Supervisory control using fuzzy logic for fault ride-through capability of a hybrid system in grid supporting mode

This paper demonstrates a novel fuzzy-supervisory control algorithm for power extraction and management in a grid-tied low concentration photovoltaic (LCPV) system with battery energy storage system (BESS). The novelty of this paper lies in avoiding dump load (DL) at the dc link, to regulate dc link voltage (Vdc) under all conditions, with an increase in power dispatch. This increases system efficiency and lessen power extraction from BESS. The supervisory controller directs all converters and maintains power balance at the dc link. Enhanced reactive power (Q) support of the grid inverter during a grid fault is controlled by using the magnitude of grid voltage sag. This control prevents islanding of the dc micro-grid as per the Indian grid code. Variation in duty cycle of the converter for optimum power extraction from LCPV generator is done by using fuzzy logic. Power references of converters depend on different operational modes and grid condition.