Topology reconstruction of the district heating network for maximizing comprehensive benefits of thermal storage

The supply-demand imbalance of the district heating system (DHS) is becoming increasingly prominent due to the deep power peak shaving of combined heat and power (CHP), renewable energy heating and the self-regulation of heating users. The large-scale district heating network (DHN) has a considerable water capacity. However, the conventional DHN topology cannot fully unleash the heat storage potential of the primary return water network. In this study, a DHN topology reconstruction method that configures bypass branches on the primary or secondary side of the plate heat exchanger (PHE) at heat substations is proposed and establishes a double-level optimization model for the network topology reconstruction scheme to maximize the comprehensive economic benefits of the project. To improve the performance of the genetic algorithm, based on the interior point algorithm, the configuration position of the additional bypass branch is limited to a few effective bypass locations. The case calculation based on the Chengde DHN demonstrates that adding bypass branches to a few heat substations can achieve the maximum comprehensive economic benefits. Moreover, additional bypass branches are preferably configured within heat substations at the far end of the primary network and are preferably configured on the primary side of PHE.