Reactive Power Compensation and DC link Voltage Control using Fuzzy-PI on Grid-connected PV System with d-STATCOM

Abstract

Massive PV power generation connecting to grid will bring many challenges, such as voltage stability, reactive power compensation, operational reliability and so on. In order to realize local loads reactive power compensation and improve controllability of PV system, it should use novel switching devices and advanced control methodology of Voltage Source Converter(VSC). This paper focuses on control strategy of VSC to realize local loads reactive power compensation and stabilize DC link voltage. To some extent, VSC can be used as d-STATCOM. This paper also introduces SiC MOSFET, which can realize higher switching frequency. The control strategy of VSC (d-STATCOM) includes two parts: DC link voltage control and inner current loop control. By using Fuzzy-PI, DC link voltage can be made smoother and stabler. A parameter-self-adjustable Fuzzy-PI controller has simpler structure and higher robustness when fuzzy logic control and PI control are combined together appropriately. Active power current of inner current loop is controlled by tracking output variables of DC link voltage, while reactive power current is corrected by tracking local loads reactive power consumption. The simulation result shows grid-connected PV system with d-STATCOM can compensate local loads reactive power, output active power stably and keep grid-connected voltage steady.