Power quality issues and feasibility study in a DC residential renewable energy system.

摘要

This research work aims to study power quality issues and the feasibility of a DC residence. The evaluated residence is in the area of Mayaguez, PR. Feasibility studies includes the design of a hybrid power system to supply a stand-alone residence, analysis of current AC home appliances and an adaptation of appliances to be supplied by DC power, a wiring analysis and an economic analysis. Power quality issues are to be conducted in the DC bus and at the point of common coupling with the utility grid. DC ripple, transients and flicker are studied at the DC bus; power factor, displacement factor, harmonics and THD is measured at loads that incorporate BLDC motors. Feasibility results show that though lower power consumption is achieved, low power appliances are feasible; high power loads are not suitable for low voltage DC supply. Concerning the wiring analysis, there was a reduction in cable size for the air conditioning units, the removal of the cable for the water heater, and, the addition of a circuit to supply the microwave. Simulations show that the most relevant power quality issues are DC ripple and noise, one associated with another. BLDC motors, one of the DC appliances, produce DC current ripple, along with DC/DC converters, which in turn produces noise and slight degradation of the motor performance. Finally, the economic analysis results show that, although no option considered has a positive net present value, there is a significant difference in the total system costs and in the payback period when considering a DC residence, as compared to an AC residence.