An Analytic Method for Removal of Decaying DC Component from Phasor Estimates

This paper presents an analytic method to suppress the phasor-estimation error caused by the decaying dc offset. The proposed technique is based on four sampled data. They are the first two and the last two sampled data within the sampling window. The method can be implemented in full cycle and half cycle based on the type of harmonics exists in fault signals. The half cycle method, which is faster than full cycle method, can be used if only odd harmonics exist in the signals. The performance of the proposed algorithm is evaluated by using computer-simulated signals and electromagnetic transients program-generated signals. The obtained results show that the proposed method can estimate the accurate phasor of the fundamental frequency component regardless of not only the primary decaying dc offset but also the secondary decaying dc offset. In addition, the immunity of the proposed method is tested in existence of noise and harmonics.