Comprehensive Evaluation Of The Health Status For Medium Voltage Circuit Breakers

Circuit breaker is the essential part of the grid system,Its mechanical health is a factor that can not be ignored for its stable operation.At this time,the faults of the circuit breakers are hard to distinguish,but exists a huge security risk.Therefore,the subject of this study is comprehensive evaluation of the health status for medium voltage circuit breakers,which quantifies the mechanical performance of circuit breakers,finds out the potential security risks of circuit breakers,and provides reference suggestions about maintenance or replacement for customers.The research object is ABB 12kV iVD4 intelligent circuit breaker,and the research is focused on the following contents:(1)The existing after-sales data is investigated to determine the actualoperation of the relatively high incidence of several typical mechanical faults:unsmooth transmission chain,relax of opening spring,buffer failure and lack of lubricant.Through a variety of fault combination tests,the original data sets of force signals,displacement signals,and vibration signals in these combination modes of faults can be obtained for subsequent faults evaluation or analysis.(2)The raw data sets of signals are pre-processed to exact the relevent features and combine features together.the corresponding combined scores of features are obtained by Laplacian Score and Fisher Score,then the combined features are sorted in descending order by the size of combined features.The classifier is used to verity the accuracy of the feature subset,obtain the optimal feature subset,choose the best number of features,and assign feature weights according to the size of the combined score.(3)A comprehensive evaluation model for circuit breakers based on matter-element theory is established.First of all,the referenced samples of the feature sets are used to determine the distance between types of various faults and the type of healthy samples by calculating the mahalanobis distance,then circuit breaker status level is divided to health,transition,minor fault and serious fault and choose their representative sample types.(4)For the original feature set of ABB's iVD4 circuit breaker,acomprehensive evaluation model for circuit breaker based on regression model is established.Using the referenced sample feature set,taking the 0-meaning result of the selected features as the input,and using the percentile conversion result of the mahalanobis distance as the output,using multiple regression method to establish the equation between the input and the output.The equation is checked for correctness.Classic area and section area are determined under all index levels are determined by statistics theory,the accuracy of the matter-element model is verified by testing the sample sets.The zero-averaged result of the selected features is used as input,and the mahalanobis distance percentage conversion result is used as output.The empirical formula is established by using regression method.After regression testing,the formula is valid.The formula is verified by the test samples,and the accuracy rate reaches 100%,and it has the ability to distinguish unknown samples.(5)The two evaluation models are used to evaluate an ABB iVD4 circuit breaker,respectively,and the mechanical state of the equipment is obtained by the matter-element method.The regression method of getting the output score is also within the health status score which is set.In summary,the mechanical health of the circuit breaker is determined to be good,and there is no decrease in mechanical performance.