Accurate estimation of single-phase grid voltage fundamental amplitude and frequency by using a frequency adaptive linear Kalman filter

This paper reports the performance of a linear Kalman filter (LKF)-based technique to estimate the single-phase grid voltage fundamental amplitude and frequency under distorted grid conditions. An enhanced frequency-locked loop is combined with the LKF to obtain the frequency adaptive capability of the technique. A frequency domain analysis is presented to show the effect of tuning the parameters of the LKF. When compared with a non-LKF, such as the extended KF, the technique is linear and computationally efficient, as it does not contain derivative operations and nonlinear terms. The technique is less affected by dc offset and harmonics, and also shows improved convergence property as compared with an extended complex KF. Simulation and experimental results are provided to validate the performance of the technique.