A risk assessment method for vacuum on-load tap changer

Abstract

This application discloses a risk assessment method for vacuum on-load tap changers, relating to the field of power equipment reliability assessment technology. Based on the actual circuit topology and vacuum tube parameters of the vacuum on-load tap changer, it quantitatively calculates power load parameters such as the number of operations, recovery voltage, fault current, and arc voltage of each vacuum tube. Furthermore, it establishes a unified correlation model between the single-tube failure probability, fault impact weight, and overall system risk. For topology conditions with coupling mechanisms, it can also correct the risk transmission and amplification effects between vacuum tubes by adjusting the model through the coupling mechanism, thereby improving the relevance, accuracy, and consistency of the risk assessment results. Compared to existing schemes that only focus on condition monitoring, abnormal alarms, or fault diagnosis, this method can more realistically reflect the differences in the contribution of each vacuum tube to the overall system's operational safety, providing a basis for maintenance decisions, life management, and operational optimization.

Description

Technical Field

[0001] This application relates to the field of power equipment reliability assessment technology, specifically to a risk assessment method for vacuum on-load tap changers. Background Technology

[0002] Vacuum on-load tap changers are key power devices combining vacuum arc extinguishing technology and on-load voltage regulation technology, and are widely used in power transformers requiring on-load voltage regulation. Compared with traditional oil-based arc extinguishing methods, vacuum on-load tap changers have advantages such as fast insulation recovery speed, high breaking capacity, and less contamination of insulating oil, thus finding increasingly widespread application in high-voltage, large-capacity transformers. However, the tap-changing process of a vacuum on-load tap changer involves the coordinated operation of multiple vacuum tubes, transition branches, and corresponding circuit topologies. Different vacuum tubes exhibit significant differences in the electrical load they bear in terms of the number of operations, recovery voltage, fault current, and arc voltage. These load differences directly affect the failure probability of each vacuum tube and its impact on the overall operational safety of the transformer.

[0003] In existing technologies, the evaluation and diagnosis of vacuum on-load tap changers focus primarily on switching status monitoring, anomaly warning, or fault diagnosis. For example, Chinese patent CN112444577B discloses a method for evaluating the switching status of a vacuum on-load tap changer, which mainly judges the switching status based on the total acetylene content and the increment of voltage regulation times. Chinese patent CN113884870A discloses a monitoring system and method for a transformer vacuum on-load tap changer, mainly for monitoring and warning of electrical defects such as vacuum bubble faults. Chinese patent CN102680890B discloses a fault diagnosis method for a transformer on-load tap changer, which mainly uses dissolved gases in oil and their ratios to construct criteria for diagnosing abnormal states of the tap changer. In addition, existing disclosures also include online monitoring devices based on multi-signal collaborative monitoring, which still focus on signal acquisition, threshold comparison, and anomaly alarms. The above solutions have certain functions in operating status identification, fault alarms, and defect monitoring, but overall they tend to be more inclined to state judgment based on single-type feature quantities or monitoring signals.

[0004] Furthermore, from the perspective of system reliability analysis, while existing research and publicly available solutions have proposed approaches to reliability assessment or importance analysis of on-load tap changers, they mostly focus on system-level reliability analysis from the perspectives of fault mode classification, fault trees, multi-state multi-valued decision graphs, or probability importance. The emphasis is on describing the relationship between fault factors and system reliability, rather than establishing a unified quantitative relationship between power load parameters, single-tube failure probability, single-tube failure impact, and overall system risk, considering the differences in power load distribution among the vacuum tubes within the vacuum on-load tap changer under actual circuit topologies. Especially under different topologies, coupling effects may exist between vacuum tubes, and existing technologies typically lack specific identification and adjustment mechanisms for such coupling mechanisms, making it difficult to accurately reflect the mutual transmission and amplification effects of risks among vacuum tubes under coupled operating conditions. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, this application proposes the following technical solution: In a first aspect, embodiments of this application provide a risk assessment method for vacuum on-load tap changers, including: Based on the circuit topology and vacuum tube parameters of the vacuum on-load tap changer, calculate the power load parameters of each vacuum tube and determine whether there is a coupling mechanism in the circuit topology. The power load parameters include: number of operations, recovery voltage, fault current and arc voltage. If the circuit topology does not have a coupling mechanism, the failure probability of each vacuum tube and the failure influence weight of each vacuum tube are calculated according to the constructed vacuum tube failure probability model and vacuum tube failure influence weight model, respectively. If the circuit topology has a coupling mechanism, a coupling mechanism adjustment model is introduced to calculate the failure probability of each vacuum tube and the failure influence weight of each vacuum tube in conjunction with the vacuum tube failure probability model and the vacuum tube failure influence weight model, respectively. A comprehensive risk model is constructed by combining the failure probability of each vacuum tube and the failure impact weight of each vacuum tube, and the risk assessment of the vacuum on-load tap changer is realized by using the comprehensive risk model.

[0006] In one possible implementation, determining whether the circuit topology has a coupling mechanism includes: Determine the common node relationships, coupling capacitance relationships, action timing overlap relationships, and voltage recovery propagation paths among the vacuum tubes; Construct a directional coupling relationship matrix between vacuum tubes, and determine whether a coupling mechanism exists based on the directional coupling relationship matrix.

[0007] In one possible implementation, determining the common node relationship, coupling capacitance relationship, timing overlap relationship, and voltage recovery propagation path among the vacuum tubes includes: Suppose that there are M vacuum tubes in the vacuum on-load tap changer, denoted as M. For any vacuum tube Define its action-sensitive time window as ,in: Vacuum tube At the start of the action, Vacuum tube The moment of recovery and stabilization; Install vacuum tube The set of connection points is Then the vacuum tube and The co-node relationship coefficient is defined as: Thus, a common point relation matrix is ​​constructed: ,in: Indicates the number of elements in the set; Install vacuum tube and The equivalent coupling capacitance between them is vacuum tube The total associated capacitance is: ,in: vacuum tube The equivalent capacitance to ground is defined as the coupling capacitance relationship coefficient. Thus, the coupling capacitance relationship matrix is ​​constructed. ; Install vacuum tube and The action-sensitive time windows are respectively and The overlap length of their time windows is then: Define the action timing overlap coefficient as: Thus, an action timing overlap matrix is ​​constructed: ; Install vacuum tube arrive There exists a voltage recovery propagation path. The path consists of several branches e, and the propagation impedance of each branch is... The total path impedance is defined as follows: The path propagation coefficient is defined as: Thus, the voltage recovery propagation path matrix is ​​constructed. ,in: This is the impedance attenuation coefficient; Finally, define the action direction factor: According to the above Construct the direction matrix ,in: It is an indicator function.

[0008] In one possible implementation, based on the co-occurrence relation matrix... Coupling capacitance relationship matrix Action timing overlap matrix: Voltage recovery propagation path matrix and direction matrix Determine the directional coupling matrix: in: This represents the Hadamard product, which is the multiplication of corresponding elements of two matrices. Indicates the weight of the relationship between co-nodes. Indicates the weights of the coupling capacitance relationship. Indicates the weight of the overlapping relationship between actions in time sequence. Indicates the weight of the voltage recovery propagation path. ; When the If there are off-diagonal elements in the system that are greater than a preset threshold, or if the overall coupling strength of the system is greater than a preset overall threshold, it is determined that there is a coupling mechanism in the vacuum on-load tap changer.

[0009] In one possible implementation, the vacuum tube failure probability model is as follows: in: For the first The probability of failure of a vacuum tube The normalization coefficient is used to ensure that the sum of the failure probabilities of each vacuum tube is 1. The recovery voltage during the j-th action. This represents the number of times the vacuum tube operates during a single forward / reverse switching cycle.

[0010] In one possible implementation, the weighting model for the impact of vacuum tube failure is as follows: in: No. The impact of a vacuum tube failure on the weighting The normalization coefficients ensure that the sum of the weights of the impact of each vacuum tube failure is 1. For the first Arc voltage during the next action For the first Fault current during the next operation.

[0011] In one possible implementation, the coupling mechanism regulation model is as follows: in: A vacuum tube that serves to couple the effects; For being All vacuum tubes affected by coupling , To affect the before and after Damage probability value, where m and n are the values ​​before and after the effect. Affects the weight value.

[0012] In one possible implementation, the construction of a comprehensive risk model based on the failure probability of each vacuum tube and the failure impact weight of each vacuum tube includes: in: For the collection of all vacuum tubes, A subset of faulty vacuum tubes; This is a subset of normally functioning vacuum tubes.

[0013] In one possible implementation, the risk assessment of the vacuum on-load tap changer using the comprehensive risk model includes: The comprehensive risk model is used to calculate the comprehensive risk of different design schemes. Compare the overall risks of different design schemes and output the evaluation results.

[0014] Secondly, embodiments of this application provide a risk assessment system for a vacuum on-load tap changer, characterized in that it includes: The acquisition module is used to calculate the power load parameters of each vacuum tube and determine whether there is a coupling mechanism in the circuit topology based on the circuit topology and vacuum tube parameters of the vacuum on-load tap changer. The power load parameters include: number of operations, recovery voltage, fault current and arc voltage. The first calculation module is used to calculate the failure probability of each vacuum tube and the failure influence weight of each vacuum tube according to the constructed vacuum tube failure probability model and vacuum tube failure influence weight model, respectively, if the circuit topology does not have a coupling mechanism. The second calculation module is used to introduce a coupling mechanism adjustment model if the circuit topology has a coupling mechanism, and calculate the failure probability of each vacuum tube and the failure influence weight of each vacuum tube in conjunction with the vacuum tube failure probability model and the vacuum tube failure influence weight model, respectively. The risk assessment module is used to construct a comprehensive risk model by combining the failure probability of each vacuum tube and the failure impact weight of each vacuum tube, and to use the comprehensive risk model to realize the risk assessment of the vacuum on-load tap changer.

[0015] In this embodiment, based on the actual circuit topology and vacuum tube parameters of the vacuum on-load tap changer, the electrical load parameters such as the number of operations, recovery voltage, fault current, and arc voltage of each vacuum tube are quantitatively calculated. Furthermore, a unified correlation model is established between the single-tube fault probability, fault impact weight, and overall system risk. For topology conditions with coupling mechanisms, the model can be adjusted through these mechanisms to correct for risk transmission and amplification effects between vacuum tubes, thereby improving the relevance, accuracy, and consistency of risk assessment results. Compared to existing solutions that only focus on condition monitoring, abnormal alarms, or fault diagnosis, this approach more realistically reflects the differences in the contribution of each vacuum tube to the overall system's operational safety, providing a basis for maintenance decisions, lifespan management, and operational optimization. Attached Figure Description

[0016] Figure 1 A flowchart illustrating a risk assessment method for a vacuum on-load tap changer provided in this application embodiment; Figure 2 This is a schematic diagram of the vacuum tube failure probability and impact weight calculation model provided in an embodiment of this application; Figure 3 This is a schematic diagram illustrating the determination of the comprehensive risk calculation model provided in the embodiments of this application; Figure 4 A schematic diagram of a two-vacuum-tube circuit is provided in an embodiment of this application; Figure 5 This is a schematic diagram of a four-vacuum-tube circuit provided in an embodiment of this application. Detailed Implementation

[0017] The present solution will now be described in conjunction with the accompanying drawings and specific embodiments.

[0018] See Figure 1 The risk assessment method for vacuum on-load tap changers provided in this embodiment includes: S101, based on the circuit topology and vacuum tube parameters of the vacuum on-load tap changer, calculate the power load parameters of each vacuum tube and determine whether there is a coupling mechanism in the circuit topology. The power load parameters include: number of operations, recovery voltage, fault current and arc voltage.

[0019] In this embodiment, after obtaining the power load parameters of each vacuum tube, the first step is to determine whether a coupling mechanism exists in the circuit topology. This includes determining the common node relationships, coupling capacitance relationships, overlapping action timing relationships, and voltage recovery propagation paths among the vacuum tubes. A directional coupling relationship matrix between the vacuum tubes is constructed, and the existence of a coupling mechanism is determined based on this matrix.

[0020] Specifically, suppose there are M vacuum tubes in the vacuum on-load tap changer, denoted as M0. For any vacuum tube Define its action-sensitive time window as ,in: Vacuum tube At the start of the action, Vacuum tube The moment of recovery and stabilization.

[0021] Install vacuum tube The set of connection points is Then the vacuum tube and The co-node relationship coefficient is defined as: Thus, a common point relation matrix is ​​constructed: ,in: Indicates the number of elements in the set. When When, it means and There is no shared node relationship; when The larger the value, the higher the degree of node sharing between the two, and the stronger the coupling between the shared nodes.

[0022] Install vacuum tube and The equivalent coupling capacitance between them is vacuum tube The total associated capacitance is: ,in: vacuum tube The equivalent capacitance to ground is defined as the coupling capacitance relationship coefficient. Thus, the coupling capacitance relationship matrix is ​​constructed. . The larger, the more it means Voltage disturbances are transmitted to via capacitive coupling. The higher the proportion.

[0023] Install vacuum tube and The action-sensitive time windows are respectively and The overlap length of their time windows is then: Define the action timing overlap coefficient as: Thus, an action timing overlap matrix is ​​constructed: .when When, it indicates that the sensitive regions of the two actions do not overlap; when The larger the value, the greater the likelihood that the two elements will influence each other within the same transient window.

[0024] Install vacuum tube arrive There exists a voltage recovery propagation path. The path consists of several branches e, and the propagation impedance of each branch is... The total path impedance is defined as follows: The path propagation coefficient is defined as: Thus, the voltage recovery propagation path matrix is ​​constructed. ,in: This is the impedance attenuation coefficient. From arrive The stronger the recovery voltage propagation capability, the better. The larger.

[0025] Finally, define the action direction factor: According to the above Construct the direction matrix ,in: It is an indicator function.

[0026] According to the co-point relationship matrix Coupling capacitance relationship matrix Action timing overlap matrix: Voltage recovery propagation path matrix and direction matrix Determine the directional coupling matrix: in: This represents the Hadamard product, which is the multiplication of corresponding elements of two matrices. Indicates the weight of the relationship between co-nodes. Indicates the weights of the coupling capacitance relationship. Indicates the weight of the overlapping relationship between actions in time sequence. Indicates the weight of the voltage recovery propagation path. When the described If there are off-diagonal elements in the system that are greater than a preset threshold, or if the overall coupling strength of the system is greater than a preset overall threshold, it is determined that there is a coupling mechanism in the vacuum on-load tap changer.

[0027] S102, if the circuit topology does not have a coupling mechanism, then calculate the failure probability of each vacuum tube and the failure influence weight of each vacuum tube according to the constructed vacuum tube failure probability model and vacuum tube failure influence weight model respectively.

[0028] In this step, since it has been determined in S101 that there is no significant coupling mechanism in the current circuit topology of the vacuum on-load tap changer, each vacuum tube can be considered to independently bear its corresponding electrical load parameters under the current evaluation condition. At this time, there is no obvious risk transmission, risk amplification, or load redistribution caused by changes in the state of adjacent branches among the vacuum tubes. Therefore, single-tube-level risk quantification calculation can be performed directly based on parameters such as the number of times each vacuum tube operates, recovery voltage, fault current, and arc voltage.

[0029] Specifically, participate in Figure 2 The vacuum tube failure probability model described in this embodiment is as follows: in: For the first The probability of failure of a vacuum tube The normalization coefficient is used to ensure that the sum of the failure probabilities of each vacuum tube is 1. The recovery voltage during the j-th action. This represents the number of times the vacuum tube operates during a single forward / reverse switching cycle.

[0030] In one implementation, the failure probability of each vacuum tube is first calculated based on a vacuum tube failure probability model. This model uses the recovery voltage corresponding to each action of the vacuum tube during a single forward / reverse switching cycle as the primary characteristic, cumulatively representing the recovery voltage experienced by the same vacuum tube at multiple action moments, and converting the calculation results for each vacuum tube into a unified probability distribution using a normalization coefficient. Since the recovery voltage reflects the insulation recovery load level of the vacuum tube after interruption, a higher recovery voltage generally means greater electrical stress experienced by the vacuum tube during switching, and a correspondingly higher probability of failure. Therefore, the failure probability model can transform the differences in voltage stress among different vacuum tubes into comparable failure probability results, thereby obtaining the basic damage probability of each vacuum tube under the current uncoupled operating condition.

[0031] The weighting model for the impact of vacuum tube failure is as follows: in: No. The impact of a vacuum tube failure on the weighting The normalization coefficients ensure that the sum of the weights of the impact of each vacuum tube failure is 1. For the first Arc voltage during the next action For the first Fault current during the next operation.

[0032] Furthermore, the fault impact weight of each vacuum tube is calculated based on the vacuum tube fault impact weight model. This model uses the arc voltage and fault current of each vacuum tube during operation as the main calculation basis. By characterizing the arc load and current surge that may be caused when a vacuum tube fails, it quantifies the impact of different vacuum tube failures on the entire system. Specifically, the fault impact weight does not merely indicate whether a particular vacuum tube is easily damaged, but rather characterizes the contribution of that vacuum tube, once it fails, to the overall operational safety, switching stability, and subsequent branch operating status of the vacuum on-load tap changer. After normalization, comparable impact weight results can be obtained for each vacuum tube.

[0033] In this step, since the correction effect of coupling factors is not considered, the obtained fault probability and fault impact weight can be used as the basic risk parameters for each vacuum tube under the current circuit topology. On the one hand, the results can directly reflect the risk differences of each vacuum tube due to uneven power load distribution. On the other hand, it also provides input data for the subsequent construction of a comprehensive risk model. For vacuum on-load tap changers with simple structure, relatively independent branches, no significant common node coupling between vacuum tubes, no obvious coupling capacitor transfer, and separated operating timing, the calculation results obtained in this step can accurately characterize the independent contribution of each vacuum tube to the overall risk.

[0034] S103, if the circuit topology has a coupling mechanism, then a coupling mechanism adjustment model is introduced, which is used in conjunction with the vacuum tube failure probability model and the vacuum tube failure influence weight model to calculate the failure probability and failure influence weight of each vacuum tube.

[0035] If a coupling mechanism is determined in S101, it indicates that at least some of the vacuum tubes inside the current vacuum on-load tap changer are not independent of each other, and they have mutual influence relationships in terms of common node connection, coupling capacitance, voltage recovery propagation path, or overlapping action timing. In this case, if the evaluation is still performed only according to the independent vacuum tube calculation method in S102, it may not accurately reflect the transmission effect of the failure of one vacuum tube on the load distribution, operating conditions, and risk level of other vacuum tubes, thus causing the evaluation results to deviate from the actual operating conditions. Therefore, this step further introduces a coupling mechanism adjustment model based on the basic fault probability model and the basic fault influence weight model to correct the risk parameters under coupled operating conditions.

[0036] Specifically, the vacuum tubes that exert coupling influence, as well as the set of target vacuum tubes affected by coupling, can be identified first based on the directional coupling relationship matrix obtained in S101. For each vacuum tube with coupling influence, when its state changes or a fault occurs, the recovery voltage, fault current, or arc load borne by other associated vacuum tubes will be redistributed through common node potential changes, coupling capacitor voltage transmission, overlapping action windows, and recovery voltage propagation paths. Based on this, this step uses a coupling mechanism adjustment model to adjust the original fault probability value and fault influence weight value of the affected vacuum tubes, so that the adjusted result can reflect the true risk state under coupling influence.

[0037] This embodiment introduces the following coupling mechanism adjustment model: in: A vacuum tube that serves to couple the effects; For being All vacuum tubes affected by coupling , To affect the before and after Damage probability value, where m and n are the values ​​before and after the effect. Affects the weight value.

[0038] In the coupling mechanism adjustment model, the initial vacuum tube is the vacuum tube that exerts a coupling effect, and the affected set is the set of all vacuum tubes affected by the initial vacuum tube. The probability correction term in the model characterizes the change in the damage probability of the affected vacuum tubes before and after the coupling effect, and the weight correction term characterizes the change in the degree of fault impact of the affected vacuum tubes before and after the coupling effect. In other words, this step does not establish a completely new model independent of the basic model, but rather, based on the single-tube risk results already given by the basic fault probability model and the basic fault impact weight model, it performs a secondary correction on the risk parameters of the relevant vacuum tubes according to the coupling relationship, thereby forming a fault probability and fault impact weight applicable to the coupled operating conditions.

[0039] Through the above methods, for topologies with coupling mechanisms, a fault in a vacuum tube no longer manifests as mere self-damage, but may further induce related vacuum tubes to experience higher recovery voltages, repetitive operating loads, or more severe fault current surges. This can cause local risks to propagate to adjacent vacuum tubes, and even amplify the overall system risk. Therefore, the fault probability and fault impact weights corrected by the coupling mechanism adjustment model more accurately reflect the transmissibility and correlation of internal risks in vacuum on-load tap changers under complex topology conditions compared to the uncorrected baseline results.

[0040] Furthermore, in practical implementation, the adjustment can be performed only on vacuum tube pairs with coupling strength greater than a preset threshold in the directional coupling relationship matrix, or it can be performed uniformly on all vacuum tubes with coupling relationships, to balance computational accuracy and efficiency. The corrected failure probability and failure impact weight of each vacuum tube are used as the final single-tube risk parameters under coupled conditions and input into the subsequent comprehensive risk model to complete the risk assessment at the system level.

[0041] S104. A comprehensive risk model is constructed by combining the failure probability of each vacuum tube and the failure impact weight of each vacuum tube. The comprehensive risk model is used to realize the risk assessment of the vacuum on-load tap changer.

[0042] according to Figure 3 The process, after obtaining the failure probability and failure impact weight of each vacuum tube, further constructs a comprehensive risk model to achieve a unified assessment from single vacuum tube risk quantification to overall system risk quantification. In this step, the comprehensive risk model does not only perform isolated analysis of the failure of a single vacuum tube, but comprehensively considers the possible combinations of failure states of different vacuum tubes from the perspective of the entire system, as well as the degree of impact of each failure state combination on the overall operational reliability of the vacuum on-load tap changer, thereby obtaining a comprehensive risk value that can characterize the overall risk level of the target circuit structure.

[0043] Specifically, all vacuum tubes constitute the complete set, faulty vacuum tubes constitute the fault subset, and normally functioning vacuum tubes constitute the normal subset. By traversing or combining the states corresponding to different fault subsets, the fault probability and fault impact weight of each vacuum tube can be integrated at the system level to obtain the risk contribution under various fault scenarios, and finally summarize to form the comprehensive risk result of the target vacuum on-load tap changer. This comprehensive risk result not only reflects the damage tendency of a single vacuum tube itself, but also reflects the degree of impact of the vacuum tube failure on the overall function, switching continuity, and safety of the system. Therefore, it can more comprehensively characterize the overall risk of the vacuum on-load tap changer than a single fault probability or a single impact weight. In this embodiment, the comprehensive risk model is as follows: in: For the collection of all vacuum tubes, A subset of faulty vacuum tubes; This is a subset of normally functioning vacuum tubes.

[0044] In one implementation, the failure probabilities and impact weights of each vacuum tube obtained under different design schemes can be substituted into the comprehensive risk model to calculate the comprehensive risk value corresponding to each design scheme, and the results can be compared. The lower the comprehensive risk value, the lower the overall risk level of the vacuum on-load tap changer under a given operating condition and the higher the structural reliability; conversely, it indicates that there is still room for further optimization in the vacuum tube load distribution, coupling relationship handling, or circuit parameter configuration of the design scheme. Therefore, this step can not only be used for risk assessment of existing equipment, but also for reliability optimization among different circuit topologies, different numbers of vacuum tubes, different transition resistance configurations, or different coupling structure schemes.

[0045] The comprehensive risk model established in this step can uniformly map the single-tube-level risk results obtained in S102 or S103 to the overall system-level risk assessment results, thereby achieving quantitative risk assessment of vacuum on-load tap changers. Compared with existing methods that rely solely on a single monitored quantity, a single vacuum tube, or a localized fault phenomenon for judgment, the comprehensive risk value obtained in this step can more comprehensively reflect the differences in the contribution of different vacuum tubes to the overall system's operational safety under different operating conditions, and can provide quantitative basis for the design comparison, maintenance decisions, life management, and operational optimization of vacuum on-load tap changers.

[0046] The risk assessment method provided in the above embodiments is illustrated below using a two-vacuum-tube circuit and a four-vacuum-tube circuit, respectively.

[0047] The first type is a two-vacuum-tube, two-resistor transition circuit that is independent of each other, such as... Figure 4 As shown. Two vacuum tubes. and The number of actions is 2. The voltage recovered during the first action was The fault current is The voltage recovered in the second operation was The fault current is . The voltage recovered during the first action was The fault current is The voltage recovered in the second operation was The fault current is The arc voltage in the vacuum tube remains unchanged and can be removed.

[0048] According to the formula for calculating the probability of failure ,get The probability of damage is 0.5. The probability of damage is 0.5. This is calculated according to the fault impact weighting formula. ,get The influence weight is 0.5. The impact weight is 0.5. Based on the comprehensive risk value calculation formula... The overall risk value of the circuit was found to be 0.5.

[0049] The independent dual-vacuum-tube dual-resistor circuit has a combined risk of 0.5 and symmetrical load distribution, making it a benchmark for comparing the risk improvement effect of coupled redundant structures.

[0050] The second type is a four-vacuum-tube, two-resistor transition circuit with coupling effect, such as... Figure 5 As shown.

[0051] Four vacuum tubes , , and Each action is performed only once. Action recovery voltage is The fault current is ; Action recovery voltage is The fault current is ; Action recovery voltage is The fault current is ; Action recovery voltage is The fault current is The arc voltage in the vacuum tube remains unchanged and can be removed. and , and There is a coupling effect between them. When damaged, The action is performed twice. The voltage recovered during the first action was The fault current is The voltage recovered in the second operation was The fault current is ; When damaged, The action is performed twice. The voltage recovered during the first action was The fault current is The voltage recovered in the second operation was The fault current is .

[0052] According to the formula for calculating the probability of failure Under normal circumstances, The probability of damage is 0.145. The probability of damage is 0.355. The probability of damage is 0.355. The probability of damage is 0.145. Consider... and , and The coupling effect between them When damaged, The probability of damage is 0.5; When damaged, The probability of damage is 0.5.

[0053] According to the formula for calculating the weight of fault impact Under normal circumstances, The influence weight is 0.226. The influence weight is 0.274. The influence weight is 0.274. The influence weight is 0.226. Consider... and , and The coupling effect between them When damaged, The influence weight is 0.5; When damaged, The influence weight is 0.5.

[0054] According to the formula for calculating the comprehensive risk value The overall risk value of the circuit was obtained as 0.10948. Compared with the independent two-transistor circuit, the risk is significantly reduced, verifying the reliability advantage of the coupled redundancy design, and also proving that the evaluation method can accurately quantify the risk mitigation effect of the coupling mechanism.

[0055] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, the simultaneous existence of A and B, or the existence of B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0056] The above description is merely a specific embodiment of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. The protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method of risk assessment for a vacuum on-load tap changer, characterized in that, include: Based on the circuit topology and vacuum tube parameters of the vacuum on-load tap changer, calculate the power load parameters of each vacuum tube and determine whether there is a coupling mechanism in the circuit topology. The power load parameters include: number of operations, recovery voltage, fault current and arc voltage. If the circuit topology does not have a coupling mechanism, the failure probability of each vacuum tube and the failure influence weight of each vacuum tube are calculated according to the constructed vacuum tube failure probability model and vacuum tube failure influence weight model, respectively. If the circuit topology has a coupling mechanism, a coupling mechanism adjustment model is introduced, which is used in conjunction with the vacuum tube failure probability model and the vacuum tube failure influence weight model to calculate the failure probability and failure influence weight of each vacuum tube. A comprehensive risk model is constructed by combining the failure probability of each vacuum tube and the failure impact weight of each vacuum tube, and the risk assessment of the vacuum on-load tap changer is realized by using the comprehensive risk model.

2. The risk assessment method for vacuum on-load tap changers according to claim 1, characterized in that, The determination of whether the circuit topology has a coupling mechanism includes: Determine the common node relationships, coupling capacitance relationships, action timing overlap relationships, and voltage recovery propagation paths among the vacuum tubes; Construct a directional coupling relationship matrix between vacuum tubes, and determine whether a coupling mechanism exists based on the directional coupling relationship matrix.

3. The risk assessment method for vacuum on-load tap changers according to claim 2, characterized in that, The determination of the common node relationship, coupling capacitance relationship, action timing overlap relationship, and voltage recovery propagation path among the vacuum tubes includes: Suppose that there are M vacuum tubes in the vacuum on-load tap changer, denoted as M. For any vacuum tube Define its action-sensitive time window as ,in: Vacuum tube At the start of the action, Vacuum tube The moment of recovery and stabilization; Install vacuum tube The set of connection points is Then the vacuum tube and The co-node relationship coefficient is defined as: Thus, a common point relation matrix is ​​constructed: ,in: Indicates the number of elements in the set; Install vacuum tube and The equivalent coupling capacitance between them is vacuum tube The total associated capacitance is: ,in: vacuum tube The equivalent capacitance to ground is defined as the coupling capacitance relationship coefficient. Thus, the coupling capacitance relationship matrix is ​​constructed. ; Install vacuum tube and The action-sensitive time windows are respectively and The overlap length of their time windows is then: The action timing overlap coefficient is defined as follows: Thus, an action timing overlap matrix is ​​constructed: ; Install vacuum tube arrive There exists a voltage recovery propagation path. The path consists of several branches e, and the propagation impedance of each branch is... The total path impedance is defined as follows: The path propagation coefficient is defined as: Thus, the voltage recovery propagation path matrix is ​​constructed. ,in: This is the impedance attenuation coefficient; Finally, define the action direction factor: According to the above Construct the direction matrix ,in: It is an indicator function.

4. The risk assessment method for vacuum on-load tap changers according to claim 3, characterized in that, The process of constructing a directional coupling relationship matrix between vacuum tubes and determining whether a coupling mechanism exists based on the directional coupling relationship matrix includes: According to the co-point relationship matrix Coupling capacitance relationship matrix Action timing overlap matrix: Voltage recovery propagation path matrix and direction matrix Determine the directional coupling matrix: in: This represents the Hadamard product, which is the multiplication of corresponding elements of two matrices. Indicates the weight of the relationship between co-nodes. Indicates the weight of the coupling capacitance relationship. Indicates the weight of the overlapping relationship between actions in time sequence. Indicates the weight of the voltage recovery propagation path. ; When the If there are off-diagonal elements in the system that are greater than a preset threshold, or if the overall coupling strength of the system is greater than a preset overall threshold, it is determined that there is a coupling mechanism in the vacuum on-load tap changer.

5. The risk assessment method for vacuum on-load tap changers according to claim 1, characterized in that, The vacuum tube failure probability model is as follows: in: For the first The probability of failure of a vacuum tube The normalization coefficient is used to ensure that the sum of the failure probabilities of each vacuum tube is 1. The recovery voltage during the j-th action. This represents the number of times the vacuum tube operates during a single forward / reverse switching cycle.

6. The risk assessment method for vacuum on-load tap changers according to claim 5, characterized in that, The weighting model for the impact of vacuum tube failure is as follows: in: No. The impact of a vacuum tube failure on the weighting The normalization coefficients ensure that the sum of the weights of the impact of each vacuum tube failure is 1. For the first Arc voltage during the next action For the first Fault current during the next operation.

7. The risk assessment method for vacuum on-load tap changers according to claim 6, characterized in that, The coupling mechanism regulation model is as follows: in: A vacuum tube that serves to couple the effects; For being All vacuum tubes affected by coupling , To affect the before and after Damage probability value, where m and n are the values ​​before and after the effect. Affects the weight value.

8. The risk assessment method for vacuum on-load tap changers according to claim 6 or 7, characterized in that, The comprehensive risk model constructed based on the failure probability and failure impact weight of each vacuum tube includes: in: For the collection of all vacuum tubes, A subset of faulty vacuum tubes; This is a subset of normally functioning vacuum tubes.

9. The risk assessment method for vacuum on-load tap changers according to claim 1, characterized in that, The risk assessment of vacuum on-load tap changers using the comprehensive risk model includes: The comprehensive risk model is used to calculate the comprehensive risk of different design schemes. Compare the overall risks of different design schemes and output the evaluation results.

10. A risk assessment system for vacuum on-load tap changers, characterized in that, include: The acquisition module is used to calculate the power load parameters of each vacuum tube and determine whether there is a coupling mechanism in the circuit topology based on the circuit topology and vacuum tube parameters of the vacuum on-load tap changer. The power load parameters include: number of operations, recovery voltage, fault current and arc voltage. The first calculation module is used to calculate the failure probability of each vacuum tube and the failure influence weight of each vacuum tube according to the constructed vacuum tube failure probability model and vacuum tube failure influence weight model, respectively, if the circuit topology does not have a coupling mechanism. The second calculation module is used to introduce a coupling mechanism adjustment model if the circuit topology has a coupling mechanism, and calculate the failure probability of each vacuum tube and the failure influence weight of each vacuum tube in conjunction with the vacuum tube failure probability model and the vacuum tube failure influence weight model, respectively. The risk assessment module is used to construct a comprehensive risk model by combining the failure probability of each vacuum tube and the failure impact weight of each vacuum tube, and to use the comprehensive risk model to realize the risk assessment of the vacuum on-load tap changer.

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