Flexibility enhancement of combined heat and power unit integrated with source and grid-side thermal energy storage

The potential of improvement of both overall energy efficiency and penetration of renewable energy for the combined heat and power (CHP) unit was investigated by integrating the source-side and grid-side thermal energy storage (TES) systems simultaneously. The mathematical model of the proposed thermal system was established, with which the flexibility-enhancing features across diverse operating conditions were analyzed. The flexibility improvement rate, heat consumption rate, TES cycle efficiency and energy efficiency were revealed. Moreover, the wind power consumption, coal-savings and net annual revenue of CHP unit integrated with different TES were presented. The results indicated that the flexibility improvement rate of source-side TES, grid-side TES and dual TES is 2.4 %, 21.2 % and 26.2 %, respectively. The heat consumption rate of a CHP unit integrated with source-side TES system is lower compared to that of a traditional CHP unit when power load ratio is below 50 %. The CHP unit integrated with a dual TES system exhibited a maximum increase in wind power accommodation rate of 37.7 % and a maximum reduction in standard coal consumption of 7.7 %. The proposed systems offer a promising approach for enhancing the flexibility of CHP units to accommodate more renewable energy.