一种新型的小汽轮机给水泵变速恒频发电系统

为节能减排,火力发电厂采用主汽轮机再热蒸汽驱动小汽轮机带动锅炉给水泵供水,通过调节小汽轮机进汽阀开度的方式来控制转速。但该方案在阀门处产生节流损失,轻载时对系统效率影响更大。为此,提出一种小汽轮机、给水泵和电机三者同轴连接结构,用全功率变流器驱动电机,实现给水泵变频调速,并将剩余能量馈回电网,实现节能。运行时阀门全开,调节电机电磁转矩来吸收轴系功率,平稳快速控制给水泵速度,避免阀门损耗。从汽轮机-给水泵的转速转矩及机械耦合特性出发,建立了该发电系统的数学模型,针对工况切换下的调速要求,研究了运行稳定性和抑制功率波动尖峰的控制策略及控制参数设计。最后通过仿真分析以及小功率系统的物理动模实验,验证了系统运行的可行性和有效性。

Novel Variable-speed Constant-frequency Generation System for Small Steam Turbine and Boiler Feed Pump

In order to save energy, small steam turbine usually uses reheat steam from main steam turbine to drive boiler feed pump (BFP) in power plants, which usually controls speed by adjusting the opening of the intake valve of the steam turbine. This method will result in valve loss, especially in the condition of light load. In this paper, a new steam-driven BFP system with a motor which is driven by full-power converter is proposed. Steam turbine, pump and motor are coaxially connected. With the valve in a wide-open position, speed is controlled by adjusting the electro-magnetic torque of the motor for generating, thus the valve loss can be reduced. Based on speed-torque characteristics of turbines and pumps, this paper established the mathematical model of the turbine feed pump. According to the speed regulation requirements between the condition switching, the control strategy and control parameter design of the system stability and power fluctuation peak suppression are studied. Finally, the feasibility and effectiveness of the system is verified by simulation analysis and the physical dynamic model experiment.