Enhanced Estimation of Frequency and Symmetrical Component Phasors of Three-Phase Voltage Signals

This paper develops a simple algorithm for estimating traditional symmetrical component phasors and the frequency of a three-phase voltage signal. The proposed approach relies on the concept of transformation, wherein the SC phasors and frequency are estimated using the projections of the signal in a synchronously rotating reference frame. With well-designed filters and a simple sigma-point Kalman filtering, the proposed approach can meet the accuracy and timing requirements needed for P-Class Applications. The proposed approach adopts a two-stage filtering comprising a finite impulse response filter and an adaptive moving average filter designed to meet the requirements for P-class applications. Further, to estimate the frequency and phasors from the filtered signals, a sigma-point Kalman filter approach is developed. The proposed sigma-point Kalman filter relies on a relatively simple state-space model comprising three states. The proposed approach is analyzed for scenarios corresponding to steady-state tests and dynamic tests recommended in IEEE Std. C37.118.