基于软开关技术的大型发电机灭磁系统改进

传统灭磁过程中强拉灭磁开关引起的过电压及大电弧带来的危害,使得大型发电机的灭磁问题成为一个重要的研究课题。电力电子软开关技术为大型发电机灭磁提供了新的途径。以三峡电厂励磁参数为基础,设计出一种基于软开关技术的灭磁系统及其相应的控制电路,提出一种新的非线性电阻灭磁建压方式,即"并联充电,串联放电",使得灭磁过程中的冲击电压显著减小,当灭磁主回路电流降为零时拉开灭磁主开关。由理论分析和仿真可知从灭磁系统启动到非线性电阻启动时间为0.07 s,灭磁时间为0.4 s,说明了该系统快速、安全、可靠的灭磁功效。

Improvement of de-excitation system for large generators based on soft-switching technology

The damage of overvoltage and big arc caused by strongly pulling out the magnetic switch in the traditional process of de-excitation makes the de-excitation problem of the large generator become an important research subject. The technology of power electronics soft-switching provides a new way for the de-excitation of the large generator. In this paper, a de-excitation system and its corresponding control circuit is designed based on the excitation parameters of the Three Gorges Power Plant. And it proposes a new way to build pressure nonlinear resistor in de-excitation, namely "parallel charged, series discharged", which significantly reduces the impact of voltage in de-excitation process, the de-excitation main switch is pulled off when the main circuit current reduces to zero. The theoretical and simulation analysis prove that the time from the start of de-excitation system to the start time of the nonlinear resistor is 0.07s. The de-excitation time is 0.4s, indicating that the de-excitation system is fast, safe and reliable.