特高压气体绝缘组合开关设备中特快速瞬态过电压测量系统的标定

Calibration of Very Fast Transient Overvoltage Measurement System for Ultra High Voltage Gas Insulated Switchgear

气体绝缘组合开关设备(gas insulated switchgear,GIS)中隔离开关操作会产生特快速瞬态过电压(very fast transient overvoltage,VFTO)。VFTO的全波形包含数十MHz的高频成分和准直流的低频成分。因此,VF-TO测量系统要有良好的瞬态响应和稳态响应特性,这就要求对测量系统的频率响应特性和分压比进行严格的标定。为此,利用阶跃波在均匀传输线中传输的原理,自行设计了阶跃电压行波发生装置,根据电容分压式测量系统输入和输出信号的关系,推导了在输入为理想阶跃信号的情况下,输出信号上升时间和测量系统3dB高频截止频率的关系,标定了测量系统的高频特性。根据测量系统低压臂时间常数和3dB低频截止频率的关系,标定了低频特性,测量系统带宽为0.003Hz～87.5MHz。对安装于实际GIS中的测量系统,使用已知幅值的工频和雷电波标定测量系统的分压比为6.6×105。可见,该测量系统满足对VFTO全过程波形进行测量的要求。

Very fast transient overvoltage（VFTO） is also generated during the operation of disconnect switch of gas insulated switchgear（GIS）.The full waveform of VFTO includes not only high frequency components up to several tens of MHz,but also low frequency components.Therefore,the measurement system must have perfect performance of transient and steady-state response.It is very important to calibrate the frequency characteristic and voltage ratio of the measurement system in order to make sure whether the measurement system can measure the full waveform of VFTO accurately.According to the principle of wave propagation along uniform transmission line,we established an apparatus generating step voltage wave;according to the output and input signals of the measurement system,we obtained a relation between the rise time of output signal and 3 dB high cutoff frequency of the measurement system when the input signal was ideal step signal,and calibrated the high frequency characteristic using the apparatus;according to the relation between low voltage arm time constant and 3 dB low cutoff frequency,we calibrated the low frequency characteristic.The 3 dB bandwidth of the measurement system was 0.003 Hz^87.5 MHz.When the measurement system was installed in actual GIS,the voltage ratio of the measurement system was determined for power frequency voltage and lightning voltage to be 6.6×105.It is revealed that the measurement system can be used to measure full waveform of VFTO generated in ultra high voltage GIS.