Steam is generated during the operation of the power generation device, in addition to the part consumed by the system, there is a relatively large amount of residual steam, with a relatively low grade (saturation). Through the analysis and demonstration, the last two 12MW steam-supplementing and condensing turbines are used to fully utilize the waste heat of the residual steam, as a result, about 10 KV power (1.2 KWH/set) is generated per hour and is supplied to the 10 KV power grid of the unit, thus greatly reducing the external electricity, condensing all the steam into water and recycling it, and also reducing the noise pollution to the environment.