Enhancing CHP operational flexibility through district heating network topology reconfiguration: A bilevel optimization framework for heat-storage bypass configuration under uncertain electricity prices

In the context of electricity spot markets, high renewable energy penetration constrains the operational flexibility and economic performance of combined heat and power units. A heat-storage bypass based on district heating network topology reconfiguration is an effective solution to these challenges. This paper proposes a bilevel optimization model for heat-storage bypass branch configurations at heat substations. The inner-level model employs discrete event simulation to rapidly and accurately characterize the dynamic heat-release process of the primary district heating network, while effectively handling the uncertainty in peak-valley electricity prices. The outer-level model reduces the dimensionality of the search space by identifying effective bypass-enabled heat substations and conducts a quantitative economic assessment of all feasible configuration schemes. A case study based on a real district heating network in Gansu Province shows that the incremental benefit exhibits diminishing marginal returns as the number of bypass installations increases. The maximum overall benefit under peak-valley conditions can be achieved by installing bypasses at only a small number of heat substations. Compared with the conventional heat storage method, the net present value increases by 31%, demonstrating strong economic viability and substantial potential for broader deployment.