Energy-saving Optimization Of AGC And Coordinated Control In A900MW Supercritical Unit

In view of the features of900MW supercritical units in Shanghai WaigaoqiaoNo.2Power Generation Co.,Ltd. contains deficiencies since putting into operation.These deficiencies include slow load responding rate, which leads to AutomaticGeneration Control test failure and high pressure control valves running underthrottling conditions, which result in the loss of high pressure cylinder stream inlet. Inthis work, more attentions have been focused on enhancing AGC ability, fulfilling thefull opening of high pressure control valve and optimizing unit sub control systems.The control strategy of current Coordinated Control System and AGC was improvedand perfected based on the theoretical analysis and on-site experiment.In the optimizing work, these technologies have been applied as follow. The HPcontrol valves keep open by adjusting pressure set point so as to reduce the loss ofthrottling and enhance HP cylinder efficiency. Load changing ability is improvedthrough condensate throttling with frequency conversion condensate pump.Requirements for unit’s AGC have been satisfied through the optimization for boilerrate control. The primary frequency control function is realized with the technique ofcondensate throttling and control valve limit adjustment. Each coal feeder has beenrealized to carry on caloric value adjustment. The operation methods have beenstandardized through compiling AGC operating regulations.Deming cycle is applied in the optimizing project for quality management. TheAGC ability and energy-saving are constantly improved and enhanced according tothe sequence of plan, do, check and act. The efficiency of the unit has been improvedby leaps and bounds after two rounds of PDCA cycle. The qualified rate of AGC testreaches80%, which reduces approximately3.2million yuan electricity punishmentannually. The full opening of HP control valves lead to1.28g/kWh reduction of coalconsumption, which brings over10million yuan direct economic benefits a year. Inaddition, machine wear and the possibility of man-made wrong operation have beenlowered and experiences can be provided for other units for CCS optimization.