Solar PV Integrated UPQC Using Fuzzy Logic Controller for a Grid Connected System

This paper introduces optimal utilization of solar photovoltaic array integrated PV-UPQC-S by modified p-q theory based control for clean energy generation along with power quality improvement. UPQC is designed by the integration of series and shunt VSCs sharing a common DC bus capacitor. Voltage disturbance like sag, swell, unbalance and harmonics are being compensated by UPQC along with mitigation of source current harmonics. Series VSC simultaneously delivers active and reactive power using theory of power angle control of UPQC to coordinate load reactive power and hence named as UPQC-S. The fundamental frequency positive sequence (FFPS) components of voltages at PCC are extracted using generalized cascaded delay signal cancellation (GCDSC) technique to generate reference signals using p-q theory based control for the PV-UPQC-S. This helps in control of distorted PCC voltages. The series voltage source converter (VSC) shares a part of the reactive power of the load even under nominal grid conditions, thereby reducing the rating of shunt VSC. The PV array is integrated at the DC-bus of the UPQC, provides a part of active load power thus reducing demand on the supply system. The DC voltage is maintained constant using Fuzzy Logic Controller.  The shunt and series reference signals derived from the control algorithm and sensed signals are injected into FLC to generate switching signals. The proposed system can work under multiple disturbance such as irradiation variation, PCC voltage disturbance and harmonics occurring simultaneously. The dynamic performance of modified p-q theory based PV-UPQC-S is verified by simulating the system in Matlab-Simulink with combination of linear and nonlinear loads.