基于无锁相环的电容电流测量精度的研究

Study on Capacitive Current Measuring Accuracy without Phase-Locked Loop

阐述了电容电流对煤矿电网的危害,介绍了多种电容电流测量方法,尤其突出了较多的是注入信号法。在使用注入信号法计算电容电流的时候,往往因忽略了不平衡电压的存在。这样使得基于注入信号法的对地电容电流测量结果会产生较大的测量误差。为了提高测量精度,消除不平衡电压的影响,提出了无锁相环的滤波方法,使用标准的正弦信号、余弦信号替代了锁相环的滤波方法。并在MATLAB中进行的仿真,论证了该方法能够准确滤除工频信号,提高电容电流的测量精度。

The harm of capacitive current to coal mine is first discussed. Several capacitance current measurement methods are introduced, and the most commonly used is the signal injection method. In the calculation of capacitance current with the method, the existence of unbalanced voltage is often ignored, which will produce large error for ground capacitance current measurement result. To improve the measurement precision and eliminate the influence of unbalance voltage, the paper proposes a filter method without phase-locked toop, which uses standard sine and cosine signal instead of phase-locked loop filter method. Simulations with MATLAB verify that the method can accurately filter out power frequency signal and improve capacitance currency measurement accuracy.