A Modified Dynamic Synchrophasor Estimation Algorithm Considering Frequency Deviation

Abstract

When the power system is suffered from disturbances, such as unbalance, load variation, and fault occurrence, not only the phase and magnitude of the power signal will change but also the fundamental frequency can deviate away from the nominal one up to 5 Hz as per IEEE standard C37.118. As large frequency deviation will lead to great errors on Taylor approximation, the accuracy can be improved by expanding the dynamic characteristics in form of Taylor series near real fundamental frequency of supplied signals instead of nominal frequency (50/60 Hz). The corresponding coefficient against the different frequency estimations is applied to the dynamic phasor estimator to yield accurate synchrophasor estimation with the consideration of large frequency deviation. First, raw phasors attained by short time Fourier transform, are employed to provide the frequency estimation. Then, according to the frequency estimation, the coefficient matrix calculated off-line in form of lookup table is selected to calculate phasor estimation at the center of data window. Finally, a shift process is taken to give phasor estimation at report time. Simulated signals, PSCAD-generated signal, RTDS-generated data, and field data are employed to evaluate the performance of the proposed algorithm. The results show that the proposed algorithm can get more accurate phasor estimations than our previous work at most of the time with the cost of minor increase of computational power.