Harmonic Detection of Power Grid Based on the Optimal Reduced-Order Observer

With the rapid development of micro grid and smart grid, high-precision detection of grid harmonic signals has received a broader attention. How to ensure robustness and convergence speed simultaneously is a critical encountered issue in applications. To this end, this paper proposes a optimal reduced-order observer. Firstly, passing the current with harmonic disturbances through an auxiliary filter, measurable signals related to the harmonic frequency can be obtained. Then, the disturbed current is decomposed into an known function and an unknown intermediate variable to be estimated driven by the fundamental wave. And to continue, optimal reduced order observer is designed to estimate the unknown parameter, with which the algorithm yields the expected fundamental current detection performance. Finally, the stability and robustness analysis are carried out by the Lyapunov Theorem and the H∞ index performance. The effectiveness of the new harmonics detection method are verified by various of simulations.