Method and device for checking reactive power switching strategy of extra-high voltage ac substation

Abstract

The application discloses a method and device for checking reactive power switching strategy of an extra-high voltage AC substation, comprising: determining the upper limit of steady-state overvoltage and the upper limit of reactive power exchange of the extra-high voltage AC substation; determining the reactive power switching strategy of the main transformer of the substation according to the upper limit of reactive power exchange; calculating the steady-state overvoltage of the extra-high voltage substation under an extreme mode according to the reactive power switching strategy, the upper limit of steady-state overvoltage and the upper limit of reactive power exchange, and adjusting the steady-state overvoltage through relevant reactive power switching measures; performing AC-DC fault and power fluctuation fault transient stability simulation on the extra-high voltage AC substation, if the system is unstable, supplementing the control measures; on the basis of system stability, if the transient overvoltage of the current extra-high voltage substation is out of limit, adjusting the control measures until the system is stable and the transient overvoltage meets preset requirements. The application improves the analysis efficiency of the checking of the reactive power switching strategy of the extra-high voltage AC substation.

Description

Technical Field

[0001] This invention relates to the field of safe and stable operation of ultra-high voltage AC / DC hybrid power grids, specifically to a method and apparatus for verifying reactive power switching strategies in ultra-high voltage AC substations. Background Technology

[0002] With the continuous increase in inter-regional transmission capacity, multiple ultra-high voltage AC / DC projects have been completed and put into operation, the scale of AC / DC hybrid power grids has become increasingly large, the integrated characteristics of power grid structure have become increasingly prominent, and the mutual influence between ultra-high voltage AC / DC systems has become more significant, posing new challenges to the safe and stable operation of the actual power grid.

[0003] The configuration of reactive power compensation equipment in ultra-high voltage AC / DC hybrid power grids is closely related to the system's operating voltage level. Low voltage operation increases network losses and power supply costs, while also reducing the power limit of transmission lines, thus decreasing system stability. Overvoltage operation accelerates insulation aging in electrical equipment, potentially causing equipment damage and leading to system failures or even stability disruptions. Therefore, the proper configuration of reactive power compensation equipment can effectively improve the system's reactive power distribution and voltage level, mitigate various potential safety risks from abnormal voltage operation, and enhance the stability of AC / DC hybrid power grids.

[0004] Currently, the verification of reactive power switching strategies in UHV AC substations generally suffers from problems such as unclear calculation logic, cumbersome calculation content, and high time costs. There is an urgent need to propose a logically rigorous, concise, and computationally efficient method for verifying reactive power switching strategies. This method would be helpful for conducting stability characteristic analysis on AC / DC hybrid power grids with significant grid changes, and would be of great significance for identifying safety hazards under different operating modes and ensuring the safe and efficient operation of the actual power grid. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for verifying reactive power switching strategies in ultra-high voltage AC substations, comprising:

[0006] Determine the upper limit of steady-state overvoltage and the upper limit of reactive power exchange for the UHV AC substation; based on the upper limit of reactive power exchange, determine the reactive power switching strategy of the main transformer of the UHV AC substation.

[0007] Based on the aforementioned reactive power switching strategy, and through the upper limit of steady-state overvoltage and the upper limit of reactive power exchange, the steady-state overvoltage of the UHV substation under extreme conditions is calculated, and the steady-state overvoltage is adjusted through relevant reactive power switching measures.

[0008] Transient stability simulations of AC / DC faults and power fluctuation faults are performed on the UHV AC substation. If the system becomes unstable, additional safety control measures are implemented. If the transient overvoltage of the current UHV substation exceeds the limit after the system has stabilized, the safety control measures are adjusted until the system is stable and the transient overvoltage meets the preset requirements.

[0009] Furthermore, based on the aforementioned upper limit of reactive power exchange, the reactive power switching strategy for the main transformer of the UHV AC substation is determined, including:

[0010] Select the reactive power switching strategy of the main transformer based on the transmission direction and capacity of the UHV transmission line;

[0011] Power flow calculations are used to determine whether the voltage on the 1000kV side and the 500kV side of the UHV substation, as well as the reactive power exchange on both sides, exceed the limits.

[0012] If any limit is exceeded, the reactive power resources in the vicinity of the UHV substation will be switched on first, and the voltage will be adjusted to be within a reasonable operating range and the reactive power exchange amount will not exceed the upper limit of the reactive power exchange amount.

[0013] When the reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limit, the reactive power resources of the main transformer in the UHV AC substation are switched, and it is judged again whether the voltage and reactive power exchange of the 1000kV side and 500kV side in the UHV substation meet the requirements. This process is repeated until the system operation mode and the reactive power switching strategy of the main transformer in the UHV AC substation are determined.

[0014] Furthermore, based on the aforementioned reactive power switching strategy, and through the upper limit of steady-state overvoltage and the upper limit of reactive power exchange, the steady-state overvoltage of the UHV substation under extreme conditions is calculated, and the steady-state overvoltage is adjusted through relevant reactive power switching measures, including:

[0015] A jumper fault simulation was conducted on an ultra-high voltage interconnection line, and the steady-state overvoltage value was calculated.

[0016] Determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system and the steady-state overvoltage both meet the preset requirements.

[0017] Based on the current system operation mode, select either side of the UHV tie line for series compensation maintenance and calculate the steady-state overvoltage caused by the UHV tie line jumper.

[0018] Determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system, the steady-state overvoltage under extreme conditions, and the steady-state overvoltage under series compensation maintenance conditions all meet the preset requirements.

[0019] Furthermore, it also includes:

[0020] If the preset requirements still cannot be met after the reactive power switching measures are invoked, series compensation maintenance is not recommended under this operating mode.

[0021] Furthermore, transient stability simulations of AC / DC faults and power fluctuation faults are performed on the aforementioned UHV AC substation. If the system becomes unstable, supplementary safety control measures are implemented, including:

[0022] The system simulates single-pole blocking faults, jumper faults, and power fluctuation faults on some UHVDC lines and performs transient stability simulations. If the system becomes unstable, additional safety control measures are implemented.

[0023] Furthermore, based on the stability of the system, if the transient overvoltage of the current UHV substation exceeds the limit, the safety control measures will be adjusted, including:

[0024] After a fault occurs, once the system is stable, determine whether the transient overvoltages of the 1000kV and 500kV of the current UHV station exceed the limits. If they do, adjust the safety control measures.

[0025] This invention also provides a device for verifying reactive power switching strategies in ultra-high voltage AC substations, comprising:

[0026] The reactive power switching strategy determination unit is used to determine the upper limit of steady-state overvoltage and the upper limit of reactive power exchange in the UHV AC substation; and to determine the reactive power switching strategy of the main transformer in the UHV AC substation based on the upper limit of reactive power exchange.

[0027] The steady-state overvoltage calculation unit is used to calculate the steady-state overvoltage of the UHV substation under extreme conditions based on the reactive power switching strategy, the upper limit of steady-state overvoltage, and the upper limit of reactive power exchange, and to adjust the steady-state overvoltage through relevant reactive power switching measures.

[0028] The fault simulation unit is used to perform transient stability simulation of AC / DC faults and power fluctuation faults in the UHV AC substation. If the system becomes unstable, additional safety control measures are implemented. If the transient overvoltage of the current UHV substation exceeds the limit after the system has stabilized, the safety control measures are adjusted until the system is stable and the transient overvoltage meets the preset requirements.

[0029] Furthermore, the reactive power switching strategy determination unit includes:

[0030] The reactive power switching strategy selection subunit is used to select the main transformer reactive power switching strategy based on the transmission direction and capacity of the UHV interconnection line.

[0031] The power flow calculation subunit is used to determine whether the voltage on the 1000kV side and the 500kV side of the UHV substation and the reactive power exchange on both sides exceed the limits through power flow calculation.

[0032] The reactive power resource switching subunit is used to prioritize switching reactive power resources in the vicinity of the UHV substation if any limit is exceeded, and to adjust the voltage to a reasonable operating range and the reactive power exchange amount not exceeding the upper limit of the reactive power exchange amount.

[0033] The reactive power switching strategy determination subunit is used to switch the reactive power resources of the main transformer in the UHV AC substation when the reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limit. It then re-determines whether the voltage and reactive power exchange of the 1000kV and 500kV sides in the UHV substation meet the requirements. This process is repeated until the system operation mode and the reactive power switching strategy of the main transformer in the UHV AC substation are determined.

[0034] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described in any of the preceding claims.

[0035] The present invention also provides a readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method as described in any one of the preceding claims.

[0036] This invention provides a method and apparatus for verifying reactive power switching strategies in ultra-high voltage AC substations. The method is logically clear and easy to implement. Using this method in the calculation of reactive power switching strategies in ultra-high voltage AC substations can significantly improve the efficiency of strategy verification and is helpful for analyzing and studying large AC / DC hybrid power grids with significant grid structure changes, thereby improving the safety and stability of power grid operation. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating a method for verifying reactive power switching strategies in ultra-high voltage AC substations provided by the present invention.

[0038] Figure 2 This is a flowchart of the verification process for reactive power switching strategy in UHV AC substations provided by the present invention.

[0039] Figure 3 This is a schematic diagram of a device structure provided by the present invention for verifying the reactive power switching strategy of an ultra-high voltage AC substation. Detailed Implementation

[0040] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0041] Example 1

[0042] Figure 1 This is a flowchart of a method for verifying reactive power switching strategies in ultra-high voltage AC substations, provided by the present invention. The following is based on... Figure 1 The method provided by this invention will be described in detail.

[0043] Step S101: Determine the upper limit of steady-state overvoltage and the upper limit of reactive power exchange of the UHV AC substation; based on the upper limit of reactive power exchange, determine the reactive power switching strategy of the main transformer of the UHV AC substation.

[0044] The reactive power exchange on the 1000kV and 500kV sides of the UHV AC substation is directly related to the steady-state overvoltage caused by UHV line jumpers, and a steady-state overvoltage upper limit U needs to be set in advance. ct and the upper limit of reactive power exchange Q ct .

[0045] Based on the transmission direction and capacity of the UHV transmission lines, a reactive power switching strategy for the main transformer is selected. Power flow calculations are used to determine whether the voltage and reactive power exchange on the 1000kV and 500kV sides of the UHV substation exceed limits. If either exceeds a limit, reactive power resources in the vicinity of the UHV substation are switched first, and the voltage is adjusted to a reasonable operating range while the reactive power exchange does not exceed the upper limit. When reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limit, the reactive power resources of the main transformer in the UHV AC substation are switched, and the voltage and reactive power exchange on the 1000kV and 500kV sides of the UHV substation are again checked to see if they meet the requirements. This process is repeated until the system operating mode and the reactive power switching strategy for the main transformer in the UHV AC substation are determined.

[0046] Step S102: Based on the reactive power switching strategy, the steady-state overvoltage limit and the reactive power exchange limit are used to calculate the steady-state overvoltage of the UHV substation under extreme conditions, and the steady-state overvoltage is adjusted through relevant reactive power switching measures.

[0047] A jumper fault simulation was conducted on the UHV interconnection line to calculate the steady-state overvoltage value. It was then determined whether the steady-state overvoltage value exceeded the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeded the limit, the steady-state overvoltage was adjusted by reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV line and the steady-state overvoltage both met the preset requirements.

[0048] Based on the current system operation mode, select either side of the UHV tie line for series compensation maintenance, and calculate the steady-state overvoltage caused by the UHV tie line jumper; determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV, the steady-state overvoltage under extreme mode, and the steady-state overvoltage under series compensation maintenance mode all meet the preset requirements.

[0049] If the reactive power switching measures fail to meet the preset requirements after being invoked, series compensation maintenance is not recommended under this operating mode.

[0050] Step S103: Perform transient stability simulation of AC / DC faults and power fluctuation faults on the UHV AC substation. If the system becomes unstable, supplementary safety control measures are implemented. If the transient overvoltage of the current UHV substation exceeds the limit on the basis of system stability, adjust the safety control measures until the system is stable and the transient overvoltage meets the preset requirements.

[0051] The system simulates single-pole blocking faults, jumper faults, and power fluctuation faults on certain UHVDC lines, and performs transient stability simulations. If the system becomes unstable, additional safety control measures are implemented. After a fault, once the system stabilizes, it is determined whether the transient overvoltages on the 1000kV and 500kV sides of the current UHV station exceed the limits. If they do, the safety control measures are adjusted until the system stabilizes and the transient overvoltages meet the preset requirements.

[0052] Example 2

[0053] like Figure 2 The flowchart shown illustrates that this invention is achieved through the following technical solution, which includes the following parts:

[0054] Step 1: Verification of existing reactive power switching strategy

[0055] (1) Given the upper limit of steady-state overvoltage U ct and the upper limit of reactive power exchange Q ct

[0056] Before the verification calculation, the voltage operating range during normal system operation and the reactive power switching strategy of the existing UHV AC substation main transformers need to be given. In addition, the reactive power exchange between the 1000kV and 500kV sides of the UHV AC substation is directly related to the steady-state overvoltage caused by UHV line jumpers; therefore, a steady-state overvoltage upper limit U needs to be pre-set. ct and the upper limit of reactive power exchange Q ct .

[0057] (2) Judgment of over-limit of 1000kV and 500kV voltage and reactive power exchange on both sides in UHV substation

[0058] Under a given operating mode, based on the transmission direction and capacity of the UHV interconnection line, the corresponding reactive power switching strategy of the main transformer is selected, and the voltage on the 1000kV side and the 500kV side of the UHV station and the reactive power exchange on both sides are judged by power flow calculation to determine whether they exceed the limits.

[0059] If any limit is exceeded, priority should be given to switching on low-capacitance / low-resistance equipment in the vicinity of the UHV substation, adjusting the voltage to within a reasonable operating range and ensuring that the reactive power exchange does not exceed Q. ct When the reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limits, the reactive power resources of the main transformer within the UHV AC substation are utilized. This involves switching on the low-capacitance, low-resistance equipment on the low-voltage side of the main transformer, and then reassessing whether the voltage and reactive power exchange on both the 1000kV and 500kV sides of the UHV substation meet the requirements. This process is repeated until the system operating mode (near the UHV AC substation) and the reactive power switching strategy of the UHV AC substation's main transformer are determined.

[0060] Step 2: Steady-state overvoltage calculation under extreme conditions

[0061] (1) Determine the extreme methods

[0062] Under the system operation mode determined in step 1, the calculation requirements for steady-state overvoltage caused by the tripping of the UHV tie line are determined, the reactive power switching strategy of the low-voltage side of the UHV main transformer is determined, the extreme mode is formed and the power flow is calculated.

[0063] (2) Judgment of excessive reactive power exchange between the 1000kV and 500kV sides of the UHV line

[0064] Determine whether the reactive power exchange between the 1000kV side and the 500kV side of the UHV system exceeds Q. ct If the reactive power exchange exceeds the limit, adjustments can be made through relevant reactive power switching measures, with the following priority order:

[0065] ① Implement low capacitance / low reactance in the vicinity of the ultra-high voltage substation;

[0066] ② Disconnect the air-charging (ground-charging) lines in the vicinity of the UHV substation;

[0067] ③ Change the tap of the main transformer in the ultra-high voltage station.

[0068] (3) Judgment of steady-state overvoltage exceeding the limit caused by UHV interconnection line jumper

[0069] A jumper fault simulation was conducted on an ultra-high voltage (UHV) interconnection line to calculate the steady-state overvoltage value and determine whether the steady-state overvoltage exceeds U. ct If the steady-state overvoltage exceeds the limit, then jump to step 2 (2) for adjustment until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system and the steady-state overvoltage both meet the requirements.

[0070] (4) Judgment of steady-state overvoltage limit under the maintenance mode of UHV interconnection line series repair

[0071] Under the system operation mode obtained in step (3), series compensation maintenance is performed on one side of the UHV tie line. The steady-state overvoltage caused by the UHV tie line jumper is calculated, and it is determined whether its value exceeds U. ct If the steady-state overvoltage exceeds the limit, proceed to step (2) in step 2 for adjustment until the reactive power exchange between the 1000kV and 500kV sides of the UHV system, the steady-state overvoltage under extreme conditions, and the steady-state overvoltage under series compensation maintenance all meet the requirements. If the above requirements still cannot be met simultaneously after all reactive power resources have been mobilized, it is not recommended to arrange series compensation maintenance under this method.

[0072] Step 3: AC / DC Fault / Power Fluctuation Verification

[0073] (1) Simulation of single-pole blocking fault in UHVDC line

[0074] Under the system operation mode determined in step 1, a single-pole blocking fault is set for some UHVDC lines, and transient stability simulation is performed.

[0075] (2) Determine if the system is stable

[0076] Determine if the system is stable after the fault. If the system is unstable, implement additional safety control measures, such as adjusting the switching / load, to ensure system stability.

[0077] (3) Judgment of transient / steady-state overvoltage limits caused by faults

[0078] After the system stabilizes following a fault, determine whether the transient / steady-state overvoltages at the 1000kV and 500kV levels of the current UHV station exceed the limits. If the transient / steady-state overvoltages exceed the limits, adjust the safety control measures until the system stabilizes and the transient / steady-state overvoltages meet the requirements.

[0079] (4) Simulation of jumper fault in UHV AC line

[0080] Set up a partial UHV AC line disconnection fault and perform transient stability simulation, then jump to step 3(2).

[0081] (5) Power fluctuation fault simulation

[0082] Set the value to P. t The power fluctuation fault is detected, and transient stability simulation is performed. Then, the process jumps to step 3 (2).

[0083] Once all the above calculations are completed and the requirements are met, the strategy verification is complete.

[0084] Based on the same inventive concept, this invention also provides a device 300 for verifying the reactive power switching strategy of ultra-high voltage AC substations, such as... Figure 3 As shown, it includes:

[0085] The reactive power switching strategy determination unit 310 is used to determine the upper limit of steady-state overvoltage and the upper limit of reactive power exchange in the UHV AC substation; and to determine the reactive power switching strategy of the main transformer of the UHV AC substation based on the upper limit of reactive power exchange.

[0086] The steady-state overvoltage calculation unit 320 is used to calculate the steady-state overvoltage of the UHV substation under extreme conditions based on the reactive power switching strategy, the upper limit of steady-state overvoltage, and the upper limit of reactive power exchange, and to adjust the steady-state overvoltage through relevant reactive power switching measures.

[0087] The fault simulation unit 330 is used to perform transient stability simulation of AC / DC faults and power fluctuation faults in the UHV AC substation. If the system becomes unstable, additional safety control measures are implemented. If the transient overvoltage of the current UHV substation exceeds the limit after the system stabilizes, the safety control measures are adjusted until the system stabilizes and the transient overvoltage meets the preset requirements.

[0088] Furthermore, the reactive power switching strategy determination unit includes:

[0089] The reactive power switching strategy selection subunit is used to select the main transformer reactive power switching strategy based on the transmission direction and capacity of the UHV interconnection line.

[0090] The power flow calculation subunit is used to determine whether the voltage on the 1000kV side and the 500kV side of the UHV substation and the reactive power exchange on both sides exceed the limits through power flow calculation.

[0091] The reactive power resource switching subunit is used to prioritize switching reactive power resources in the vicinity of the UHV substation if any limit is exceeded, and to adjust the voltage to a reasonable operating range and the reactive power exchange amount not exceeding the upper limit of the reactive power exchange amount.

[0092] The reactive power switching strategy determination subunit is used to switch the reactive power resources of the main transformer in the UHV AC substation when the reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limit. It then re-determines whether the voltage and reactive power exchange of the 1000kV and 500kV sides in the UHV substation meet the requirements. This process is repeated until the system operation mode and the reactive power switching strategy of the main transformer in the UHV AC substation are determined.

[0093] This invention provides a method and apparatus for verifying reactive power switching strategies in ultra-high voltage AC substations. The method is logically clear and easy to implement. Using this method in the calculation of reactive power switching strategies in ultra-high voltage AC substations can significantly improve the efficiency of strategy verification and is helpful for analyzing and studying large AC / DC hybrid power grids with significant grid structure changes, thereby improving the safety and stability of power grid operation.

[0094] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0095] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0096] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0097] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for verifying reactive power switching strategies in ultra-high voltage AC substations, characterized in that, include: Determine the upper limit of steady-state overvoltage and the upper limit of reactive power exchange for UHV AC substations; Based on the aforementioned upper limit of reactive power exchange, the reactive power switching strategy for the main transformer of the UHV AC substation is determined, specifically including: Select the reactive power switching strategy of the main transformer based on the transmission direction and capacity of the UHV transmission line; Power flow calculations are used to determine whether the voltage on the 1000kV side and the 500kV side of the UHV substation, as well as the reactive power exchange on both sides, exceed the limits. If any limit is exceeded, the reactive power resources in the vicinity of the UHV substation will be switched on first, and the voltage will be adjusted to be within a reasonable operating range and the reactive power exchange amount will not exceed the upper limit of the reactive power exchange amount. When the reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limit, the reactive power resources of the main transformer in the UHV AC substation are switched, and it is judged again whether the voltage and reactive power exchange of the 1000kV side and 500kV side in the UHV substation meet the requirements. This process is repeated until the system operation mode and the reactive power switching strategy of the main transformer in the UHV AC substation are determined. Based on the aforementioned reactive power switching strategy, and using the upper limit of steady-state overvoltage and the upper limit of reactive power exchange, the steady-state overvoltage of the UHV substation under extreme conditions is calculated, and the steady-state overvoltage is adjusted through relevant reactive power switching measures, specifically including: A jumper fault simulation was conducted on an ultra-high voltage interconnection line, and the steady-state overvoltage value was calculated. Determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system and the steady-state overvoltage both meet the preset requirements. Based on the current system operation mode, select either side of the UHV tie line for series compensation maintenance and calculate the steady-state overvoltage caused by the UHV tie line jumper. Determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system, the steady-state overvoltage under extreme conditions, and the steady-state overvoltage under series compensation maintenance conditions all meet the preset requirements. Transient stability simulations of AC / DC faults and power fluctuation faults are performed on the UHV AC substation. If the system becomes unstable, additional safety control measures are implemented. If the transient overvoltage of the current UHV substation exceeds the limit after the system has stabilized, the safety control measures are adjusted until the system is stable and the transient overvoltage meets the preset requirements.

2. The method according to claim 1, characterized in that, Also includes: If the preset requirements still cannot be met after the reactive power switching measures are invoked, series compensation maintenance is not recommended under this operating mode.

3. The method according to claim 1, characterized in that, Transient stability simulations of AC / DC faults and power fluctuation faults were performed on the aforementioned UHV AC substation. If the system became unstable, supplementary safety control measures were implemented, including: The system simulates single-pole blocking faults, jumper faults, and power fluctuation faults on some UHVDC lines and performs transient stability simulations. If the system becomes unstable, additional safety control measures are implemented.

4. The method according to claim 1, characterized in that, Based on the stability of the system, if the transient overvoltage of the current UHV substation exceeds the limit, the safety control measures shall be adjusted, including: After a fault occurs, once the system is stable, determine whether the transient overvoltages of the 1000kV and 500kV of the current UHV station exceed the limits. If they do, adjust the safety control measures.

5. A device for verifying reactive power switching strategies in ultra-high voltage AC substations, characterized in that, include: The reactive power switching strategy determination unit is used to determine the upper limit of steady-state overvoltage and the upper limit of reactive power exchange in UHV AC substations. Based on the aforementioned upper limit of reactive power exchange, the reactive power switching strategy for the main transformer of the UHV AC substation is determined, specifically including: The reactive power switching strategy selection subunit is used to select the main transformer reactive power switching strategy based on the transmission direction and capacity of the UHV interconnection line. The power flow calculation subunit is used to determine whether the voltage on the 1000kV side and the 500kV side of the UHV substation and the reactive power exchange on both sides exceed the limits through power flow calculation. The reactive power resource switching subunit is used to prioritize switching reactive power resources in the vicinity of the UHV substation if any limit is exceeded, and to adjust the voltage to a reasonable operating range and the reactive power exchange amount not exceeding the upper limit of the reactive power exchange amount. The reactive power switching strategy determination subunit is used to switch the reactive power resources of the main transformer in the UHV AC substation when the reactive power resources in the vicinity of the UHV substation are insufficient to meet the reactive power exchange limit. It then re-determines whether the voltage and reactive power exchange of the 1000kV and 500kV sides in the UHV substation meet the requirements. The process is repeated until the system operation mode and the reactive power switching strategy of the main transformer in the UHV AC substation are determined. The steady-state overvoltage calculation unit is used to calculate the steady-state overvoltage of the UHV substation under extreme conditions based on the reactive power switching strategy, the upper limit of steady-state overvoltage, and the upper limit of reactive power exchange, and to adjust the steady-state overvoltage through relevant reactive power switching measures. Specifically, it includes: A jumper fault simulation was conducted on an ultra-high voltage interconnection line, and the steady-state overvoltage value was calculated. Determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system and the steady-state overvoltage both meet the preset requirements. Based on the current system operation mode, select either side of the UHV tie line for series compensation maintenance and calculate the steady-state overvoltage caused by the UHV tie line jumper. Determine whether the steady-state overvoltage value exceeds the upper limit of steady-state overvoltage. If the steady-state overvoltage exceeds the limit, adjust the steady-state overvoltage through reactive power switching measures until the reactive power exchange between the 1000kV side and the 500kV side of the UHV system, the steady-state overvoltage under extreme conditions, and the steady-state overvoltage under series compensation maintenance conditions all meet the preset requirements. The fault simulation unit is used to perform transient stability simulation of AC / DC faults and power fluctuation faults in the UHV AC substation. If the system becomes unstable, additional safety control measures are implemented. If the transient overvoltage of the current UHV substation exceeds the limit after the system has stabilized, the safety control measures are adjusted until the system is stable and the transient overvoltage meets the preset requirements.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 4.

7. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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