Comparative Analysis of DSOGI-PLL& Adaptive Frequency Loop-PLL for Voltage and Frequency control of PMSG-BESS based Hybrid Standalone WECS

Abstract

3-phase PLL (phase-locked-loop) are the key elements for frequency & phase estimation of a balanced/disturbance voltage of the power system subjected to disturbances. Accurate measurement of generator speed in wind energy conversion system (WECS) is the most crucial task and it is worsening in disturbed voltage states. A dual-second-order-generalized-integrator (DSOGI)-PLL based control for load side bidirectional voltage source converter (VSC) is discussed in this paper for standalone hybrid variable speed WECS comprising of permanent magnet synchronous generator (PMSG) and & battery energy storage system (BESS). DSOGI-PLL based control scheme is presented here for voltage and frequency control. A MATLAB/Simulink-model is prepared for the system under study and a detailed simulation is performed. The effectiveness of the controller under study is checked by comparing it with Adaptive frequency loop-PLL based controller for different working conditions; like variable wind velocity, load variation, load disturbances, and faults. It is concluded from the simulation study that DSOGI-PLL gives comparative better performance during transient like: fault and unbalanced/disturbed voltage conditions. DSOGI-PLL removes the harmonics and disturbances from the signal (dq-axis component generation) as compared to Adaptive frequency loop-PLL. Proposed controller provides excellent control for VSC. BESS is able to perform load balancing during variations in wind-velocity and load.