Method and system for calculating influence degree of grid-connected device on transient voltage stability of power system

Abstract

The application discloses a kind of grid-connected equipment influence degree calculation method and system to power system transient voltage stability, it is related to power system safety and stability analysis field, method includes: by primary time domain simulation obtains network equation during transient, node voltage and the active and reactive power data of grid-connected equipment;For each time point, using network equation calculates the sensitivity of grid-connected equipment power to node voltage;According to node voltage, grid-connected equipment power and sensitivity, the influence degree of grid-connected equipment to node transient voltage stability is calculated;The transient voltage stability influence degree of each grid-connected equipment to all nodes is summarized, and the transient voltage stability influence degree of grid-connected equipment to power system is obtained.The application only needs to evaluate the influence of all grid-connected equipment on the transient voltage stability of power system in different time periods by one simulation, provides decision basis for the optimization control of grid-connected equipment, and improves the calculation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power system security and stability analysis, and in particular to a method and system for calculating the influence degree of grid-connected equipment on transient voltage stability of a power system. BACKGROUND

[0002] Stable voltage is one of the key indicators to ensure the normal operation of power equipment, and transient voltage stability is defined as the ability of all busbars of a power system to maintain stable voltage after the system is subjected to a large disturbance. At present, whether the duration of busbar voltage being lower than the set threshold in the transient process is greater than the set time is used to judge the transient voltage stability. With the increasing scale of new energy power generation and DC transmission applications, the influence of new energy units being disconnected from the grid due to high voltage and DC transmission systems being locked out due to high voltage on the safe and stable operation of the power system is increasing. Therefore, whether the duration of busbar voltage being higher than the set threshold in the transient process is greater than the set time should also be used as a judgment index of transient voltage stability.

[0003] The existing technology focuses on studying transient low voltage stability, calculating transient low voltage stability margin based on busbar transient voltage curve, and using the perturbation method to calculate the sensitivity of the change of node reactive power compensation or device reactive voltage control parameter to the transient low voltage stability margin, as an index for measuring the influence of node reactive power compensation or device reactive voltage control parameter on transient low voltage stability. Based on the perturbation method, two time-domain simulation calculations are required to obtain the influence degree of a variable. For a large-scale power system, the calculation amount of obtaining the influence degree of all grid-connected equipment is huge. SUMMARY

[0004] In view of the above problems, the present application is proposed.

[0005] Therefore, the technical problem solved by the present application is how to determine the influence degree of all grid-connected equipment on the transient voltage stability of a power system based on one time-domain simulation calculation.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a method for calculating the influence degree of grid-connected equipment on the transient voltage stability of a power system, comprising:

[0008] For a preset power system operating state and a preset disturbance, the network equation at each time point in the transient process, the voltage at each preset node, and the active and reactive power injected into the power grid by each preset grid-connected equipment are obtained through one time-domain simulation;

[0009] For each time point in the preset transient period, the sensitivity of the active and reactive power injected into the power grid by each preset grid-connected equipment to the voltage at each preset node is calculated according to the network equation corresponding to each time point, respectively;

[0010] For each preset grid-connected device and each preset node, the influence degree of the preset grid-connected device on the transient voltage stability of the preset node in the preset transient period is calculated according to the preset node voltage, the active power and the reactive power of the preset grid-connected device injected into the power grid, and the sensitivity of the active power and the reactive power of the preset grid-connected device injected into the power grid to the voltage of each preset node in the preset transient period.

[0011] For each preset grid-connected device, the influence degree of the preset grid-connected device on the transient voltage stability of the power system in the preset transient period is calculated according to the influence degree of the preset grid-connected device on the transient voltage stability of each preset node in the preset transient period.

[0012] As an optimal solution of the method for calculating the influence degree of the grid-connected device on the transient voltage stability of the power system, wherein:

[0013] The transient voltage stability includes two types of transient low-voltage stability and transient high-voltage stability.

[0014] As an optimal solution of the method for calculating the influence degree of the grid-connected device on the transient voltage stability of the power system, wherein:

[0015] The calculation of the sensitivity of the active power and the reactive power of the preset grid-connected device injected into the power grid to the voltage of each preset node includes:

[0016] For the device with only reactive power grid connection, the sensitivity of the active power of the preset grid-connected device injected into the power grid to the voltage of each preset node is set to 0; for the device with only active power grid connection, the sensitivity of the reactive power of the preset grid-connected device injected into the power grid to the voltage of each preset node is set to 0.

[0017] As an optimal solution of the method for calculating the influence degree of the grid-connected device on the transient voltage stability of the power system, wherein:

[0018] The influence degree of the preset grid-connected device on the transient voltage stability of the preset node in the preset transient period includes the influence degree of the preset grid-connected device on the transient low-voltage stability of the preset node in the preset transient period, and the calculation formula is:

[0019]

[0020] Wherein, λ b.vd is the influence degree of the preset grid-connected device on the transient low-voltage stability of the preset node b in the preset transient period, n is the number of time points in the preset transient period, V b.u , V b.d are the upper and lower limits of the steady-state voltage of the preset node b, V b.i is the voltage of the preset node b at the i th time point in the preset transient period, and a is a set parameter; S b.v.i.p , S b.v.i.qSensitivity of active power and reactive power injected into the power grid by the preset grid-connected device at the ith time point in the preset transient period to the voltage of the preset node b, P i , Q i Active power and reactive power injected into the power grid by the preset grid-connected device at the ith time point in the preset transient period, t i Time corresponding to the ith time point in the preset transient period, V d.cr Voltage threshold value in the transient low-voltage stability criterion, and β is a set parameter.

[0021] As an optimal scheme of the method for calculating the influence degree of the grid-connected device on the transient voltage stability of the power system, wherein

[0022] The influence degree of the preset grid-connected device on the transient voltage stability of the preset node in the preset transient period further includes the influence degree of the preset grid-connected device on the transient high-voltage stability of the preset node in the preset transient period, and the calculation formula is:

[0023]

[0024] Wherein, λ b.vu Influence degree of the preset grid-connected device on the transient high-voltage of the preset node b in the preset transient period, n is the number of time points in the preset transient period, V b.u , V b.d Upper and lower limits of the steady-state voltage of the preset node b, V b.i Voltage of the preset node b at the ith time point in the preset transient period, and α is a set parameter, and α is greater than 0; S b.v.i.p , S b.v.i.q Sensitivity of active power and reactive power injected into the power grid by the preset grid-connected device at the ith time point in the preset transient period to the voltage of the preset node b, P i , Q i Active power and reactive power injected into the power grid by the preset grid-connected device at the ith time point in the preset transient period, t i Time corresponding to the ith time point in the preset transient period, V u.cr Voltage threshold value in the transient high-voltage stability criterion, and γ is a set parameter.

[0025] As an optimal scheme of the method for calculating the influence degree of the grid-connected device on the transient voltage stability of the power system, wherein

[0026] The influence degree of the preset grid-connected device on the transient voltage stability of the power system in the preset transient period includes the influence degree of the preset grid-connected device on the transient low-voltage stability of the power system in the preset transient period, and the calculation formula is:

[0027]

[0028] wherein λ vd is the influence degree of the preset grid-connected device on the transient low-voltage stability of the power system in the preset transient period.

[0029] As a preferred solution of the method for calculating the influence degree of the grid-connected device on the transient voltage stability of the power system, wherein:

[0030] The influence degree of the preset grid-connected device on the transient voltage stability of the power system in the preset transient period further includes an influence degree of the preset grid-connected device on the transient high-voltage stability of the power system in the preset transient period, and the calculation formula is:

[0031]

[0032] wherein λ vu is the influence degree of the preset grid-connected device on the transient high-voltage stability of the power system in the preset transient period.

[0033] In a second aspect, an embodiment of the present application provides a system for calculating the influence degree of a grid-connected device on the transient voltage stability of a power system, comprising:

[0034] A time-domain simulation calculation module is configured to, for a preset power system operating state and a preset disturbance, obtain, through one time-domain simulation, network equations at each time point in a transient process, each preset node voltage, and active power and reactive power injected into the power grid by each preset grid-connected device;

[0035] A voltage sensitivity calculation module is configured to, for each time point in a preset transient period, calculate, according to the network equation corresponding to each time point, the sensitivity of active power and reactive power injected into the power grid by each preset grid-connected device to each preset node voltage;

[0036] A node influence degree calculation module is configured to, for each preset grid-connected device and each preset node, calculate, according to the preset node voltage, the active power and reactive power injected into the power grid by the preset grid-connected device, and the sensitivity of the active power and reactive power injected into the power grid by each preset grid-connected device to each preset node voltage in the preset transient period, the influence degree of the preset grid-connected device on the transient voltage stability of the preset node in the preset transient period;

[0037] A power system influence degree calculation module is configured to, for each preset grid-connected device, calculate, according to the influence degree of the preset grid-connected device on the transient voltage stability of each preset node in the preset transient period, the influence degree of the preset grid-connected device on the transient voltage stability of the power system in the preset transient period.

[0038] In a third aspect, an embodiment of the present application provides a computing device, comprising:

[0039] a memory and a processor;

[0040] The memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions, when the one or more programs are executed by the one or more processors, so that the one or more processors implement the grid-connected device transient voltage stability influence degree calculation method of the power system according to any one of the embodiments of the present application.

[0041] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium storing computer executable instructions, which, when executed by a processor, implement the grid-connected device transient voltage stability influence degree calculation method of the power system.

[0042] The present application has the following beneficial effects: the present application can give the influence degree of all grid-connected devices in the power grid on the transient low voltage stability and the transient high voltage stability of the power system in different time periods in the transient process through only one time domain simulation calculation, thereby providing a decision basis for the transient voltage stability optimization control of various grid-connected devices such as power sources, loads, energy storage devices and reactive power compensation devices, and improving the calculation efficiency of the optimization decision. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and any person skilled in the art can obtain other drawings according to these drawings without any creative labor.

[0044] Figure 1 is the overall flowchart of the grid-connected device transient voltage stability influence degree calculation method of the power system according to the first embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative labor should be within the protection scope of the present application.

[0046] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the concept of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0047] Second, the "one embodiment" or "an embodiment" referred to herein means a specific feature, structure, or characteristic under discussion. Each of the various embodiments presented in this specification are not necessarily mutually exclusive, but can be selectively implemented in various embodiments of the application.

[0048] Embodiment 1

[0049] With reference to Figure 1 For a first embodiment of the application, the embodiment provides a method for calculating the influence degree of a grid-connected device on transient voltage stability of a power system, comprising:

[0050] S1: for a preset power system operating state and a preset disturbance, obtaining network equations at each time point in a transient process, each preset node voltage, active power and reactive power injected into the power grid by each preset grid-connected device through a time-domain simulation;

[0051] It should be noted that the change amount of active power and reactive power injected into the power grid by the power device and the voltage sensitivity of active power and reactive power to the nodes in the power grid are two key factors affecting the node voltage. In the case that each node voltage in the power grid is near the rated value, the active voltage sensitivity is relatively small compared to the reactive voltage sensitivity, and the active power and reactive power change amount is not much different, so the influence of active power change on node voltage can be ignored, but the node voltage fluctuation is large in the transient process, so the influence of active power change on node voltage needs to be considered. In addition, the degree of deviation of the node voltage from the normal value in the transient process and the cumulative effect of the device on the node voltage also need to be considered.

[0052] S2: for each time point in a preset transient period, calculating the sensitivity of active power and reactive power injected into the power grid by each preset grid-connected device to each preset node voltage according to the network equation corresponding to each time point;

[0053] In the embodiment of the application, calculating the sensitivity of active power and reactive power injected into the power grid by each preset grid-connected device to each preset node voltage comprises:

[0054] For a device with only reactive power grid connection, the sensitivity of active power injected into the power grid by the preset grid-connected device to each preset node voltage is set to 0; for a device with only active power grid connection, the sensitivity of reactive power injected into the power grid by the preset grid-connected device to each preset node voltage is set to 0.

[0055] S3: for each preset grid-connected device and each preset node, calculating the influence degree of the preset grid-connected device on the transient voltage stability of the preset node in the preset transient period according to the preset node voltage, the active power and reactive power injected into the power grid by the preset grid-connected device, and the sensitivity of the active power and reactive power injected into the power grid by the preset grid-connected device to the preset node voltage in the preset transient period;

[0056] In this embodiment, the influence of the preset grid-connected equipment on the transient voltage stability of the preset node within the preset transient period includes the influence of the preset grid-connected equipment on the transient low voltage stability of the preset node within the preset transient period, and the calculation formula is as follows:

[0057]

[0058] Where, λ b.vd The transient low voltage stability impact of the grid-connected equipment on the preset node b within a preset transient period, where n is the number of time points within the preset transient period, and V b.u V b.d These are the upper and lower limits of the preset steady-state voltage at node b, respectively, V b.i The voltage of node b at the i-th time point within the preset transient period is α, which is a set parameter; S b.v.i.p S b.v.i.q Let P be the sensitivity of the active power injected into the grid by the preset grid-connected equipment to the voltage of the preset node b, and the sensitivity of the reactive power injected into the grid to the voltage of the preset node b, respectively, at the i-th time point within the preset transient period. i Q i These represent the active and reactive power injected into the grid by the pre-connected equipment at the i-th time point within the pre-defined transient period, t. i V is the time corresponding to the i-th time point within the preset transient period. d.cr β is the voltage threshold value in the transient low voltage stability criterion, and β is a set parameter.

[0059] In this embodiment, the influence of the preset grid-connected equipment on the transient voltage stability of the preset node during the preset transient period also includes the influence of the preset grid-connected equipment on the transient high voltage stability of the preset node during the preset transient period, and the calculation formula is as follows:

[0060]

[0061] Where, λ b.vu The transient high voltage impact of the grid-connected equipment on the preset node b within a preset transient period, where n is the number of time points within the preset transient period, and V b.u V b.d These are the upper and lower limits of the preset steady-state voltage at node b, respectively, V b.i The voltage of node b at the i-th time point within the preset transient period is set, where α is a set parameter and α is greater than 0; S b.v.i.p S b.v.i.q Let P be the sensitivity of the active power injected into the grid by the preset grid-connected equipment to the voltage of the preset node b, and the sensitivity of the reactive power injected into the grid to the voltage of the preset node b, respectively, at the i-th time point within the preset transient period. i Q i These represent the active and reactive power injected into the grid by the pre-connected equipment at the i-th time point within the pre-defined transient period, t. iV is the time corresponding to the i-th time point within the preset transient period. u.cr γ is the voltage threshold value in the transient high voltage stability criterion, and γ is a set parameter.

[0062] Specifically, α is a setting parameter, greater than 0, usually set to 2; β is a setting parameter, greater than 1, usually set to 1.1; γ is a setting parameter, less than 1, usually set to 0.9.

[0063] S4: For each preset grid-connected device, calculate the impact of the preset grid-connected device on the transient voltage stability of the power system within the preset transient period, based on the impact of the preset grid-connected device on the transient voltage stability of each preset node within the preset transient period.

[0064] In this embodiment of the application, the impact of the preset grid-connected equipment on the transient voltage stability of the power system during the preset transient period includes the impact of the preset grid-connected equipment on the transient low voltage stability of the power system during the preset transient period, and the calculation formula is as follows:

[0065]

[0066] Where, λ vd The preset impact of grid-connected equipment on the transient low voltage stability of the power system during the preset transient period.

[0067] In this embodiment of the application, the influence of the preset grid-connected equipment on the transient voltage stability of the power system during the preset transient period also includes the influence of the preset grid-connected equipment on the transient high voltage stability of the power system during the preset transient period, and the calculation formula is as follows:

[0068]

[0069] Where, λ vu This is to preset the impact of grid-connected equipment on the transient high-voltage stability of the power system during the preset transient period.

[0070] It should be noted that, in the embodiments of this application, transient voltage stability includes two types: transient low voltage stability and transient high voltage stability.

[0071] The above is a schematic scheme for calculating the impact of grid-connected equipment on the transient voltage stability of the power system according to this embodiment. It should be noted that the technical solution of the system for calculating the impact of grid-connected equipment on the transient voltage stability of the power system is based on the same concept as the technical solution of the above-described method for calculating the impact of grid-connected equipment on the transient voltage stability of the power system. Details not described in detail in this embodiment can be found in the description of the above-described method for calculating the impact of grid-connected equipment on the transient voltage stability of the power system.

[0072] The grid-connected device influence degree on power system transient voltage stability calculation system in the embodiment comprises:

[0073] The time domain simulation calculation module is configured to obtain network equations, preset node voltages, and active and reactive power injected into the power grid by each preset grid-connected device in a transient process through one time domain simulation for a preset power system operating state and a preset disturbance.

[0074] The voltage sensitivity calculation module is configured to calculate the sensitivity of active and reactive power injected into the power grid by each preset grid-connected device to each preset node voltage according to the network equation corresponding to each time point in a preset transient period.

[0075] The node influence degree calculation module is configured to calculate the influence degree of each preset grid-connected device on the transient voltage stability of each preset node in the preset transient period according to the preset node voltage, the active and reactive power injected into the power grid by each preset grid-connected device, and the sensitivity of the active and reactive power injected into the power grid by each preset grid-connected device to the voltage of each preset node in the preset transient period.

[0076] The power system influence degree calculation module is configured to calculate the influence degree of each preset grid-connected device on the transient voltage stability of the power system in the preset transient period according to the influence degree of each preset grid-connected device on the transient voltage stability of each preset node in the preset transient period.

[0077] The embodiment also provides a computing device suitable for the grid-connected device influence degree on power system transient voltage stability calculation method, which comprises:

[0078] The storage and the processor; the storage is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions to realize the grid-connected device influence degree on power system transient voltage stability calculation method proposed in the above embodiment.

[0079] The embodiment also provides a storage medium having a computer program stored thereon, and the program is executed by a processor to realize the grid-connected device influence degree on power system transient voltage stability calculation method proposed in the above embodiment.

[0080] The storage medium proposed in the embodiment and the grid-connected device influence degree on power system transient voltage stability calculation method proposed in the above embodiment belong to the same inventive concept, and the technical details not described in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0081] Embodiment 2

[0082] Referring to Tables 1-4, for an embodiment of the present application, a method for calculating the influence degree of a grid-connected device on transient voltage stability of a power system is provided. In order to verify the beneficial effects of the present application, a simulation experiment is performed for scientific demonstration.

[0083] Step 1: Time-domain simulation and data preparation

[0084] 1. Set simulation parameters:

[0085] The operating state and disturbance condition of the power system are preset.

[0086] It is assumed that the power system contains 5 nodes and 3 grid-connected devices. Each device injects active and reactive power at different time points.

[0087] 2. Perform time-domain simulation:

[0088] Run the simulation program to obtain the network equation at each time point in the transient process.

[0089] Obtain the voltage of each node and the active and reactive power injected by the grid-connected device into the power grid, as shown in Table 1:

[0090] Table 1: Node voltage and grid-connected device power injection data

[0091]

[0092] Step 2: Sensitivity calculation

[0093] 1. Calculate voltage sensitivity:

[0094] For each time point, the sensitivity of the preset grid-connected device to the active and reactive power injected into the power grid to the voltage of each preset node is calculated using the network equation.

[0095] For grid-connected devices with only reactive power, the sensitivity of active power to node voltage is set to 0; and for grid-connected devices with only active power, the sensitivity of reactive power to node voltage is set to 0, as shown in Table 2:

[0096] Table 2: Calculation results of node voltage sensitivity

[0097]

[0098] Step 3: Influence degree calculation

[0099] 1. Calculate low voltage stability influence degree:

[0100] For each preset node, within the preset transient period, the influence degree of the preset grid-connected device on transient low voltage stability is calculated according to the voltage and sensitivity at each time point.

[0101] Record the calculation results, considering whether the node voltage is below the low voltage threshold.

[0102] 2. Calculate the high-voltage stability impact degree:

[0103] For each preset node, within the preset transient period, calculate the impact degree of the preset grid-connected device on transient high-voltage stability according to the voltage and sensitivity at each time point.

[0104] Record the calculation results, consider whether the node voltage is above the high-voltage threshold, the results are shown in Table 3:

[0105] Table 3 Voltage stability impact degree evaluation results

[0106]

[0107]

[0108] Step 4: System impact degree calculation

[0109] 1. Calculate the impact degree of grid-connected devices on the transient voltage stability of the power system:

[0110] For each grid-connected device, combine its impact degree on the transient voltage stability of all preset nodes to calculate the impact degree of the device on the overall transient low-voltage and high-voltage stability of the power system.

[0111] Summarize the results to evaluate the contribution and impact of each grid-connected device on system stability, the results are shown in Table 4:

[0112] Table 4 System impact degree calculation results

[0113] Grid connected device number Low voltage stability impact total High voltage stability impact total 1 -0.000659 0 2 -0.000707 0 … … …

[0114] Simulation results:

[0115] 1. Data collection:

[0116] Suppose the simulation data includes the voltage values of each node at different time points and the injected power data of the grid-connected devices.

[0117] Calculate the sensitivity value of each node and the impact degree of each grid-connected device on the node voltage.

[0118] 2. Impact degree evaluation:

[0119] The calculation results of low-voltage stability impact degree and high-voltage stability impact degree show that some grid-connected devices have a greater impact on node voltage stability, especially in high disturbance conditions.

[0120] Through system impact degree calculation, the impact of grid-connected devices on the overall stability of the power system is evaluated, and it is found that some devices have a significant impact on system voltage stability during the transient process.

[0121] The simulation embodiment successfully calculates the influence degree of grid-connected equipment on transient voltage stability of the power system. Through the sensitivity analysis and influence degree evaluation of the system, the role of each grid-connected equipment on the stability of the power system can be better understood, thereby providing data support for the optimization management of the power grid.

[0122] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the present application, and they should be covered in the scope of claims of the present application.

Claims

1. A method for calculating the influence degree of grid-connected equipment on transient voltage stability of a power system, characterized in that, The method comprises the following steps: For the preset power system operating state and the preset disturbance, network equations at each time point in the transient process, each preset node voltage, active power and reactive power of each preset grid-connected device injected into the power grid are obtained through one-time time domain simulation; For each time point in the preset transient period, the sensitivity of the active power and the reactive power of each preset grid-connected device injected into the power grid to the voltage of each preset node is calculated according to the network equation corresponding to each time point; For each preset grid-connected device and each preset node, the influence degree of the preset grid-connected device on the transient voltage stability of the preset node in the preset transient period is calculated according to the preset node voltage, the active power and the reactive power of the preset grid-connected device injected into the power grid, and the sensitivity of the active power and the reactive power of the preset grid-connected device injected into the power grid to the voltage of each preset node in the preset transient period; For each preset grid-connected device, the influence degree of the preset grid-connected device on the transient voltage stability of the power system in the preset transient period is calculated according to the influence degree of the preset grid-connected device on the transient voltage stability of each preset node in the preset transient period.

2. The method of claim 1, wherein the method comprises: The transient voltage stability includes two types of transient low voltage stability and transient high voltage stability.

3. The method of claim 2, wherein the method comprises: The calculation of the sensitivity of the active power and the reactive power of each preset grid-connected device injected into the power grid to the voltage of each preset node comprises: For the device with only reactive power grid connection, the sensitivity of the active power of the preset grid-connected device injected into the power grid to the voltage of each preset node is set to 0; for the device with only active power grid connection, the sensitivity of the reactive power of the preset grid-connected device injected into the power grid to the voltage of each preset node is set to 0.

4. The method of claim 3, wherein the method comprises: The influence degree of the preset grid-connected device on the transient low voltage stability of the preset node in the preset transient period comprises the influence degree of the preset grid-connected device on the transient low voltage stability of the preset node in the preset transient period, and the calculation formula is: wherein λ b.vd is a preset transient low-voltage stability influence degree of the preset grid-connected device on the preset node b within a preset transient period, n is a time point number within the preset transient period, V b.u , V b.d are an upper limit and a lower limit of a steady-state voltage of the preset node b, respectively, V b.i is a voltage of the preset node b at an i-th time point within the preset transient period, and a is a set parameter; S b.v.i.p , S b.v.i.q are a real power sensitivity and a reactive power sensitivity of the preset grid-connected device to the voltage of the preset node b when connected to the power grid at the i-th time point within the preset transient period, P i , Q i are a real power and a reactive power of the preset grid-connected device when connected to the power grid at the i-th time point within the preset transient period, t i is a time corresponding to the i-th time point within the preset transient period, and V d.cr is a voltage threshold in the transient low-voltage stability criterion, and β is a set parameter.

5. The method of claim 4, wherein the method comprises: The influence degree of the preset grid-connected device on the transient high voltage stability of the preset node in the preset transient period comprises the influence degree of the preset grid-connected device on the transient high voltage stability of the preset node in the preset transient period, and the calculation formula is: wherein λ b.vu is a preset transient high voltage influence degree of the preset grid-connected device on the preset node b within a preset transient period, n is a time point number within the preset transient period, V b.u , V b.d are respectively an upper limit and a lower limit of a steady-state voltage of the preset node b, V b.i is a voltage of the preset node b at an i-th time point within the preset transient period, and a is a set parameter, a being greater than 0; S b.v.i.p , S b.v.i.q are respectively a real power sensitivity and a reactive power sensitivity of the preset grid-connected device to the voltage of the preset node b at the i-th time point within the preset transient period, P i , Q i are respectively a real power and a reactive power of the preset grid-connected device injected into the power grid at the i-th time point within the preset transient period, t i is a time corresponding to the i-th time point within the preset transient period, V u.cr is a voltage threshold value in a transient high voltage stability criterion, and γ is a set parameter.

6. The method of claim 5, wherein the method comprises: The influence degree of the preset grid-connected device on the transient low voltage stability of the power system in the preset transient period comprises the influence degree of the preset grid-connected device on the transient low voltage stability of the power system in the preset transient period, and the calculation formula is: wherein λ vd is the preset transient low-voltage stability influence degree of the preset grid-connected device on the power system within the preset transient period.

7. The method of claim 6, wherein the method further comprises: calculating the influence degree of the grid-connected device on the transient voltage stability of the power system based on the calculated influence degree of the grid-connected device on the transient voltage stability of the power system. The influence degree of the preset grid-connected device on the transient high voltage stability of the power system in the preset transient period comprises the influence degree of the preset grid-connected device on the transient high voltage stability of the power system in the preset transient period, and the calculation formula is: wherein λ vu is the preset transient high-voltage stability influence degree of the preset grid-connected device on the power system within the preset transient period.

8. A system for calculating the influence degree of the transient voltage stability of a power system using the grid-connected device according to any one of claims 1 to 7, characterized by The method comprises the following steps: The time domain simulation calculation module is used for obtaining, for the preset power system operating state and the preset disturbance, network equations at each time point in the transient process, each preset node voltage, active power and reactive power of each preset grid-connected device injected into the power grid through one-time time domain simulation; The voltage sensitivity calculation module is used for calculating, for each time point in the preset transient period, the sensitivity of the active power and the reactive power of each preset grid-connected device injected into the power grid to the voltage of each preset node according to the network equation corresponding to each time point; The node influence degree calculation module is configured to calculate, for each preset grid-connected device and each preset node, an influence degree of the preset grid-connected device on transient voltage stability of the preset node in the preset transient period according to the preset node voltage, active and reactive power injected into the power grid by the preset grid-connected device, and sensitivity of the active and reactive power injected into the power grid by the preset grid-connected device to the preset node voltage in the preset transient period. The power system influence degree calculation module is configured to calculate, for each preset grid-connected device, an influence degree of the preset grid-connected device on transient voltage stability of the power system in the preset transient period according to the influence degree of the preset grid-connected device on transient voltage stability of each preset node in the preset transient period. 9.A computing device, comprising: a memory and a processor; the memory is configured to store computer executable instructions, and the processor is configured to execute the computer executable instructions, which, when executed by the processor, implement the steps of the method for calculating an influence degree of a grid-connected device on transient voltage stability of a power system according to any one of claims 1 to 7. 10.A computer readable storage medium storing computer executable instructions, which, when executed by a processor, implement the steps of the method for calculating an influence degree of a grid-connected device on transient voltage stability of a power system according to any one of claims 1 to 7.

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