The technology of overload valve can effectively improve the flexibility of the unit,but there are also problems in the process of using the unit with overload valve,such as steam flow excitation,throttling loss,and reduced unit efficiency.In order to limit the opening of the overload valve,some units set the valve limit to-5％,but this approach can easily lead to integral saturation,which seriously affects the power control of the unit.To address this issue,the manufacturer modified the control logic,removing the overload valve from the control system,effectively solving the problem of integral saturation.The impact of removing the overload valve on the units primary frequency modulation power response is discussed.Through simulation analysis,it is found that the feedforward coefficient after removing the steam injection valve is only 0.8 times the original coefficient,reducing the primary frequency modulation power support capability.The setting different flow characteristic functions or different feedforward coefficient modules before and after the removal of the overload valve is proposed to address the impact of the switching of the overload valve on the primary frequency modulation power response characteristics.
overload valveremovingprimary frequency regulationfeedforward
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