A method and system for assessing earthquake risk of main transformer in substation

Abstract

A method and system for assessing the seismic risk of a transformer substation main transformer, comprising: based on a pre-established earthquake damage index system, conducting experiments on the main transformer to be assessed under different earthquake intensities and according to different performance level requirements; evaluating the obtained experimental results with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability; and assessing the risk of the main transformer based on the probability of vulnerability. The present invention divides the seismic resistance level into three indicators, proposes the range of each seismic performance indicator corresponding to each indicator, and realizes a comprehensive and accurate risk assessment of many components of the main transformer in earthquake-prone areas.

Description

Technical Field

[0001] The present invention relates to the field of substation design, and in particular to a method and system for assessing the seismic hazard of a main transformer in a substation. Background Art

[0002] In the case of earthquakes, especially in earthquake-prone areas, the power system is seriously damaged by earthquakes. In the context of modern life being highly electrified, power supply to disaster areas after earthquakes has become the most urgent need after access. The main transformer is a key device for power conversion in the power grid system. It is divided into types such as step-up, step-down and current conversion. This type of equipment has a complex structure and involves many components. Many components are easily damaged in earthquakes, causing damage to the main transformer. Due to the complex structure and strict testing requirements of the transformer, it is difficult to repair the earthquake-damaged substation at the substation site. In high-voltage substations, the main transformer equipment is large in size, heavy in weight, and difficult to transport. It is even more difficult to transport the replacement transformer to the earthquake-damaged substation after an earthquake. Therefore, it is of great significance to evaluate the possibility of earthquake damage to the main transformer to ensure the seismic performance of the main transformer and reduce the earthquake damage of the main transformer. On the other hand, for many substations that have been built, it is necessary to take structural strengthening measures or determine the number of spare parts. Evaluating the possibility of earthquake damage to the main transformer is also a necessary prerequisite for structural strengthening measures or determining the number of spare parts. Summary of the invention

[0003] In order to solve the problem in the prior art of lacking an assessment of the possibility of earthquake damage to a main transformer, the present invention provides a method and system for assessing the earthquake risk of a main transformer in a substation.

[0004] The technical solution provided by the present invention is:

[0005] A method for assessing seismic hazard of a main transformer in a substation, comprising:

[0006] Based on the pre-established earthquake damage index system, the main transformer to be evaluated is tested under different earthquake intensities and according to different performance level requirements;

[0007] The obtained experimental results are compared with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability;

[0008] The criticality of the main transformer is evaluated based on the vulnerability probability.

[0009] Preferably, the earthquake damage index system includes the following indicators:

[0010] The main transformer body overturns, the main transformer body collides with surrounding equipment, the high-voltage tube is damaged, the internal winding structure of the body is damaged, the external cooling system is damaged, the transformer body oil tank or external oil pillow fails to seal or is structurally damaged, and the main transformer measurement and control device is damaged.

[0011] Preferably, the performance level includes:

[0012] When the voltage level of the main transformer is above 500 kV or is within the designated installation area, the seismic performance index of the main transformer is set to the first performance level;

[0013] When the voltage level of the main transformer is above 35 kV and below 500 kV, the seismic performance index of the main transformer is set to the second performance level;

[0014] When the voltage level of the main transformer is below 35 kV, the seismic performance index of the main transformer is set to the third performance level.

[0015] Preferably, the obtained experimental results are judged against the safety critical values ​​under different earthquake intensities and performance level requirements, and the obtained vulnerability probability includes:

[0016] By using a scaled test or a numerical model analysis method, the overturning of the main transformer body, the collision between the main transformer body and surrounding equipment, and the damage to the high-voltage pipe are analyzed, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities is determined;

[0017] By means of experimental analysis, the degree of damage to the winding structure inside the main body and the damage to the external heat dissipation system is analyzed, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities is determined;

[0018] Through the expert evaluation and analysis method, the failure of the sealing of the transformer main body oil tank or the external oil pillow or the degree of structural damage and the degree of damage to the main transformer measurement and control device are analyzed, and the probability of vulnerability exceeding the safety critical value required at different levels under various earthquake intensities is determined.

[0019] Preferably, the damage degree of the main transformer body overturning, the main transformer body colliding with surrounding equipment and the high-voltage pipe damage is analyzed by scaled test or numerical model analysis method, and the probability of exceeding the safety critical value required at different levels under various earthquake intensities includes:

[0020] The acceleration level is set in a pre-established scaled physical model or finite element model, and the earthquake response calculation is performed based on a predetermined number of earthquake historical records to obtain the functional relationship between the earthquake input acceleration peak value and the earthquake response index;

[0021] According to the functional relationship, the probability of overturning degree of the main transformer body, impact damage degree between the main transformer body and surrounding equipment, and damage degree of the high-voltage pipe exceeding the preset critical values ​​of different levels under various earthquake intensities is obtained.

[0022] Preferably, the test analysis method is used to analyze the degree of damage of the winding structure inside the body and the damage of the external heat dissipation system, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities, including:

[0023] According to the pre-acquired test earthquake records, simulation tests are carried out under different levels of earthquake conditions to obtain test results;

[0024] According to the test results, a fitting function of the seismic acceleration peak and the seismic response index is obtained, and the probability test parameters of the fitting function are solved. Based on the probability test parameters, the probability of damage to the internal winding structure of the main body and the external heat dissipation system exceeding the preset critical values ​​required at different levels under various earthquake intensities is obtained.

[0025] Preferably, the assessing the danger of the main transformer based on the vulnerability probability includes:

[0026] According to the vulnerability probability and the preset weight value of the earthquake damage index system, the danger value of the main transformer is evaluated;

[0027] The danger of the main transformer is evaluated according to the danger value. If the danger value is greater than or equal to the preset danger threshold values ​​of various earthquake intensities and performance levels, the earthquake danger is evaluated as dangerous; otherwise, it is safe.

[0028] Preferably, the risk value of the main transformer is evaluated according to the vulnerability probability and a preset earthquake damage index system weight value, as shown in the following formula:

[0029]

[0030] In the formula, p tij is the probability that the jth earthquake damage index system exceeds the safety critical value at the ith performance level when the earthquake intensity is t, f j is the j-th weight, where i=1···3; j=1,2···J; t= represents the earthquake intensity, and the value is 6, 7, 8 or 9; J is the number of indicators.

[0031] A system for assessing the seismic risk of a main transformer in a substation, the system comprising:

[0032] Experimental module: Based on the pre-established earthquake damage index system, the main transformer to be evaluated is tested under different earthquake intensities and according to different performance level requirements;

[0033] Probability acquisition module: The experimental results are compared with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability;

[0034] An evaluation module is configured to evaluate the danger of the main transformer based on the vulnerability probability.

[0035] Preferably, the experimental module conducts experiments using the following earthquake damage index system:

[0036] The main transformer body overturns, the main transformer body collides with surrounding equipment, the high-voltage tube is damaged, the internal winding structure of the body is damaged, the external cooling system is damaged, the transformer body oil tank or external oil pillow fails to seal or is structurally damaged, and the main transformer measurement and control device is damaged.

[0037] Preferably, the experimental module conducts experiments at the following performance levels, including:

[0038] First performance level: When the voltage level of the main transformer is above 500 kV or is within the specified installation area, the seismic performance index of the main transformer;

[0039] Second performance level: when the voltage level of the main transformer is above 35 kV and below 500 kV, the seismic performance index of the main transformer;

[0040] The third performance level: when the voltage level of the main transformer is below 35kV, the seismic performance index of the main transformer is increased.

[0041] Preferably, the probability acquisition module includes:

[0042] Scaled experiment or numerical model analysis submodule: Through scaled experiment or numerical model analysis, the damage degree of the main transformer body overturning, the main transformer body colliding with surrounding equipment and the high-voltage pipe damage is analyzed, and the probability of being damaged exceeding the safety critical value required at different levels under various earthquake intensities;

[0043] Test analysis submodule: through the test analysis method, analyze the damage degree of the internal winding structure damage and the external heat dissipation system damage of the main body, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities;

[0044] Expert evaluation submodule: Through the expert evaluation analysis method, the failure of the sealing of the transformer body oil tank or the external oil pillow or the degree of structural damage and the degree of damage to the main transformer measurement and control device are analyzed, and the probability of vulnerability exceeding the safety critical value required at different levels under various earthquake intensities is determined.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a method for assessing the seismic hazard of a substation main transformer, including: based on a pre-established earthquake damage index system, conducting experiments on the main transformer to be assessed under different earthquake intensities and according to different performance level requirements; judging the obtained experimental results with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability; and assessing the hazard of the main transformer based on the probability of vulnerability. The present invention realizes a comprehensive hazard assessment of many components of the main transformer in earthquake-prone areas; by parameterizing the seismic performance indicators of each component under each seismic resistance level, it satisfies the safety assessment of the main transformer under different regions and different performance requirements, and realizes an accurate assessment of the seismic damage resistance and hazard of the main transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A flow chart of a method for assessing earthquake risk of a main transformer in a substation according to the present invention;

[0047] Figure 2 It is a schematic diagram of the main transformer vulnerability probability assessment method of the present invention. DETAILED DESCRIPTION

[0048] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the accompanying drawings and examples.

[0049] Embodiment 1:

[0050] S1: Based on the pre-established earthquake damage index system, the main transformer to be evaluated is tested under different earthquake intensities and according to different performance level requirements:

[0051] The main transformers of high-voltage substations have common structural characteristics, which are composed of the main oil tank, winding, external bushing, external fan heat device, external oil pillow and key components of the measurement and control device. The types of damage caused by the reciprocating inertial force of earthquakes can be summarized as follows: overall overturning, component damage, and seal failure, which can be specifically divided into:

[0052] The overturning of the main transformer body refers to the overturning of the main transformer under the combined action of lateral and vertical seismic forces when the main transformer body and the foundation are not firmly fixed, which includes tipping and obvious displacement.

[0053] The main transformer body collides with surrounding facilities. For main transformer equipment with vibration isolation design, the displacement between the main transformer equipment and the vibration isolation layer under seismic load causes the main transformer equipment to collide with the surrounding BOXIN structure and its piers, or other structures and be damaged.

[0054] High-voltage bushing damage refers to the inertial force generated by the high-voltage bushing under the action of an earthquake, which forms shear force and bending moment, leading to breakage at weak locations, such as the inter-node bonding position, the connection between the bushing root and the flange, or the top of the bushing is displaced too much and collides with other equipment or components.

[0055] The winding structure inside the body is damaged. The commonly used transformer core is generally made of silicon steel sheets, which is an extremely complex assembly. At the same time, in order to reduce the vibration under the magnetic induction force, the core and winding components need to be fastened in a complex way. Due to insulation requirements, they need to be placed in the transformer oil medium. This kind of complex structure is prone to various types of damage under the vibration caused by earthquakes. Here, the damage to the main components inside the transformer body is classified into one category.

[0056] Damage to the external cooling system. The radiator is an external part of the transformer body. Since it is mostly cantilevered and fixed on the side of the transformer, structural analysis shows that damage to the external cooling system is more likely to occur, and its damage mode is relatively independent of the damage to other parts, mostly damage to the connection and oil pipeline seal.

[0057] The transformer body oil tank or external oil pillow has sealing failure or structural damage. The main transformer oil pillow and oil tank are connected as a whole to provide an insulating oil medium environment inside the transformer body.

[0058] The main transformer measurement and control device is damaged. The main transformer equipment includes a variety of measurement and control devices including oil chromatography, vibration, temperature and pressure. Damage to the measurement and control device will affect the normal operation of the main transformer, but it is easier to repair than damage to other main structures or main components.

[0059] In view of the fact that there are many modes of seismic damage to the main transformer, the seismic damage to the main transformer can be divided into the following three levels by performance level. Each level corresponds to a different level of seismic performance indicators under different intensities.

[0060] In the selection of seismic performance level targets, the target performance level can be selected according to the requirements of relevant specifications and the importance level of the substation where the transformer is located. Performance level 1 represents higher seismic requirements or higher seismic safety factor redundancy, performance level 2 represents general seismic safety requirements, and performance level 3 represents basic seismic safety requirements.

[0061] The risk of earthquake occurrence refers to the seismic zoning location of the substation where the transformer is located, or the parameters given in the earthquake safety assessment report of the construction site, that is, the earthquake intensity corresponding to the common earthquakes, defense earthquakes and rare earthquakes in the site.

[0062] S2: The obtained experimental results are compared with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of damage

[0063] The safety critical values ​​under different earthquake intensities and performance level requirements are determined when the main transformer is manufactured. Different types of transformers have safety critical values ​​to ensure the safe use of the main transformer under different earthquake intensities and level requirements.

[0064]

[0065] The above indicator system can be transformed into indicator values ​​and weights in a parameterized manner, as shown in the following table. In practical applications, the indicator weights can be adjusted appropriately as needed.

[0066]

[0067] Calculation method of earthquake risk of main transformer

[0068] The calculation method of the seismic hazard of the main transformer is divided into the following steps:

[0069] Calculation of probability value of seismic index vulnerability;

[0070] Selection of seismic performance level targets;

[0071] Risk of earthquakes;

[0072] Earthquake hazard of main transformer;

[0073] like Figure 2 As shown in the figure, in obtaining the probability value of seismic vulnerability, it is to solve the probability of exceeding the critical value of each parameter under different performance levels and different earthquake intensities, which are P6ij under 6-degree input, P7ij under 7-degree input, P8ij under 8-degree input, and P9ij under 9-degree input. For example, when the performance level is level 1, under 7-degree earthquake input, the probability of the body anti-overturning safety factor index a11>cr711 is P711. For the calculation of these probability values, different types of indicators can be calculated by different methods. For the bottom stress and top displacement of the bushing, the body anti-overturning and the body anti-collision coefficient, they can be determined by scaled test or numerical model analysis. For the seismic safety factor of the winding structure and the external heat dissipation system, it can be determined by test. For the seismic safety factor of the transformer oil sealing and the measurement and control device, it can be determined by expert evaluation.

[0074] Methods for determining vulnerability probability by scaled-down tests or numerical model analysis: Establish a scaled-down physical model or finite element model of the object to be evaluated, determine the acceleration level according to the relationship between intensity and peak acceleration, select more than 10 earthquake records of the same site type from the historical earthquake record database, and linearly scale the historical earthquake records according to the above acceleration peak to obtain the input for vulnerability analysis. Perform earthquake response calculations to obtain the functional relationship between the earthquake input acceleration peak and the earthquake response index, and solve the probability test parameters of the fitting function to obtain the probability of the earthquake response exceeding the critical value under a certain acceleration peak, which is used as the vulnerability value.

[0075] The method for determining the vulnerability probability through seismic tests is as follows: a test earthquake record time history is generated, and earthquake simulation shaking table tests are carried out under different levels of earthquake input. The functional relationship between the earthquake input acceleration peak value and the seismic response index is fitted based on the test results, and the probability test parameters of the fitting function are solved to obtain the probability of the seismic response exceeding the critical value under a certain acceleration peak value, which is used as the vulnerability value.

[0076] Method for determining the probability of vulnerability by expert evaluation: The expert evaluation method is conducted in the form of a meeting. The owner designates an expert convener, who then contacts experts to form an evaluation committee. The evaluation committee makes a request for funding to the design unit and equipment manufacturer, and after collecting the required information, conducts the evaluation in the form of a meeting or letter of inquiry. The expert committee for earthquake safety assessment should be composed of experts in the fields of structure and electrical engineering, with no less than 5 people. The evaluation committee may require the design unit or equipment manufacturer to go to the site to provide relevant earthquake-resistant design instructions. The expert committee determines the probability of each indicator of the transformer exceeding the limit under earthquake inputs of different intensity levels based on the materials provided as a vulnerability conclusion.

[0077] S3: Evaluate the danger of the main transformer based on the vulnerability probability.

[0078] To calculate the earthquake hazard of the transformer, the following formula can be used:

[0079] When a 6-degree earthquake is input, the earthquake risk of the transformer at the i-th performance level is

[0080] When the earthquake input is 7 degrees, the earthquake risk of the transformer at the i-th performance level is

[0081] When an 8-degree earthquake is input, the earthquake risk of the transformer at the i-th performance level is

[0082] When a 9-degree earthquake is input, the earthquake risk of the transformer at the i-th performance level is

[0083] In the formula, p 9ijis the probability that the jth earthquake damage index value exceeds the critical value under the ith performance standard during the 9th earthquake, f j is the weight of the j-th earthquake damage index system, where i = 1···3; j = 1, 2···J, where J is the number of indicators.

[0084] Embodiment 2:

[0085] Based on the same inventive concept, the present invention also provides a substation main transformer seismic risk assessment system, comprising:

[0086] Experimental module: Based on the pre-established earthquake damage index system, the main transformer to be evaluated is tested under different earthquake intensities and according to different performance level requirements;

[0087] Probability acquisition module: The experimental results are compared with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability;

[0088] An evaluation module is configured to evaluate the danger of the main transformer based on the vulnerability probability.

[0089] The experimental module is tested through the following earthquake damage index system:

[0090] The main transformer body overturns, the main transformer body collides with surrounding equipment, the high-voltage tube is damaged, the internal winding structure of the body is damaged, the external cooling system is damaged, the transformer body oil tank or external oil pillow fails to seal or is structurally damaged, and the main transformer measurement and control device is damaged.

[0091] The experimental module is tested at the following performance levels, including:

[0092] First performance level: When the voltage level of the main transformer is above 500 kV or is within the specified installation area, the seismic performance index of the main transformer;

[0093] Second performance level: when the voltage level of the main transformer is above 35 kV and below 500 kV, the seismic performance index of the main transformer;

[0094] The third performance level: when the voltage level of the main transformer is below 35kV, the seismic performance index of the main transformer is increased.

[0095] The probability acquisition module includes:

[0096] Scaled experiment or numerical model analysis submodule: Through scaled experiment or numerical model analysis, the damage degree of the main transformer body overturning, the main transformer body colliding with surrounding equipment and the high-voltage pipe damage is analyzed, and the probability of being damaged exceeding the safety critical value required at different levels under various earthquake intensities;

[0097] Test analysis submodule: through the test analysis method, analyze the damage degree of the internal winding structure damage and the external heat dissipation system damage of the main body, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities;

[0098] Expert evaluation submodule: Through the expert evaluation analysis method, the failure of the sealing of the transformer body oil tank or the external oil pillow or the degree of structural damage and the degree of damage to the main transformer measurement and control device are analyzed, and the probability of vulnerability exceeding the safety critical value required at different levels under various earthquake intensities is determined.

[0099] The scaled experiment or numerical model analysis submodule includes:

[0100] Response relationship acquisition unit: sets the acceleration level in a pre-established scaled physical model or finite element model, and performs earthquake response calculation based on a predetermined number of earthquake historical records to obtain the functional relationship between the earthquake input acceleration peak and the earthquake response index;

[0101] The first probability calculation unit is: solving the functional relationship to obtain the vulnerability probability that the overturning degree of the main transformer body, the impact damage degree between the main transformer body and surrounding equipment, and the damage degree of the high-voltage pipe exceed the preset critical values ​​of different levels required under each earthquake intensities under the preset acceleration peak.

[0102] The test analysis submodule includes:

[0103] Test unit: Based on the pre-acquired test earthquake records, simulated tests are carried out under different levels of earthquake conditions to obtain test results;

[0104] The second probability calculation unit: obtains the fitting function of the earthquake acceleration peak and the earthquake response index according to the test results, and solves the probability test parameters of the fitting function, and obtains the probability of damage of the internal winding structure of the main body and the external heat dissipation system exceeding the preset critical values ​​of different levels required under various earthquake intensities based on the probability test parameters.

[0105] The evaluation module comprises:

[0106] Danger value assessment submodule: assessing the danger value of the main transformer according to the vulnerability probability and the preset weight value of the earthquake damage index system;

[0107] Evaluation submodule: Evaluate the danger of the main transformer according to the danger value. If the danger value is greater than or equal to the preset danger threshold values ​​of various earthquake intensities and performance levels, the earthquake danger is evaluated as dangerous; otherwise, it is safe.

[0108] The danger value assessment submodule assesses the danger value of the main transformer by the following formula:

[0109]

[0110] In the formula, p tij is the probability that the jth earthquake damage index system exceeds the safety critical value at the ith performance level when the earthquake intensity is t, f j is the j-th weight, where i=1···3; j=1,2···J; t= represents the earthquake intensity, and the value is 6, 7, 8 or 9; J is the number of indicators.

[0111] Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0112] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0113] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0114] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0115] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0116] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0117] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A method for assessing the seismic risk of a main transformer in a substation, characterized in that: include: Based on the pre-established earthquake damage index system, the main transformer to be evaluated is tested under different earthquake intensities and according to different performance level requirements; The obtained experimental results are compared with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability; Assessing the danger of the main transformer based on the vulnerability probability; The earthquake damage index system includes the following indicators: The main transformer body overturns, the main transformer body collides with surrounding equipment, the high-voltage tube is damaged, the internal winding structure of the body is damaged, the external cooling system is damaged, the transformer body oil tank or external oil pillow fails to seal or is structurally damaged, and the main transformer measurement and control device is damaged; The obtained experimental results are evaluated with the safety critical values ​​under different earthquake intensities and performance level requirements, and the obtained vulnerability probability includes: By using a scaled test or a numerical model analysis method, the overturning of the main transformer body, the collision between the main transformer body and surrounding equipment, and the damage to the high-voltage pipe are analyzed, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities is determined; By means of experimental analysis, the degree of damage to the winding structure inside the main body and the damage to the external heat dissipation system is analyzed, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities is determined; Through the expert evaluation and analysis method, the failure of the sealing of the transformer main body oil tank or the external oil pillow or the degree of structural damage and the degree of damage to the main transformer measurement and control device are analyzed, and the probability of vulnerability exceeding the safety critical value required at different levels under various earthquake intensities is determined.

2. The method according to claim 1, characterized in that The performance levels include: When the voltage level of the main transformer is above 500 kV or is within the designated installation area, the seismic performance index of the main transformer is set to the first performance level; When the voltage level of the main transformer is above 35 kV and below 500 kV, the seismic performance index of the main transformer is set to the second performance level; When the voltage level of the main transformer is below 35 kV, the seismic performance index of the main transformer is set to the third performance level.

3. The method according to claim 1, characterized in that The scaled test or numerical model analysis method is used to analyze the damage degree of the main transformer body overturning, the main transformer body colliding with surrounding equipment, and the damage to the high-voltage pipe, and the probability of exceeding the safety critical value required at different levels under various earthquake intensities, including: The acceleration level is set in a pre-established scaled physical model or finite element model, and the earthquake response calculation is performed based on a predetermined number of earthquake historical records to obtain the functional relationship between the earthquake input acceleration peak value and the earthquake response index; According to the functional relationship, the probability of overturning degree of the main transformer body, impact damage degree between the main transformer body and surrounding equipment, and damage degree of the high-voltage pipe exceeding the preset critical values ​​of different levels under various earthquake intensities is obtained.

4. The method according to claim 1, characterized in that The test analysis method is used to analyze the damage degree of the internal winding structure damage and the external heat dissipation system damage of the main body, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities, including: According to the pre-acquired test earthquake records, simulation tests are carried out under different levels of earthquake conditions to obtain test results; According to the test results, a fitting function of the seismic acceleration peak and the seismic response index is obtained, and the probability test parameters of the fitting function are solved. Based on the probability test parameters, the probability of damage to the internal winding structure of the main body and the external heat dissipation system exceeding the preset critical values ​​required at different levels under various earthquake intensities is obtained.

5. The method according to claim 1, characterized in that The step of evaluating the danger of the main transformer based on the vulnerability probability includes: According to the vulnerability probability and the preset weight value of the earthquake damage index system, the danger value of the main transformer is evaluated; The danger of the main transformer is evaluated according to the danger value. If the danger value is greater than or equal to the preset danger threshold values ​​of various earthquake intensities and performance levels, the earthquake danger is evaluated as dangerous; otherwise, it is safe.

6. The method according to claim 5, characterized in that The risk value of the main transformer is evaluated according to the vulnerability probability and the preset weight value of the earthquake damage index system, as shown in the following formula: Where P tij is the probability that the jth earthquake damage index system exceeds the safety critical value at the ith performance level when the earthquake intensity is t, f j is the j-th weight, where i=1···3; j=1,2···J; t represents the earthquake intensity, which takes values ​​of 6, 7, 8 or 9; J is the number of indicators.

7. A substation main transformer seismic risk assessment system, characterized in that: The system comprises: Experimental module: Based on the pre-established earthquake damage index system, the main transformer to be evaluated is tested under different earthquake intensities and according to different performance level requirements; Probability acquisition module: The experimental results are compared with the safety critical values ​​under different earthquake intensities and performance level requirements to obtain the probability of vulnerability; Evaluation module: evaluating the danger of the main transformer based on the vulnerability probability; The experimental module is tested through the following earthquake damage index system: The main transformer body overturns, the main transformer body collides with surrounding equipment, the high-voltage tube is damaged, the internal winding structure of the body is damaged, the external cooling system is damaged, the transformer body oil tank or external oil pillow fails to seal or is structurally damaged, and the main transformer measurement and control device is damaged; The probability acquisition module includes: Scaled experiment or numerical model analysis submodule: Through scaled experiment or numerical model analysis, the damage degree of the main transformer body overturning, the main transformer body colliding with surrounding equipment and the high-voltage pipe damage is analyzed, and the probability of being damaged exceeding the safety critical value required at different levels under various earthquake intensities; Test analysis submodule: through the test analysis method, analyze the damage degree of the internal winding structure damage and the external heat dissipation system damage of the main body, and the probability of damage exceeding the safety critical value required at different levels under various earthquake intensities; Expert evaluation submodule: Through the expert evaluation analysis method, the failure of the sealing of the transformer body oil tank or the external oil pillow or the degree of structural damage and the degree of damage to the main transformer measurement and control device are analyzed, and the probability of vulnerability exceeding the safety critical value required at different levels under various earthquake intensities is determined.

8. The system according to claim 7, characterized in that The experimental module is tested at the following performance levels, including: First performance level: When the voltage level of the main transformer is above 500 kV or is within the specified installation area, the seismic performance index of the main transformer; Second performance level: when the voltage level of the main transformer is above 35 kV and below 500 kV, the seismic performance index of the main transformer; The third performance level: when the voltage level of the main transformer is below 35kV, the seismic performance index of the main transformer is increased.

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