Multi-objective operation optimization and evaluation of large-scale NG distributed energy system driven by gas-steam combined cycle in China

Many pilot projects of large-scale distributed energy resources (DER) system have been constructed recent years in China and operation strategies make a great impact on their benefits and further development. This paper presents a multi-objective (joint) optimization model for the large-scale DER system of Guangzhou Higher Education Mega Center to obtain the optimal operation strategies under different daily periods: peak periods, flat periods, and valley periods. The prime mover used in this investigation is a gas-steam combined cycle based on combined gas turbines and steam turbines, and the DER system is evaluated under three different operation optimization modes: joint optimization mode of variable operational cost (VOC) and primary energy rate (PER), VOC optimization mode, and PER optimization mode. The primary energy consumption (PEC), PER, operational costs, and investment benefits of the DER system under different operation strategies of above three optimization modes are evaluated comparing with the buildings using conventional technologies. Results indicate that the VOC optimization mode provides the best combined cooling, heating, and power (CCHP) performance during flat periods by yielding the lowest PEC (133.78 kton/year) and operational cost (million $ 35.98/year), and the joint optimization mode shows the best performance during peak periods by producing the lowest PEC (80.42 kton/year) and similar low operational costs (million $ 21.74/year) to VOC optimization mode (million $ 20.89/year).