54-Pulse VSC Based High-Power Grid Interfaced Solar PV Plant With DC-Coupled Battery Energy Storage and Distributed MPPT

This article presents a solar photovoltaic plant with dc-coupled battery energy storage (BES) system configured with a high-power 54-pulse voltage source converter (VSC) and distributed maximum power point tracking boost dc–dc converters. Dc-coupled BES allows storing excess solar energy and dispatching the same during nonsolar hours, thus improving VSC utilization and reducing the payback period. The 54-pulse VSC is configured with three sets of identical 18-pulse VSCs, which are developed with two-level converters and a medium voltage (MV) transformer. The MV transformer is configured with series-connected different phase-shifted zigzag and star primary windings and delta secondary windings. The VSC configuration has lower voltage and current harmonics, and reduces switching losses. The 54-pulse VSC is operated with 90–110% of voltage variation to provide 0–100% of nominal reactive power (capacitive and reactive) support to the grid. The solar PV-BES plant is simulated in MATLAB-Simulink and then real-time implementation is done in OPAL-RT to evaluate its steady state, harmonics, and dynamic responses.