Fuzzy Sliding Mode based PI Controlled UPFC for Optimized WECS Dynamics during Fault Ride Through

Abstract

With the enormous global growth in electrical power demand and the associated decrease in conventional power resources, electricity generation from renewable energy sources have been furiously sought worldwide, as they represent infinite and clean natural resources. Wind energy is one of the most efficient renewable energy sources. However, due to the fluctuating behaviour of wind energy and the need of electronic devices to link wind turbine generator with existing electricity grids, problems such as frequency oscillations, voltage instability and harmonic distortion may arise. Flexible alternative current transmission system (FACTS) devices, such as unified power flow controller (UPFC), can provide technical solutions to improve the overall performance of wind energy conversion systems (WECS). This paper presents a comparative study of transient stability and reactive power compensation issues in an autonomous wind energy conversion system (WECS) using robust fuzzy-sliding mode based unified power flow controller (UPFC). It is noted from the simulation results that the performance of UPFC is superior to static VAR compensator and static synchronous compensator in improving the voltage profile of the WECS. Further, fuzzy and fuzzy-sliding mode based UPFC controller is designed in order to improve the transient performance. Simulation results reflect the robustness of the proposed fuzzy-sliding mode controller for better reactive power management to improve the voltage stability in comparison with the conventional PI and fuzzy-PI controllers. In addition to this, system stability analysis is performed based on Eigen value, bode and Popov for supporting the robustness of the proposed controller.