三峡左岸电站VGS发电机转子磁轭安装工艺

Installation technology of VGS generator rotor's magnet yoke of TGP's left power plant

对于超大型发电机转子磁轭的现场叠装,如何保证磁轭的叠装质量,控制磁轭的圆度、半径、垂直度、同心度,从而保证机组飞轮力矩(GD2)的平衡及空气间隙的大小和均匀性,磁轭叠装是一个非常关键的工序。三峡左岸电站使用VGS提供的发电机,根据其转子结构、工艺、技术等特点,安装时采用自由状态下的叠片方式,消除转子挠度对磁轭外形尺寸的影响;采用"二步法"而非螺旋型的叠装方式,利用磁轭片本身形成通风槽道;采用棒状电阻加热器加热磁轭,热量从磁轭内部往内外两侧传递,从而取得应有的膨胀量,并加装同一种规格的垫片,使每个磁轭键位置具有同样的预紧量;采用多种组合键进行调整,使转子安装的整体质量得到较好控制。

In the in-situ stacking of magnet yokes of a large-scale generator rotor, how to ensure the stacking quality of magnet yokes and how to control the circularity, radius, perpendicularity, concentricity of magnet yokes, and thereby to guarantee the balance of flywheel moments (GD\+2) of the generating unit and the required size and evenness of airgaps is of significance, and the stacking and installation of magnet yokes is a key working operation. The generators of the Three Gorges left hydropower station were supplied by VGS Group, in accordance with the structural, technologic and technical characteristics of the generator rotors, the magnet yokes were stacked in a free state to eliminate the effect of rotor deflection on the external size of magnet yokes and installed by using a 'two-step method' other than spiral one, with ventilation ducts configured by magnet yoke pieces themselves. Stick-shaped electric resistance heators were used, letting heat be transferred from the interior of magnet yokes to the inside and outside to get available expansion. Filling pieces with same size were additionally installed to provide the same preset space for tightening at every magnet yoke key. Various composite keys were used for adjustment in order to well control the comprehensive installation quality of rotors.