Combined with the operation parameters of Wu Jing Second Power Plant

the mathematic model for coordinated control system in a subcritical 600 MW unit was established

on the basis of the coordinated control model.By Simulink software

simulation on this model was conducted and the results were compared with the unit operation data.With a constant opening degree of regulating valve

when the coal feed quantity was changed

the maximum error between the simulated value and actual value of the main steam pressure was below 0.3 MPa

and that of the turbine power was less than 3 MW.When the coal feed quantity was kept constant and the opening degree of regulating valve varied

the maximum error between the simulated value and actual value of the main steam pressure was within 0.2 MPa

and that of the turbine power was below 4.5 MW.The small dynamic error between the model and the unit operation demonstrated the feasibility of the above mathematic model for coordinated control system.Based on this model

the unit coordinated control system was improved

by direct energy balance(DEB) method.The simulation results showed that

the improved unit coordinated control system had high response speed and strong anti-interference

and can control the fluctuation of main steam pressure well.