Circulating Current Mitigation in IGBT-based Master-Slave centralized Inverters

This paper introduces an enhanced algorithm designed to mitigate circulating current in master-slave centralized inverters (MSCI) based on Insulated Gate Bipolar Transistor (IGBT) technology for Photovoltaic (PV) power plants. MSCI is favored in PV power plants due to its smaller footprint, higher efficiency, and reliability compared to alternative configurations. In the centralized architecture, the inverters are typically interconnected (paralleled) without the use of an isolation transformer. Consequently, variations in the Common Mode Voltage (CMV) at their terminals result in a circulating current comprising DC, triplen, and higher-order harmonics circulating within the MSCI. This negatively impacts the performance and efficiency of MSCI systems. The paper proposes an enhanced circulating current mitigation algorithm, incorporating CMV equalization and dead-band compensation alongside a conventional space vector modulation (SVM) technique. The effectiveness of the proposed algorithm is demonstrated through simulations conducted in MATLAB/SIMULINK under diverse loading conditions.