Regional power grid main network load balancing strategy generation method

Abstract

The invention provides a regional power grid main network load balance strategy generation method, and belongs to the technical field of power system operation control. According to the method, when a 220-kilovolt overload plant station exists in a regional power grid, operation modes such as 110-kilovolt bus split operation of a 220-kilovolt transformer substation, 110-kilovolt line switch bus switching, 110-kilovolt and 35-kilovolt transformer substation operation mode adjustment and the like are comprehensively considered, the load plant station meeting the requirement is transferred to serve as an adjustment unit, a strategy calculation unit is used for obtaining a current adjustment unit combination, and a strategy calculation unit is used for calculating the current adjustment unit combination. And a result obtained after load transfer is completed according to the combination is checked through a historical load curve, so that an optimal regional power grid main network load balancing strategy is obtained. According to the invention, an optimal power grid operation mode adjustment scheme can be quickly formed when the 220KV main equipment or section of a superior power supply is overloaded due to emergency power failure of a 110KV and above main transformer or line of a regional power grid, so that the load balance of the whole grid is realized, and the safe and stable operation of the regional power grid is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of power system operation control, and in particular relates to a method for generating a load balancing strategy for a regional power grid main network. Background Art

[0002] Emergency power outages of 110 kV and above main transformers or lines in regional power grids cause overloads of 220 kV main equipment or sections of the upper power supply, which needs to be eliminated quickly to maintain the safe and stable operation of normal equipment. Equipment overload can be eliminated through load transfer, but the formulation of current transfer plans mainly relies on the operating experience of dispatchers, making it difficult to quickly form the optimal plan. In addition, during the peak load period in summer, most 220 kV substations are heavily loaded and have a low acceptable load margin. Usually, multiple load transfers will be carried out to achieve load balance across the entire network, which will increase the number of switch operations and take a long time, increasing the operational risk of the power grid.

[0003] The parallel operation of 220 kV substations plays an important role in improving power supply reliability. During peak load periods, the main transformer N-1 will cause serious overload of equipment. At this time, the 110 kV busbar of the 220 kV substation is often operated in parallel to improve the power supply capacity of the substation, which will sacrifice the reliability of power supply of the power grid. Therefore, when the 220 kV main equipment or section of the regional power grid is overloaded, it is necessary to comprehensively consider the safety, reliability and economy of the power grid operation and select a suitable adjustment plan to achieve load balance of the entire network. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method for generating a load balancing strategy for the main network of a regional power grid. The present invention can quickly form an optimal power grid operation mode adjustment plan when the main transformer or line of the regional power grid 110 kV or above is overloaded, causing the upper power supply 220 kV main equipment or section to be overloaded, so as to achieve load balancing of the entire network and ensure the safe and stable operation of the regional power grid.

[0005] The embodiment of the present invention provides a method for generating a load balancing strategy for a regional power grid main network, comprising:

[0006] 1) Determine the current regional power grid: if there is a 220 kV overloaded plant, enter the first round of regional power grid main grid load balance optimization;

[0007] 2) Based on the result of step 1), determine whether the 110 kV busbars of the 220 kV overloaded power plant in the regional power grid are in parallel operation:

[0008] If they are operated in parallel, go to step 3) to eliminate overload of the central main transformer section; if they are operated in separate columns, go to step 6) to eliminate overload of the central main transformer;

[0009] 3) Taking the 220 kV overloaded central main transformer section as the current overload object, a load transfer scheme is sought through a preset strategy calculation unit to eliminate the overload of the central main transformer section; the specific steps of the strategy calculation unit are as follows:

[0010] 3-1) Determine the overload load of the overload object;

[0011] 3-2) Obtain the adjustment unit combination sequence under the overload object. The specific steps are as follows:

[0012] 3-2-1) Obtain the 110 kV plant and 35 kV plant under the overload object;

[0013] 3-2-2) From the load plants and stations obtained in step 3-2-1), empty charging lines, single power plants and stations, line transformer groups, power plants, and important users are screened to obtain the screened load plants and stations;

[0014] 3-2-3) sequentially traverse the selected load plants obtained in step 3-2-2) and determine whether their high-voltage side busbars are running in separate columns or in parallel, thereby determining the load transfer mode; wherein:

[0015] If any of the selected load plants is a split-operation plant, half of the load of the load plant under the overload object is transferred to form an adjustment unit corresponding to the load plant;

[0016] If any of the selected load plants is a parallel operation plant, half of the load of the plant under the direct-connected main transformer or the direct-connected main transformer section is transferred to form an adjustment unit corresponding to the load plant, or the whole load of the load plant is transferred to form an adjustment unit corresponding to the load plant;

[0017] 3-2-4) According to the result of step 3-2-3), the adjustment units corresponding to each selected load plant are respectively combined into 1 unit, 2 units, ..., X units to form an adjustment unit combination, where X is the total number of plants after screening, and then all the obtained adjustment unit combinations are formed into an adjustment unit combination sequence;

[0018] Among them, in a single adjustment unit combination, any parallel operation plant selects one adjustment unit formed by transferring half of the load of the plant directly connected to the main transformer or under the main transformer section, or one adjustment unit formed by transferring the entire station load for combination;

[0019] 3-3) selecting an adjustment unit combination whose transferable load is greater than or equal to the overload load of the overload object from the adjustment unit combination sequence obtained in step 3-2), and then sorting the selected adjustment unit combinations in ascending order of transferable load to form a subsequence;

[0020] 3-4) From the subsequence obtained in step 3-3), select the first adjustment unit combination as the current candidate combination;

[0021] 3-5) Perform corresponding load transfer according to each adjustment unit in the current candidate combination;

[0022] 3-6) Using the preset historical load curve, the overload object load after the load transfer in step 3-5) is superimposed and calculated to verify whether the overload object is still overloaded after the load transfer according to the current selected combination:

[0023] If it is not overloaded, keep the current combination to be selected and go to step 3-7);

[0024] If it is still overloaded, continue to select the next adjustment unit combination in the subsequence obtained in step 3-3) as the new current candidate combination, and then return to step 3-5) until the overload phenomenon of the overloaded object can be eliminated after load transfer according to the current candidate combination, then retain the current candidate combination and enter step 3-7);

[0025] 3-7) Using the preset historical load curve, perform superposition calculation verification on the direct-connected main transformer or the direct-connected main transformer section after the load transfer of the current candidate combination retained in step 3-6), so as to determine whether there is an overload on the direct-connected main transformer or the main transformer section after the load transfer according to the current candidate combination:

[0026] If it does not exist, the overload of the overload object is eliminated successfully and does not cause overload of the directly connected main transformer or the directly connected main transformer section, and the current candidate combination is output as a perfect combination;

[0027] If it exists, then ignore the load transfer according to the current candidate combination, continue to select the next adjustment unit combination in the subsequence obtained in step 3-3) as the new current candidate combination, and then return to step 3-5);

[0028] If after traversing all the adjustment unit combinations in the subsequence obtained in step 3-3) in sequence, there is no combination that can eliminate the overload of the overloaded object and not cause overload of the directly connected main transformer or the directly connected main transformer section after the corresponding load transfer according to each adjustment unit in any combination, then the adjustment unit combination that eliminates the overload of the overloaded object and has the smallest transferable load in the subsequence obtained in step 3-3) is output as a non-perfect combination;

[0029] 4) Judgment:

[0030] 4-1) If the output of step 3) is a perfect combination, then the perfect combination is the current load balancing strategy of the main power grid in the region, and the method ends;

[0031] 4-2) If the output of step 3) is a non-perfect combination, the operation mode of the 110 kV busbar of the overloaded direct-connected plant station caused by the corresponding load transfer of each adjustment unit in the non-perfect combination is read, where:

[0032] 4-2-1) If the overloaded 110 kV busbar of the direct-connected plant and station is in parallel operation, the overloaded direct-connected main transformer section is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer section by repeating the strategy calculation unit;

[0033] Among them, if a perfect combination for eliminating the overload of the direct-connected main transformer section is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: a non-perfect combination for eliminating the overload of the central main transformer section and a perfect combination for eliminating the overload of the direct-connected main transformer section, and the method ends; if a non-perfect combination for eliminating the overload of the direct-connected main transformer section is found, the non-perfect combination for eliminating the overload of the central main transformer section and the non-perfect combination for eliminating the overload of the direct-connected main transformer section are ignored, and then step 5) is entered;

[0034] 4-2-2) If the overloaded 110 kV busbar of the direct-connected plant and station is operated in separate columns, the overloaded direct-connected main transformer is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer by repeating the strategy calculation unit;

[0035] Among them, if a perfect combination for eliminating overload of the directly connected main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: a non-perfect combination for eliminating overload of the central main transformer section and a perfect combination for eliminating overload of the directly connected main transformer, and the method ends; if a non-perfect combination for eliminating overload of the directly connected main transformer is found, the non-perfect combination for eliminating overload of the central main transformer section and the non-perfect combination for eliminating overload of the directly connected main transformer are ignored, and then step 5 is entered;

[0036] 5) Based on the initial operation mode of overload of the central main transformer section, the overloaded central plant station 110 kV busbar is divided into sections, and the calculation and verification are performed according to the preset historical load curve to determine whether the central main transformer is overloaded:

[0037] If it does not exist, then generate the current load balancing strategy of the main grid of the power grid in the region, which is the 110 kV busbar splitting of the overloaded central plant station, and the method ends;

[0038] If it exists, go to step 6);

[0039] 6) Taking the 220 kV overloaded central main transformer as the current overload object, repeat the strategy calculation unit to find a load transfer solution to eliminate the overload of the central main transformer, wherein:

[0040] If a perfect combination for eliminating the overload of the central main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the perfect combination of the overloaded central plant station 110 kV busbar split operation and eliminating the overload of the central main transformer, and the method ends; if a non-perfect combination for eliminating the overload of the central main transformer is found, go to step 7);

[0041] 7) Based on the imperfect combination for eliminating overload of the central main transformer outputted in step 6), the operation mode of the overloaded direct-connected plant station 110 kV busbar caused by corresponding load transfer according to each adjustment unit in the imperfect combination is read, wherein:

[0042] If the overloaded 110 kV busbar directly connected to the plant station is operated in separate columns, proceed to step 9);

[0043] If the overloaded direct-connected plant 110 kV busbar is in parallel operation, the overloaded direct-connected main transformer section is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer section by repeating the strategy calculation unit; wherein, if a perfect combination for eliminating the overload of the direct-connected main transformer section is found, the current load balancing strategy of the main grid of the power grid in the region is generated, including: the overloaded central plant 110 kV busbar is operated in parallel, the non-perfect combination for eliminating the overload of the central main transformer, and the perfect combination for eliminating the overload of the direct-connected main transformer section; if a non-perfect combination for eliminating the overload of the direct-connected main transformer section is found, the non-perfect combination for eliminating the overload of the direct-connected main transformer section is ignored, and the overloaded central plant 110 kV busbar is operated in parallel and the non-perfect combination for eliminating the overload of the central main transformer is used, and then step 8 is entered;

[0044] 8) After the overloaded 110 kV busbars of the direct-connected plant and station are separated, the calculation and verification are performed according to the preset historical load curve to determine whether there is an overload on the direct-connected main transformer:

[0045] If it does not exist, the load balancing strategy of the main grid of the power grid in the current region is generated, including: split operation of the overloaded central plant station 110 kV bus, an imperfect combination of eliminating overload of the central main transformer, and split operation of the 110 kV bus of the direct-connected plant station, and the method ends; if it exists, enter step 9);

[0046] 9) taking the overloaded direct-connected main transformer as the current overload object, and finding a load transfer scheme to eliminate the overload of the direct-connected main transformer by repeating the strategy calculation unit;

[0047] Among them, if the perfect combination of eliminating the overload of the directly connected main transformer is found, the load balancing strategy of the main grid of the current power grid in the region will be generated, including: the imperfect combination of split operation of the overloaded central plant and station 110 kV busbar, eliminating the overload of the central main transformer, and the perfect combination of split operation of the directly connected plant and station 110 kV busbar, eliminating the overload of the directly connected main transformer;

[0048] If a non-perfect combination for eliminating overload of the direct-connected main transformer is found, the non-perfect combination for eliminating overload of the direct-connected main transformer, the direct-connected plant 110 kV busbar splitting, and the non-perfect combination for eliminating overload of the central main transformer are ignored, and then based on the overloaded central plant 110 kV busbar splitting operation mode, step 10 is entered;

[0049] 10) Load balancing is achieved by switching the 110 kV outgoing line of the overloaded central main transformer. The specific steps are as follows:

[0050] 10-1) Obtain the 110 kV load plant and 35 kV load plant under the main transformer of the same station;

[0051] 10-2) From the load plants obtained in step 10-1), empty charging lines, single power plants, line transformer groups, power plants, and important users are screened out, and load plants that have a unique contact relationship between the main transformer and the directly connected plant at the same station are sorted out to obtain sorted load plants;

[0052] 10-3) sequentially traverse the sorted load plants and stations obtained in step 10-2) and determine whether their high-voltage side busbars are running in separate columns or in parallel, thereby determining the load transfer mode; wherein:

[0053] If any of the sorted load plants is a split-line operation plant, half of the load of the plant under the main transformer of the same station is transferred to form an adjustment unit corresponding to the load plant;

[0054] If any of the sorted load plants is a parallel operation plant, half of the load of the plant under the directly connected plant is transferred to form an adjustment unit corresponding to the load plant, or the whole load of the load plant is transferred to form an adjustment unit corresponding to the load plant;

[0055] 10-4) According to the result of step 10-3), the adjustment units corresponding to each load plant after sorting are respectively combined into 1 unit, 2 units, ..., Y units to form a connection adjustment unit combination, wherein Y is the total number of load plants after sorting in step 10-2); then all the obtained connection adjustment unit combinations are sorted from large to small according to their corresponding transferable load amounts to obtain a connection adjustment unit combination sequence;

[0056] Among them, in a single interconnection adjustment unit combination, any parallel operation plant station chooses to transfer one adjustment unit formed by half of the load of the plant station under the directly connected plant station or one adjustment unit formed by transferring the entire station load for combination;

[0057] 10-5) Select each connection adjustment unit combination in the connection adjustment unit combination sequence obtained in step 10-4) in turn, perform corresponding load transfer according to each adjustment unit in the combination, and perform superposition calculation verification using a preset historical load curve after the transfer to determine whether the opposite main transformer or the opposite main transformer section is overloaded after the transfer, wherein:

[0058] If the transfer does not cause overload of the opposite main transformer or the opposite main transformer section, the current contact adjustment unit combination is output and the process goes to step 10-6);

[0059] If the transfer causes the opposite main transformer or the opposite main transformer section to be overloaded, continue to select the next contact adjustment unit combination in the contact adjustment unit combination sequence for load transfer, until the corresponding load transfer is performed according to the current contact adjustment unit combination and it is verified that the opposite main transformer or the opposite main transformer section is not overloaded, then the current contact adjustment unit combination is output and step 10-6 is entered;

[0060] If after traversing all the contact adjustment unit combinations in the sequence in step 10-4), there is no load transfer according to each adjustment unit in any contact adjustment unit combination that does not cause overload of the opposite main transformer or the opposite main transformer section, then no load transfer is performed under the main transformer at the same station, and the process goes to step 10-6);

[0061] 10-6) Select the non-zero load outgoing lines under the central main transformer except the power plant, and then combine the selected load outgoing lines with 1 outgoing line, 2 outgoing lines, ..., Z outgoing lines to form an outgoing line combination, where Z is the total number of outgoing lines after screening, and then combine all the outgoing line combinations into an outgoing line combination sequence;

[0062] 10-7) selecting an outgoing line combination under the central main transformer that is less than or equal to the acceptable capacity of the main transformer at the same station from the outgoing line combination sequence obtained in step 10-6) and sorting the combined load levels from large to small to form an outgoing line subsequence;

[0063] 10-8) Select each outgoing line combination from the outgoing line subsequence obtained in step 10-7) as the current outgoing line combination for mother-to-mother switching, and then use the preset historical load curve for superposition calculation verification to calculate whether the main transformer at the same station is overloaded after mother-to-mother switching:

[0064] If it is not overloaded, the current output line combination is output and the process goes to step 11);

[0065] If overloaded, the next outgoing line combination is selected from the outgoing line sub-sequence as the new current outgoing line combination for mother-to-mother inversion, and then the preset historical load curve is used for superposition calculation verification until the mother-to-mother inversion is performed according to the current outgoing line combination and it is verified that it does not cause overload of the main transformer at the same station, then the current outgoing line combination is output and the process goes to step 11);

[0066] If after traversing all outgoing line combinations in the outgoing line subsequence in sequence, there is no outgoing line combination that reverses the bus and after verification, it does not cause the main transformer at the same station to be overloaded, then the bus reverse operation is not performed and the load transfer operation of the main transformer at the same station is ignored; then based on the overloaded central plant station 110 kV busbar split operation mode, enter step 12);

[0067] 11) Perform superposition calculation and verification based on the preset historical load curve to determine whether the central main transformer is overloaded after the mother is switched:

[0068] If the overload of the central main transformer is eliminated, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the 110 kV busbar of the central plant station is operated in parallel, the load combination of the main transformer at the same station transferred to the external station, and the load combination of the central main transformer to the main transformer at the same station, and the method ends;

[0069] If the central main transformer is still overloaded, go to step 12);

[0070] 12) Taking the overloaded central main transformer as the current overload object, repeating the strategy calculation unit, and finding a load transfer solution to eliminate the overload of the central main transformer;

[0071] Among them, if the perfect combination to eliminate the overload of the central main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the overloaded central plant station 110 kV busbar is operated separately, the load combination of the main transformer at the same station is transferred to the external station, the load combination of the central main transformer to the main transformer at the same station is reversed, and the perfect combination to eliminate the overload of the central main transformer is generated, and the method ends;

[0072] If a non-perfect combination for eliminating the overload of the central main transformer is found, and the current round is the first round of regional power grid main network load balancing optimization, then proceed to step 13); if a non-perfect combination for eliminating the overload of the central main transformer is found, and the current round is the second round of regional power grid main network load balancing optimization, then proceed to step 14); if a non-perfect combination for eliminating the overload of the central main transformer is found, and the current round is the third round of regional power grid main network load balancing optimization, then proceed to step 18);

[0073] 13) Based on the load combination of the overloaded central plant station 110 kV busbar split operation, the same station main transformer transferred to the external station, the central main transformer to the same station main transformer load combination, and the non-perfect combination of eliminating the overload of the central main transformer in the first round of regional power grid main grid load balance optimization, determine the overloaded central main transformer or central main transformer section in the second round of regional power grid main grid load balance optimization, select the overloaded central main transformer or central main transformer section in the second round of regional power grid main grid load balance optimization The load level corresponding to the maximum overload in the historical curve verification is selected as the initial load of the second round of regional power grid main grid load balance optimization, and return to step 2) to perform the second round of regional power grid main grid load balance optimization;

[0074] 14) Based on the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the outer station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the second round of regional power grid main grid load balance optimization, the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization is determined, and the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization is compared with the overloaded central main transformer or central main transformer section in the first round of regional power grid main grid load balance optimization:

[0075] If they are different main transformers or main transformer sections, the load level corresponding to the moment of maximum overload of the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization in the historical curve verification is selected as the initial load of the third round of regional power grid main grid load balance optimization, and return to step 2) to perform the third round of regional power grid main grid load balance optimization;

[0076] If they are the same main transformer or main transformer section, the imperfect combination for eliminating overload of the central main transformer in the second round of regional power grid main grid load balance optimization is ignored, and the process goes to step 15);

[0077] 16) Based on the load combination of the overloaded central plant station 110 kV busbar in the second round of regional power grid main network load balancing optimization, the load combination of the main transformer in the same station transferring to the external station, and the load combination of the central main transformer transferring to the main transformer in the same station, the overloaded central main transformer in the second round of regional power grid main network load balancing optimization is taken as the overload object, and steps 3-2) are repeated to obtain the adjustment unit combination sequence of the overloaded central main transformer in the second round of regional power grid main network load balancing optimization, and then the adjustment unit combination whose transferable load is greater than or equal to the overload load of the central main transformer in the second round of regional power grid main network load balancing optimization is selected from the adjustment unit combination sequence and a subsequence is formed in the order of the transferable load from small to large; the adjustment unit combination is selected from the subsequence in turn, and the corresponding load is transferred according to each adjustment unit in the combination. After each transfer, the preset historical load curve is used for superposition calculation verification to determine whether the central main transformer in the second round of regional power grid main network load balancing optimization is overloaded after the transfer according to the load combination corresponding to the current adjustment unit combination:

[0078] If it is not overloaded, the current adjustment unit combination is output and the process goes to step 16);

[0079] If it is still overloaded, the next adjustment unit combination in the subsequence is selected to continue load transfer, verification and judgment until the overload of the central main transformer in the second round of regional power grid main network load balance optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit in the current adjustment unit combination, then the current adjustment unit combination is output and step 16 is entered;

[0080] 16) Based on the adjustment unit combination output from step 15), determine the current overloaded main transformer or main transformer section, and judge whether the overloaded main transformer or main transformer section is the same as the initial central main transformer or central main transformer section of the first round of regional power grid main network load balance optimization:

[0081] If different, proceed to step 17);

[0082] If they are the same, continue to select the next adjustment unit combination in the subsequence obtained in step 15) to continue load transfer, verification and judgment, until the overload of the central main transformer in the second round of regional power grid main network load balance optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit in the new current adjustment unit combination, and the overloaded main transformer or main transformer section caused by the corresponding load transfer according to each adjustment unit in the current adjustment unit combination is different from the initial central main transformer or central main transformer section in the first round of regional power grid main network load balance optimization, then output the current adjustment unit combination and enter step 17);

[0083] 17) Based on the adjustment unit combination output from step 16), determine the central main transformer or central main transformer section for the third round of regional power grid main network load balancing optimization, select the load level corresponding to the moment of the maximum overload of the overloaded central main transformer or central main transformer section in the third round of regional power grid main network load balancing optimization in the historical curve verification as the initial load of the third round of regional power grid main network load balancing optimization, and return to step 2) to perform the third round of regional power grid main network load balancing optimization;

[0084] 18) Based on the load combination of the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the outer station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the third round of regional power grid main grid load balance optimization, determine the current overloaded main transformer or main transformer section, and compare the current overloaded main transformer or main transformer section with the overloaded central main transformer or central main transformer section in the first round of regional power grid main grid load balance optimization and the second round of regional power grid main grid load balance optimization:

[0085] If it is a different main transformer or main transformer section, the generated regional power grid main network load balancing strategy includes: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the overloaded central plant station 110 kV busbar split operation in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer, and the method ends;

[0086] If they are the same main transformer or main transformer section, the imperfect combination for eliminating overload of the central main transformer in the third round of regional power grid main grid load balance optimization is ignored, and the process goes to step 19);

[0087] 19) Based on the load combination of the overloaded central plant station 110 kV busbar in the third round of regional power grid main grid load balancing optimization, the load combination of the main transformer in the same station transferring to the external station, and the load combination of the central main transformer transferring to the main transformer in the same station, the overloaded central main transformer in the third round of regional power grid main grid load balancing optimization is taken as the overload object, and step 3-2) is repeated to obtain the adjustment unit combination sequence of the overloaded central main transformer in the third round of regional power grid main grid load balancing optimization, and then select the adjustment unit combination whose transferable load is greater than or equal to the overload load of the central main transformer in the third round of regional power grid main grid load balancing optimization from the current adjustment unit combination sequence and form a subsequence in the order of the transferable load from small to large; select the adjustment unit combination from the subsequence in turn, and perform the corresponding load transfer according to each adjustment unit in the combination. After each transfer, the preset historical load curve is used for superposition calculation verification to determine whether the central main transformer in the third round of regional power grid main grid load balancing optimization is overloaded after the transfer according to the load combination corresponding to the current adjustment unit combination:

[0088] If it is not overloaded, the current adjustment unit combination is output and the process goes to step 20);

[0089] If it is still overloaded, continue to select the next adjustment unit combination in the subsequence to continue load transfer, verification and judgment until the overload of the central main transformer in the third round of regional power grid main network load balance optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit of the current adjustment unit combination, then output the current adjustment unit combination and enter step 20);

[0090] 20) Based on the adjustment unit combination outputted in step 19), determine the current overloaded main transformer or main transformer section, and judge whether the overloaded main transformer or main transformer section is the same as the central main transformer or central main transformer section of the first or second round of regional power grid main network load balance optimization:

[0091] If they are different, the current adjustment unit combination is output, and the load balancing strategy of the regional power grid main network is generated, including: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the overloaded central plant station 110 kV busbar split operation in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the current adjustment unit combination for eliminating the overload of the central main transformer, and the method ends;

[0092] If they are the same, continue to select the next adjustment unit combination in the subsequence obtained in step 19) to continue load transfer, verification and judgment, until the corresponding load transfer according to each adjustment unit in the new current adjustment unit combination can eliminate the overload of the central main transformer in the third round of regional power grid main network load balancing optimization, and the overloaded main transformer or main transformer section caused by the corresponding load transfer according to each adjustment unit in the current adjustment unit combination is different from the central main transformer or central main transformer section in the first or second round, then output the current adjustment unit combination, and generate a regional power grid main network load balancing strategy including: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the third round of overloaded regional power grid main network load balancing optimization The central plant station 110 kV busbar is operated in a separate column, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the current adjustment unit combination that eliminates the overload of the central main transformer, and the method ends.

[0093] The characteristics and beneficial effects of the present invention are:

[0094] Compared with relying on the dispatcher's operating experience to formulate a load balancing plan, the present invention comprehensively considers the advantages and disadvantages of operating modes such as 220 kV substation 110 kV busbar split operation, 110 kV line switch bus reversal, and 110 kV and 35 kV substation operation mode adjustment, and considers the long-term load level of the power grid. By combining multiple adjustment methods, a regional power grid load balancing strategy is quickly generated, eliminating the problem of overload of main equipment or sections. The results are more accurate, reducing the number of switch operations, and ensuring the safety, reliability, and economy of large power grid operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 The present invention is an overall flow chart of a method for generating a load balancing strategy for a regional power grid main network in a specific implementation of the present invention.

[0096] Figure 2 The figure is a flow chart of a strategy calculation unit in a specific implementation of the present invention.

[0097] Figure 3 The present invention is a flowchart of balancing the 110 kV load outgoing line staggered bus load in a 220 kV substation in a specific implementation of the present invention.

[0098] Specific implementation instructions

[0099] The present invention proposes a method for generating a load balancing strategy for a regional power grid main network. The content of the present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments, and the technical solutions therein will be described clearly and completely.

[0100] The embodiment of the present invention proposes a method for generating a load balancing strategy for a regional power grid main network. In the embodiment, a certain 220 kV overloaded main transformer is defined as a central main transformer, a non-overloaded 220 kV main transformer at the same station as the central main transformer is defined as a main transformer at the same station, a 220 kV main transformer that has a 110 kV or 35 kV connection relationship with the central main transformer is defined as a direct-connected main transformer, and a 220 kV main transformer that has a 110 kV or 35 kV connection relationship with the direct-connected main transformer is defined as a secondary-connected main transformer. The overall process is as follows: Figure 1 As shown, the following steps are included:

[0101] 1) Read the current regional power grid operation mode, model, parameters, and expected fault information. If there is a 220 kV overloaded plant or station, enter the first round of regional power grid main grid load balance optimization.

[0102] 2) Based on the result of step 1), determine whether the 110 kV busbars of the 220 kV overloaded power plant in the regional power grid are in parallel operation:

[0103] If they are operated in parallel, go to step 3) to eliminate overload of the central main transformer section; if they are operated in separate columns, go to step 6) to eliminate overload of the central main transformer;

[0104] 3) Taking the 220 kV overloaded central main transformer section as the current overload object, a load transfer scheme is sought through a preset strategy calculation unit to eliminate the overload of the central main transformer section; the overall process of the strategy calculation unit is as follows: Figure 2 As shown, the specific steps are as follows:

[0105] 3-1) Determine the overload load of the overload object;

[0106] 3-2) Obtain the adjustment unit combination sequence under the overload object. The specific steps are as follows:

[0107] 3-2-1) Obtain the 110 kV load plant and station and 35 kV load plant and station under the overload object;

[0108] 3-2-2) From the load plants and stations obtained in step 3-2-1), empty charging lines, single power plants and stations, line transformer groups, power plants, and important users are screened to obtain the screened load plants and stations;

[0109] 3-2-3) sequentially traverse the selected load plants obtained in step 3-2-2) and determine whether their high-voltage side busbars are running in separate columns or in parallel, thereby determining the load transfer mode; wherein:

[0110] If the high-voltage busbar of any selected load plant is in split operation, half of the load of the load plant under the overload object is transferred to form an adjustment unit corresponding to the load plant;

[0111] If the high-voltage side busbar of any selected load plant is in parallel operation, half of the load of the load plant is transferred to the directly connected main transformer or under the directly connected main transformer section to form an adjustment unit corresponding to the load plant, or the entire station load of the load plant is transferred to form an adjustment unit corresponding to the load plant;

[0112] 3-2-4) According to the result of step 3-2-3), the adjustment units corresponding to each screened load plant are combined into 1 unit, 2 units, ..., X units to form an adjustment unit combination, where X is the total number of plants after screening, and then all the obtained adjustment unit combinations are combined into an adjustment unit combination sequence.

[0113] It should be noted that, in the present embodiment, in a single adjustment unit combination, any parallel-operating plant station can only choose to combine with one adjustment unit formed by transferring half of the load of the plant station under the directly connected main transformer or the main transformer section, or one adjustment unit formed by transferring the entire station load. These two methods cannot appear in the same combination at the same time.

[0114] 3-3) Select an adjustment unit combination whose transferable load is greater than or equal to the overload load of the overload object from the adjustment unit combination sequence obtained in step 3-2), and then sort the selected adjustment unit combinations in order of transferable load from small to large to form a subsequence.

[0115] 3-4) From the subsequence obtained in step 3-3), select the first adjustment unit combination as the current candidate combination.

[0116] 3-5) Perform corresponding load transfer according to each adjustment unit in the current candidate combination;

[0117] 3-6) Using the preset historical load curve to perform superposition calculation verification on the load of the overload object after the load transfer in step 3-5) (in this embodiment, the historical load curve of the 220 kV overload object is obtained by superimposing the historical load curve of the 110 kV main transformer it carries based on the grid operation mode adjusted in step 3-5), and the historical load curve in this embodiment can select the date and time period, and the temperature, humidity, work and rest, production period and other factors are comprehensively considered during the specific implementation) to determine whether the overload object is still overloaded after the load transfer according to the current selected combination:

[0118] If it is not overloaded, keep the current combination to be selected and go to step 3-7);

[0119] If it is still overloaded, continue to select the next adjustment unit combination in the subsequence obtained in step 3-3) as the new current candidate combination, and then return to step 3-5) until the overload phenomenon of the overloaded object can be eliminated after load transfer according to the current candidate combination, then retain the current candidate combination and enter step 3-7).

[0120] 3-7) Using the preset historical load curve, the directly connected main transformer or the directly connected main transformer section after the load transfer of the current candidate combination retained in step 3-6) is superimposed and calculated for verification (in this embodiment, the historical load curve of the 220 kV directly connected main transformer or the directly connected main transformer section is obtained by superimposing the historical load curve of the 110 kV main transformer it carries based on the grid operation mode adjusted in step 3-5)) to determine whether there is an overload of the directly connected main transformer or the main transformer section after the load transfer according to the current candidate combination:

[0121] If it does not exist, the overload of the overload object is eliminated successfully and does not cause overload of the directly connected main transformer or the directly connected main transformer section, and the current candidate combination is output as a perfect combination;

[0122] If it exists, then ignore the load transfer according to the current candidate combination, continue to select the next adjustment unit combination in the subsequence obtained in step 3-3) as the new current candidate combination, and then return to step 3-5);

[0123] If after traversing all the adjustment unit combinations in the subsequence obtained in step 3-3) in sequence, there is no combination of adjustment units in any combination that can eliminate the overload of the overloaded object and not cause overload of the directly connected main transformer or the directly connected main transformer section after the corresponding load transfer is performed according to the adjustment units in any combination, then the adjustment unit combination in the subsequence obtained in step 3-3) that eliminates the overload of the overloaded object and has the smallest transferable load is output as a non-perfect combination.

[0124] 4) Judgment:

[0125] 4-1) If the output of step 3) is a perfect combination, then the perfect combination is the current load balancing strategy of the main power grid in the region, and the method ends;

[0126] 4-2) If the output of step 3) is a non-perfect combination, the operation mode of the 110 kV busbar of the overloaded direct-connected plant station caused by the corresponding load transfer of each adjustment unit in the non-perfect combination is read, where:

[0127] 4-2-1) If the overloaded 110 kV busbar of the direct-connected plant and station is in parallel operation, the overloaded direct-connected main transformer section is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer section by repeating the strategy calculation unit;

[0128] Among them, if a perfect combination for eliminating the overload of the direct-connected main transformer section is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: a non-perfect combination for eliminating the overload of the central main transformer section and a perfect combination for eliminating the overload of the direct-connected main transformer section, and the method ends; if a non-perfect combination for eliminating the overload of the direct-connected main transformer section is found, the non-perfect combination for eliminating the overload of the central main transformer section and the non-perfect combination for eliminating the overload of the direct-connected main transformer section are ignored, and then step 5) is entered;

[0129] 4-2-2) If the overloaded 110 kV busbar of the direct-connected plant and station is operated in separate columns, the overloaded direct-connected main transformer is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer by repeating the strategy calculation unit;

[0130] Among them, if a perfect combination for eliminating overload of the directly connected main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: a non-perfect combination for eliminating overload of the central main transformer section and a perfect combination for eliminating overload of the directly connected main transformer, and the method ends; if a non-perfect combination for eliminating overload of the directly connected main transformer is found, the non-perfect combination for eliminating overload of the central main transformer section and the non-perfect combination for eliminating overload of the directly connected main transformer are ignored, and then step 5 is entered).

[0131] 5) Based on the initial operation mode of overload of the central main transformer section, the overloaded central plant station 110 kV busbar is divided into sections, and the calculation and verification are performed according to the preset historical load curve to determine whether the central main transformer is overloaded:

[0132] If it does not exist, then generate the current load balancing strategy of the main grid of the power grid in the region, which is the 110 kV busbar splitting of the overloaded central plant station, and the method ends;

[0133] If it exists, go to step 6).

[0134] 6) Taking the 220 kV overloaded central main transformer as the current overload object, repeat the strategy calculation unit to find a load transfer solution to eliminate the overload of the central main transformer, wherein:

[0135] If a perfect combination for eliminating overload of the central main transformer is found, the load balancing strategy for the main grid of the current power grid in the region is generated, including: separate operation of the 110 kV busbar of the overloaded central plant station and a perfect combination for eliminating overload of the central main transformer, and the method ends; if a non-perfect combination for eliminating overload of the central main transformer is found, proceed to step 7).

[0136] 7) Based on the imperfect combination for eliminating overload of the central main transformer outputted in step 6), the operation mode of the overloaded direct-connected plant station 110 kV busbar caused by corresponding load transfer according to each adjustment unit in the imperfect combination is read, wherein:

[0137] If the overloaded 110 kV busbar directly connected to the plant station is operated in separate columns, proceed to step 9);

[0138] If the overloaded direct-connected plant 110 kV busbar is in parallel operation, the overloaded direct-connected main transformer section is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer section by repeating the strategy calculation unit; wherein, if a perfect combination for eliminating the overload of the direct-connected main transformer section is found, the current load balancing strategy of the main grid of the power grid in the region is generated, including: the overloaded central plant 110 kV busbar is operated in parallel, the non-perfect combination for eliminating the overload of the central main transformer, and the perfect combination for eliminating the overload of the direct-connected main transformer section; if a non-perfect combination for eliminating the overload of the direct-connected main transformer section is found, the non-perfect combination for eliminating the overload of the direct-connected main transformer section is ignored, and based on the overloaded central plant 110 kV busbar being operated in parallel and the non-perfect combination for eliminating the overload of the central main transformer, step 8 is entered).

[0139] 8) After the overloaded 110 kV busbars of the direct-connected plant and station are separated, the calculation and verification are performed according to the preset historical load curve to determine whether there is an overload on the direct-connected main transformer:

[0140] If it does not exist, the current load balancing strategy for the main grid of the power grid in the region is generated, including: split operation of the overloaded central plant 110 kV bus, an imperfect combination to eliminate overload of the central main transformer, and split operation of the 110 kV bus directly connected to the plant, and the method ends; if it exists, go to step 9).

[0141] 9) taking the overloaded direct-connected main transformer as the current overload object, and finding a load transfer scheme to eliminate the overload of the direct-connected main transformer by repeating the strategy calculation unit;

[0142] Among them, if the perfect combination of eliminating the overload of the directly connected main transformer is found, the load balancing strategy of the main grid of the current power grid in the region will be generated, including: the imperfect combination of split operation of the overloaded central plant and station 110 kV busbar, eliminating the overload of the central main transformer, and the perfect combination of split operation of the directly connected plant and station 110 kV busbar, eliminating the overload of the directly connected main transformer;

[0143] If a non-perfect combination for eliminating overload of the direct-connected main transformer is found, the non-perfect combination for eliminating overload of the direct-connected main transformer, the direct-connected plant 110 kV busbar splitting, and the non-perfect combination for eliminating overload of the central main transformer are ignored, and then based on the overloaded central plant 110 kV busbar splitting operation mode, proceed to step 10).

[0144] 10) Load balancing is achieved by switching the 110 kV outgoing line to the overloaded central main transformer. The overall process of switching the 110 kV outgoing line to the overloaded central main transformer is as follows: Figure 3 As shown, the specific steps are as follows:

[0145] 10-1) Obtain the 110 kV load plant and 35 kV load plant under the main transformer of the same station;

[0146] 10-2) From the load plants obtained in step 10-1), empty charging lines, single power plants, line transformer groups, power plants, and important users are screened out, and then the load plants that have a unique connection relationship between the main transformer and the directly connected plant at the same station are sorted out (that is, if there is only a unique 110 kV or 35 kV connection plant between the main transformer and the directly connected plant at the same station, such load plants are sorted out), and the sorted load plants are obtained;

[0147] 10-3) sequentially traverse the sorted load plants and stations obtained in step 10-2) and determine whether their high-voltage side busbars are running in separate columns or in parallel, thereby determining the load transfer mode; wherein:

[0148] If any of the sorted load plants is a split-line operation plant, half of the load of the plant under the main transformer of the same station is transferred to form an adjustment unit corresponding to the load plant;

[0149] If any of the sorted load plants is a parallel operation plant, half of the load of the plant under the directly connected plant is transferred to form an adjustment unit corresponding to the load plant, or the whole load of the load plant is transferred to form an adjustment unit corresponding to the load plant;

[0150] 10-4) According to the result of step 10-3), the adjustment units corresponding to each load plant after sorting are combined into 1 unit, 2 units, ..., Y units to form a connection adjustment unit combination, where Y is the total number of load plants after sorting in step 10-2); then all the obtained connection adjustment unit combinations are sorted from large to small according to their corresponding transferable load amounts to obtain a connection adjustment unit combination sequence.

[0151] It should be noted that, in this embodiment, in a single interconnected adjustment unit combination, any parallel-operating plant station can only choose to combine with one adjustment unit formed by transferring half of the load of the plant station under the directly connected plant station or one adjustment unit formed by transferring the entire station load. These two methods cannot appear in the same combination at the same time.

[0152] 10-5) Select each connection adjustment unit combination in the connection adjustment unit combination sequence obtained in step 10-4) in turn, perform corresponding load transfer according to each adjustment unit in the combination, and perform superposition calculation verification using a preset historical load curve after the transfer to determine whether the opposite side power station main transformer or main transformer section is overloaded after the transfer, wherein:

[0153] If the transfer does not cause overload of the opposite main transformer or the opposite main transformer section, the current contact adjustment unit combination is output and the process goes to step 10-6);

[0154] If the transfer causes the opposite main transformer or the opposite main transformer section to be overloaded, continue to select the next contact adjustment unit combination in the contact adjustment unit combination sequence for load transfer, until the corresponding load transfer is performed according to each adjustment unit in the current contact adjustment unit combination and it is verified that the opposite main transformer or the opposite main transformer section is not overloaded, then the current contact adjustment unit combination is output and step 10-6 is entered;

[0155] If after traversing all the interconnected adjustment unit combinations in the sequence in step 10-4), there is no load transfer according to each adjustment unit in any interconnected adjustment unit combination that does not cause overload of the opposite main transformer or the opposite main transformer section, then no load transfer is performed under the main transformer at the same station, and the process goes to step 10-6).

[0156] 10-6) Select the non-zero load outgoing lines under the central main transformer except the power plant, and then combine the selected load outgoing lines with 1 outgoing line, 2 outgoing lines, ..., Z outgoing lines to form an outgoing line combination, where Z is the total number of outgoing lines after screening, and then combine all the outgoing line combinations into an outgoing line combination sequence.

[0157] 10-7) Selecting the outgoing line combinations whose load levels are less than or equal to the acceptable capacity of the main transformer at the same station from the outgoing line combination sequence obtained in step 10-6) and sorting them from large to small according to the load level to form an outgoing line sub-sequence.

[0158] 10-8) Select each outgoing line combination from the outgoing line subsequence obtained in step 10-7) as the current outgoing line combination for mother-to-mother switching, and then use the preset historical load curve for superposition calculation verification to calculate whether the main transformer at the same station is overloaded after mother-to-mother switching:

[0159] If it is not overloaded, the current output line combination is output and the process goes to step 11);

[0160] If overloaded, the next outgoing line combination is selected from the outgoing line sub-sequence as the new current outgoing line combination for mother-to-mother inversion, and then the preset historical load curve is used for superposition calculation verification until the mother-to-mother inversion is performed according to the current outgoing line combination and it is verified that it does not cause overload of the main transformer at the same station, then the current outgoing line combination is output and the process goes to step 11);

[0161] If after traversing all the outgoing line combinations in the outgoing line sub-sequence in turn, no outgoing line combination is found to be inverted and after verification, it does not cause overload of the main transformer at the same station, then the inverted bus operation will not be performed and the load transfer operation of the main transformer at the same station will be ignored; then based on the 110 kV busbar split operation mode of the overloaded central plant station, enter step 12).

[0162] 11) Perform superposition calculation and verification based on the preset historical load curve to determine whether the central main transformer is overloaded after the mother is switched:

[0163] If the overload of the central main transformer is eliminated, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the 110 kV busbar of the central plant station is operated in parallel, the load combination of the main transformer at the same station transferred to the external station, and the load combination of the central main transformer to the main transformer at the same station, and the method ends;

[0164] If the central main transformer is still overloaded, go to step 12).

[0165] 12) Taking the overloaded central main transformer as the current overload object, repeating the strategy calculation unit, and finding a load transfer solution to eliminate the overload of the central main transformer;

[0166] Among them, if the perfect combination to eliminate the overload of the central main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the overloaded central plant station 110 kV busbar is operated separately, the load combination of the main transformer at the same station is transferred to the external station, the load combination of the central main transformer to the main transformer at the same station is reversed, and the perfect combination to eliminate the overload of the central main transformer is generated, and the method ends;

[0167] If a non-perfect combination that eliminates the overload of the central main transformer is found, and the current round is the first round of regional power grid main network load balancing optimization, then proceed to step 13); if a non-perfect combination that eliminates the overload of the central main transformer is found, and the current round is the second round of regional power grid main network load balancing optimization, then proceed to step 14); if a non-perfect combination that eliminates the overload of the central main transformer is found, and the current round is the third round of regional power grid main network load balancing optimization, then proceed to step 18).

[0168] 13) Based on the load combination of the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the first round of regional power grid main network load balancing optimization, determine the overloaded central main transformer or central main transformer section in the second round of regional power grid main network load balancing optimization, select the overloaded central main transformer or central main transformer section in the second round of regional power grid main network load balancing optimization The load level corresponding to the maximum overload in the historical curve verification at the time is selected as the initial load of the second round of regional power grid main network load balancing optimization, and return to step 2) to perform the second round of regional power grid main network load balancing optimization.

[0169] 14) Based on the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the outer station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the second round of regional power grid main grid load balance optimization, the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization is determined, and the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization is compared with the overloaded central main transformer or central main transformer section in the first round of regional power grid main grid load balance optimization:

[0170] If they are different main transformers or main transformer sections, the load level corresponding to the moment of maximum overload of the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization in the historical curve verification is selected as the initial load of the third round of regional power grid main grid load balance optimization, and return to step 2) to perform the third round of regional power grid main grid load balance optimization;

[0171] If they are the same main transformer or main transformer section, the imperfect combination for eliminating overload of the central main transformer in the second round of regional power grid main grid load balancing optimization is ignored, and the process goes to step 15).

[0172] 15) Based on the load combination of the overloaded central plant station 110 kV busbar in the second round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferring to the external station, and the load combination of the central main transformer transferring to the main transformer at the same station, the overloaded central main transformer in the second round of regional power grid main network load balancing optimization is taken as the overload object, and steps 3-2) are repeated to obtain the adjustment unit combination sequence of the overloaded central main transformer in the second round of regional power grid main network load balancing optimization, and then the adjustment unit combination whose transferable load is greater than or equal to the overload load of the central main transformer in the second round of regional power grid main network load balancing optimization is selected from the adjustment unit combination sequence and a subsequence is formed in the order of the transferable load from small to large; the adjustment unit combination is selected from the subsequence in turn, and the corresponding load is transferred according to each adjustment unit in the combination. After each transfer, the preset historical load curve is used for superposition calculation verification to determine whether the central main transformer in the second round of regional power grid main network load balancing optimization is overloaded after the load transfer according to the current adjustment unit combination:

[0173] If it is not overloaded, the current adjustment unit combination is output and the process goes to step 16);

[0174] If it is still overloaded, the next adjustment unit combination in the subsequence is selected to continue load transfer, verification and judgment until the corresponding load transfer is performed according to each adjustment unit in the current adjustment unit combination, and the overload of the central main transformer in the second round of regional power grid main network load balance optimization can be eliminated. Then the current adjustment unit combination is output and step 16 is entered).

[0175] 16) Based on the adjustment unit combination output from step 15), determine the current overloaded main transformer or main transformer section, and judge whether the overloaded main transformer or main transformer section is the same as the central main transformer or central main transformer section of the first round of regional power grid main network load balance optimization:

[0176] If different, go to step 17);

[0177] If they are the same, continue to select the next adjustment unit combination in the subsequence obtained in step 15) to continue load transfer, verification and judgment until the corresponding load transfer according to each adjustment unit in the new current adjustment unit combination can eliminate the overload of the central main transformer in the second round of regional power grid main network load balancing optimization, and the overloaded main transformer or main transformer section caused by the corresponding load transfer according to each adjustment unit in the current adjustment unit combination is different from the central main transformer or central main transformer section in the first round of regional power grid main network load balancing optimization, then output the current adjustment unit combination and enter step 17).

[0178] 17) Based on the adjustment unit combination output from step 16), determine the central main transformer or central main transformer section for the third round of regional power grid main network load balancing optimization, select the overloaded central main transformer or central main transformer section for the third round of regional power grid main network load balancing optimization at the time when the overload is the largest in the historical curve verification as the initial load for the third round of regional power grid main network load balancing optimization, and return to step 2) to perform the third round of regional power grid main network load balancing optimization.

[0179] 18) Based on the load combination of the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the outer station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the third round of regional power grid main grid load balance optimization, determine the current overloaded main transformer or main transformer section, and compare the current overloaded main transformer or main transformer section with the overloaded central main transformer or central main transformer section in the first round of regional power grid main grid load balance optimization and the second round of regional power grid main grid load balance optimization:

[0180] If it is a different main transformer or main transformer section, the generated regional power grid main network load balancing strategy includes: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the overloaded central plant station 110 kV busbar split operation in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer, and the method ends;

[0181] If they are the same main transformer or main transformer section, the imperfect combination for eliminating overload of the central main transformer in the third round of regional power grid main grid load balancing optimization is ignored, and the process goes to step 19).

[0182] 19) Based on the load combination of the overloaded central plant station 110 kV busbar in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer in the same station transferring to the external station, and the load combination of the central main transformer transferring to the main transformer in the same station, the overloaded central main transformer in the third round of regional power grid main network load balancing optimization is taken as the overload object, and step 3-2) is repeated to obtain the adjustment unit combination sequence of the overloaded central main transformer in the third round of regional power grid main network load balancing optimization, and then the adjustment unit combination whose transferable load is greater than or equal to the overload load of the central main transformer in the third round of regional power grid main network load balancing optimization is selected from the current adjustment unit combination sequence and a subsequence is formed in the order of the transferable load from small to large. Adjustment unit combinations are selected from the subsequence in turn, and the corresponding load is transferred according to each adjustment unit in the combination. After each transfer, the preset historical load curve is used for superposition calculation verification to determine whether the central main transformer in the third round of regional power grid main network load balancing optimization is overloaded after the load transfer according to the current adjustment unit combination:

[0183] If it is not overloaded, the current adjustment unit combination is output and the process goes to step 20);

[0184] If it is still overloaded, the next adjustment unit combination in the subsequence is selected to continue load transfer, verification and judgment until the overload of the central main transformer in the third round of regional power grid main network load balancing optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit in the current adjustment unit combination. Then the current adjustment unit combination is output and step 20 is entered).

[0185] 20) Based on the adjustment unit combination outputted in step 19), determine the current overloaded main transformer or main transformer section, and judge whether the overloaded main transformer or main transformer section is the same as the central main transformer or central main transformer section of the first or second round of regional power grid main network load balance optimization:

[0186] If they are different, the current adjustment unit combination is output, and the load balancing strategy of the regional power grid main network is generated, including: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the overloaded central plant station 110 kV busbar split operation in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the current adjustment unit combination for eliminating the overload of the central main transformer, and the method ends;

[0187] If they are the same, the next adjustment unit combination in the subsequence obtained in step 19) is selected to continue load transfer, verification and judgment until the overload of the central main transformer in the third round of regional power grid main network load balancing optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit in the new current adjustment unit combination, and the overloaded main transformer or main transformer section caused by the corresponding load transfer according to each adjustment unit in the current adjustment unit combination is different from the central main transformer or central main transformer section in the first or second round, then the current adjustment unit combination is output, and the regional power grid main network load balancing strategy is generated, including: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the third round of overloaded regional power grid main network load balancing optimization The central plant station 110 kV busbar is operated in a separate column, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the current adjustment unit combination that eliminates the overload of the central main transformer, and the method ends.

[0188] Regarding the description of the present invention, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that any person of ordinary skill in the art can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or perform equivalent replacements on some of the technical features thereof; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for generating a load balancing strategy for a regional power grid main network, characterized in that: include: 1) Determine the current regional power grid: if there is a 220 kV overloaded plant, enter the first round of regional power grid main grid load balance optimization; 2) Based on the result of step 1), determine whether the 110 kV busbars of the 220 kV overloaded power plants and stations in the regional power grid are in parallel operation: If they are operated in parallel, then go to step 3) to eliminate the overload of the central main transformer section; if they are operated in separate columns, then go to step 6) to eliminate the overload of the central main transformer; 3) Taking the 220 kV overloaded central main transformer section as the current overload object, a load transfer scheme is sought through a preset strategy calculation unit to eliminate the overload of the central main transformer section; the specific steps of the strategy calculation unit are as follows: 3-1) Determine the overload load of the overload object; 3-2) Obtain the adjustment unit combination sequence under the overload object. The specific steps are as follows: 3-2-1) Obtain the 110 kV plant and 35 kV plant under the overload object; 3-2-2) From the load plants and stations obtained in step 3-2-1), empty charging lines, single power plants and stations, line transformer groups, power plants, and important users are screened to obtain the screened load plants and stations; 3-2-3) sequentially traverse the selected load plants obtained in step 3-2-2) and determine whether their high-voltage side busbars are running in separate columns or in parallel, thereby determining the load transfer mode; wherein: If any of the selected load plants is a split-operation plant, half of the load of the load plant under the overload object is transferred to form an adjustment unit corresponding to the load plant; If any of the selected load plants is a parallel operation plant, half of the load of the plant under the direct-connected main transformer or the direct-connected main transformer section is transferred to form an adjustment unit corresponding to the load plant, or the whole load of the load plant is transferred to form an adjustment unit corresponding to the load plant; 3-2-4) According to the result of step 3-2-3), the adjustment units corresponding to each selected load plant are respectively combined into 1 unit, 2 units, ..., X units to form an adjustment unit combination, where X is the total number of plants after screening, and then all the obtained adjustment unit combinations are formed into an adjustment unit combination sequence; Among them, in a single adjustment unit combination, any parallel operation plant selects one adjustment unit formed by transferring half of the load of the plant directly connected to the main transformer or under the main transformer section, or one adjustment unit formed by transferring the entire station load for combination; 3-3) selecting an adjustment unit combination whose transferable load is greater than or equal to the overload load of the overload object from the adjustment unit combination sequence obtained in step 3-2), and then sorting the selected adjustment unit combinations in ascending order of transferable load to form a subsequence; 3-4) From the subsequence obtained in step 3-3), select the first adjustment unit combination as the current candidate combination; 3-5) Perform corresponding load transfer according to each adjustment unit in the current candidate combination; 3-6) Using the preset historical load curve, the overload object load after the load transfer in step 3-5) is superimposed and calculated to verify whether the overload object is still overloaded after the load transfer according to the current selected combination: If it is not overloaded, keep the current combination to be selected and go to step 3-7); If it is still overloaded, continue to select the next adjustment unit combination in the subsequence obtained in step 3-3) as the new current candidate combination, and then return to step 3-5) until the overload phenomenon of the overloaded object can be eliminated after load transfer according to the current candidate combination, then retain the current candidate combination and enter step 3-7); 3-7) Using the preset historical load curve, perform superposition calculation verification on the direct-connected main transformer or the direct-connected main transformer section after the load transfer of the current candidate combination retained in step 3-6), so as to determine whether there is an overload on the direct-connected main transformer or the main transformer section after the load transfer according to the current candidate combination: If it does not exist, the overload of the overload object is eliminated successfully and does not cause overload of the directly connected main transformer or the directly connected main transformer section, and the current candidate combination is output as a perfect combination; If it exists, then ignore the load transfer according to the current candidate combination, continue to select the next adjustment unit combination in the subsequence obtained in step 3-3) as the new current candidate combination, and then return to step 3-5); If after traversing all the adjustment unit combinations in the subsequence obtained in step 3-3) in sequence, there is no combination that can eliminate the overload of the overloaded object and not cause overload of the directly connected main transformer or the directly connected main transformer section after the corresponding load transfer according to each adjustment unit in any combination, then the adjustment unit combination that eliminates the overload of the overloaded object and has the smallest transferable load in the subsequence obtained in step 3-3) is output as a non-perfect combination; 4) Judgment: 4-1) If the output of step 3) is a perfect combination, then the perfect combination is the current load balancing strategy of the main power grid in the region, and the method ends; 4-2) If the output of step 3) is a non-perfect combination, the operation mode of the 110 kV busbar of the overloaded direct-connected plant station caused by the corresponding load transfer of each adjustment unit in the non-perfect combination is read, where: 4-2-1) If the overloaded 110 kV busbar of the direct-connected plant and station is in parallel operation, the overloaded direct-connected main transformer section is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer section by repeating the strategy calculation unit; Among them, if a perfect combination for eliminating the overload of the direct-connected main transformer section is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: a non-perfect combination for eliminating the overload of the central main transformer section and a perfect combination for eliminating the overload of the direct-connected main transformer section, and the method ends; if a non-perfect combination for eliminating the overload of the direct-connected main transformer section is found, the non-perfect combination for eliminating the overload of the central main transformer section and the non-perfect combination for eliminating the overload of the direct-connected main transformer section are ignored, and then step 5) is entered; 4-2-2) If the overloaded 110 kV busbar of the direct-connected plant and station is operated in separate columns, the overloaded direct-connected main transformer is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer by repeating the strategy calculation unit; Among them, if a perfect combination for eliminating overload of the directly connected main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: a non-perfect combination for eliminating overload of the central main transformer section and a perfect combination for eliminating overload of the directly connected main transformer, and the method ends; if a non-perfect combination for eliminating overload of the directly connected main transformer is found, the non-perfect combination for eliminating overload of the central main transformer section and the non-perfect combination for eliminating overload of the directly connected main transformer are ignored, and then step 5 is entered; 5) Based on the initial operation mode of overload of the central main transformer section, the overloaded central plant station 110 kV busbar is divided into sections, and the calculation and verification are performed according to the preset historical load curve to determine whether the central main transformer is overloaded: If it does not exist, then generate the current load balancing strategy of the main grid of the power grid in the region, which is the 110 kV busbar splitting of the overloaded central plant station, and the method ends; If it exists, go to step 6); 6) Taking the 220 kV overloaded central main transformer as the current overload object, repeat the strategy calculation unit to find a load transfer solution to eliminate the overload of the central main transformer, wherein: If a perfect combination for eliminating the overload of the central main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the perfect combination of the overloaded central plant station 110 kV busbar split operation and eliminating the overload of the central main transformer, and the method ends; if a non-perfect combination for eliminating the overload of the central main transformer is found, go to step 7); 7) Based on the imperfect combination for eliminating overload of the central main transformer outputted in step 6), the operation mode of the overloaded direct-connected plant station 110 kV busbar caused by corresponding load transfer according to each adjustment unit in the imperfect combination is read, wherein: If the overloaded 110 kV busbar directly connected to the plant station is operated in separate columns, proceed to step 9); If the overloaded direct-connected plant 110 kV busbar is in parallel operation, the overloaded direct-connected main transformer section is taken as the current overload object, and the load transfer scheme is found to eliminate the overload of the direct-connected main transformer section by repeating the strategy calculation unit; wherein, if a perfect combination for eliminating the overload of the direct-connected main transformer section is found, the current load balancing strategy of the main grid of the power grid in the region is generated, including: the overloaded central plant 110 kV busbar is operated in parallel, the non-perfect combination for eliminating the overload of the central main transformer, and the perfect combination for eliminating the overload of the direct-connected main transformer section; if a non-perfect combination for eliminating the overload of the direct-connected main transformer section is found, the non-perfect combination for eliminating the overload of the direct-connected main transformer section is ignored, and the overloaded central plant 110 kV busbar is operated in parallel and the non-perfect combination for eliminating the overload of the central main transformer is used, and then step 8 is entered; 8) After the overloaded 110 kV busbars of the direct-connected plant and station are separated, the calculation and verification are performed according to the preset historical load curve to determine whether there is an overload on the direct-connected main transformer: If it does not exist, the load balancing strategy of the main grid of the power grid in the current region is generated, including: split operation of the overloaded central plant station 110 kV bus, an imperfect combination of eliminating overload of the central main transformer, and split operation of the 110 kV bus of the direct-connected plant station, and the method ends; if it exists, enter step 9); 9) taking the overloaded direct-connected main transformer as the current overload object, and finding a load transfer scheme to eliminate the overload of the direct-connected main transformer by repeating the strategy calculation unit; Among them, if the perfect combination of eliminating the overload of the directly connected main transformer is found, the load balancing strategy of the main grid of the current power grid in the region will be generated, including: the imperfect combination of split operation of the overloaded central plant and station 110 kV busbar, eliminating the overload of the central main transformer, and the perfect combination of split operation of the directly connected plant and station 110 kV busbar, eliminating the overload of the directly connected main transformer; If a non-perfect combination for eliminating overload of the direct-connected main transformer is found, the non-perfect combination for eliminating overload of the direct-connected main transformer, the direct-connected plant 110 kV busbar splitting, and the non-perfect combination for eliminating overload of the central main transformer are ignored, and then based on the overloaded central plant 110 kV busbar splitting operation mode, step 10 is entered; 10) Load balancing is achieved by switching the 110 kV outgoing line of the overloaded central main transformer. The specific steps are as follows: 10-1) Obtain the 110 kV load plant and 35 kV load plant under the main transformer of the same station; 10-2) From the load plants obtained in step 10-1), empty charging lines, single power plants, line transformer groups, power plants, and important users are screened out, and load plants that have a unique contact relationship between the main transformer and the directly connected plant at the same station are sorted out to obtain sorted load plants; 10-3) sequentially traverse the sorted load plants and stations obtained in step 10-2) and determine whether their high-voltage side busbars are running in separate columns or in parallel, thereby determining the load transfer mode; wherein: If any of the sorted load plants is a split-line operation plant, half of the load of the plant under the main transformer of the same station is transferred to form an adjustment unit corresponding to the load plant; If any of the sorted load plants is a parallel operation plant, half of the load of the plant under the directly connected plant is transferred to form an adjustment unit corresponding to the load plant, or the whole load of the load plant is transferred to form an adjustment unit corresponding to the load plant; 10-4) According to the result of step 10-3), the adjustment units corresponding to each load plant after sorting are respectively combined into 1 unit, 2 units, ..., Y units to form a connection adjustment unit combination, wherein Y is the total number of load plants after sorting in step 10-2); then all the obtained connection adjustment unit combinations are sorted from large to small according to their corresponding transferable load amounts to obtain a connection adjustment unit combination sequence; Among them, in a single interconnection adjustment unit combination, any parallel operation plant station chooses to transfer one adjustment unit formed by half of the load of the plant station under the directly connected plant station or one adjustment unit formed by transferring the entire station load for combination; 10-5) Select each connection adjustment unit combination in the connection adjustment unit combination sequence obtained in step 10-4) in turn, perform corresponding load transfer according to each adjustment unit in the combination, and perform superposition calculation verification using a preset historical load curve after the transfer to determine whether the opposite main transformer or the opposite main transformer section is overloaded after the transfer, wherein: If the transfer does not cause overload of the opposite main transformer or the opposite main transformer section, the current contact adjustment unit combination is output and the process goes to step 10-6); If the transfer causes the opposite main transformer or the opposite main transformer section to be overloaded, continue to select the next contact adjustment unit combination in the contact adjustment unit combination sequence for load transfer, until the corresponding load transfer is performed according to the current contact adjustment unit combination and it is verified that the opposite main transformer or the opposite main transformer section is not overloaded, then the current contact adjustment unit combination is output and step 10-6 is entered; If after traversing all the contact adjustment unit combinations in the sequence in step 10-4), there is no load transfer according to each adjustment unit in any contact adjustment unit combination that does not cause overload of the opposite main transformer or the opposite main transformer section, then no load transfer is performed under the main transformer at the same station, and the process goes to step 10-6); 10-6) Select the non-zero load outgoing lines under the central main transformer except the power plant, and then combine the selected load outgoing lines with 1 outgoing line, 2 outgoing lines, ..., Z outgoing lines to form an outgoing line combination, where Z is the total number of outgoing lines after screening, and then combine all the outgoing line combinations into an outgoing line combination sequence; 10-7) selecting an outgoing line combination under the central main transformer that is less than or equal to the acceptable capacity of the main transformer at the same station from the outgoing line combination sequence obtained in step 10-6) and sorting the combined load levels from large to small to form an outgoing line subsequence; 10-8) Select each outgoing line combination from the outgoing line subsequence obtained in step 10-7) as the current outgoing line combination for mother-to-mother switching, and then use the preset historical load curve for superposition calculation verification to calculate whether the main transformer at the same station is overloaded after mother-to-mother switching: If it is not overloaded, the current output line combination is output and the process goes to step 11); If overloaded, the next outgoing line combination is selected from the outgoing line sub-sequence as the new current outgoing line combination for mother-to-mother inversion, and then the preset historical load curve is used for superposition calculation verification until the mother-to-mother inversion is performed according to the current outgoing line combination and it is verified that it does not cause overload of the main transformer at the same station, then the current outgoing line combination is output and the process goes to step 11); If after traversing all outgoing line combinations in the outgoing line subsequence in sequence, there is no outgoing line combination that reverses the bus and after verification, it does not cause the main transformer at the same station to be overloaded, then the bus reverse operation is not performed and the load transfer operation of the main transformer at the same station is ignored; then based on the overloaded central plant station 110 kV busbar split operation mode, enter step 12); 11) Perform superposition calculation and verification based on the preset historical load curve to determine whether the central main transformer is overloaded after the mother is switched: If the overload of the central main transformer is eliminated, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the 110 kV busbar of the central plant station is operated in parallel, the load combination of the main transformer at the same station transferred to the external station, and the load combination of the central main transformer to the main transformer at the same station, and the method ends; If the central main transformer is still overloaded, go to step 12); 12) Taking the overloaded central main transformer as the current overload object, repeating the strategy calculation unit, and finding a load transfer solution to eliminate the overload of the central main transformer; Among them, if the perfect combination to eliminate the overload of the central main transformer is found, the load balancing strategy of the main grid of the current power grid in the region is generated, including: the overloaded central plant station 110 kV busbar is operated separately, the load combination of the main transformer at the same station is transferred to the external station, the load combination of the central main transformer to the main transformer at the same station is reversed, and the perfect combination to eliminate the overload of the central main transformer is generated, and the method ends; If a non-perfect combination for eliminating the overload of the central main transformer is found, and the current round is the first round of regional power grid main network load balancing optimization, then proceed to step 13); if a non-perfect combination for eliminating the overload of the central main transformer is found, and the current round is the second round of regional power grid main network load balancing optimization, then proceed to step 14); if a non-perfect combination for eliminating the overload of the central main transformer is found, and the current round is the third round of regional power grid main network load balancing optimization, then proceed to step 18); 13) Based on the load combination of the overloaded central plant station 110 kV busbar split operation, the same station main transformer transferred to the external station, the central main transformer to the same station main transformer load combination, and the non-perfect combination of eliminating the overload of the central main transformer in the first round of regional power grid main grid load balance optimization, determine the overloaded central main transformer or central main transformer section in the second round of regional power grid main grid load balance optimization, select the overloaded central main transformer or central main transformer section in the second round of regional power grid main grid load balance optimization The load level corresponding to the maximum overload in the historical curve verification is selected as the initial load of the second round of regional power grid main grid load balance optimization, and return to step 2) to perform the second round of regional power grid main grid load balance optimization; 14) Based on the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the outer station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the second round of regional power grid main grid load balance optimization, the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization is determined, and the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization is compared with the overloaded central main transformer or central main transformer section in the first round of regional power grid main grid load balance optimization: If they are different main transformers or main transformer sections, the load level corresponding to the moment of maximum overload of the overloaded central main transformer or central main transformer section in the third round of regional power grid main grid load balance optimization in the historical curve verification is selected as the initial load of the third round of regional power grid main grid load balance optimization, and return to step 2) to perform the third round of regional power grid main grid load balance optimization; If they are the same main transformer or main transformer section, the imperfect combination for eliminating overload of the central main transformer in the second round of regional power grid main grid load balance optimization is ignored, and the process goes to step 15); 15) Based on the load combination of the overloaded central plant station 110 kV busbar in the second round of regional power grid main network load balancing optimization, the load combination of the main transformer in the same station transferring to the external station, and the load combination of the central main transformer transferring to the main transformer in the same station, the overloaded central main transformer in the second round of regional power grid main network load balancing optimization is taken as the overload object, and steps 3-2) are repeated to obtain the adjustment unit combination sequence of the overloaded central main transformer in the second round of regional power grid main network load balancing optimization, and then select the adjustment unit combination whose transferable load is greater than or equal to the overload load of the central main transformer in the second round of regional power grid main network load balancing optimization from the adjustment unit combination sequence and form a subsequence in the order of the transferable load from small to large; select the adjustment unit combination from the subsequence in turn, and perform the corresponding load transfer according to each adjustment unit in the combination. After each transfer, the preset historical load curve is used for superposition calculation verification to determine whether the central main transformer in the second round of regional power grid main network load balancing optimization is overloaded after the transfer according to the load combination corresponding to the current adjustment unit combination: If it is not overloaded, the current adjustment unit combination is output and the process goes to step 16); If it is still overloaded, the next adjustment unit combination in the subsequence is selected to continue load transfer, verification and judgment until the overload of the central main transformer in the second round of regional power grid main network load balance optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit in the current adjustment unit combination, then the current adjustment unit combination is output and step 16 is entered; 16) Based on the adjustment unit combination output from step 15), determine the current overloaded main transformer or main transformer section, and judge whether the overloaded main transformer or main transformer section is the same as the initial central main transformer or central main transformer section of the first round of regional power grid main network load balance optimization: If different, go to step 17); If they are the same, continue to select the next adjustment unit combination in the subsequence obtained in step 15) to continue load transfer, verification and judgment, until the overload of the central main transformer in the second round of regional power grid main network load balance optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit in the new current adjustment unit combination, and the overloaded main transformer or main transformer section caused by the corresponding load transfer according to each adjustment unit in the current adjustment unit combination is different from the initial central main transformer or central main transformer section in the first round of regional power grid main network load balance optimization, then output the current adjustment unit combination and enter step 17); 17) Based on the adjustment unit combination output from step 16), determine the central main transformer or central main transformer section for the third round of regional power grid main network load balancing optimization, select the load level corresponding to the moment of the maximum overload of the overloaded central main transformer or central main transformer section in the third round of regional power grid main network load balancing optimization in the historical curve verification as the initial load of the third round of regional power grid main network load balancing optimization, and return to step 2) to perform the third round of regional power grid main network load balancing optimization; 18) Based on the load combination of the overloaded central plant station 110 kV busbar split operation, the load combination of the main transformer at the same station transferred to the outer station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer in the third round of regional power grid main grid load balance optimization, determine the current overloaded main transformer or main transformer section, and compare the current overloaded main transformer or main transformer section with the overloaded central main transformer or central main transformer section in the first round of regional power grid main grid load balance optimization and the second round of regional power grid main grid load balance optimization: If it is a different main transformer or main transformer section, the generated regional power grid main network load balancing strategy includes: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the overloaded central plant station 110 kV busbar split operation in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the imperfect combination of eliminating the overload of the central main transformer, and the method ends; If they are the same main transformer or main transformer section, the imperfect combination for eliminating overload of the central main transformer in the third round of regional power grid main grid load balance optimization is ignored, and the process goes to step 19); 19) Based on the load combination of the overloaded central plant station 110 kV busbar in the third round of regional power grid main grid load balancing optimization, the load combination of the main transformer in the same station transferring to the external station, and the load combination of the central main transformer transferring to the main transformer in the same station, the overloaded central main transformer in the third round of regional power grid main grid load balancing optimization is taken as the overload object, and step 3-2) is repeated to obtain the adjustment unit combination sequence of the overloaded central main transformer in the third round of regional power grid main grid load balancing optimization, and then select the adjustment unit combination whose transferable load is greater than or equal to the overload load of the central main transformer in the third round of regional power grid main grid load balancing optimization from the current adjustment unit combination sequence and form a subsequence in the order of the transferable load from small to large; select the adjustment unit combination from the subsequence in turn, and perform the corresponding load transfer according to each adjustment unit in the combination. After each transfer, the preset historical load curve is used for superposition calculation verification to determine whether the central main transformer in the third round of regional power grid main grid load balancing optimization is overloaded after the transfer according to the load combination corresponding to the current adjustment unit combination: If it is not overloaded, the current adjustment unit combination is output and the process goes to step 20); If it is still overloaded, continue to select the next adjustment unit combination in the subsequence to continue load transfer, verification and judgment until the overload of the central main transformer in the third round of regional power grid main network load balance optimization can be eliminated after the corresponding load transfer is performed according to each adjustment unit of the current adjustment unit combination, then output the current adjustment unit combination and enter step 20); 20) Based on the adjustment unit combination outputted in step 19), determine the current overloaded main transformer or main transformer section, and judge whether the overloaded main transformer or main transformer section is the same as the central main transformer or central main transformer section of the first or second round of regional power grid main network load balance optimization: If they are different, the current adjustment unit combination is output, and the load balancing strategy of the regional power grid main network is generated, including: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the overloaded central plant station 110 kV busbar split operation in the third round of regional power grid main network load balancing optimization, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the current adjustment unit combination for eliminating the overload of the central main transformer, and the method ends; If they are the same, continue to select the next adjustment unit combination in the subsequence obtained in step 19) to continue load transfer, verification and judgment, until the corresponding load transfer according to each adjustment unit in the new current adjustment unit combination can eliminate the overload of the central main transformer in the third round of regional power grid main network load balancing optimization, and the overloaded main transformer or main transformer section caused by the corresponding load transfer according to each adjustment unit in the current adjustment unit combination is different from the central main transformer or central main transformer section in the first or second round, then output the current adjustment unit combination, and generate a regional power grid main network load balancing strategy including: the output results of the first and second rounds of regional power grid main network load balancing optimization, and the third round of overloaded regional power grid main network load balancing optimization The central plant station 110 kV busbar is operated in a separate column, the load combination of the main transformer at the same station transferred to the external station, the load combination of the central main transformer to the main transformer at the same station, and the current adjustment unit combination that eliminates the overload of the central main transformer, and the method ends.

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