Dynamic flexibility optimization of integrated energy system based on two-timescale model predictive control

The dynamic performance (or flexibility) of the combined heating and power (CHP) unit operating in a heat-led mode is restricted by the strong interdependence between electricity generation and thermal generation. This paper proposes a method that balances the flexibility and the heating quality using a coupled two-timescale model predictive control (MPC) scheme. The indoor temperatures of thermal users are regulated in a comfort region by a slow timescale MPC using zone control; a fast MPC is used as the coordinated control system (CCS). The two controllers are coupled in that both controllers use the extraction steams as their controlled variable. In this way, the dynamic flexibility of the CHP unit is improved by utilizing energy buffers from district heating systems and buildings. The proposed scheme is verified using a simulation study on a real heating system with 2 CHP units, 28 thermal nodes, and 58 pipelines. The result shows that the dynamic performance of the system is improved considerably while the temperatures of thermal users remain in their comfort regions.