基于VFC器件在A/D变换时采样波形的畸变与恢复

Recovering the Output Wave of VFC

电力系统故障录波 ,对分析电网故障、评价保护动作以及故障测距等 ,均有重要意义。目前 ,故障录波装置中多采用VFC(电压频率变换器 )作A/D器件。若将VFC的采样结果直接用于故障录波 ,则由于故障信号中存在直流衰减分量 ,导致所录波形产生畸变 ,不能反映故障信号的真实形态 ,有违故障录波的本意。为了满足继电保护故障录波的需要 ,讨论了以VFC作A/D器件引起的波形畸变问题 ,并根据畸变产生的原因提出用一周期积分提取衰减分量 ,再用傅氏变换提取各周期分量的恢复算法。大量的数字仿真计算表明 :该算法用于故障录波是可行的。

The faulty waveform recording in power system is important for the analysis of power network fault, the evaluation of protection's operation characteristic, fault location, and so on.But for the recording devices using voltage frequency converter (VFC) as analog digital converter (A/D),if the sampled data is directly used to record waveform, there will be error in the waveform recorded, and it could not indicate the real fault signal. To meet the demand of faulty waveform recording in protective relay, the problem of wave distortion, caused by VFC,is discussed. And an effective algorithm for wave recovery is presented. Digital simulation calculations indicate that the algorithm is feasible when used in waveform recording.