Droop Control With Improved Disturbance Adaption for FACTS Based PV System With Two Power Conversion Stages

Abstract

Droop control has commonly been used with distributed generators for relating their terminal parameters with power generation. The generators have also been assumed to have enough capacities for supplying the required power. This is however not always true, especially with renewable sources with no or insufficient storage for cushioning climatic changes. In addition, most droop-controlled literatures have assumed a single dc-ac inverter with its input dc source fixed. Front-end dc-dc converter added to a two-stage photovoltaic (PV) system has therefore usually been ignored. To address these unresolved issues, an improved droop scheme for a two-stage PV system has been developed in the paper. The Proposed scheme uses the STATCOM control structure in both grid-connected and islanded modes, which together with properly tuned synchronizers, and mitigates the harmonics, by providing Reactive power and Load current Subsequently the proposed scheme adapts well with internal PV and external grid fluctuations, and is hence more precise with its tracking, as compared with the traditional droop scheme. Simulation and experimental results are obtained using MATLAB Simulink.