Research on retrofitting strategy of coal-fired power plants combined with thermal energy storage system for peak shaving

This study proposes a power generation strategy for coupling a thermal storage system using molten salt as heat storage materials with a thermal power plant, aiming to enhance grid flexibility and increase the installed capacity of renewable energy power plants through retrofitting the thermal power plant. The study presents three charging schemes, three discharging schemes, and a “charging–discharging” scheme under heating conditions. A steady-state model is established to simulate different operating conditions for each scheme, evaluating the effects of variations in main parameters on system performance, and calculating the net present value (NPV) and payback period (PBP) of the system under the optimal configuration. The results show that, under non-heating conditions, the optimal configuration has a peak shaving capacity of 225.46 MWh, with a round-trip efficiency of 56.31 %, and a PBP of 12.59 years. Under heating conditions, when m˙brs is 50 t/h, the system's total energy utilization efficiency is 56.24 %. The system under heating conditions offers the best economic performance, with a PBP of 8.05 years and an NPV of 31.70 million dollars. The sensitivity of economic benefits under heating conditions is quantified by fitting curves to guide scheme selection.