Research on the Phase-Locked Detection Method of Grid Voltage Based on an Improved Extended Kalman Filter under Grid Fault Conditions

When a short-circuit fault occurs in the grid voltage, it is necessary to quickly and effectively detect the phase and frequency of the grid voltage under different fault states, so that it can quickly respond to the grid fault. First of all, the phase and frequency of the grid voltage under the fault state are detected based on the complex extended Kalman filter algorithm in this paper. And the mathematical model and simulation model are established. The simulation results show that the detected phase and frequency of the grid voltage have a large error. Based on this, this paper proposes an improved extended Kalman filter algorithm and establishes a simulation model. By comparing and analyzing the simulation results, it is concluded that the improved algorithm enhances the detection accuracy of the grid voltage phase and frequency under different fault states. Finally, an experimental platform with EP4CE30F23C7 as the core is built to experimentally verify the improved extended Kalman filter algorithm. The experimental results show that the proposed improved algorithm can effectively realize the phase-locked of grid voltage under different fault conditions.