This invention relates to the field of power grid fault voltage distribution calculation technology, and in particular to a method and system for rapid calculation of power grid fault voltage distribution under the access of new energy sources. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Calculation of grid fault voltage distribution refers to the calculation of voltage drops at various nodes in the power grid after a fault. On the one hand, by obtaining the voltage of each node after a fault, the fault current of each branch can be calculated, thus providing a basis for the design of power grid relay protection. On the other hand, by observing the voltage distribution of nodes after a fault at different locations in the network, the reactive power demand of each node in the network can be clarified, guiding the optimal allocation of reactive power in the power grid. Therefore, calculating the grid fault voltage distribution is of great significance for the safe and stable operation of the power grid.

[0004] As the proportion of new energy sources in the power system continues to increase, their external characteristics after a fault differ significantly from those of synchronous machines. Synchronous machine control is often too slow to respond after a fault, thus exhibiting stable voltage source characteristics. New energy fault ride-through control, on the other hand, possesses rapid response capabilities, and its fault external characteristics are determined by the fault ride-through control strategy, failing to exhibit the voltage source characteristics of synchronous machines. Therefore, the integration of new energy sources presents significant challenges to grid fault analysis, making the calculation of fault voltage distribution at various grid nodes more complex.

[0005] Currently, for traditional power systems containing only synchronous machines, the process involves first forming a composite sequence network after a fault using the symmetric component method and establishing the nodal admittance matrix. Then, boundary conditions are determined based on the fault location and type. Finally, the linear equation system U = Y is solved. -1 I. Determine the fault voltage distribution. After the integration of new energy sources, their external fault characteristics differ from those of synchronous machines, making it impossible to model them as independent voltage sources. Furthermore, due to the nonlinearity introduced by the integration of new energy sources, the above equations are generally calculated using nonlinear equation solving methods such as the Newton-Raphson method, which makes the calculation process quite complex. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a method and system for rapidly calculating grid fault voltage distribution under renewable energy access. Based on typical renewable energy fault ride-through control strategies, the external characteristics of renewable energy are modeled using equivalent methods. Simultaneously, the nonlinear equation calculations introduced by renewable energy access are avoided, enabling rapid calculation of grid fault voltage distribution under certain accuracy requirements.

[0007] In some implementations, the following technical solutions are adopted:

[0008] A method for rapid calculation of grid fault voltage distribution under renewable energy access includes:

[0009] Considering the fault ride-through control strategy for new energy sources, a controlled voltage source model for new energy sources is established.

[0010] Based on the network topology of new energy grid access, determine the network node admittance matrix Y;

[0011] Calculate the fault current injected into each node after a grid fault occurs; where, when the node is an active node and the connected power source is a new energy unit, based on the new energy controlled voltage source model, the phase change of the new energy grid connection point voltage before and after the fault is ignored, and the fault current injected into the node by the power source is calculated.

[0012] The node admittance matrix Y is corrected based on the location of the fault point;

[0013] The fault voltage of each node is calculated using the corrected admittance matrix of each node and the fault current injected into each node.

[0014] In other embodiments, the following technical solutions are adopted:

[0015] A system for rapid calculation of grid fault voltage distribution under renewable energy access includes:

[0016] The model building module is configured to consider the fault ride-through control strategy of new energy sources and build a model of the controlled voltage source of new energy sources.

[0017] The admittance matrix establishment module is configured to determine the network node admittance matrix Y based on the network topology structure of new energy access to the power grid.

[0018] The fault current calculation module is configured to calculate the fault current injected into each node after a fault occurs in the power grid. When the node is an active node and the power source connected to it is a new energy unit, the fault current injected into the node is calculated based on the new energy voltage source model, ignoring the phase change of the voltage at the new energy grid connection point before and after the fault.

[0019] The admittance matrix correction module is configured to correct the node admittance matrix Y based on the location of the fault point;

[0020] The fault voltage calculation module is configured to calculate the fault voltage of each node using the corrected admittance matrix of each node and the fault current injected into each node.

[0021] In other embodiments, the following technical solutions are adopted:

[0022] A terminal device includes a processor and a memory, wherein the processor is used to implement instructions; the memory is used to store multiple instructions, which are adapted to be loaded and executed by the processor to perform the above-described method for rapid calculation of grid fault voltage distribution under new energy access.

[0023] In other embodiments, the following technical solutions are adopted:

[0024] A computer-readable storage medium storing a plurality of instructions adapted for loading and execution by a processor of a terminal device of the above-described method for rapid calculation of grid fault voltage distribution under new energy access.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] (1) Based on the typical new energy fault ride-through control strategy, the present invention performs equivalent modeling of the external characteristics of new energy; and compares the active and reactive current characteristics of new energy with the voltage source model of synchronous machine, which facilitates the construction of the equivalent model of new energy.

[0027] (2) When calculating the injected fault current of the active node of the connected power source is a new energy unit, the present invention ignores the phase change of the terminal voltage of the new energy grid connection point before and after the fault, and uses the terminal voltage phase before the fault to determine the phase of the equivalent electromotive force of the new energy, thereby avoiding nonlinear iterative calculation, reducing the calculation complexity and improving the calculation speed.

[0028] Other features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] Figures 1(a)-(b) show the synchronous machine voltage source model and its phasor diagram in the embodiments of the present invention;

[0030] Figure 2 This is a new energy controlled voltage source model in the embodiments of the present invention;

[0031] Figure 3 This is a schematic diagram of a three-machine, nine-node network in an embodiment of the present invention;

[0032] Figures 4(a)-(b) show the sub-transient fault stage and the node voltage during the transient fault stage when node 6 fails in the embodiment of the present invention;

[0033] Figures 5(a)-(b) show the node voltage during the sub-transient fault stage and the transient fault stage when node 7 fails in the embodiment of the present invention;

[0034] Figures 6(a)-(b) show the node voltages during the subtransient fault stage and the transient fault stage when there is a fault in branches 4-6 in the embodiments of the present invention.

[0035] Figure 7 This is a schematic diagram of a method for rapid calculation of grid fault voltage distribution under new energy access in an embodiment of the present invention. Detailed Implementation

[0036] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Example 1

[0039] In one or more embodiments, a method for rapid calculation of grid fault voltage distribution under new energy access is disclosed, combined with Figure 7 Specifically, it includes the following process:

[0040] (1) Considering the fault ride-through control strategy of new energy sources, establish a model of the controlled voltage source of new energy sources;

[0041] In this embodiment, to prevent the impact of renewable energy disconnection after a grid fault, renewable energy is generally required to have a certain fault ride-through capability. Fault ride-through control strategies are used to ensure that renewable energy remains connected to the grid during a fault. Currently, a typical renewable energy fault ride-through control strategy is reactive current control, which requires renewable energy units to respond quickly when the grid connection point voltage drops, providing a certain amount of reactive current to support the recovery of the terminal voltage. The magnitude of the reactive current must meet the following requirements:

[0042] I q ≥K Q (0.9-U m )×I n (1)

[0043] Among them, U m I represents the line voltage amplitude at the new energy grid connection point. n For the rated current of the new energy unit, K Q I is the reactive current coefficient, typically taken as 1.5. q This refers to the reactive current of new energy generating units.

[0044] For active current, it is generally kept unchanged from the value before the fault. However, since renewable energy sources typically operate in unity power factor mode before the fault, i.e., the reactive current is 0, the reactive current generated after the fault will inevitably occupy a portion of the current capacity. Therefore, considering the current capacity limitation, the active current after the fault can be expressed as:

[0045]

[0046] Among them, I p0 I represents the active current value before the fault. pmax The maximum remaining active current capacity under the current reactive current, I p This represents the active current of the new energy unit after the fault.

[0047] To establish an equivalent model of the external characteristics of new energy sources that is easy to calculate, its active and reactive current characteristics can be compared with the voltage source model of a synchronous machine. The voltage source model of a synchronous machine and its phasor diagram are shown in Figure 1(a)-(b).

[0048] Where E is the electromotive force of the synchronous machine, X s The stator reactance of the synchronous machine is given. In different fault stages, E is taken as the subtransient electromotive force E” and the transient electromotive force E’, respectively. s They are also correspondingly taken as subtransient reactance X” and transient reactance X’, and according to the phasor diagram in Figure 1(b), we can obtain:

[0049]

[0050] The active and reactive current outputs of the synchronous machine voltage source model can be obtained as follows:

[0051]

[0052] Where U is the grid connection point voltage of the synchronous machine, δ is the power angle of the synchronous machine, and X is the voltage at the grid connection point of the synchronous machine. s For synchronous electromechanical reactors.

[0053] For ease of calculation, the renewable energy source under reactive current control can also be modeled as a voltage source model similar to that of a synchronous machine. Substituting the per-unit fault output current characteristics of the renewable energy source into equation (4), we get:

[0054]

[0055] According to the principle of corresponding equality, we can obtain:

[0056]

[0057] Simplifying the above equation yields the equivalent electromotive force E, power angle δ, and reactance parameter X of the new energy voltage source model. eq The calculation formulas are as follows:

[0058]

[0059] Where δ is the equivalent power angle of the new energy controlled voltage source model, I p0 K represents the active current output of the new energy unit before the fault. Q X is the reactive current coefficient in the fault ride-through strategy for new energy sources, E is the equivalent electromotive force of the controlled voltage source model for new energy sources, and X is the reactive current coefficient. eq This is the equivalent reactance of the controlled voltage source model for new energy sources.

[0060] It can be seen that as long as the fault ride-through control strategy of the renewable energy source and its active power output before the fault are clearly defined, the voltage source model can be established. It should be noted that renewable energy sources are generally grid-connected and cannot be modeled as independent voltage sources identical to synchronous machines. The phase of the equivalent electromotive force in its voltage source model needs to be determined based on the phase of the voltage at the grid connection point. Therefore, the post-fault equivalent external characteristic model of the renewable energy source established using the above method is actually a... Figure 2 The phase-controlled voltage source model is shown.

[0061] (2) Based on the network topology of new energy access to the power grid, determine the network node admittance matrix Y;

[0062] Specifically, for a power grid with n nodes, m branches, a synchronous machines, and b renewable energy sources, to determine the fault voltage distribution after a fault in a certain node or branch, it is first necessary to define the network topology and establish the network node admittance matrix Y. The diagonal elements of this matrix are... ii Self-admittance is numerically equal to the current injected into the network from node i when a unit voltage is applied to node i and all other nodes are grounded; the off-diagonal element Y in the matrix ij Mutual admittance is numerically equal to the current injected into the network from node j when a unit voltage is applied to node i and all other nodes are grounded. ii With Y ij The calculation method is as follows:

[0063]

[0064] Where j is another node connected to node i; y ij Let y be the admittance value of branch ij. If node i and node j are not directly connected, then y ij =0; y i0 Let y be the admittance of node i to the ground branch. In this embodiment, the load adopts a constant impedance model, and the admittance y of the connected node to the ground branch is taken into account. i0 Participate in the calculation.

[0065] (3) Calculate the fault current injected into each node after a fault occurs in the power grid;

[0066] According to U=Y -1 To determine the voltage distribution after a fault, it is necessary to clarify the fault current injected into each node. Specifically:

[0067] ① For passive nodes, the sum of their injected current vectors is 0, that is, the element at the corresponding position of column vector I is 0. For active nodes, the fault current emitted by them needs to be calculated based on the equivalent model of the power supply after the fault.

[0068] ② For active nodes, if the power source connected to the active node is a synchronous machine, it can be modeled as a constant voltage source. Due to the widespread application of fast relay protection devices, faulty components can be quickly disconnected from the power grid after a short circuit. Therefore, it can be approximated that the power frequency component of the short-circuit current is equal to its initial value within a short time after the short circuit. Thus, the equivalent electromotive force after the fault can be determined based on the terminal voltage before the fault. and terminal current The calculation is as follows:

[0069]

[0070] in, Let X' be the subtransient electromotive force of the synchronous machine, and X' be the subtransient reactance. It can be calculated directly from the data before the fault occurred.

[0071] After the fault has persisted for a period of time, the subtransient electrical quantities have largely decayed. At this point, the parameters of the synchronous machine voltage source model should be modified to transient parameters for calculation, including the transient electromotive force. The calculation method is similar to that for subtransient electromotive force:

[0072]

[0073] Where X' is the transient reactance of the synchronous machine. Transient electromotive force. It can also be calculated directly from the data before the fault.

[0074] ③ If the power source connected to the active node is a new energy unit, then a controlled voltage source model is established according to the aforementioned method for establishing a new energy controlled voltage source model. The phase of the equivalent electromotive force in this model needs to be determined based on the phase of the voltage at the new energy grid connection point after the fault. This introduces nonlinear calculations. Therefore, to improve the calculation speed, the phase change of the voltage at the new energy grid connection point before and after the fault is ignored in this method. In this way, the phase of the equivalent electromotive force of the new energy can be determined using the phase of the voltage before the fault, thereby avoiding nonlinear iterative calculations. Under the above assumptions, the electromotive force phasor of the new energy equivalent controlled voltage source model is:

[0075]

[0076] In the formula, θu0 δ represents the voltage phase at the grid connection point of the new energy source before the fault, and δ is the equivalent power angle of the controlled voltage source model.

[0077] Once the electromotive force of each active node is determined, the fault current injected into that node can be calculated using the following formula:

[0078]

[0079] Where X is the internal equivalent reactance of the power supply, which is the subtransient reactance or transient reactance for synchronous machines, and X in equation (7) for new energy sources. eq . For the electromotive force phasor of the power source, This is the voltage phasor at the power supply grid connection port.

[0080] Substituting equation (12) into the system of equations I = YU, and multiplying the voltage column vector into the node admittance matrix, we can obtain the following for any active node i:

[0081]

[0082] At this point, the voltage at node i after the fault still exists on the left side of the equation. This unknown quantity can be moved to the right side of the equation, and the above equation becomes:

[0083]

[0084] It can be seen that after correcting the self-admittance of the source node in the node admittance matrix by adding the equivalent admittance inside the power source, each element in the left current column vector can be calculated based on the data before the fault.

[0085] (4) Correct the node admittance matrix Y based on the location of the fault point;

[0086] The impact of a fault on the entire network can also be reflected by modifying the node admittance matrix. There are two correction methods depending on the location of the fault:

[0087] ① If the fault occurs at node i, let the grounding transition resistance be R. f This is equivalent to adding an impedance of magnitude R at node i. f The ground-to-ground branch, therefore the self-admittance Y of node i in the node admittance matrix. ii Plus The correction can be made.

[0088] ② If the fault occurs on branch ij, and the distance from the fault point to node i is k times the length of branch ij, the grounding transition resistance is still denoted as R. fIn this case, the fault point can be regarded as the newly added node n+1, and the node admittance matrix also needs to be increased by one dimension accordingly. At this time, nodes i and j no longer have a direct connection relationship, but are connected to node n+1 respectively. Therefore, the relevant elements of the node admittance matrix need to be modified as follows:

[0089]

[0090] (5) Using the corrected admittance matrices of each node and the fault current injected into each node, the linear equation system U = Y is calculated. -1 I can then be used to determine the fault voltage distribution at each node in the entire network.

[0091] This embodiment establishes a system in DIGSILENT Powerfactory as follows: Figure 3 The proposed calculation method was verified by simulation using the three-machine nine-node model shown. The parameters of each unit and the voltage data of each node during steady-state operation are shown in Tables 1 and 2.

[0092] Table 1 Parameters of each unit

[0093]

[0094] Table 2 Voltage data for each node

[0095] Node number 1 2 3 4 5 6 7 8 9 Voltage / pu 1.034 1.025 1.036 1.019 0.991 1.004 1.026 1.018 1.037

[0096] By setting up faults at different locations and of different degrees, the simulation results were compared with the fault voltage distribution calculated by the proposed fast calculation method. The results are as follows:

[0097] (1) Figures 4(a)-(b) show the fault at node 6 (Bus6), and the transition resistance R f Simulation results of node voltages during the subtransient fault stage and the transient fault stage when the resistance is 60Ω;

[0098] The voltage values ​​of each node are shown in Table 3 below:

[0099] Table 3 Voltage values ​​at each node

[0100]

[0101] The maximum error between the simulated voltage and the rapidly calculated voltage is 4.5%.

[0102] (2) Figures 5(a)-(b) show the fault at node 7 (Bus7), and the transition resistance R f Simulation results of node voltages during the subtransient fault stage and the transient fault stage when the resistance is 80Ω;

[0103] The voltage values ​​of each node are shown in Table 4 below:

[0104] Table 4 Voltage values ​​at each node

[0105]

[0106]

[0107] The maximum error between the simulated voltage and the rapidly calculated voltage is 4.9%.

[0108] (3) Figures 6(a)-(b) show the fault at 50% distance from node 4 in branch 4-6, and the transition resistance R f Simulation results of node voltages during the subtransient fault stage and the transient fault stage when the resistance is 60Ω;

[0109] The voltage values ​​of each node are shown in Table 5 below:

[0110] Table 5 Voltage values ​​at each node

[0111]

[0112] The maximum error between the simulated voltage and the rapidly calculated voltage is 4.1%.

[0113] According to the comparison results, the fault voltage distribution calculated by the fast calculation method of grid fault voltage distribution under new energy access proposed in this embodiment has an error of less than 5% compared with the simulation results. The calculation accuracy meets the engineering requirements and has the advantage of fast calculation speed, which simplifies the fault analysis and calculation of the grid under new energy access to a certain extent.

[0114] Example 2

[0115] In one or more embodiments, a system for rapid calculation of grid fault voltage distribution under new energy access is disclosed, comprising:

[0116] The model building module is configured to consider the fault ride-through control strategy of new energy sources and build a model of the controlled voltage source of new energy sources.

[0117] The admittance matrix establishment module is configured to determine the network node admittance matrix Y based on the network topology structure of new energy access to the power grid.

[0118] The fault current calculation module is configured to calculate the fault current injected into each node after a fault occurs in the power grid. When the node is an active node and the power source connected to it is a new energy unit, the fault current injected into the node is calculated based on the new energy controlled voltage source model, ignoring the phase change of the voltage at the new energy grid connection point before and after the fault.

[0119] The admittance matrix correction module is configured to correct the node admittance matrix Y based on the location of the fault point;

[0120] The fault voltage calculation module is configured to calculate the fault voltage of each node using the corrected admittance matrix of each node and the fault current injected into each node.

[0121] It should be noted that the specific implementation methods of the above modules have been described in Example 1, and will not be detailed here.

[0122] Example 3

[0123] In one or more embodiments, a terminal device is disclosed, including a server. The server includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the method for rapid calculation of grid fault voltage distribution under new energy access as described in Embodiment 1. For simplicity, further details are omitted here.

[0124] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0125] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0126] In the implementation process, each step of the above method can be completed by the integrated logic circuits in the processor hardware or by software instructions.

[0127] Example 4

[0128] In one or more embodiments, a computer-readable storage medium is disclosed, wherein a plurality of instructions are stored, the instructions being adapted to be loaded by a processor of a terminal device and executed by the method for rapid calculation of grid fault voltage distribution under new energy access as described in Embodiment 1.

[0129] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for rapid calculation of grid fault voltage distribution under new energy access, characterized in that, include: Considering the fault ride-through control strategy for new energy sources, a model of the new energy voltage source is established; The equivalent electromotive force, power angle, and reactance parameters of the new energy voltage source model are as follows: in, The equivalent power angle for the controlled voltage source model of new energy sources. This represents the active current output of the new energy unit before the fault. This refers to the reactive current coefficient in the fault ride-through strategy for new energy sources. The equivalent electromotive force for the controlled voltage source model of new energy. The equivalent reactance for the controlled voltage source model of new energy sources; Based on the network topology of new energy grid access, determine the network node admittance matrix Y; Calculate the fault current injected into each node after a grid fault occurs; where, when the node is an active node and the connected power source is a new energy unit, based on the new energy voltage source model, the phase change of the voltage at the new energy grid connection point before and after the fault is ignored, and the fault current injected into the node by the power source is calculated. The node admittance matrix Y is corrected based on the location of the fault point; The fault voltage of each node is calculated using the corrected admittance matrix of each node and the fault current injected into each node.

2. The method for rapid calculation of grid fault voltage distribution under new energy access as described in claim 1, characterized in that, Diagonal elements of the network node admittance matrix Y Self-admittance is numerically equal to the current injected into the network from node i when a unit voltage is applied to node i and all other nodes are grounded. Off-diagonal elements in the network node admittance matrix Y Mutual admittance is numerically equal to the current injected into the network from node j when a unit voltage is applied to node i and all other nodes are grounded.

3. The method for rapid calculation of grid fault voltage distribution under new energy access as described in claim 1, characterized in that, When a node is a passive node, the vector sum of the node-injected currents is 0, that is, the fault current injected into the node is 0.

4. The method for rapid calculation of grid fault voltage distribution under new energy access as described in claim 1, characterized in that, When a node is an active node and the power supply connected to the node is a synchronous machine, the equivalent electromotive force after the fault is calculated based on the terminal voltage and terminal current before the fault. Then, based on the internal voltage of the power supply, the equivalent electromotive force after the fault, and the internal equivalent reactance of the power supply, the fault current injected into each node is calculated.

5. The method for rapid calculation of grid fault voltage distribution under new energy access as described in claim 1, characterized in that, When a node is an active node and the power source connected to the node is a new energy unit, the phase change of the terminal voltage of the new energy grid connection point before and after the fault is ignored. The phase of the terminal voltage before the fault is used as the phase of the equivalent electromotive force of the new energy after the fault. The electromotive force of the new energy voltage source model is calculated. Then, based on the internal voltage of the power source, the equivalent electromotive force after the fault, and the internal equivalent reactance of the power source, the fault current injected into each node is calculated.

6. The method for rapid calculation of grid fault voltage distribution under new energy access as described in claim 1, characterized in that, The node admittance matrix Y is corrected based on the location of the fault point, specifically as follows: If the fault occurs at node i, let the grounding transition resistance be... The self-admittance of node i in the node admittance matrix. Plus Make corrections; If the fault occurs on branch ij, and the distance from the fault point to node i is a proportion of the length of branch ij, then... Let the grounding transition resistance be . The fault point is considered as the newly added (n+1)th node, and the node admittance matrix is ​​also increased by one dimension accordingly.

7. A system for rapid calculation of grid fault voltage distribution under new energy access, characterized in that, include: The model building module is configured to consider the fault ride-through control strategy of new energy sources and build a new energy voltage source model. The equivalent electromotive force, power angle, and reactance parameters of the new energy voltage source model are as follows: in, The equivalent power angle for the controlled voltage source model of new energy sources. This represents the active current output of the new energy unit before the fault. This refers to the reactive current coefficient in the fault ride-through strategy for new energy sources. The equivalent electromotive force for the controlled voltage source model of new energy. The equivalent reactance for the controlled voltage source model of new energy sources; The admittance matrix establishment module is configured to determine the network node admittance matrix Y based on the network topology structure of new energy access to the power grid. The fault current calculation module is configured to calculate the fault current injected into each node after a fault occurs in the power grid. When the node is an active node and the power source connected to it is a new energy unit, the fault current injected into the node is calculated based on the new energy voltage source model, ignoring the phase change of the voltage at the new energy grid connection point before and after the fault. The admittance matrix correction module is configured to correct the node admittance matrix Y based on the location of the fault point; The fault voltage calculation module is configured to calculate the fault voltage of each node using the corrected admittance matrix of each node and the fault current injected into each node.

8. A terminal device comprising a processor and a memory, the processor for implementing instructions; the memory for storing multiple instructions, characterized in that, The instructions are adapted to be loaded by a processor and executed by the method for rapid calculation of grid fault voltage distribution under new energy access as described in any one of claims 1-6.

9. A computer-readable storage medium storing a plurality of instructions, characterized in that, The instructions are adapted to be loaded and executed by the processor of the terminal device using the method for rapid calculation of grid fault voltage distribution under new energy access as described in any one of claims 1-6.

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