Smoothing Output Fluctuations of Wind Turbines and Enhancing Power System Frequency Using Coefficient Diagram Method

Abstract

Due to recent expansion of renewable energy applications, Wind Energy System (WES) is receiving much interest all over the world. However, output fluctuations of wind generators can cause network frequency variations in power systems, which can consequently decrease the power quality. This problem of output fluctuations needs to be solved for further expanding wind energy conversion into power system. On the other hand, area load change and abnormal conditions can lead to mismatches in frequency and these mismatches have to be corrected by the load frequency system. This paper therefore proposes a new load frequency control (LFC) design using Coefficient Diagram Method (CDM) in the presence of wind turbines (WT), for improving network frequency quality. The CDM technique reduces the effect of uncertainty due to governor and turbine parameters variations and load disturbance. Digital simulation performed on a single-area power system with wind turbines validates the effectiveness of the proposed scheme. Results show that, with the proposed CDM technique, the overall closed loop system performance demonstrated robustness. Performance comparisons between the proposed controller, a classical integral control and Model predictive control is carried out confirming the superiority of the proposed technique in presence of doubly fed induction generator (DFIG) WT.