Research Of Circuit Breaker Condition Monitoring System Based On Vibration Signal

High-voltage circuit breaker is one of the most important control and protection equipment in power system,and its operation reliability directly affects the stable operation of power system.Therefore,the condition fault monitoring of high voltage circuit breaker is one of the research hotspots at present.The vibration signal of high voltage circuit breaker contains a lot of information that can reflect the state of the equipment.In fault diagnosis,extracting the characteristic value of the vibration signal is an effective means,and also an important way of non-invasive mechanical fault monitoring.In this study,a condition monitoring system of high voltage circuit breaker is designed.The system uses vibration signals for monitoring and analysis,and adopts time-frequency domain algorithm to realize feature extraction and analysis of energy in characteristic frequency band,which effectively realizes the condition monitoring of high voltage circuit breaker by vibration signals.Firstly,the hardware part of the high voltage circuit breaker condition monitoring system is designed,which mainly includes vibration sensor,signal conditioning module,high-speed data acquisition card and monitoring host computer.Among them,the core unit is vibration sensor,which plays a decisive role in the monitoring performance of the whole system.The basic principle of signal conversion is analyzed,and the rationality of the model selection of vibration sensor is analyzed.The debugging proves that the designed hardware system can meet the performance requirements of the system and realize the functions of acquisition,conversion,transmission and display of vibration signals.Secondly,the software part of the high voltage circuit breaker condition monitoring system is designed.With LabVIEW as the development platform,the program of the high voltage circuit breaker condition monitoring system is written using the modular design idea.The software part mainly realizes the signal analysis function.The algorithm with time domain and frequency domain conversion function is used to further analyze the vibration signal,which can realize the monitoring of the high voltage circuit breaker status.Then,the analysis theory of high-voltage circuit breaker vibration signal is studied,mainly using Fourier transform theory and wavelet packet theory.The Fourier transform theory can not divide the frequency band,and its analysis results are difficult to further draw the conclusion of condition monitoring.However,the vibration signal analysis based on the wavelet packet energy spectrum can characterize the energy content of the vibration signal at any scale,providing a theoretical guarantee in the condition monitoring of high voltage circuit breaker.Finally,the high voltage circuit breaker condition monitoring system is tested under normal temperature condition and cold condition respectively.The results show that the wavelet packet energy spectrum analysis can directly display the proportion of energy distribution in different frequency bands,which is conducive to the establishment of the characteristic fingerprint database of the on-off vibration of highvoltage circuit breakers under normal conditions,and provides a reference for further fault diagnosis.At the same time,the vibration signal of the high-voltage circuit breaker is monitored under the fault state and compared with the normal state.The results show that the proportion of the vibration signal increases significantly in the frequency band higher than 4k Hz under the fault state,which provides a reliable criterion for fault diagnosis.