Grid Synchronization and Islanding Detection Control Algorithm for Two-stage Three-phase SPV System

Abstract

ABSTRACT Integration of distributed energy sources (DER) with the conventional grid through power electronic interface has emerged as a boon for reliable and good quality power to end-users. The existing control algorithms for the power electronic interface are normally feedback algorithms which help in grid synchronization and effective power dispatch. In this work, an adaptive feedforward-feedback control algorithm is proposed for optimal solar power management of two-stage three-phase grid-integrated solar photovoltaic (SPV) system. Proposed control algorithm enables feeding of SPV energy to load and into the grid, and also act to balance grid currents, compensates reactive power, eliminates harmonics and protect load and source during adverse islanding condition. Phase-locked loop (PLL) used in the feedback part of the algorithm facilitates the effective synchronization of the SPV system. Asymmetric fuzzy logic control (FLC) is used for DC-link voltage stabilization during load variation. Feedforward algorithm ensures fast dynamic response for variable atmospheric and grid operating conditions. Moreover, for protection of SPV arrays and the loads coupled at point of common coupling (PCC), islanding detection followed by interfacing inverter shutdown feature is added in the proposed algorithm. Quantitative analysis of the system is provided in order to investigate the effectiveness of the proposed algorithm. The effectiveness of the algorithm is evaluated using simulation studies performed on MATLAB/ Simulink software.