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.
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