Aiming to effectively improve the responsiveness of primary frequency modulation of thermal power unit under deep peaking

the scheme of primary frequency modulation technology of multivariable co-optimization is carried out in this study. This scheme includes throttling of main steam regulating valve

condensed water throttling

bypassing feedwater regulation

additional extraction steam adjustment and other technologies. The characteristics of primary frequency modulation have been analyzed in detail through various variable load characteristics tests

which give full play to the advantages and coupling gains of various technologies and have been successfully applied in a 1 000 MW USC unit. On the base of maintaining the responsiveness of primary frequency modulation

the operation opening of main steam regulating valve and the operation efficiency of high pressure cylinder increase by 5.3% and 3.1% on average

equal coal consumption reduces about 1.5 g/(kW·h)

which has considerable economic benefit. The multivariable co-optimization technology in this study can be applied to the optimization of primary frequency modulation and AGC of thermal power units and the technological transformation projects of improving the flexibility of thermal power unit.