“…Thus, frequency tracking and estimation is necessary to respond to such unwanted conditions. Different techniques and algorithms have been introduced in the literature to estimate frequency, including discrete Fourier transform and its modifications [1][2][3], phase-locked loop [4][5][6], adaptive filters [7][8][9][10] and recursive state estimation-based non-linear observers [8,11], adaptive notch filters [12][13][14], recursive total least-square [15], continuous-time adaptive filter [16], state space algorithms based on Kalman filters [17][18][19][20]. A review of the frequency estimation methods can be found in [6,21,22].…”