Modelling and optimization of CHP based district heating system with renewable energy production and energy storage

Renewable energy source (RES) is playing an increasingly important role to reduce fossil fuels in district heating (DH) and to alleviate the accompanying environmental impact. In this paper, a combined heat and power (CHP) based DH system with RES and energy storage system (ESS) is studied. A modelling and optimization method is developed for planning and operating such CHP-DH systems. The objective of the optimization is to minimize the overall costs of the net acquisition for heat and power in deregulated power market. A planning model consisting of energy balances and constraints for system control and operation is built and an efficient algorithm is developed. We demonstrate the method in a CHP-DH system with a solar thermal plant and a thermal energy storage (TES). Results indicate that the developed method is efficient and flexible for planning and operating CHP-DH systems. To simulate the future situation, we also optimize the same CHP-DH system with a higher share of RES and a bigger TES. Results show that TES is used more intensively in the future with more fluctuating CHP load and a higher share of RES.