Abstract: Measuring principle of grid fundamental wave based on algebraic polynomial model is proposed. Its main idea is to optimize parameters of algebraic polynomial model so as to accurately fit the power grid fundamental wave signal to be measured based on the recursive least squares (RLS), and then the steepest descent method was adopted to iteratively calculate zeros of the fitting polynomial model, and then fundamental frequency was obtained according to time difference of the adjacent two zeros. Fundamental wave amplitude could be obtained according to the fitting model values corresponding to the middle of the adjacent two zero points. Finally, initial phase of the fundamental wave could be obtained by the first sample data. Simulation results show that the method proposed is an effective detection method, which has very high detection accuracy and strong noise immunity ability.

Key words: grid fundamental wave, fundamental wave detection, algebra polynomial, curve fitting