Frequency adaptive linear Kalman filter for fast and accurate estimation of grid voltage parameters

This paper presents a comparative analysis of three different quadrature signal generators such as the frequency locked loop (FLL) based linear Kalman filter (LKF) (LKF-FLL), the second order generalized integrator (SOGI) and FLL based quadrature signal generator (QSG) (SOGI-FLL) and the extended Kalman filter (EKF). In the LKF-FLL technique, the FLL is integrated with the LKF, where the LKF tracks the orthogonal waveforms of the gird voltage fundamental component based on the fundamental frequency estimated by the FLL. The LKF-FLL technique provides better steady state results and also takes smaller convergence time during the transients as compared to the SOGI-FLL and the EKF techniques. Moreover, the LKF-FLL technique is less complex than the EKF. Synthetically generated grid voltage waveforms are used in MATLAB/Simulink to depict the superior performance of the LKF-FLL technique.