An improved Taylor weighted least squares method for estimating synchrophasor

摘要

Accurate phasor estimation is critical to the reliable operation of power systems, particularly under interference and dynamic conditions. Taylor weighted least square (TWLS) method has been widely used due to its good dynamic performance. However, TWLS is sensitive to frequency deviation, and cannot consider anti-interference and dynamic performance capabilities simultaneously. To overcome these shortcomings, an accurate phasor estimation method for M-class phasor measurement units (PMUs) with a low computational burden is proposed to improve TWLS in this paper. The method contains three steps: (1) A phasor measurement filter (PMF) is designed by selecting parameters of TWLS method to prioritize dynamic phasor accuracy and a high level of suppression on high-frequency interferences; (2) A finite impulse response (FIR) lowpass filter is designed by the equal-ripple method is put forward to suppress low-frequency interferences; (3) Phasor amplitude is corrected under off-nominal conditions. In addition, a frequency and rate-of-change-of-frequency (ROCOF) estimation method based on the filtering analysis of least square (LS) method is proposed to improve their accuracy under dynamic conditions. Simulation and experimental test results show that the proposed method can require lower computational burden to provide higher accuracy measurements under off-nominal, dynamic and interference conditions, compared with some improved TWLS methods.