Comparative study on the improvement of a distributed energy system performance by optimized operation strategy from design to operation

Abstract

The operation strategy directly affects the optimal design and operation performance of distributed energy systems (DESs). Following electrical load (FEL) and following thermal load (FTL) strategies, for example, cannot achieve the flexible scheduling of DESs. As a result, this paper proposes an optimized operation strategy with the optimization objectives of minimizing operating costs and reducing carbon emissions. A multi-objective system optimization model with a minimum total cost and a minimum fossil energy consumption as optimization objectives are established based on the optimized operation strategy. The design and operation of the proposed DES are optimized according to loads of a public building in Changsha, and the results are compared with those under the FEL and FTL strategies. The study demonstrates that the optimized operation strategy can avoid using the gas boiler under the design conditions, which improves the system’s operating efficiency and lowers the total system cost and fossil energy consumption. Compared to the FEL and FTL strategies, the total cost reduction rate of the system under the optimized operation strategy is 1.44% and 1.69%, respectively, and the fossil energy saving rate is 3.25% and 2.3%. Different from the design condition is that the optimized operation strategy under winter and summer operating conditions can not only improve the operating efficiency but also avoid the waste of waste heat from CHP units and reduce the grid power consumption, which makes the total system cost and fossil energy consumption under the optimized operation strategy significantly smaller than those under the FEL and FTL strategies, especially than the FEL strategy. Under the summer operation condition, the optimized operation strategy’s fossil energy saving rate and total cost reduction rate are 6.76% and 12.01%, while the rates are 22.38% and 36.20% in winter. Even if the energy price fluctuates, the total system cost and fossil energy consumption under the optimized operation strategy are less than those under the FEL and FTL strategies. Therefore, the proposed optimized operation strategy can improve the system’s energy efficiency and reduce total cost under the design and operation conditions.