Phase-change heat storage installation in combined heat and power plants for integration of renewable energy sources into power system

•Install a phase-change heat storage facility in CHP for improving adjustability.•Propose a thermal resistance network to analyze the integrated system.•Optimize the operation mode of the integrated system by the linear programming.•Reduce the wind energy loss effectively by the heat storage facility.•Provide a guidance for the optimal design of heat storage facility.

Due to the nature of fluctuation and intermittence, integration of renewable energy sources (RESs) requests more flexibility of power systems. However, the “heat-led” operation mode limits the adjustability of combined heat and power (CHP) plants, and reduce the accommodation of RESs. This paper studies an integrated thermal and power system and introduces a phase-change heat storage (HS) facility into the CHP plant to improve the adjustability, where the heat released from the extraction steam is not consistent to the heat load at each moment. Furthermore, the heat transfer processes in the HS facility are modelled as a thermal resistance network, which provides the feasibility for analyzing the integrated system in a unified model. On this basis, the operation plan of the integrated system is optimized by the linear programming (LP) method to minimize the wind energy loss. The results show that: 1) HS facility installation increases the flexibility of power system, and reduces the wind energy loss from 18.7% to 11.2%. 2) Heat transfer processes should be carefully taken into account for precisely setting the power generations of each plant. 3) The phase-change temperatures of HS materials should be between 90 °C and 100 °C for the maximum wind power accommodation.