Multiple Nonlinear Harmonic Oscillator-Based Frequency Estimation for Distorted Grid Voltage

In the presence of nonlinear loads and various disturbances, harmonics and dc bias may corrupt the grid voltage signal leading to distorted grid. Frequency estimation of distorted grid signal is a challenging issue. In this paper, multiresonant nonlinear harmonic oscillators-based frequency estimation technique is reported for the distorted power grid. The proposed approach has also been applied for detecting the sequences of the unbalanced grid. In the proposed approach, a nonlinear harmonic oscillator is used as the proxy of the grid signal. Then, using the frequency-locked loop, an adaptive approach is proposed to estimate the frequency and other parameters (sequences) in the presence of harmonics and dc component. Local stability analysis and parameter tuning are provided. Comparative experimental results are provided with two other nonlinear state-of-the-art techniques. Experimental results demonstrated the suitability of the proposed technique.