采用双馈电机的抽水蓄能机组技术概述

A Review on the Pumped-Storage Power Plants Using Doubly-Fed Machines

传统的可逆式水泵水轮机和同步发电电动机组成的二机式抽水蓄能机组,存在一些固有的缺点,例如无法兼顾水轮机工况和水泵工况的最优效率、水泵工况下不能灵活调节吸收的有功功率,这些缺点都与机组转速不可调节有关。采用双馈电机的抽水蓄能机组技术,机组转速可在一定范围内调节,便可以解决上述问题。双馈电机的转子采用了交流励磁,转子提供到气隙的合成旋转磁场仍保持与定子旋转磁场保持同步。交流励磁电源采用电压源型变流器,变流元件为全控型电力电子元件绝缘柵级晶体管(IGBT)或注入增强柵级晶体管(IEGT),采用脉宽调制技术获得幅值和频率可调节的交流输出电压。电压源型变流器不仅是机组的励磁电源,还可以用作机组在水泵工况启动时的电源。

Conventional pumped-storage reversible machine sets consisting of a motor-generator and a reversible pump-turbine,have some inherent shortcomings,the crucial ones of which are the difficulty to reach a compromise between the efficiencies in two operation modes and the inconvenience in absorbed power regulation during pumping operation.All the shortcomings are caused by the invariableness of the speed of units.Using the doubly-fed machine sets,the speed of which is adjustable in some extents,the mentioned shortcomings shall be avoided consequently.Since the rotor winding shall be energized by the AC excitation source,the compound rotating magnetic field presented in the air gap by the rotor shall keep synchronized with the stator field.The AC excitation source is a voltage source converter,using fully controllable IGBT or IEGT as power elements and PWM control to generate adjustable output AC voltage.Besides the role of excitation power source,the voltage source converter is also used to start the doubly-fed machine during pumping mode start-up.