A CVT Error Identification Method Based on Polynomial Fitting and MACGR

Capacitive voltage transformer (CVT) is an important metering equipment in power grid, which can cause metering error in long-term operation. Therefore, error identification of CVT is an urgent problem to be solved. This study presents a CVT error identification method based on polynomial fitting and maximum approximate coefficient growth rate (MACGR). First, the three-phase voltages on the secondary side of the CVT are measured. Then, the collected CVT secondary voltages are decomposed by wavelet analysis method, and MACGR of each phase of CVT is calculated as the error fitting index of CVT. Then, the error is fitted by polynomial fitting method using MACGR, which can be applied to CVT error identification. The CVT online test system of China Electric Power Research Institute is used to carry out the error identification experiment. In the experiment, the correlation coefficient and RMSE between the fitted and measured values are 0.985264 and 0.023512, respectively. The results show that the proposed method can accurately identify the ratio difference of CVT voltage.