Dynamic Frequency and Amplitude Estimation for Three-Phase Unbalanced Power Systems Using the Unscented Kalman Filter

We present a dynamic frequency and amplitude estimation algorithm for unbalanced three-phase power systems with harmonics. To develop the algorithm, we first construct a nonlinear dynamic model of the complex representation of the three-phase voltage with harmonic content and then apply an unscented Kalman filter to estimate magnitudes and frequencies of the fundamental component and its harmonics. Performance evaluation of the algorithm via Monte Carlo simulation shows the accurate tracking and fast convergence time when the frequency and amplitude of the grid voltage waveform change continuously or abruptly. Specifically, we benchmark the proposed algorithm with two types of input amplitudes and two types of frequency changes.