In this paper a sub-space based fundamental frequency estimator of multiple signal classification (MUSIC) algorithm for distorted power system signals is proposed. Noise and signal sub-spaces are obtained from eigenvalue decomposition and desired frequency is estimated. Distortion level of the power system signals which have been observed from measurements may affect the accuracy of frequency measurement in a power system. Thus, the proposed method is employed to decompose noise sub-space for white and harmonic noises which are common in power systems. Computer simulations have been carried out for the performance analysis of the proposed method and the comparison results of the proposed method for different signal to noise ratios (SNR) are given. The fast tracking performance of the proposed approach in power system frequency estimation is emphasized.