High-accuracy and low-complexity phasor estimation method for PMU calibration

Due to the increasing development of renewables in power systems, the requirements for phasor measurement units (PMUs) becomes higher. A PMU calibrator is an important tool to test and calibrate PMUs to ensure their measurement performance. This device can provide accurate reference values for error analysis of PMUs. In this paper, a phasor algorithm with low computational complexity and high accuracy is proposed for the PMU calibrator. This method reduces the processor requirements and development costs of the calibrator, thereby facilitating its popularization. At first, an enhanced discrete Fourier transform (DFT) method is put forward: 1) the frequency response of the windowed DFT method is analyzed to reveal its large measurement errors under dynamic conditions; 2) the parameter requirements of the DFT window that is regarded as a lowpass filter are analyzed, and thus a lowpass filter with better filtering performance is designed as the window coefficients to improve the estimation accuracy. Then, based on the enhanced DFT algorithm, a calibrator algorithm framework consisting of two-stage filters and a signal recognition module is established. This algorithm can consider the anti-interference ability and dynamic measurement accuracy at a low reporting rate. Simulation and experimental test results show that the proposed calibrator algorithm provides high-accuracy measurements of the static and dynamic signals with low computational complexity.