An improved discrete fourier transformation based synchronous phasor measurement algorithm using frequency tracking founded on extended Kalman filter

It is hard to perform synchronous sampling during synchronous phasor measurement by discrete Fourier transformation (DFT) under signal frequency deviation that causes the picket fence effect, which seriously affects the accuracy of synchronous phasor measurement. For this reason, an improved DFT based synchronous phasor measurement algorithm is proposed. Firstly, an extended Kalman filter (EKF) based frequency tracking algorithm is led in to establish an algorithm for power frequency measurement, and the principle of synchronous phasor measurement algorithm is presented; on this basis, the measured results are divided into integer part and fractional part, and the phasor measurement error due to frequency deviation is analyzed and the interpolation calculation is applied to the fractional part to improve the accuracy of synchronous phasor measurement. The performance of the proposed algorithm is validated by the steady signals containing harmonic and noise constituents as well as the signals with the jump of amplitude, phase angle, frequency, harmonics and noise level. Simulation results show that the EKF based frequency tracking algorithm can trace the power frequency quickly, and the proposed synchronous phasor measurement algorithm can eliminate or weaken the affects of harmonics, noise and frequency deviation on synchronous measurement, thus the accuracy of phasor measurement can be improved.