Day-ahead multi-objective optimization of CHP unit with heat storage considering flexibility

Abstract Nowadays, with the growing number of renewable energy capacities, the flexibility of the energy system has become an indicator that must be considered under the impact of frequent peak regulation. However, more flexibility always means less economy. The purpose of this paper is to tackle the contradiction between flexibility and the economy in the energy system. Based on day-ahead load prediction, a multi-objective optimization method is proposed here considering the objectives of excess of power variation and operation cost. NSGA-II is used to deal with the optimization problem by forming a Pareto frontier containing all the optimized results. We take the microgrid system composed of two combined heat and power units and a molten salt heat storage tank as a case study. Two typical results that emphasize flexibility and economic indicator are analyzed respectively and compared with each other, which reduce general guidance of the operation mode’s selection.