Abstract: Proposes a medium and high pressure composite steam supply system that is suitable for peak shaving operation. The main body is a pressure matcher, which uses the main steam to extract reheated steam for external heat supply. When the load is reduced, the way of regulating the intermediate control valve in combination with the steam compressor compression pressure rise is used to maintain the pressure of reheated steam entering the matcher at the design point, so that the pressure matcher can always operate at the design point under low load, meet the flow requirements of external steam supply, and analyze and predict the operation performance of the system. Taking a 300 MW unit as an example, economic analysis was conducted under peak shaving mode. Compared to conventional pressure matching methods, the medium and high pressure composite steam supply system can reduce the minimum online load of the unit during peak shaving operation by maintaining the rated steam supply flow rate from 80% to 40%, and the output heat of the boiler is reduced by 280 MW, equivalent to a reduction of standard coal consumption of 38 t/h. Through the application of medium and high pressure composite steam supply systems, the participation of cogeneration units in deep peak shaving has a significant effect on coal reduction and carbon reduction.