Research On Transient Characteristics Analysis And Detection Technology Of Breaking Capacitive Current Re-strike In Breakers

As the most important control and protection equipment in power system,circuit breakers,whether SF6 or vacuum circuit breakers,can not effectively avoid the occurrence of re-breakdown.Serious over voltage caused by shunt compensation capacitor removal by circuit breaker will damage the insulation of circuit breaker and capacitor,affect the normal operation of protection device,and then endanger the safe and stable operation of power system.The monitoring and identification of capacitor switch re-breakdown transient is an effective means to identify the early fault of circuit breaker.If the single-phase re-breakdown fault of circuit breaker is not monitored and eliminated in time,the early fault may develop into multi-phase and multiple re-breakdown,which will cause great harm to the system.The existing literature has carried out a preliminary study on the mechanism and characteristics of breakdown of circuit breakers,but the current establishment of breakdown characteristics is not perfect,and does not involve the research of extraction methods of breakdown features for waveform disturbance detection.Based on the different operation modes of system and capacitor bank neutral point,the transient voltage and current waveforms collected at capacitor ports are analyzed in this paper.The typical transient waveform characteristics of single-phase and inter-phase re-breakdown phenomena occurring in the time-frequency domain when circuit breakers cut off compensating capacitors are established under the high frequency arc extinguishing theory and the power frequency arc extinguishing theory,respectively.The method of feature extraction based on wavelet transform and harmonic model(TLS-ESPRIT)is studied and verified by simulation experiments.The results show that when the neutral point of the capacitor bank is not grounded,the typical transient characteristics of single-phase and inter-phase re-breakdown under the operation mode of neutral point grounding/non-grounding/arc suppression coil grounding in the system are not significantly different,only the oscillation frequency and attenuation time constant of the re-breakdown transient are different,and the typical transient characteristics and electricity of the system and capacitor bank when the neutral point is grounded are different.There are obvious differences in the typical transient characteristics when the neutral point of the container is not grounded.From the angle of waveform characteristics,this paper establishes a comprehensive and perfect typical transient characteristics of re-breakdown,which provides a theoretical basis for the detection and identification of re-breakdown transient of circuit breakers,and then effectively promotes the related research work based on re-breakdown characteristics of circuit breakers.