The Analysis And Optimization Design Of Coordinated Control System For600MW Supercritical Unit

Compared with sub-critical units, supercritical units have high efficiency, economy, etc. Supercritical units have become the main units of China’s current coal-fired power generating industry. Supercritical unit has supercritical parameters on main export steam superheater pressure of the unit. It has steam processes with supercritical parameters and necessity for using once-through boiler. Coordinated control system is the link between the dispatching, boiler and steam turbine control systems. It is used for ensuring the rapid response to the grid load changes but also the unit’s own stability. Supercritical unit has its unique characteristics compared with sub-critical unit, such as the once-through characteristics, strong coupling, varying parameters operation mode, etc. So it raises higher standard for supercritical units control system.For a600MW supercritical power plant unit, the thesis analyzed the structure of coordinated control system including load command setting loop, steam pressure setting loop, boiler/turbine master loop and some other master loops. Also the thesis elaborated the operation modes, their inter-relationship and the control tactics of the coordinated control system. Then the thesis raised the measures of improving and optimizing the control loop including boiler/turbine master control, fuel master control and feed water control for the problems of the unit control system presenting during processing. Through the result of the variable load test, the performance of the coordinated control system has improved dramatically and achieved the thermal control request.