Impact of Various Characteristics of Electricity and Heat Demand on the Optimal Configuration of a Microgrid

The impact of various characteristics of electricity demand and heat demand on the optimal configuration of a microgrid was analyzed using a methodology developed to design the number and capacity for each piece of equipment (e.g., gas engines, batteries, thermal storage tanks) in microgrids that have combined heat and power systems. Three types of microgrids were analyzed: one consisting of an office building and an apartment building, another consisting of a hospital and an apartment building, and another consisting of a hotel, office building, and retail area. In the methodology, the annual cost was minimized by considering the partial load efficiency of a gas engine and its scale economy, and the optimal number and capacity of each piece of equipment and the annual operational schedule were determined using the optimal planning method. Based on calculations using this design methodology, (1) the optimal number of gas engines is determined by the ratio of the off-peak to peak electricity demand and by the ratio of heat demand to electricity demand, (2) a battery required to supply electricity for a limited time during a peak demand period is used auxiliary, and (3) the thermal storage tank for space cooling and space heating can be selected to minimize the use of auxiliary equipment such as a gas absorption chiller. (C) 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(2): 6-13, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20867