Carbon reduction and flexibility enhancement of the CHP-based cascade heating system with integrated electric heat pump

•Proposed a heat-power decoupling process with waste heat recovery using electric heat pump in CHP plant.•Detailed thermodynamic model of the novel system in full working condition is established.•The energy efficiency of the novel system is improved as well as its operational flexibility.•Peak-shaving performance and energy-saving effect of the system are simulated through an integrated energy system dispatch model.