Grid Interactive Solar PV and Battery Operated Air Conditioning System: Energy Management and Power Quality Improvement

Abstract

The drop in solar panel cost over past decade has accelerated the usage of solar photovoltaic (SPV) in various applications. In tropical countries, air conditioning unit is extensively used for cooling comfort. In this paper, PV generation is utilized with a battery energy storage (BES) for an air conditioner to reduce the impact of energy consumption from utility grid. Recently, air conditioning units are adopted with variable speed drive (VFD) that creates peaky nature of the input grid current due to the AC-DC conversion. The diode bridge rectifier (DBR) used for such conversion, does not allow bidirectional current flow. In this paper, considering such facts and taking the benefit of the VFD technology, an energy management methodology is proposed using PV array and BES to reduce the power consumption of air conditioning unit as well as it feeds excess PV generation to the grid with improved power quality. The DC power produced by the PV panel and BES is fed to DC bus of the VFD directly with the help of dual active bridge (DAB) converter, that eliminates DC-AC conversion stage. A voltage source converter (VSC) is interfaced as a front-end converter of VFD, to feed PV generation to the grid when air conditioner is not operating. This system is useful from multistory buildings to small consumers where the air conditioners are extensively used and PV array is installed. The concept of the system is validated by implementing in a prototype in the laboratory scale. The system is investigated with different possible scenarios. Under all test conditions, the THD of the grid current is found within the limits of the IEC 6100-3-2 standard.