Harmonics Analysis in Power System using Phase-Locking Technique

A phase locked-loop (PLL) technique based on sliding-Goertzel DFT (sGDFT) algorithm is proposed to measure harmonic components of a distorted signal for power system application. A single comb filter is allowed to drive different resonators that are designed from sliding Goertzel filter (SGF) by selecting different bin - k: values. This allows the input signal to split into its harmonic components as an on-line function of time. If input frequency is drifted from its nominal value, sampling frequency is adjusted adaptively by sampling pulses generator to avoid magnitude and phase errors. The proposed technique reduces the potential instabilities and accumulated errors by introducing a damping factor in sliding-Goertzel algorithm design.