Adaptive Kalman filter for Voltage Sag detection in Power System

this paper proposed an adaptive kalman filter to detect the voltage sag problem in power system, the state covariance matrix is changed through the simulation to enhance the kalman filter in order to detect the amplitude changing of the fundamental component. In the proposed method, there is no need to estimate the noise covariance matrices, which is usually needs a lot of calculation and assumptions, it will depend only on updating the state covariance matrix, where there is no need for extra calculations. The proposed algorithm was tested in several severe circumstances such as high order harmonics and frequency changing.