Stability analysis of power measurement based on adaptive notch filter

An adaptive notch filter (ANF) -based fundamental-frequency and harmonic-frequency is deliberated in the paper, which can be applied to power measurement. The stability of ANF is proved by mathematical derivations. Considering the situation of the input signal contains not only the fundamental and harmonic components but also some interference signals with unknown frequencies, the model of error system of ANF is constructed. By using of the theory of nonlinear systems, it is proved that the boundary of the error system´s outputs which represent the range of the ANF system´s errors are convergent. Simulation and experiment results also indicate the convergence of the error system.