基于弧触头接触振动特征分析的高压 SF₆ 断路器电寿命在线监测方法

Evaluating the electrical life of a high-voltage circuit breaker is important to ensure the safe and stable operation of power systems. However, the current life assessment mainly depends on the cumulative open-off current method and the dynamic resistance measurement method. The former is based on prediction and inference, which is inaccurate, while the latter cannot be used online. Therefore, based on a real 126 kV GIS device, this paper studies the method of electric life evaluation based on arc contact point analysis. After controlling the closing action of the circuit breaker, the control coil current, vibration, travel, and dynamic resistance signals are collected, and the signals are aligned. By marking the contact position between the arc contact and the main contact of the circuit breaker based on the characteristic points reflected on different signals, it is discovered that a high-frequency vibration signal is generated after the arc contact. According to variational mode decomposition (VMD) and short time Fourier transform (STFT), its frequency distribution is in the high-frequency range above 10 kHz and has strong independence. The dynamic resistance measurement on the contact shows that high-frequency vibration occurs after the arc contact, before the main contact, and moves with the arc contact. Therefore, high-frequency vibration characteristics are used to predict the contact position of the arc contact. The mechanism of this high-frequency vibration generation is studied. 3D modeling of the dynamic and static contacts is constructed, and COMSOL software is used for dynamic simulation. The measured travel curve is imported into the COMSOL simulation model to simulate the real motion state of the contact before and after contact. After the moving contact touches the static contact, the metal flap of the contact generates high-frequency signals with similar frequencies under friction and opening and closing knocking. By adjusting the position of the mechanism pull rod to change the contact rigid contact point, high-frequency characteristic vibration frequency is related to the contact rigid contact point. Furthermore, based on characteristic vibration frequency analysis, an online monitoring method is proposed for arc contact points. The inherent deviation between the position of the vibration characteristic frequency and the rigid junction point is measured through a calibration process. In the online situation, by detecting the position of vibration feature points and compensating for inherent offset, the position of the rigid joint can be derived. The results of the on-site porcelain column circuit breaker indicate that the maximum error of this method is about 0.905 mm, which is expected to achieve large-scale promotion and application in the online monitoring of high-voltage circuit breakers.