For the No.3 subcritical 600MW unit of Shenhua Guohua Jinjie Energy Co.

Ltd.of Shaanxi Province

the response of fuel amount on the steam pressure changes has long pure delay and large inertia.According to this characteristic

an improved direct energy balance(DEB) control system which increased the dynamic pre-over modulation fuel feed-forward control system was proposed to replace the existing simple direct instruction balance(DIB) control system.Field application showed that

the improved coordination control system overcame the impact of long delay link on the main steam pressure regulation.When the unit load command changed

the control system quickly regulated the valve opening of steam turbine

thus

response delay of boiler master control to load changes was eliminated or reduced;through rationally configuring larger proportions of the dynamic pre-overshoot fuel feedforward volume

the heat storage was timely improved

so the dynamic deviation of main steam pressure was reduced.Before the main steam pressure changes

EDB control system dynamically pre-regulates fuel quantity according to the boiler heat signal

so the main steam pressure can quickly track its set value.Therefore

the improved DEB control system has good adaptive ability on the long delay

large inertia system.