In the No.1and No.2supercritical 600 MW units in Huaneng Shanghai Shidongkou Second Power Plant

under the unit automatic generation control(AGC)

large control deviation of the main steam temperature

main steam pressure and superheating ratio at steam separator intermediate point resulted in low input ratio of the AGC.Combining with the operation situation of the unit

optimization on control logic of several subsystems was performed

such as the unit coordinated control system

the main and reheat steam temperature control system

and the feed flow rate control system.The variable load test with load variation rate of 1.5%/min was conducted on the optimized control system.The results show that

the absolute values of the main steam temperature deviation of the two units during load variation are both below 5 ℃

that of the reheat steam temperature are below 10℃

and that of the superheating ratio at steam separator intermediate point are below 6superheating ratio at steam separator intermediate point.Moreover

the absolute value of the main steam pressure deviation of the two units are both less than 0.6MPa

and that of the power are less than 2MW

indicating the optimized control system makes the fluctuation of the steam turbine regulating valve opening small

and the load response quick

which satisfies the AGC'requirements.