Optimization And Control Strategy Of Regenerative Extraction Feedwater Pump Turbine System

China's energy structure,which is dominated by coal-fired power generation,has caused tremendous pressure on the environment.The ultra-supercritical secondary reheating technology is an important way to improve the energy efficiency of coal-fired units.With the improvement of steam parameters,the problem of high superheat of regenerative extraction of secondary reheating units has become increasingly prominent.Traditional solutions have limited effect on the utilization of extraction superheat.The MC system adopts stepped double-turbine regenerative system,which can reduce multi-stage regenerative extraction superheat.It is of scientific significance and application value to study the optimal design scheme and operation control strategy of the reheating system of the secondary reheat unit.In this paper,the 1000 MW ultra-supercritical secondary reheat unit is taken as the research object,and the thermal system of the regenerative extraction feedwater pump turbine unit is established on the basis of the conventional system.In allusion to the power matching problem,the control methods of the inlet throttle regulation,exhaust steam regulation and generator balance are analyzed.Based on the EBSILON software,the thermodynamic system models are established and the thermodynamic performances of different schemes are analyzed,and the generator balance scheme is confirmed to be the optimal configuration scheme.The regenerative extraction feedwater pump turbine unit based on generator balance is taken as the research object.The dynamic mathematical model is established,and the dynamic simulation platform is developed based on LabVIEW software.Step perturbation test shows that the platform can fully presents the dynamic characteristics of the main parameters of steam turbine under external disturbances.Based on the operation characteristics of the regenerative extraction feedwater pump turbine system,the control strategy suitable for unit start-up,variable load operation and triggering accident is proposed.Through a series of dynamic simulation tests,the dynamic operation characteristics of steam turbine units are studied,and the feasibility of the control strategy is verified.