Dynamic time-of-use scheme implementation in a stand-alone microgrid system

Abstract

The purpose of this study is to develop a dynamic time-of-use (d-TOU) tariff scheme for microgrid (MG) systems in islanded mode. A MG system consists of renewable energy sources (RES) which generate limited energy with certain degree of uncertainty. Thus, energy consumption can be controlled effectively by the implementation of d-TOU tariff. For this purpose, a MG system was designed using HOMER simulation tool to fulfil residential load demand from RES and battery storage as a backup. The average cost of energy (COE) was obtained from the HOMER’s optimized net present cost (NPC) of the system. Then, a day was divided into three time-zones, i.e. peak hours, mid-peak hours, and off-peak hours based on the generation profile. Considering the generation cost in each time-zone, the average COE was transformed into a d-TOU tariff structure with distinct electricity price for each time-zone. The results showed that electricity price in each time-zone was higher than conventional electricity prices, but greenhouse gas (GHG) emission from the designed MG system was found 85% lesser than conventional electricity generation. Finally, the impact of demand response (DR) was evaluated, which showed that only 10% load-shift from peak hours to off-peak hours saved consumers’ annual electricity bills by 3.46%, and increased utility’s annual profit by 57.89% at the same time. Similarly, shifting 20% load from peak hours to off-peak hours resulted in 10.58% reduction in consumers’ electricity bills annually along with 105.26% increase in the utility’s annual profit. The results validated that efficient implementation of d-TOU tariff and DR in a MG system, result in the peak load shaving, reduction in consumers’ electricity bills, increased utility’s profit, and reduction in GHG emissions.