Wavelet transform and damped recursive least squares method for evaluation of measurement uncertainty in EV charging pile meters

To solve the problem of inaccurate estimation of relative errors in real-time monitoring of charging pile meters, a model is proposed based on the wavelet transform and damped recursive least squares (WT-DRLS) method to assess the measurement error and uncertainty of electric meters. An energy conservation equation for the charging pile power system is established, along with two variables representing energy conversion efficiency and measurement error. The estimated value of the energy conversion efficiency is obtained by using wavelet transform for noise reduction. Subsequently, a damped recursive least square method with a sliding window is developed to exclude disturbances from circuit load flow and external environmental factors, which enables the calculation of the measurement uncertainty of electric meters. The proposed method supports online monitoring of charging pile meter performance. Data from an actual DC charging station are collected for validation. The experimental results show that the proposed method is effective and stable and outperforms the state-of-the-art methods.