电容式电压互感器电压暂降测量误差分析及校正

电压暂降是影响现代电网最为突出的电能质量问题之一，在进行大范围高压系统电压暂降监测时，必须考虑到含储能元件的电容式电压互感器（capacitor voltage transformer，CVT）所造成的不利影响。根据CVT结构推导了其测量电压暂降的误差并指出了影响该误差的内外部因素，而后构建了仿真模型，详细研究了暂降初相角、残余电压、CVT参数及负荷对电压暂降持续时间、暂降幅值以及相位跳变等特征量的影响及敏感度，最后提出一种基于虚拟阻抗补偿的CVT电压暂降测量误差校正方法，消除了电压暂降不确定性造成的测量误差多样性问题，仿真结果表明该方法的有效性，为普遍采用CVT的高压系统电压暂降准确测量提供了可行的校正方案。

Error Analysis and Correction of Voltage Sag Measurement for Capacitor Voltage Transformer

Voltage sag is one of the most prominent power quality problems in modern power grid. When monitoring voltage sag in a large range of high-voltage systems, the adverse effects caused by capacitor voltage transformer (CVT) with energy storage elements must be considered. According to the structure of the CVT, the error of voltage sag measurement is deduced, and the internal and external factors influencing the error are identified. Then, a simulation model is built, and a study is made in detail on the influences and sensitivities of the initial phase angle of sag, residual voltage, CVT parameters and load on voltage sag duration, sag amplitude and phase jump. Finally, a virtual impedance compensation based method is proposed for CVT’s voltage sag measurement error correction, which eliminates the problem of measurement error diversity caused by voltage sag uncertainty. The simulation results show that the method is effective and provides a feasible correction scheme for the accurate measurement of voltage sag in the high-voltage system which widely adopts CVT.