Grid Interconnection of Renewable Energy Sources Using Unified Power Quality Conditioner: A Fuzzy Logic-Based Approach

Abstract

This paper proposes distributed generation-integrated unified power quality conditioner (UPQC-DG) with adaptive fuzzy proportional–integral (AFPI) controller to improve the power quality (PQ) of a distribution network. In the proposed system, the DG units are integrated at dc-link of the UPQC to provide additional functionalities. The additional functionalities which are unique to the proposed system is to (i) export the available active power from renewable energy sources to the grid, (ii) compensate long term PQ problems, (iii) compensate voltage interruption. Additionally, the dc-link voltage of the system is controlled by using the proposed AFPI controller to effectively improve the dynamic performance of the system during disturbances. Unlike conventional PI controller, in the proposed controller, the gains are not fixed. It is dynamically adjusted by the fuzzy logic-based intelligent supervisory control system according to system operating conditions. The effectiveness of the proposed system is verified using extensive simulation studies and necessary results are compared with the existing literature.