Power grid framework structure adjustment method and system based on key site identification, and medium

Abstract

The application discloses a power grid network structure adjustment method and system based on key station identification and a medium, relates to the technical field of power systems and their automation, and establishes an electrical coupling degree index set based on direct current coupling degree and alternating current coupling degree, calculates the comprehensive index of each alternating current station to obtain a key station sequence, accurately measures and identifies key stations that have an important influence on the safety and stability of a power grid, and splits the high-voltage bus of the key station and adjusts the network structure, so that the disturbance impact of the key station on the power grid when the key station is completely stopped can be reduced, the safety and stability level of the power grid is improved, and necessary strong network foundation conditions for preventing large-scale power failure accidents are provided; the disturbance impact of the key station on the power grid when the key station is completely stopped can be reduced, the safety and stability level of the power grid is improved, and necessary support for preventing large-scale power failure accidents is provided.

Description

Technical Field

[0001] This invention relates to the field of power systems and their automation technology, specifically to a method, system, and medium for adjusting the power grid structure based on key site identification. Background Technology

[0002] With the continuous construction and development of the power grid, the scale of the power grid has expanded rapidly and the grid structure has become more complex. While promoting the optimization of power grid resources on a large scale, the safety and stability characteristics of the power grid have also become increasingly complex. Under serious faults, it may cause large-scale chain effects and lead to large-scale power outages.

[0003] Existing research indicates that there are certain critical nodes in the power grid that have a significant impact on the safe and stable operation of the power system. When such nodes experience severe failures (such as a complete substation outage), the integrity of the power grid structure is greatly compromised, which further affects the safe operation and efficient power transmission capabilities of the AC / DC hybrid power grid. Summary of the Invention

[0004] The technical problem this invention aims to solve is that there are certain critical nodes in the power grid that have a significant impact on the safe and stable operation of the power system. When such nodes experience severe failures, the integrity of the power grid structure is greatly compromised, further affecting the safe operation and efficient transmission capacity of the AC / DC hybrid power grid. The purpose of this invention is to provide a method, system, and medium for adjusting the power grid structure based on critical site identification. This involves establishing a set of electrical coupling degree indices based on DC and AC coupling degrees, calculating the comprehensive indices of each AC site to obtain a sequence of critical sites, accurately measuring and identifying critical sites that have a significant impact on the safety and stability of the power grid, and reducing the disturbance impact on the power grid when a complete power outage occurs at a critical site by splitting the high-voltage busbars of the critical sites and adjusting the grid structure. This improves the safety and stability level of the power grid and provides the necessary robust grid foundation for preventing large-scale power outages.

[0005] This invention is achieved through the following technical solution:

[0006] This solution provides a method for adjusting the power grid structure based on key site identification, including:

[0007] Key site identification: Obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure, and establish an electrical coupling degree index set based on DC coupling degree and AC coupling degree; after standardizing the electrical coupling degree index set, calculate the comprehensive index of each AC site, and rank the AC sites by criticality based on the comprehensive index to obtain the key site sequence.

[0008] Adjustment of the power grid structure under bus split operation based on key site sequence;

[0009] The adjusted power grid structure is subjected to a pre-set fault safety check, and the power grid structure that passes the pre-set fault safety check is run.

[0010] The working principle of this solution is as follows: The purpose of this invention is to provide a method, system, and medium for adjusting the power grid structure based on critical site identification. It establishes a set of electrical coupling degree indices based on DC and AC coupling degrees, calculates the comprehensive indices of each AC site to obtain a sequence of critical sites, accurately measures and identifies critical sites that have a significant impact on the safety and stability of the power grid, and reduces the disturbance impact on the power grid when a complete outage occurs at a critical site by splitting the operation of the high-voltage busbars at the critical sites and adjusting the grid structure. This improves the safety and stability level of the power grid and provides the necessary robust grid foundation for preventing large-scale power outages.

[0011] A further optimized solution is that the method for obtaining the DC coupling degree includes:

[0012] The coupling degree of the k-th AC station to the i-th DC station is calculated using the following formula. : ;

[0013] In the formula, This indicates the total number of DC transmission systems in a hybrid AC / DC power grid. This indicates the total number of AC buses in the power grid; This represents the multi-infeed short-circuit ratio of the i-th DC line under the initial grid structure of the AC / DC hybrid power grid. It represents the multi-infeed short-circuit ratio of the i-th DC circuit when the k-th AC station is completely shut down and all AC lines connected to that AC station are disconnected.

[0014] A further optimization scheme is to determine the multi-infeed short-circuit ratio of the i-th DC circuit under the initial grid structure of the AC / DC hybrid power grid. Obtained according to the following formula:

[0015] ;

[0016] In the formula, This represents the rated voltage of the busbar of the i-th DC converter station; This represents the rated DC transmission power of the i-th cycle; This represents the self-impedance value of the converter station bus of the i-th DC transmission line under the initial grid structure. Let represent the equivalent impedance of the parallel reactive power compensation of the converter station bus of the i-th DC line under the initial grid structure. This represents the multi-feed interaction factor between the i-th DC and the j-th DC under the initial grid structure. The multi-feed interaction factor between the i-th DC and the j-th DC is calculated according to the following formula:

[0017] ;

[0018] In the formula, This represents the mutual impedance between the i-th and j-th DC converter buses.

[0019] A further optimized solution is that the method for obtaining the AC coupling degree includes:

[0020] The AC coupling degree of the k-th AC station is calculated according to the following formula. :

[0021] ;

[0022] In the formula This represents the maximum transmission power at a specified transmission section under the initial grid structure of an AC / DC hybrid power grid. This represents the maximum transmission power of a specified transmission section when all AC substations are shut down.

[0023] A further optimized solution is that the method for obtaining the maximum transmission power includes:

[0024] T1 obtains the active power of each power plant in the AC / DC hybrid power grid, as well as the basic power flow mode of the grid; (the basic power flow mode of the grid is determined by load forecasting, inputting the initial grid structure, the unit generation cost coefficient of each power plant, and using the power system economic dispatch method to calculate the optimal power flow of the grid, thus obtaining the active power of each power plant and the basic power flow mode of the grid.) Select key transmission sections; key transmission sections are specified by the experience of grid dispatching personnel, or selected through dynamic security scanning, specifically as follows: considering main transmission sections with voltage levels of 500kV or above. For each transmission line, N-1 faults of three-phase permanent short circuit are generated, and these are aggregated to form a set of anticipated faults. For any fault scenario in the set of anticipated faults, time-domain simulation is performed to obtain the disturbance curve of the power grid after the fault. The transient stability margin of the power grid under each fault scenario is calculated using the extended equal area method. The fault scenario with the lowest stability margin is selected as the critical fault, and the faulted line is selected as the critical transmission line. For the critical fault, the branch potential energy method is used to identify the critical cut set with the lowest stability margin. Finally, the transmission section formed by the critical transmission line and the critical cut set line is selected as the critical transmission section.

[0025] T2. Stability verification of critical transmission sections: Considering the scenario of a three-phase permanent short-circuit N-1 fault occurring on any line within the critical transmission section, time-domain simulations are performed one by one, and the transient stability margin of the power grid under the fault scenario is calculated using the extended equal-area method. The minimum value of the transient stability margin of the power grid is taken as the stability margin of the critical transmission section. ;

[0026] T3. Analysis of the sensitivity of generator active power to stability margin: Transient stability margin calculations based on time-domain simulation and the extended equal-area method are performed using the fault scenario corresponding to the minimum value in the grid transient stability margin to obtain the stability margin after active power perturbation. Let i represent the generator number. Then, calculate the sensitivity of generator i's active power to the stability margin. :

[0027] ;

[0028] T4, constructing a maximum transmission power optimization model: ;

[0029] ;

[0030] In the formula, The node admittance matrix represents the DC power flow of the power grid. Indicates the voltage phase at each node. and Let these represent the maximum and minimum active power output of the i-th generator, respectively. Indicates the rated capacity of each branch. Represents the set of AC branches of the power grid. Represents a set of generators. Represents the set of AC busbars in the power grid. This represents the stability margin of the critical transmission section calculated in step T2 above;

[0031] Solve for the active power adjustment of generator i. And update the active power of generator i according to the following formula. :

[0032] ;

[0033] T5, if If the total active power transmitted at the critical transmission section is used as the calculation result of the current section's limit transmission power, then return to step T2.

[0034] A further optimized solution is that the method for obtaining the key site sequence includes:

[0035] S1, Establish a set of electrical coupling indices based on DC coupling and AC coupling. :

[0036] ;

[0037] This represents the coupling degree of the k-th AC station to the i-th DC circuit. This represents the communication coupling degree of the k-th communication station; ; This indicates the total number of DC transmission systems in a hybrid AC / DC power grid. This indicates the total number of AC buses in the power grid;

[0038] S2, Standardization of the electrical coupling index set: ; Represents the original elements of the electrical coupling index set. Indicates to Standardized elements;

[0039] S3, calculate the entropy value and entropy weight of each indicator, and the entropy value of the j-th indicator. for: ;in, The entropy weight of the j-th index for: Where m= n= ;

[0040] S4, calculate the comprehensive index of each communication station, and the comprehensive index of communication station i. for:

[0041] ;

[0042] S5. Sort the comprehensive index values ​​of each communication station from largest to smallest to obtain the key station sequence.

[0043] A further optimization scheme is as follows: the power grid structure optimization and adjustment based on the key site sequence for bus split operation includes the following methods:

[0044] G1, obtain the sequence of key sites, and initialize the loop variable i=1;

[0045] G2, take the i-th AC station to implement high-voltage busbar split operation;

[0046] G3, under the operating state of step G2, obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure;

[0047] G4, if the DC coupling and AC coupling calculated in step G3 satisfy the following conditions:

[0048] ;

[0049] If the iteration search ends, the current power grid structure is taken as the adjusted power grid structure; otherwise, i is set to i+1 and the process returns to step G2.

[0050] A further optimization scheme is to perform a contingency safety verification on the adjusted power grid structure, including the following methods:

[0051] For the adjusted power grid structure, based on the provisions of Level 1, Level 2 and Level 3 faults in the "Guidelines for the Safety and Stability of Power Systems", time-domain simulation analysis and safety verification of each level of fault are carried out, and the safety verification results of the expected faults are output.

[0052] This solution also provides a power grid structure adjustment system based on critical site identification, used to implement the aforementioned power grid structure adjustment method based on critical site identification, including:

[0053] The critical site identification module is used to obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure, and establish an electrical coupling degree index set based on the DC coupling degree and AC coupling degree; after standardizing the electrical coupling degree index set, the comprehensive index of each AC site is calculated, and the criticality of each AC site is ranked based on the comprehensive index to obtain the critical site sequence.

[0054] The adjustment module is used to adjust the power grid structure under bus split operation based on the key site sequence;

[0055] The verification module is used to perform preset fault safety verification on the adjusted power grid structure and run the power grid structure that has passed the preset fault safety verification.

[0056] This solution also provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, can implement the above-described method for adjusting the power grid structure based on key site identification.

[0057] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0058] This invention provides a method, system, and medium for adjusting the power grid structure based on critical site identification. It establishes a set of electrical coupling degree indices based on DC and AC coupling degrees, calculates the comprehensive indices of each AC station to obtain a sequence of critical stations, accurately measures and identifies critical stations that significantly impact power grid security and stability, and reduces the disturbance impact on the power grid during complete outages at critical stations by splitting the high-voltage busbars and adjusting the grid structure. This improves the power grid's security and stability level and provides necessary robust grid foundation conditions for preventing large-scale power outages. Attached Figure Description

[0059] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0060] Figure 1 A schematic diagram of the power grid structure adjustment method based on key site identification;

[0061] Figure 2 A schematic diagram of the method for obtaining the maximum transmission power;

[0062] Figure 3 A schematic diagram illustrating the process of obtaining the key site sequence;

[0063] Figure 4 This is a schematic diagram illustrating the operating principle of a split high-voltage busbar. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0065] Existing research indicates that there are certain critical nodes in the power grid that have a significant impact on the safe and stable operation of the power system. When such nodes experience severe failures (such as a complete substation outage), the integrity of the power grid structure is greatly compromised, which further affects the safe operation and efficient power transmission capabilities of the AC / DC hybrid power grid.

[0066] In view of this, the present invention provides the following embodiments to solve the above-mentioned technical problems:

[0067] Example 1

[0068] This embodiment provides a method for adjusting the power grid structure based on key site identification, such as... Figure 1 As shown, it includes:

[0069] Step 1: Identification of key sites: Obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure, and establish an electrical coupling degree index set based on DC coupling degree and AC coupling degree; after standardizing the electrical coupling degree index set, calculate the comprehensive index of each AC site, and rank the key sites based on the comprehensive index to obtain the key site sequence.

[0070] Methods for obtaining DC coupling include:

[0071] The coupling degree of the k-th AC station to the i-th DC station is calculated using the following formula. : ;

[0072] In the formula, This indicates the total number of DC transmission systems in a hybrid AC / DC power grid. This indicates the total number of AC buses in the power grid; This represents the multi-infeed short-circuit ratio of the i-th DC line under the initial grid structure of the AC / DC hybrid power grid. It represents the multi-infeed short-circuit ratio of the i-th DC circuit when the k-th AC station is completely shut down and all AC lines connected to that AC station are disconnected.

[0073] Multiple infeed short-circuit ratio of the i-th DC line under the initial grid structure of the AC / DC hybrid power grid Obtained according to the following formula:

[0074] ;

[0075] In the formula, This represents the rated voltage of the busbar of the i-th DC converter station; This represents the rated DC transmission power of the i-th cycle; This represents the self-impedance value of the converter station bus of the i-th DC transmission line under the initial grid structure. Let represent the equivalent impedance of the parallel reactive power compensation of the converter station bus of the i-th DC line under the initial grid structure. This represents the multi-feed interaction factor between the i-th DC and the j-th DC under the initial grid structure.

[0076] The multi-feed interaction factor between the i-th DC and the j-th DC is calculated according to the following formula:

[0077] ;

[0078] In the formula, This represents the mutual impedance between the i-th and j-th DC converter buses.

[0079] Methods for obtaining the degree of electrical coupling include:

[0080] The AC coupling degree of the k-th AC station is calculated according to the following formula. :

[0081] ;

[0082] In the formula This represents the maximum transmission power at a specified transmission section under the initial grid structure of an AC / DC hybrid power grid. This represents the maximum transmission power of a specified transmission section when all AC substations are shut down.

[0083] like Figure 2 As shown, the methods for obtaining the maximum transmission power include:

[0084] T1: Obtain the active power of each power plant in the AC / DC hybrid power grid, as well as the basic power flow mode of the power grid; select key transmission sections;

[0085] The basic power flow mode of the power grid determines the load demand through load forecasting, inputs the initial grid structure and the unit generation cost coefficient of each power plant, and uses the economic dispatch method of the power system to calculate the optimal power flow of the power grid, thereby obtaining the active power of each power plant and the basic power flow mode of the power grid.

[0086] Critical transmission sections are designated by the experience of grid dispatchers or selected through dynamic security scanning, as follows: Considering a main grid with a voltage level of 500kV or above, N-1 faults of three-phase permanent short circuits are generated for each transmission line, and these are summarized to form a set of anticipated faults; for any fault scenario in the set of anticipated faults, time-domain simulation is performed to obtain the grid disturbance curve after the fault; the transient stability margin of the grid under each fault scenario is calculated using the extended equal area method, and the fault scenario with the lowest stability margin is selected as the critical fault, and its faulted line is selected as the critical transmission line; for the critical fault, the branch potential energy method is used to identify the critical cut set with the lowest stability margin, and finally, the transmission section formed by the critical transmission line and the critical cut set line is selected as the critical transmission section.

[0087] T2. Stability verification of critical transmission sections: Considering the scenario of a three-phase permanent short-circuit N-1 fault occurring on any line within the critical transmission section, time-domain simulations are performed one by one, and the transient stability margin of the power grid under the fault scenario is calculated using the extended equal-area method. The minimum value of the transient stability margin of the power grid is taken as the stability margin of the critical transmission section. ;

[0088] T3. Analysis of the sensitivity of generator active power to stability margin: Transient stability margin calculations based on time-domain simulation and the extended equal-area method are performed using the fault scenario corresponding to the minimum value in the grid transient stability margin to obtain the stability margin after active power perturbation. Let i represent the generator number. Then, calculate the sensitivity of generator i's active power to the stability margin. :

[0089] ;

[0090] T4, constructing a maximum transmission power optimization model: ;

[0091] ;

[0092] In the formula, The node admittance matrix represents the DC power flow of the power grid. Indicates the voltage phase at each node. and Let these represent the maximum and minimum active power output of the i-th generator, respectively. Indicates the rated capacity of each branch. Represents the set of AC branches of the power grid. Represents a set of generators. Represents the set of AC busbars in the power grid. This represents the stability margin of the critical transmission section calculated in step T2 above;

[0093] Solve for the active power adjustment of generator i. And update the active power of generator i according to the following formula. :

[0094] ;

[0095] T5, if If the total active power transmitted at the critical transmission section is used as the calculation result of the current section's limit transmission power, then return to step T2.

[0096] like Figure 3 As shown, the methods for obtaining the key site sequence include:

[0097] S1, Establish a set of electrical coupling indices based on DC coupling and AC coupling. :

[0098] ;

[0099] This represents the coupling degree of the k-th AC station to the i-th DC circuit. This represents the communication coupling degree of the k-th communication station; ; This indicates the total number of DC transmission systems in a hybrid AC / DC power grid. This indicates the total number of AC buses in the power grid;

[0100] S2, Standardization of the electrical coupling index set: ; Represents the original elements of the electrical coupling index set. Indicates to Standardized elements;

[0101] S3, calculate the entropy value and entropy weight of each indicator, and the entropy value of the j-th indicator. for: ;in, The entropy weight of the j-th index for: Where m= n= ;

[0102] S4, calculate the comprehensive index of each communication station, and the comprehensive index of communication station i. for:

[0103] ;

[0104] S5. Sort the comprehensive index values ​​of each communication station from largest to smallest to obtain the key station sequence.

[0105] Step 2: Adjust the power grid structure under bus split operation based on the key site sequence;

[0106] Specifically, the methods include:

[0107] G1, obtain the sequence of key sites, and initialize the loop variable i=1;

[0108] G2, select the i-th AC station to implement high-voltage busbar split operation; such as Figure 4 As shown;

[0109] G3, under the operating state of step G2, obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure;

[0110] G4, if the DC coupling and AC coupling calculated in step G3 satisfy the following conditions:

[0111] ;

[0112] If the iteration search ends, the current power grid structure is taken as the adjusted power grid structure; otherwise, i is set to i+1 and the process returns to step G2.

[0113] Step 3: Perform a pre-set fault safety check on the adjusted power grid structure, and run the power grid structure that has passed the pre-set fault safety check.

[0114] The adjusted power grid structure is subjected to contingency safety verification, including the following methods:

[0115] For the adjusted power grid structure, according to the provisions of Level 1, Level 2 and Level 3 faults in the "Guidelines for the Safety and Stability of Power Systems", time-domain simulation analysis and safety verification of each level of fault are carried out, and the safety verification results of the expected faults are output.

[0116] Example 2

[0117] This embodiment also provides a power grid structure adjustment system based on critical site identification, used to implement the power grid structure adjustment method based on critical site identification in Embodiment 1 above, including:

[0118] The critical site identification module is used to obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure, and establish an electrical coupling degree index set based on the DC coupling degree and AC coupling degree; after standardizing the electrical coupling degree index set, the comprehensive index of each AC site is calculated, and the criticality of each AC site is ranked based on the comprehensive index to obtain the critical site sequence.

[0119] The adjustment module is used to adjust the power grid structure under bus split operation based on the key site sequence;

[0120] The verification module is used to perform preset fault safety verification on the adjusted power grid structure and run the power grid structure that has passed the preset fault safety verification.

[0121] Example 3

[0122] This embodiment also provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, can implement the above-described method for adjusting the power grid structure based on key site identification.

[0123] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting the power grid structure based on key site identification, characterized in that, include: Key site identification: Obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure, and establish a set of electrical coupling degree indices based on DC coupling degree and AC coupling degree; After standardizing the electrical coupling index set, the comprehensive index of each AC station is calculated. Based on the comprehensive index, the criticality of each AC station is ranked to obtain the critical station sequence. Adjustment of the power grid structure under bus split operation based on key site sequence; Perform a pre-set fault safety check on the adjusted power grid structure, and run the power grid structure that passes the pre-set fault safety check. The method for obtaining the DC coupling degree includes: The coupling degree of the k-th AC station to the i-th DC station is calculated using the following formula. : ; In the formula, This indicates the total number of DC transmission systems in a hybrid AC / DC power grid. Indicates the total number of AC buses in the power grid; This represents the multi-infeed short-circuit ratio of the i-th DC line under the initial grid structure of the AC / DC hybrid power grid. It represents the multi-infeed short-circuit ratio of the i-th DC circuit when the k-th AC station is completely shut down and all AC lines connected to that AC station are disconnected; The method for obtaining the AC coupling degree includes: The AC coupling degree of the k-th AC station is calculated according to the following formula. : ； In the formula This represents the maximum transmission power at a specified transmission section under the initial grid structure of an AC / DC hybrid power grid. This represents the maximum transmission power of a specified transmission section when all AC substations are shut down; The method for obtaining the key site sequence includes: S1, Establish a set of electrical coupling indices based on DC coupling and AC coupling. : ； This represents the coupling degree of the k-th AC station to the i-th DC circuit. This represents the communication coupling degree of the k-th communication station; ; This indicates the total number of DC transmission systems in a hybrid AC / DC power grid. Indicates the total number of AC buses in the power grid; S2, Standardization of the electrical coupling index set: ; Represents the original elements of the electrical coupling index set. Indicates to Standardized elements; S3, calculate the entropy value and entropy weight of each indicator, and the entropy value of the j-th indicator. for: ;in, The entropy weight of the j-th index for: m= n= ; S4, calculate the comprehensive index of each communication station, and the comprehensive index of communication station i. for: ； S5. Sort the comprehensive index values ​​of each communication station from largest to smallest to obtain the key station sequence.

2. The power grid structure adjustment method based on key site identification according to claim 1, characterized in that, The multi-infeed short-circuit ratio of the i-th DC circuit under the initial grid structure of the AC / DC hybrid power grid Obtained according to the following formula: ； In the formula, This represents the rated voltage of the busbar of the i-th DC converter station; This represents the rated DC transmission power of the i-th cycle; This represents the self-impedance value of the converter station bus of the i-th DC transmission line under the initial grid structure. Let represent the equivalent impedance of the parallel reactive power compensation of the converter station bus of the i-th DC line under the initial grid structure. This represents the multi-feed interaction factor between the i-th DC and the j-th DC under the initial grid structure. The multi-feed interaction factor of the i-th DC to the j-th DC Calculate according to the following formula: ； In the formula, This represents the mutual impedance between the i-th and j-th DC converter buses.

3. The power grid structure adjustment method based on key site identification according to claim 1, characterized in that, The method for obtaining the maximum transmission power includes: T1: Obtain the active power of each power plant in the AC / DC hybrid power grid, as well as the basic power flow mode of the power grid; select key transmission sections; T2. Stability verification of critical transmission sections: Considering the scenario of a three-phase permanent short-circuit N-1 fault occurring on any line within the critical transmission section, time-domain simulations are performed one by one, and the transient stability margin of the power grid under the fault scenario is calculated using the extended equal-area method. The minimum value of the transient stability margin of the power grid is taken as the stability margin of the critical transmission section. ; T3. Analysis of the sensitivity of generator active power to stability margin: Transient stability margin calculations based on time-domain simulation and the extended equal-area method are performed using the fault scenario corresponding to the minimum value in the grid transient stability margin to obtain the stability margin after active power perturbation. Let i represent the generator number. Then, calculate the sensitivity of generator i's active power to the stability margin. : ； T4, constructing a limit transmission power optimization model: ; ； In the formula, The node admittance matrix represents the DC power flow of the power grid. Indicates the voltage phase at each node. and Let these represent the maximum and minimum active power output of the i-th generator, respectively. Indicates the rated capacity of each branch. Represents the set of AC branches of the power grid. Represents a set of generators. Represents the set of AC busbars in the power grid. This represents the stability margin of the critical transmission section calculated in step T2 above; Solve for the active power adjustment of generator i. And update the active power of generator i according to the following formula. : ； T5, if If the total active power transmitted at the critical transmission section is used as the calculation result of the current section's limit transmission power, then return to step T2.

4. The power grid structure adjustment method based on key site identification according to claim 1, characterized in that, The power grid structure optimization and adjustment based on key site sequence for bus split operation includes the following methods: G1, obtain the sequence of key sites, and initialize the loop variable i=1; G2, take the i-th AC station to implement high-voltage busbar split operation; G3, under the operating state of step G2, obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure; G4, if the DC coupling and AC coupling calculated in step G3 satisfy the following conditions: ； Then the iterative search ends, and the current power grid structure is taken as the adjusted power grid structure; Otherwise, set i = i + 1 and return to step G2.

5. The power grid structure adjustment method based on key site identification according to claim 1, characterized in that, The method for performing contingency safety verification on the adjusted power grid structure includes: For the adjusted power grid structure, based on the provisions of Level 1, Level 2 and Level 3 faults in the "Guidelines for the Safety and Stability of Power Systems", time-domain simulation analysis and safety verification of each level of fault are carried out, and the safety verification results of the expected faults are output.

6. A power grid structure adjustment system based on key site identification, characterized in that, The method for adjusting the power grid structure based on key site identification as described in any one of claims 1-5 includes: The critical site identification module is used to obtain the DC coupling degree and AC coupling degree in the hybrid power grid structure, and establish an electrical coupling degree index set based on the DC coupling degree and AC coupling degree; after standardizing the electrical coupling degree index set, the comprehensive index of each AC site is calculated, and the criticality of each AC site is ranked based on the comprehensive index to obtain the critical site sequence. The adjustment module is used to adjust the power grid structure under bus split operation based on the key site sequence; The verification module is used to perform preset fault safety verification on the adjusted power grid structure and run the power grid structure that has passed the preset fault safety verification.

7. A computer-readable medium having a computer program stored thereon, characterized in that, The computer program, when executed by a processor, can implement the power grid structure adjustment method based on key site identification as described in any one of claims 1-5.

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