Analyses and Enhancement of Linear Kalman-Filter-Based Phase-Locked Loop
Wen Xu, Chun Huang, Hui Jiang
Abstract
Linear Kalman filter-based phase-locked loop has been widely applied in grid synchronization and other power system fields. It receives considerable attention for its fast start-up transient which is superior to the traditional phase-locked loop. However, when the Kalman filter reaches its steady state, the Kalman gains will converge to constant values, which makes it degrade into the traditional synchronous reference frame phase-locked loop. The main aim of this paper is to analyze the steady state of linear Kalman filter-based phase-locked loop and make a good use of its adaptive process. Based on the analysis, a design guideline of the linear Kalman filter is introduced, which can help to tune the Kalman gains separately to meet the engineering requirements. Besides, to enhance the dynamic performance under phase jump condition, a dynamic tracking algorithm based-linear Kalman filter is proposed in this paper. Comparative tests about phase detection in power system are conducted and the results show that the proposed algorithm can greatly improve the dynamic response under phase jump condition without degrading its steady-state performance inherited by the traditional phase-locked loop.