Short-Term Disturbance Detection Based on Modulation Kalman Filter

A low-order Kalman filter model based on modulation is presented to detect real-time disturbances of short-term power quality.αβ transform result of three-phase voltage is decomposed into the fundamental signal and modulation signal.Then two characteristics of modulation signal replacing each harmonic are taken as new state variables.It reduces model orders and improves speed of transient response.Considering the characteristic of filtering error which occur mutation when there is a transient signal,the method of filtering error ratio threshold is introduced to judge initiative and terminative time of transient.Then system noise matrix Q is adapted automatically in order to reduce model error and restrain radiation.Simulation results of Matlab show that the new method has higher accuracy of steady-state and faster speed of transient response than general Kalman filters and low-pass filters.