The condensate throttling varying load technology has a response lag of 10～20 s during the flexible retrofit of coal-fired units

to solve this problem

the condensate throttling test

high pressure heater extraction adjustment test and feedwater distribution tests on an ultra-supercritical 1 000 MW unit were carried out.Especially

the security and effectiveness of the last two load-changing methods were analyzed in detail.Combining the conventional condensate throttling technology with the special layout of the regenerative system of this unit

a multivariable optimization strategy of primary frequency modulation including condensate throttling

extraction adjustment and feedwater distribution was proposed. Moreover

the improved sliding pressure optimization system was used to further improve the energy saving potential of the unit. Through the primary frequency modulation assessment test

the effectiveness and feasibility of the improved strategy was proved. The experiment proves that

after the multivariable optimization system and sliding pressure optimization system was put into service

the annual average coal consumption of the unit decreased by 1.5 g/(kW·h)

indicating the energy saving effect is dramatic.