Hierarchical evaluation framework for coupling effect enhancement of renewable energy and thermal power coupling generation system

•RETCS is a VPP that aggregates renewable energy and thermal power to the main power system through the coupling point, power sources in RETCS can coordinate as an integrated generation to improve efficiency.•The proposed coupling coordination degree (CCD) evaluation framework can effectively assess the RETCS from resource, economy, and environment subsystems.•The proposed stochastic RETCS planning model and CCD evaluation framework can investigate appropriate coordination strategies and power demand to improve the coupling effect of RETCS.