Design of Non linear Controller for Voltage and Frequency Control of Permanent Magnet Synchronous Generator Based Variable Speed Standalone Wind Energy Conversion System

Abstract

Variable speed PMSG based standalone WECS combined with BESS has proved newlineto generate maximum power from wind. At the terminals, BESS is coupled to bidirectional newlineVSC. Unpredictable variations of wind velocity and load lead to newlineoscillations in frequency and terminal voltage, and complications in power newlinemanagement. It is quite challenging to achieve voltage regulation and frequency newlinecontrol in a standalone WECS under varying operating conditions. A suitable newlinecontroller can help achieve this goal.The main challenge is the estimation of system s frequency which is fast and precise under disturbed voltage conditions, for which Phase Locked Loop (PLL) is utilized. In this thesis Adaptive Frequency Loop-PLL, Moving Average Filter newline(MAF)-PLL, and Dual Second Order Generalized Integrator (DSOGI)-PLL based newlinefrequency estimation schemes are presented. An equivalent energy system is newlinemodeled in MATLAB/Simulink and the proposed schemes are simulated and newlineanalyzed to validate the performance of various PLL based controllers for VSC. newlineThe behavior of the controllers is verified for dynamic operating conditions such newlineas variable load and wind velocity, faults and load unbalancing. A system newlineemploying control based on Adaptive Frequency Loop-PLL is assessed and newlinevalidated in MATLAB/Simulink and real time simulator (RTS) environment. newlineMAF-PLL based control facilitates frequency measurements, suppression of newlineharmonics along with voltage and frequency stabilization during varying newlineoperating conditions. The effectiveness of proposed DSOGI-PLL based newlinecontroller is compared against Adaptive Frequency Loop-PLL based controller newlineand shows better performance during transients such as faults and newlineunbalanced/disturbed load conditions substantiating its suitability as the best newlinechoice among the available PLL based controllers for VSC. Therefore DSOGIPLL newlineis considered for further research in this thesis. FOPI based control scheme is proposed for controlling terminal voltage under varied operating states. Also nonlinear MFC using iPI-SMC, iPI-DISMC, and iPI-TSMC..