特快速暂态过电压光学测量系统的设计

Design of optical VFTO measuring system

提出一种应用Pockles效应的特快速暂态过电压(VFTO)光学测量方法。通过光学敏感头感应一次VFTO信号,并将电压的变化信息通过光缆传输至电气单元进行解析,最终得到实际电压。该传感器采用光学测量方式,具有可靠性高、抗干扰能力强、测量精度高、测量频带宽的优点。设计制作的新型光学传感器的低频截止频率低于10 Hz,高频截止频率高于1 GHz。对隔离开关操作所引发的VFTO进行了测量试验,通过同步触发装置同时采集两侧安装的光学传感头和电容式传感头信号,对比验证了VFTO光学测量方法的可行性。试验结果表明:光学测量方式与电容式测量方式均反映了刀闸分合闸的过程,2种方式的分合闸持续时间测量结果吻合较好;电容式测量方式测得的VFTO振荡幅度明显小于光学方式的测量结果,光学测量方式在高频段性能要优于电容式测量方式。

An optical method of VFTO（Very Fast Transient Over-voltage） measuring based on Pockels effect is proposed. The primary signals of VFTO is acquired by the optical sensing head and transmitted via optical cable to the electric cells,where they are analyzed for obtaining the actual voltage. The optical sensor has high reliability,strong anti-interference ability,high measurement accuracy and wide frequency band. The low cut-off frequency of the designed optical sensor is lower than 10 Hz and its high cut-off frequency is higher than 1 GHz. A test system is applied to measure the VFTO generated by isolator operation,which collects the signals synchronously acquired by both optical sensor and capacitor-type sensor.Comparison of the measured waveforms verifies the feasibility of the designed optical measuring method of VFTO. The test results show that,both the capacitance measurement method and the optical measurement method reflect the process of breaker close / open operation;the close / open operation durations measured by both methods match well;the VFTO oscillation amplitude measured by capacitance measurement method is obviously smaller than that of optical measurement method;and the measuring performance of optical measurement method in high-frequency band is better than that of capacitance measurement method.