Substation Automation State Interval Fuzzy Evaluation Model And Methods

Safe and stable operation of the substation automation equipment is essential for the security of the grid.The development of condition-based maintenance has changed the form of after-the-fact maintenance.Through the real-time monitoring parameters of each index of substation automation equipment,condition-based maintenance find the problem and solve the problem in advance.It can improve the operation reliability of substation automation equipment,and it can improve the accuracy of maintenance personnel to locate the fault.It can reduce the overhaul cost.In 2015,China State Grid Corporation proposed the "four unified,four specification" requirements.Specifically: unified device appearance and interface,unified device use interface,unified monitoring screen graphics,unified master station and sub-station communication services,standardized product quality control,standardized device parameter management,standardized system application function,standardized software version management.This document prompts substation automation equipment suppliers to recommend uniform standards.This lays a foundation for condition-based maintenance of substation automation equipment.In view of the existing standards,in order to quantitatively and comprehensively evaluate the operation status of substation automation equipment,and predict the status of substation automation equipment,the main work done in this paper is as follows:Firstly,this paper finds the operation mechanism of substation automation equipment with extremely low probability of failure,and excludes the corresponding indicators in the evaluation index system.According to the failure mechanism analysis results,the principles to be followed in the selection of indicators are proposed.According to the research results,the corresponding evaluation index system is proposed for the characteristics of integrated measurement and control device,data communication gateway machine and power system synchronous phasor measurement device.Secondly,based on the substation automation equipment status evaluation index system,a sub-station automation equipment index status grading model with more than six levels is proposed.The model serves as a comparative reference for device scoring,enabling experts to score quickly and with high accuracy.Using the interval value fuzzy set theory,the corresponding scoring method is proposed.According to the above classification scheme,this paper proposes a method for interval value scores containing information on the relative importance of indicators,and establishes rules for relative importance scores.The method uses the interval value to represent the state of the device,and quantifies the uncertainty and ambiguity in the evaluation process,which is more in line with the operator’s cognitive habits.At the same time,the width of the interval value contains information on the importance of the equipment index,which reduces the expert’s evaluation workload for the same indicator.Finally,this paper establishes an empowerment and aggregation model for substation automation equipment.The model is based on the characteristics of the interval value fuzzy set,combined with the importance of the device index,calculates the weight of each indicator,and quickly reflects the degree of influence of each indicator state parameter on the device.The maximum and minimum mean weighted aggregation model is proposed.The model makes full use of the objective information in the qualitative rules,which reduces the subjective influence in the state assessment.The research results were applied to the actual equipment operation status of the substation,and the practicability of the model was verified.And compared with the fuzzy comprehensive evaluation method,it shows the difference between the two methods.The method proposed in this paper does not need to make consistency judgment due to the characteristics of the interval value,and can adapt well to the problem of more than 10 indicators.It can also provide data support for substation automation equipment status failure prediction.The state interval fuzzy evaluation method of substation automation equipment proposed in this paper can adapt well to the volatility of index parameters,without the need for experts to conduct multiple evaluations.Compared with the fuzzy comprehensive evaluation method,the results obtained by this method are closer to the actual running state of the equipment,and the possibility of equipment failure is represented by the interval value.The method can also avoid the same index score,solve the problem of difficulty in judging the relative importance,and reduce the number of comparisons in the expert scoring process by 50%.