集成抽汽背压式给水泵汽轮机的发电系统瞬态特性及控制优化研究

Transient Characteristics and Control Optimization for Power System of Steam Turbine Integrated with Back Pressure Extraction Pump

集成抽汽背压式给水泵汽轮机可以降低抽汽的过热度并提高朗肯循环的热效率。为了研究抽汽背压式给水泵汽轮机系统的动态特性及功率控制问题,本文模拟了抽汽背压式给水泵汽轮机的变负荷瞬态过程,通过权衡功率响应速度、机组经济性和除氧器压力,对主给水控制系统中的阀门切换策略进行了优化。结果表明:降负荷过程中,相比于抽汽背压式给水泵汽轮机的输出功率,给水泵消耗功率降低的幅度更为明显,造成了功率不匹配的现象;使用补汽阀调节可以减少机组的经济性损失,但是降低了抽汽背压式给水泵汽轮机功率的响应速度,且导致除氧器压力的升高;使用进汽阀调节可以提高抽汽背压式给水泵汽轮机功率的响应速度,但是节流损失较大;通过优化给水控制系统中的阀门切换策略,既可以减少给水流量的波动,并防止除氧器压力超过高限值,又能在一定程度上减少系统的经济性损失。

The integration of a back-pressure extraction steam turbine(BEST)could decrease the high superheat degree of the extraction steam and improve the Rankine cycle efficiency.This paper aims to investigate the dynamic characteristics and power control strategy of the BEST system.The dynamic characteristics of the BEST during the loading down process are simulated.The valve-switching strategy of the feedwater control system is then optimized considering the tradeoff among the power response rate,unit efficiency and the deaerator pressure.The results show that pump consumption power reduces more than the output power of the BEST during the loading down process,which causes the power mismatch of the BEST.The application of the supplementary steam valve could reduce efficiency loss.However,it decreases the power response rate of the BEST and increases the deaerator pressure.The BEST inlet valve application could improve the power response rate of the BEST but with significant efficiency loss.Optimizing the valve-switching strategy of the feedwater control system could reduce the fluctuation of the feedwater mass flow and limit deaerator pressure with lower efficiency loss.