Introduction  The large-scale grid connected of renewable energy represented by wind power results in frequent changes of generation load command in the thermal power unit. The debugging of coordinated control system parameters cannot satisfy the control quality of throttle pressure and the variation of the fuel quantity simultaneously.

  Method  Based on the simple first order inertial object, adding the integral, pure delay and non minimum phase characteristics in turn, the constraint relation between the adjustment time of the typical objects and the maximum output of the controller was summarized gradually.

  Result  Combined with the model of the boiler fuel quantity and the throttle pressure in the case of closed-loop control of the turbine-side in coordinated control system for thermal power unit, a formula is presented to describe the constraint relationship between the change of throttle pressure and fuel quantity under the disturbance of generation instruction.

  Conclusion  The simulation results and actual operation data verify the accuracy of the formula which can meet the practical requirements.