AN AC–DC HYBRID NANOGRID SYSTEM WITH SWITCHED CAPACITOR INTERLEAVED BIDIRECTIONAL CONVERTER

Abstract

A hybrid AC-DC nanogrid system with PV and battery storage is designed, to fulfill most of the nanogrid’s energy requirement from renewable energy source (RES) installed in the building itself i.e., from solar energy. Of late, most of the modern loads like LED based lighting loads, digital computer, television, mobile phone chargers, BLDC Fans, electric vehicle charger, modern refrigerators and air conditioning units require DC for its function. In a conventional system the DC from the RES converts to AC and then converts back to DC with a series of unnecessary conversion stages. The number of conversion stages can be reduced by directly providing multiple levels of DC buses (for low voltage loads, HV loads & Medium Voltages loads) along with conventional AC bus (230 V, 50 Hz) for the AC loads (Heating loads, AC motors etc.). This process will improve the reliability of the system significantly. This system requires a bidirectional DC-DC converter for the designing of DC Buses. Initially the system is designed using cascaded buck boost bidirectional converter and is then modified with switched capacitor interleaved bidirectional converter to reduce ripples, voltage stress and to improve the efficiency