A Sine Filter-Based Phasor Estimation Algorithm Using an AR Model to Eliminate the Influence of a DC Offset

An auto-regressive (AR) model-based algorithm that can eliminate the adverse influence of the exponentially decaying DC offset in the phasor estimation process using an orthogonal transform is proposed in this paper. The proposed algorithm is composed of four stages: sine filter, AR model, compensation and phasor estimation. First, the sine filter can eliminate all harmonic components in a relaying signal. Secondary, AR model is used to calculate the error due to the exponentially decaying DC offset in the sine-filtered signal. The AR model used in this paper is a second-order AR model using three successive sine-filtered signal samples. Thirdly, a compensation process is used to eliminate the error due to the exponentially decaying DC offset and to obtain a pure fundamental frequency component in the sine-filtered signal. Finally, the phasor of the pure fundamental frequency component can be estimated using the compensated signal.