Control method of small machine direct exhausting and large machine air cooling system of supercritical thermal power generating unit

The invention discloses a control method of a small machine direct exhausting and large machine air cooling system of a supercritical thermal power generating unit. The control method comprises a unit coordinated control system instruction generation and generation loop unit and a water feeding system feedforward control loop, wherein a load instruction generation and lifting load speed generation loop includes a cutting AGC loop unit and a steam condenser vacuum RB loop unit. The control system solves such problems as high fluctuation of a water feeding system along with the back pressure change, weak unit stability and non-planed stop risk in a supercritical small machine direct exhausting and large machine air cooling unit, respectively adopts different control loops and conversion functions under different working conditions to realize following-up of the target load and lifting load speed of a unit coordinated control system, adopts feedforward polygonal functions to realize rationality of feedforward am