CN109412141B - Method for automatic scanning analysis of 220kV main transformer N-1 risk power grid of power grid - Google Patents

Abstract

The invention relates to the field of electric power, in particular to an automatic risk scanning and analyzing method for a 220kV main transformer N-1 of a power grid.

Description

Method for automatic scanning analysis of 220kV main transformer N-1 risk power grid of power grid

Technical Field

The invention relates to the field of electric power, in particular to an automatic scanning analysis method for a 220kV main transformer N-1 risk power grid of a power grid.

Background

The modern society has higher and higher requirements on the power supply reliability of a power grid, finds weak links of the power grid in time, and takes corresponding pre-control measures, which is very important work related to whether the power grid can safely and stably run. The N-1 risk, also called a single fault risk, is a risk of a user power outage, damage to the stability of the system, voltage breakdown, and the like caused by a line trip after any independent element of N elements of the power system, such as a generator, a transmission line, a transformer, and the like, is cut off due to a fault.

The traditional real-time operation risk of the 220kV main transformer N-1 depends on manual analysis of a dispatcher according to data of a monitoring system and related information such as spare power automatic switching and stability configuration, the efficiency is low, the accuracy is insufficient, and the operation stability of a power grid is influenced.

Disclosure of Invention

In order to solve the defect of low accuracy caused by the fact that the traditional real-time operation risk of the 220kV main transformer N-1 depends on manual analysis of a dispatcher in the prior art, the invention provides a method for automatically scanning and analyzing a 220kV main transformer N-1 risk power grid.

In order to realize the purpose, the technical scheme is as follows:

a method for automatically scanning and analyzing the risk of a 220kV main transformer N-1 of a power grid comprises the following steps:

step S1: acquiring a main transformer of an analysis object, wherein the object main transformer meets the following conditions: (1) the equipment attribute is a main transformer; (2) the voltage grade is 220 kV; (3) the maintenance plate is not hung; (4) boosting and changing in a non-power plant;

step S2: carrying out topology analysis on the power supply range of a main transformer of an analysis object;

step S3, judging the main transformer division and parallel operation mode in the station, judging the power supply ranges of all the main transformers in the station obtained in the step S2 as the parallel operation mode if the power supply ranges of the middle sides of any two main transformers are completely consistent, otherwise, judging the split operation mode;

step S4: performing main transformer N-1 risk analysis on the condition that the split operation mode is judged in the step S3;

step S5: performing main transformer N-1 risk analysis on the condition that the parallel operation mode is judged in the step S3;

and S6, integrating the results of the step S4 and the step S5 to form a risk analysis report of the 220kV main transformer N-1.

Preferably, step S2 specifically includes the following steps:

analyzing the topology of the variable low side and the variable middle side respectively by taking a main transformer body as a starting point according to the power flow direction, and stopping after the topology of the variable low side reaches a local station 10kV bus; and carrying out topology analysis on paths of a middle-side edge transformer middle switch, a local station 110kV bus, a local station 110kV outgoing line, an opposite side 110kV substation bus or line transformer group transformer high switch, an opposite side 110kV substation main transformer and a 10kV bus, wherein for the 110kV buses running in parallel, the bus coupling power direction is not considered during the topology analysis, and after the topology analysis is completed, all equipment on the topology path of the 220kV main transformer to be analyzed and a disconnecting link or a switch isolated from other parts of the power grid are used as the power supply range of the 220kV main transformer to be analyzed and stored in the system.

Preferably, step S4 specifically includes the following steps:

s401: performing topological analysis on the direction from the step S2 to the middle-side direction to obtain any 110kV transformer substation and a 110kV bus, a main transformer and a 10kV bus contained in the transformer substation as elements, wherein all the elements form a set and are stored in the system;

s402: judging whether any transformer substation obtained in the step S401 belongs to a 110kV transformer substation in a user transformer substation maintenance table, if so, directly judging that the transformer substation is in voltage loss after the main transformer N-1 is obtained, and not performing subsequent analysis;

s403: for the 110kV transformer substation which is judged not to belong to the maintenance table of the user transformer substation in the step S402, if any main transformer change-over switch contained in the substation exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2, the main transformer of the substation, a 10kV bus supplied by the main transformer and a connected 110kV bus are judged to be multi-power supply equipment, and after the main transformer N-1 of the analysis object is analyzed, the equipment cannot cause voltage loss;

s404: if any element in the set obtained in the step S401 does not meet the power supply conditions of the multiple power supply points listed in the step S403 and the elements contain all the operated 110kV bus, main transformer and 10kV bus, judging that the 110kV transformer substation is subjected to voltage loss in the whole short-term behind the main transformer N-1 of the analysis object;

s405: and for the 110kV transformer substation which is judged to be the total-station short-time voltage loss in the step S404, judging whether the following 110kV line spare power automatic switching conditions are met: (1) the station is provided with a hot standby 110kV line switch; (2) the line switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the voltage is met, judging that the station 110kV line backup power automatic switching is successful, and after the object main transformer N-1 is analyzed, the station does not cause voltage loss;

and S406, further analyzing whether the transformer substation which does not meet the conditions listed in the step S405 meets the main spare power automatic switching conditions: (1) the station has a hot standby main transformer; (2) the main transformer is arranged in a main transformer spare power automatic switching maintenance table; (3) the main transformer high-voltage switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, after the main transformer N-1 of the analysis object is judged, the 110kV main transformer of the station is successfully switched on automatically, and no voltage loss is caused;

s407: and for the 110kV transformer substation which is judged to be subjected to short-time voltage loss of the non-total station after the main transformer N-1 of the analysis object in the step S404, judging whether the 110kV substation spare power automatic switching condition is met: (1) the station is provided with a hot standby 110kV section switch; (2) the section switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the voltage of the station main transformer N-1 is met, judging that the 110kV subsection spare power automatic switching of the station is successful, and after the object main transformer N-1 is analyzed, enabling any equipment of the station not to lose voltage;

s408: and for the transformer substations which do not meet the 110kV subsection spare power automatic switching conditions listed in the step S407, judging whether the 10kV buses with short-time voltage loss meet the main transformer spare power automatic switching conditions one by one: (1) the voltage-loss bus can be topologically connected to a hot standby main transformer change-down switch; (2) the hot standby main transformer is arranged in a main transformer standby automatic switching maintenance table; (3) the hot standby main transformer high-voltage switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, judging that the main transformer N-1 of the analysis object is successfully switched into the spare power automatic switching of the main transformer of the 10kV bus, and avoiding voltage loss;

s409: and for the transformer substations which do not meet the conditions listed in the step S408, judging whether the 10kV buses with short-time voltage loss meet the 10kV subsection spare power automatic switching conditions one by one: (1) the voltage-loss bus can be topologically connected to a hot standby section switch; (2) the bus at the other end connected with the hot standby section switch is supplied with power by a main transformer change-down switch connected with the bus; (3) the hot standby section switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, after the main transformer N-1 of an analysis object is judged, the 10kV bus segmented spare power automatic switching is successful, and no voltage loss is caused;

s410: synthesizing the analysis results of the steps S405-S409 to form a primary outcome analysis report after the main transformer N-1 of the analysis object is formed;

s411: analyzing whether the voltage-loss equipment in the preliminary result analysis report obtained in the step S410 meets one of the following two conditions of multiple spare power automatic switching: (1) the upper-level power supply of the transformer substation is a 110kV transformer substation, the 110kV transformer substation exists in the primary result analysis report obtained in the step S410, and the result is that the spare power automatic switching is successful; (2) the voltage-loss equipment can be topologically connected to a hot standby circuit switch of the local station, and the hot standby circuit switch and any circuit switch meeting the conditions listed in the step S405 have a topological connection relationship; if any one of the conditions is met, correcting the equipment result to be no pressure loss;

s412: if the voltage-loss equipment in the preliminary consequence analysis report obtained in the step S410 does not meet the conditions listed in the step S411, further analyzing whether the voltage-loss equipment meets the pilot backup automatic switching conditions: (1) the 110kV transformer substation where the voltage loss equipment is located exists in a pilot-connected spare power automatic switching maintenance table; (2) another 110kV transformer substation paired with the 110kV transformer substation in the pilot-connected spare power automatic switching maintenance table is provided with a hot standby circuit switch; (3) the hot standby line switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the above conditions are met, correcting the equipment result to be no pressure loss;

s413: analyzing the 10kV buses obtained by the topology analysis in the step S2 in the direction of the lower voltage side one by one, and judging whether the 10kV bus sectional spare power automatic switching conditions are met, specifically referring to the step S409; if the conditions are met, judging that the main transformer N-1 of the analysis object is successfully switched into the 10kV bus in a segmented spare power automatic mode, and not causing voltage loss;

s414: and summarizing the analysis results of the steps S412-S413 to form an analysis object main transformer N-1 consequence report, and after the objects obtained in the step S1 are analyzed one by one, forming a risk analysis report of the 220kV main transformer in all the split operation modes.

Preferably, step S5 specifically includes the following steps:

s501: pairing a plurality of 220kV main transformers which run in parallel to serve as one element, and storing all the elements into a system in a set mode;

s502: taking any 220kV main transformer in any element in the set obtained in the step S501 as an analysis object main transformer, and judging whether all 10kV buses supplied by the analysis object main transformer meet 10kV subsection spare power automatic switching conditions or not according to the conditions listed in the step S409;

s503, obtaining a load value of the residual 220kV main transformers paired in the elements behind the main transformer N-1 of the analysis object, wherein the load value is obtained by subtracting 10kV bus load of the analysis object main transformer which does not meet the segmented spare power automatic switching condition from the sum of all 220kV main transformer variable load in the current elements and then dividing the load value by the number of the residual main transformers;

s504: comparing the load value of the residual 220kV main transformer obtained in the step S503 with a stable value of the load value in a main transformer stable value maintenance table, and if the load value is more than or equal to the stable value, judging that the residual 220kV main transformer is subjected to stable action to remove the load after an object main transformer N-1 is analyzed;

s505: for the remaining main transformers which are obtained in the step S504 and cause the load shedding of the stable operation, obtaining a line sequence of the shedding load from the stable control and energy shedding maintenance table;

s506: in a local database obtained by analyzing an automatic E file, setting the states of the first N line switches in the sequence obtained in the step S505 as unavailable, starting from 1 by N, and analyzing and obtaining the voltage loss and spare power automatic switching conditions of a 110kV transformer substation or equipment supplied by the line switches after the safety and stability action by referring to the processes of the steps S402-S413; if the supplied 110kV transformer substation belongs to a transformer substation in a safety and stability locking spare power automatic switching maintenance table, the voltage loss of the 110kV transformer substation is directly judged without analysis;

s507: according to the analysis result obtained in the step S506, calculating the load value of the residual 220kV main transformer after the N lines are cut off by the stabilizing action according to the following method: 1. for the condition that the backup power automatic switching is successful, if the switched-on backup switch of the 110kV transformer substation supplied by the cut line or the backup switch after the backup power automatic switching action exists in the power supply range of the residual 220kV main transformer obtained in the step S2, the load value of the residual main transformer is not influenced, otherwise, the cut load value is spread to the main transformers which run in parallel; 2. if the transformer substation or the equipment is in voltage loss, dividing the removed load value equally to each main transformer which runs in parallel; analyzing all N lines one by one to obtain residual main transformer load values;

s508: judging whether the load value of each residual operating main transformer obtained in the step S507 is smaller than a fixed value in a main transformer stable fixed value maintenance table, if the load value is still larger than or equal to the fixed value, repeating the steps S506 and S507 after N +1, and stopping until the load value is smaller than the fixed value or N is equal to the number of all lines of a line sequence with loads removed;

and S509, summarizing the analysis results of the steps S502, S504 and S506-S508 to obtain the N-1 consequence of the main transformer of the analysis object, and after all elements in the set obtained in the step S501 are analyzed one by one, forming a risk analysis report of the 220kV main transformer in all parallel operation modes.

Compared with the prior art, the invention has the beneficial effects that:

according to the method, the risk report of the 220kV main transformer N-1 is obtained by utilizing a computer system to quickly and automatically analyze, the defect of manual calculation is overcome, the timeliness is strong, the accuracy is high, the working efficiency is greatly improved, the time cost and the labor cost are reduced, and the operation stability of a power grid is improved.

Drawings

FIG. 1 is a flow chart of the present invention.

Fig. 2 is a flowchart of step S4.

Fig. 3 is a flowchart of step S5.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent;

the invention is further illustrated below with reference to the figures and examples.

Example 1

As shown in fig. 1, fig. 2 and fig. 3, a method for automatically scanning and analyzing the risk of an N-1 main transformer of a 220kV power grid includes the following steps:

step S1: acquiring a main transformer of an analysis object, wherein the object main transformer meets the following conditions: (1) the equipment attribute is a main transformer; (2) the voltage grade is 220 kV; (3) the maintenance plate is not hung; (4) boosting and changing in a non-power plant;

step S2: carrying out topology analysis on the power supply range of a main transformer of an analysis object;

step S3, judging the main transformer division and parallel operation mode in the station, judging the power supply ranges of all the main transformers in the station obtained in the step S2 as the parallel operation mode if the power supply ranges of the middle sides of any two main transformers are completely consistent, otherwise, judging the split operation mode;

step S4: performing main transformer N-1 risk analysis on the condition that the split operation mode is judged in the step S3;

step S5: performing main transformer N-1 risk analysis on the condition that the parallel operation mode is judged in the step S3;

and S6, integrating the results of the step S4 and the step S5 to form a risk analysis report of the 220kV main transformer N-1.

Preferably, step S2 specifically includes the following steps:

analyzing the topology of the variable low side and the variable middle side respectively by taking a main transformer body as a starting point according to the power flow direction, and stopping after the topology of the variable low side reaches a local station 10kV bus; and carrying out topology analysis on paths of a middle-side edge transformer middle switch, a local station 110kV bus, a local station 110kV outgoing line, an opposite side 110kV substation bus or line transformer group transformer high switch, an opposite side 110kV substation main transformer and a 10kV bus, wherein for the 110kV buses running in parallel, the bus coupling power direction is not considered during the topology analysis, and after the topology analysis is completed, all equipment on the topology path of the 220kV main transformer to be analyzed and a disconnecting link or a switch isolated from other parts of the power grid are used as the power supply range of the 220kV main transformer to be analyzed and stored in the system.

Preferably, step S4 specifically includes the following steps:

s401: performing topological analysis on the direction from the step S2 to the middle-side direction to obtain any 110kV transformer substation and a 110kV bus, a main transformer and a 10kV bus contained in the transformer substation as elements, wherein all the elements form a set and are stored in the system;

s402: judging whether any transformer substation obtained in the step S401 belongs to a 110kV transformer substation in a user transformer substation maintenance table, if so, directly judging that the transformer substation is in voltage loss after the main transformer N-1 is obtained, and not performing subsequent analysis;

s403: for the 110kV transformer substation which is judged not to belong to the maintenance table of the user transformer substation in the step S402, if any main transformer change-over switch contained in the substation exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2, the main transformer of the substation, a 10kV bus supplied by the main transformer and a connected 110kV bus are judged to be multi-power supply equipment, and after the main transformer N-1 of the analysis object is analyzed, the equipment cannot cause voltage loss;

s404: if any element in the set obtained in the step S401 does not meet the power supply conditions of the multiple power supply points listed in the step S403 and the elements contain all the operated 110kV bus, main transformer and 10kV bus, judging that the 110kV transformer substation is subjected to voltage loss in the whole short-term behind the main transformer N-1 of the analysis object;

s405: and for the 110kV transformer substation which is judged to be the total-station short-time voltage loss in the step S404, judging whether the following 110kV line spare power automatic switching conditions are met: (1) the station is provided with a hot standby 110kV line switch; (2) the line switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the voltage is met, judging that the station 110kV line backup power automatic switching is successful, and after the object main transformer N-1 is analyzed, the station does not cause voltage loss;

and S406, further analyzing whether the transformer substation which does not meet the conditions listed in the step S405 meets the main spare power automatic switching conditions: (1) the station has a hot standby main transformer; (2) the main transformer is arranged in a main transformer spare power automatic switching maintenance table; (3) the main transformer high-voltage switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, after the main transformer N-1 of the analysis object is judged, the 110kV main transformer of the station is successfully switched on automatically, and no voltage loss is caused;

s407: and for the 110kV transformer substation which is judged to be subjected to short-time voltage loss of the non-total station after the main transformer N-1 of the analysis object in the step S404, judging whether the 110kV substation spare power automatic switching condition is met: (1) the station is provided with a hot standby 110kV section switch; (2) the section switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the voltage of the station main transformer N-1 is met, judging that the 110kV subsection spare power automatic switching of the station is successful, and after the object main transformer N-1 is analyzed, enabling any equipment of the station not to lose voltage;

s408: and for the transformer substations which do not meet the 110kV subsection spare power automatic switching conditions listed in the step S407, judging whether the 10kV buses with short-time voltage loss meet the main transformer spare power automatic switching conditions one by one: (1) the voltage-loss bus can be topologically connected to a hot standby main transformer change-down switch; (2) the hot standby main transformer is arranged in a main transformer standby automatic switching maintenance table; (3) the hot standby main transformer high-voltage switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, judging that the main transformer N-1 of the analysis object is successfully switched into the spare power automatic switching of the main transformer of the 10kV bus, and avoiding voltage loss;

s409: and for the transformer substations which do not meet the conditions listed in the step S408, judging whether the 10kV buses with short-time voltage loss meet the 10kV subsection spare power automatic switching conditions one by one: (1) the voltage-loss bus can be topologically connected to a hot standby section switch; (2) the bus at the other end connected with the hot standby section switch is supplied with power by a main transformer change-down switch connected with the bus; (3) the hot standby section switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, after the main transformer N-1 of an analysis object is judged, the 10kV bus segmented spare power automatic switching is successful, and no voltage loss is caused;

s410: synthesizing the analysis results of the steps S405-S409 to form a primary outcome analysis report after the main transformer N-1 of the analysis object is formed;

s411: analyzing whether the voltage-loss equipment in the preliminary result analysis report obtained in the step S410 meets one of the following two conditions of multiple spare power automatic switching: (1) the upper-level power supply of the transformer substation is a 110kV transformer substation, the 110kV transformer substation exists in the primary result analysis report obtained in the step S410, and the result is that the spare power automatic switching is successful; (2) the voltage-loss equipment can be topologically connected to a hot standby circuit switch of the local station, and the hot standby circuit switch and any circuit switch meeting the conditions listed in the step S405 have a topological connection relationship; if any one of the conditions is met, correcting the equipment result to be no pressure loss;

s412: if the voltage-loss equipment in the preliminary consequence analysis report obtained in the step S410 does not meet the conditions listed in the step S411, further analyzing whether the voltage-loss equipment meets the pilot backup automatic switching conditions: (1) the 110kV transformer substation where the voltage loss equipment is located exists in a pilot-connected spare power automatic switching maintenance table; (2) another 110kV transformer substation paired with the 110kV transformer substation in the pilot-connected spare power automatic switching maintenance table is provided with a hot standby circuit switch; (3) the hot standby line switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the above conditions are met, correcting the equipment result to be no pressure loss;

s413: analyzing the 10kV buses obtained by the topology analysis in the step S2 in the direction of the lower voltage side one by one, and judging whether the 10kV bus sectional spare power automatic switching conditions are met, specifically referring to the step S409; if the conditions are met, judging that the main transformer N-1 of the analysis object is successfully switched into the 10kV bus in a segmented spare power automatic mode, and not causing voltage loss;

s414: and summarizing the analysis results of the steps S412-S413 to form an analysis object main transformer N-1 consequence report, and after the objects obtained in the step S1 are analyzed one by one, forming a risk analysis report of the 220kV main transformer in all the split operation modes.

Preferably, step S5 specifically includes the following steps:

s501: pairing a plurality of 220kV main transformers which run in parallel to serve as one element, and storing all the elements into a system in a set mode;

s502: taking any 220kV main transformer in any element in the set obtained in the step S501 as an analysis object main transformer, and judging whether all 10kV buses supplied by the analysis object main transformer meet 10kV subsection spare power automatic switching conditions or not according to the conditions listed in the step S409;

s503, obtaining a load value of the residual 220kV main transformers paired in the elements behind the main transformer N-1 of the analysis object, wherein the load value is obtained by subtracting 10kV bus load of the analysis object main transformer which does not meet the segmented spare power automatic switching condition from the sum of all 220kV main transformer variable load in the current elements and then dividing the load value by the number of the residual main transformers;

s504: comparing the load value of the residual 220kV main transformer obtained in the step S503 with a stable value of the load value in a main transformer stable value maintenance table, and if the load value is more than or equal to the stable value, judging that the residual 220kV main transformer is subjected to stable action to remove the load after an object main transformer N-1 is analyzed;

s505: for the remaining main transformers which are obtained in the step S504 and cause the load shedding of the stable operation, obtaining a line sequence of the shedding load from the stable control and energy shedding maintenance table;

s506: in a local database obtained by analyzing an automatic E file, setting the states of the first N line switches in the sequence obtained in the step S505 as unavailable, starting from 1 by N, and analyzing and obtaining the voltage loss and spare power automatic switching conditions of a 110kV transformer substation or equipment supplied by the line switches after the safety and stability action by referring to the processes of the steps S402-S413; if the supplied 110kV transformer substation belongs to a transformer substation in a safety and stability locking spare power automatic switching maintenance table, the voltage loss of the 110kV transformer substation is directly judged without analysis;

s507: according to the analysis result obtained in the step S506, calculating the load value of the residual 220kV main transformer after the N lines are cut off by the stabilizing action according to the following method: 1. for the condition that the backup power automatic switching is successful, if the switched-on backup switch of the 110kV transformer substation supplied by the cut line or the backup switch after the backup power automatic switching action exists in the power supply range of the residual 220kV main transformer obtained in the step S2, the load value of the residual main transformer is not influenced, otherwise, the cut load value is spread to the main transformers which run in parallel; 2. if the transformer substation or the equipment is in voltage loss, dividing the removed load value equally to each main transformer which runs in parallel; analyzing all N lines one by one to obtain residual main transformer load values;

s508: judging whether the load value of each residual operating main transformer obtained in the step S507 is smaller than a fixed value in a main transformer stable fixed value maintenance table, if the load value is still larger than or equal to the fixed value, repeating the steps S506 and S507 after N +1, and stopping until the load value is smaller than the fixed value or N is equal to the number of all lines of a line sequence with loads removed;

and S509, summarizing the analysis results of the steps S502, S504 and S506-S508 to obtain the N-1 consequence of the main transformer of the analysis object, and after all elements in the set obtained in the step S501 are analyzed one by one, forming a risk analysis report of the 220kV main transformer in all parallel operation modes.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (2)

1. A method for automatically scanning and analyzing the risk of a 220kV main transformer N-1 of a power grid is characterized by comprising the following steps:

step S1: acquiring a main transformer of an analysis object, wherein the object main transformer meets the following conditions: (1) the equipment attribute is a main transformer; (2) the voltage grade is 220 kV; (3) the maintenance plate is not hung; (4) boosting and changing in a non-power plant;

step S2: carrying out topology analysis on the power supply range of a main transformer of an analysis object;

step S3, judging the main transformer division and parallel operation mode in the station, judging the power supply ranges of all the main transformers in the station obtained in the step S2 as the parallel operation mode if the power supply ranges of the middle sides of any two main transformers are completely consistent, otherwise, judging the split operation mode;

step S4: performing main transformer N-1 risk analysis on the condition that the split operation mode is judged in the step S3;

step S5: performing main transformer N-1 risk analysis on the condition that the parallel operation mode is judged in the step S3;

step S6, integrating the results of the step S4 and the step S5 to form a risk analysis report of the 220kV main transformer N-1;

step S2 specifically includes the following steps:

analyzing the topology of the variable low side and the variable middle side respectively by taking a main transformer body as a starting point according to the power flow direction, and stopping after the topology of the variable low side reaches a local station 10kV bus; carrying out topology analysis on paths of a middle-side edge transformer middle switch, a local station 110kV bus, a local station 110kV outgoing line, an opposite side 110kV substation bus or line transformer group transformer high switch, an opposite side 110kV substation main transformer and a 10kV bus, wherein for the 110kV buses running in parallel, the bus coupling power direction is not considered during the topology analysis, and after the topology analysis is completed, all equipment on the topology path of a 220kV main transformer to be analyzed and a disconnecting link or a switch isolated from other parts of a power grid are used as the power supply range of the 220kV main transformer to be analyzed and stored in a system;

step S4 specifically includes the following steps:

s401: performing topological analysis on the direction from the step S2 to the middle-side direction to obtain any 110kV transformer substation and a 110kV bus, a main transformer and a 10kV bus contained in the transformer substation as elements, wherein all the elements form a set and are stored in the system;

s402: judging whether any transformer substation obtained in the step S401 belongs to a 110kV transformer substation in a user transformer substation maintenance table, if so, directly judging that the transformer substation is in voltage loss after the main transformer N-1 is obtained, and not performing subsequent analysis;

s403: for the 110kV transformer substation which is judged not to belong to the maintenance table of the user transformer substation in the step S402, if any main transformer change-over switch contained in the substation exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2, the main transformer of the substation, a 10kV bus supplied by the main transformer and a connected 110kV bus are judged to be multi-power supply equipment, and after the main transformer N-1 of the analysis object is analyzed, the equipment cannot cause voltage loss;

s404: if any element in the set obtained in the step S401 does not meet the power supply conditions of the multiple power supply points listed in the step S403 and the elements contain all the operated 110kV bus, main transformer and 10kV bus, judging that the 110kV transformer substation is subjected to voltage loss in the whole short-term behind the main transformer N-1 of the analysis object;

s405: and for the 110kV transformer substation which is judged to be the total-station short-time voltage loss in the step S404, judging whether the following 110kV line spare power automatic switching conditions are met: (1) the station is provided with a hot standby 110kV line switch; (2) the line switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the voltage is met, judging that the station 110kV line backup power automatic switching is successful, and after the object main transformer N-1 is analyzed, the station does not cause voltage loss;

and S406, further analyzing whether the transformer substation which does not meet the conditions listed in the step S405 meets the main spare power automatic switching conditions: (1) the station has a hot standby main transformer; (2) the main transformer is arranged in a main transformer spare power automatic switching maintenance table; (3) the main transformer high-voltage switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, after the main transformer N-1 of the analysis object is judged, the 110kV main transformer of the station is successfully switched on automatically, and no voltage loss is caused;

s407: and for the 110kV transformer substation which is judged to be subjected to short-time voltage loss of the non-total station after the main transformer N-1 of the analysis object in the step S404, judging whether the 110kV substation spare power automatic switching condition is met: (1) the station is provided with a hot standby 110kV section switch; (2) the section switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the voltage of the station main transformer N-1 is met, judging that the 110kV subsection spare power automatic switching of the station is successful, and after the object main transformer N-1 is analyzed, enabling any equipment of the station not to lose voltage;

s408: and for the transformer substations which do not meet the 110kV subsection spare power automatic switching conditions listed in the step S407, judging whether the 10kV buses with short-time voltage loss meet the main transformer spare power automatic switching conditions one by one: (1) the voltage-loss bus can be topologically connected to a hot standby main transformer change-down switch; (2) the hot standby main transformer is arranged in a main transformer standby automatic switching maintenance table; (3) the hot standby main transformer high-voltage switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, judging that the main transformer N-1 of the analysis object is successfully switched into the spare power automatic switching of the main transformer of the 10kV bus, and avoiding voltage loss;

s409: and for the transformer substations which do not meet the conditions listed in the step S408, judging whether the 10kV buses with short-time voltage loss meet the 10kV subsection spare power automatic switching conditions one by one: (1) the voltage-loss bus can be topologically connected to a hot standby section switch; (2) the bus at the other end connected with the hot standby section switch is supplied with power by a main transformer change-down switch connected with the bus; (3) the hot standby section switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the conditions are met, after the main transformer N-1 of an analysis object is judged, the 10kV bus segmented spare power automatic switching is successful, and no voltage loss is caused;

s410: synthesizing the analysis results of the steps S405-S409 to form a primary outcome analysis report after the main transformer N-1 of the analysis object is formed;

s411: analyzing whether the voltage-loss equipment in the preliminary result analysis report obtained in the step S410 meets one of the following two conditions of multiple spare power automatic switching: (1) the upper-level power supply of the transformer substation is a 110kV transformer substation, the 110kV transformer substation exists in the primary result analysis report obtained in the step S410, and the result is that the spare power automatic switching is successful; (2) the voltage-loss equipment can be topologically connected to a hot standby circuit switch of the local station, and the hot standby circuit switch and any circuit switch meeting the conditions listed in the step S405 have a topological connection relationship; if any one of the conditions is met, correcting the equipment result to be no pressure loss;

s412: if the voltage-loss equipment in the preliminary consequence analysis report obtained in the step S410 does not meet the conditions listed in the step S411, further analyzing whether the voltage-loss equipment meets the pilot backup automatic switching conditions: (1) the 110kV transformer substation where the voltage loss equipment is located exists in a pilot-connected spare power automatic switching maintenance table; (2) another 110kV transformer substation paired with the 110kV transformer substation in the pilot-connected spare power automatic switching maintenance table is provided with a hot standby circuit switch; (3) the hot standby line switch exists in the power supply range of other 220kV operation main transformers except the main transformer of the analysis object obtained in the step S2; if the above conditions are met, correcting the equipment result to be no pressure loss;

s413: analyzing the 10kV buses obtained by the topology analysis in the step S2 in the direction of the lower voltage side one by one, and judging whether the 10kV bus sectional spare power automatic switching conditions are met, specifically referring to the step S409; if the conditions are met, judging that the main transformer N-1 of the analysis object is successfully switched into the 10kV bus in a segmented spare power automatic mode, and not causing voltage loss;

s414: and summarizing the analysis results of the steps S412-S413 to form an analysis object main transformer N-1 consequence report, and after the objects obtained in the step S1 are analyzed one by one, forming a risk analysis report of the 220kV main transformer in all the split operation modes.

2. The method for automatically scanning and analyzing the risk of the main transformer N-1 of the 220kV power grid according to claim 1, wherein the step S5 specifically comprises the following steps:

s501: pairing a plurality of 220kV main transformers which run in parallel to serve as one element, and storing all the elements into a system in a set mode;

s502: taking any 220kV main transformer in any element in the set obtained in the step S501 as an analysis object main transformer, and judging whether all 10kV buses supplied by the analysis object main transformer meet 10kV subsection spare power automatic switching conditions or not according to the conditions listed in the step S409;

s503, obtaining a load value of the residual 220kV main transformers paired in the elements behind the main transformer N-1 of the analysis object, wherein the load value is obtained by subtracting 10kV bus load of the analysis object main transformer which does not meet the segmented spare power automatic switching condition from the sum of all 220kV main transformer variable load in the current elements and then dividing the load value by the number of the residual main transformers;

s504: comparing the load value of the residual 220kV main transformer obtained in the step S503 with a stable value of the load value in a main transformer stable value maintenance table, and if the load value is more than or equal to the stable value, judging that the residual 220kV main transformer is subjected to stable action to remove the load after an object main transformer N-1 is analyzed;

s505: for the remaining main transformers which are obtained in the step S504 and cause the load shedding of the stable operation, obtaining a line sequence of the shedding load from the stable control and energy shedding maintenance table;

s506: in a local database obtained by analyzing an automatic E file, setting the states of the first N line switches in the sequence obtained in the step S505 as unavailable, starting from 1 by N, and analyzing and obtaining the voltage loss and spare power automatic switching conditions of a 110kV transformer substation or equipment supplied by the line switches after the safety and stability action by referring to the processes of the steps S402-S413; if the supplied 110kV transformer substation belongs to a transformer substation in a safety and stability locking spare power automatic switching maintenance table, the voltage loss of the 110kV transformer substation is directly judged without analysis;

s507: according to the analysis result obtained in the step S506, calculating the load value of the residual 220kV main transformer after the N lines are cut off by the stabilizing action according to the following method: 1. for the condition that the backup power automatic switching is successful, if the switched-on backup switch of the 110kV transformer substation supplied by the cut line or the backup switch after the backup power automatic switching action exists in the power supply range of the residual 220kV main transformer obtained in the step S2, the load value of the residual main transformer is not influenced, otherwise, the cut load value is spread to the main transformers which run in parallel; 2. if the transformer substation or the equipment is in voltage loss, dividing the removed load value equally to each main transformer which runs in parallel; analyzing all N lines one by one to obtain residual main transformer load values;

s508: judging whether the load value of each residual operating main transformer obtained in the step S507 is smaller than a fixed value in a main transformer stable fixed value maintenance table, if the load value is still larger than or equal to the fixed value, repeating the steps S506 and S507 after N +1, and stopping until the load value is smaller than the fixed value or N is equal to the number of all lines of a line sequence with loads removed;

and S509, summarizing the analysis results of the steps S502, S504 and S506-S508 to obtain the N-1 consequence of the main transformer of the analysis object, and after all elements in the set obtained in the step S501 are analyzed one by one, forming a risk analysis report of the 220kV main transformer in all parallel operation modes.

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