汽轮发电机静止励磁的轴电压问题分析

Analysis of shaft voltages generated by the static excitation system for turbo-generators

轴电压是大型汽轮发电机运行中备受关注的问题,随着静止励磁系统在汽轮发电机中的广泛应用,励磁系统产生了一个高频轴电压。它是在基本轴电压上叠加幅值为60 V的低频电压和峰值为30 V的高频电压形成的。轴电压会引起旋转机械的严重损坏,传统的接地装置不能消除高频轴电压峰值。介绍了四种产生轴电压的情况,重点是由静止励磁系统引起的轴电压的产生、传递及危害。提出在发电机的励磁端通过接地电刷对地接入一个新型无源RC电路的防范措施,将轴电压降到了无害的水平。

Static excitation systems have been widely used for turbo-generators, and as a result, shaft voltages have become a problem attracting much attention during the operation of large-capacity turbo-generators. During operation, the static excitation system will creates a high-frequency voltage which consists of a basic shaft voltage, on which a low-frequency voltage up to 60 V was superposed as well as high-frequency voltage peaks up to 30 V. Shaft. voltages may cause serious damage to the rotary machinery, and the high-frequency shaft voltage peaks cannot be eliminated by conventional grounding systems. In this paper, four types of shaft voltages were introduced, and the generation, transmission and harm of shaft voltages from static excitation systems were discussed in detail. Countermeasures were proposed in order to reduce shaft voltages to a harmless level.