Load Frequency Control And Optimization Research Of660MW Ultra Supercritical Thermal Power Unit

Based on the energy and environment status in our country, Ultra supercriticalthermal power units has become a major generating set，in domestic. With theimprovement of power grid automation and ultra supercritical unit once-throughboiler heat storage capacity is small, variable load capacity is insufficient,the demandis more higher to load frequency control. However, the stability of power gridfrequency is directly related to quality of power supply and safe, reliable andeconomic operation of power system. Therefore, ultra-supercritical thermal powerunit load frequency control optimization study has important practical significance.We found mathematical models of660MW ultra supercritical unit under differentloads which are suitable to active power and grid frequency control research andoptimize coordinated control system of plant.In the dynamic mathematic model ofsupercritical reheat steam turbine, we put forward the conception of overregulationcoefficients of the high and intermediate pressure cylinder at the same time,improvingthe traditional steam turbine model for power grid stability calculation and using thesteam generator steam turbine heat balance data,we provide a new method ofcalculating the overregulation coefficients of the high and intermediate pressurecylinder. By using the method of node pressure,we found the dynamic mathematicmodel of ultra supercritical once-through boiler, providing the method of calculatingall parameters.By using Simulink, we found three typical working conditions of100%THA,75%THA,50%THA of660MW ultra supercritical unit, doing primary frequencymodulation and AGC simulation experiments on them. The experiments resultsdemonstrate provided control model is reasonable. Based on the model, in order toovercome coal quality change and boiler time delay which cause main steam pressurefluctuation, we design a fuel—pressure control system,which optimized thecoordinated control system by substituting the main controller of the ultrasupercritical once-through boiler from integer order PID controller to the fractionalorder PID controller and put forward the concept of coefficient of power coal.We dosimulation experiment of coordinated control system steam pressure adjustment,before and after optimization respectively. Experiments show that: It can not only fast response, but also can restrain the load disturbance, improving the AGC loadadaptability.We optimized the coordinated control system of a certain660MW ultrasupercritical unit. We mainly sloved the AGC and primary frequency modulation can’tinput, because of main steam pressure and temperature fluctuations. We optimized thesteam pressure adjustment system, putting forward the concept of coefficient of powercoal.We also optimized the variable load feedforward, steam turbine power loopcontrol, water supply control,to some extent.After optimization, the AGC andprimary frequency modulation meet the requirements of the grid on the safe andstable operation of units, obtaining satisfactory control effect.