The Research On Condition Assessment Of Vacuum Circuit Breaker Based On Cloud Matter Element And Evidence Theory

With a dual role of protection and control,the circuit breaker is one of the most important devices in the power system.Vacuum circuit breakers are widely used in distribution network system because of strong arc-extinguishing ability,long service life and no pollution to the surrounding environment,and their reliability has a direct impact on the safe and stable operation of power system.The condition-based maintenance can judge whether the device is abnormal according to the device status information,and perform maintenance before the fault occurs to effectively prevent the accident.It is of great significance to carry out condition-based maintenance of vacuum circuit breaker to ensure the safe operation of circuit breaker itself and power network economically and effectively.The basis of condition-based maintenance is accurate and reliable condition assessment.Therefore,this paper proposes a vacuum circuit breaker condition assessment method based on cloud matter element and evidence theory.In this paper,the vacuum circuit breaker condition assessment is divided into four items: vacuum characteristics,mechanical characteristics,electrical characteristics and other factors according to the vacuum circuit breaker structure,operation process and common faults.Combining the needs of assessment with the actual operability,the corresponding evaluation indicators are selected to construct a multi-level indicator system for vacuum circuit breaker condition assessment.The weight calculation method based on cooperation game and variable weight theory.The constant weight of the assessment indicator is calculating by the cooperative game method which combines the weights derived from the improved analytic hierarchy process,the entropy weight method and the anti-entropy weight method.According to the indicator data,the constant weight is optimized by the variable weight formula to obtain the final weight of the indicator.The method uses the cloud matter element combined with the evidence theory to evaluate the condition of the vacuum circuit breaker.The state-level range is replaced by cloud model,and the characteristic element value in the matter-element to be evaluated is regarded as cloud droplet to calculate the correlation degree of the indicator to each state level.Combine the weights of the indicators,calculate the correlation of each evaluated item to different status levels,and obtain the evaluation results of each item.Through the evidence theory,the evaluation results of the four items are fused to obtain the evaluation level correlation degree of the vacuum circuit breaker,and the condition assessment result is obtained according to the evaluation decision method of the evidence theory.The ZN63A-12 type vacuum circuit breaker is used as a target to build a monitoring system and evaluated the condition of circuit breaker in combination with the collected indicator data and historical records.The results show that the vacuum circuit breaker condition assessment method proposed in this paper can evaluate the vacuum circuit breaker assessment effectively and accurately.