Power System Frequency Estimation Based on Adaptive Notch Filter

System frequency is useful for the electrical equipment in power system, and this paper proposes a method to estimate the power grid frequency based on the second order adaptive notch filter. It analyzes the filter amplitude-frequency response with different pole radius, and provides a guideline to choose reasonable pole radius. As for the filter parameter a, this paper uses a stochastic optimization algorithm to train it adaptively. It uses the filter output squared to establish a cost function, and calculates cost function derivative with respective to a by Newton method in each iteration. The proposed parameter training algorithm is easy to realize since it includes only two operations in each iteration, and it is also converges fast since it takes advantage of Newton method. At last, this paper uses a simulation to test the proposed method, and the simulation results show that the proposed method estimates the power grid frequency accurately.