Versatile Operational Optimization of Combined Heat and Power Systems Using the Graph Theory

Abstract The operation of combined heat and power (CHP) systems often requires switching between configurations to meet varying demands and operating requirements. This paper presents a hybrid framework for the structural optimization of integrated heat and power systems using P-graph as a tool, combined with periodic operational evaluation. The P-graph tool generates multiple feasible system configurations, selecting alternative combinations of equipment, such as boilers, gas turbines, and energy storage, for follow-up operational evaluations. The selected candidate structures can then be evaluated using a multiperiod optimization model that accounts for time-varying demand, fuel prices, startup costs, and load-dependent performance. The results show that the proposed approach identifies structurally optimal configurations under different operating conditions, with a possible 39% reduction in fuel consumption through structural reconfiguration when operating under fuel-saving mode during a low-demand period. The framework reduces the combinatorial complexity of system operation optimization and enables versatile operational switching between system equipment configurations based on conditions, such as fuel-saving and high-peak-demand conditions, thereby providing multiple backup strategies to support long-term system performance and flexibility.