Method for Exact Compensation of Voltage and Current Phasors Computed by Orthogonal Finite Impulse Response Filters During Frequency Variations

Abstract

This article presents a generic method that fully compensates for the errors introduced by orthogonal finite impulse response filters (full-cycle discrete Fourier transform, half-cycle discrete Fourier transform, Cosine filter) in phasor computation during frequency variations in power systems. To accomplish this, the proposed method uses an accurate and easily calculated estimate of the local instantaneous frequency. The method is robust and precise and can be extended to deal satisfactorily with the effect of harmonics. Also, its implementation simplicity makes it attractive for real-time applications. Simulation results are provided to demonstrate the effectiveness of the proposed method.

Keywords:

• phasor computation
• discrete Fourier transform
• orthogonal finite impulse response filters
• frequency variations
• instantaneous frequency estimation
• protective relaying
• power system measurements