±660kV中蒙直流工程送端孤岛运行方式最小功率启动研究

Study on Minimal Startup Power of ±660 kV HVDC Power Transmission System Under Islanded Operation at Sending System

直流输电系统为快响应特性系统,且存在最小电流运行方式对应的最小输送功率,以保证直流系统正常换相不发生断流现象;火电机组有慢响应特性,达到额定功率需要较长时间,因此送端孤岛运行方式下直流解锁过程与火力发电厂机组特性要相互协调配合。对送端系统孤岛运行方式下±660kV中蒙直流系统最小启动容量的选择和影响因素以及解锁过程进行了分析,提出需要注意直流解锁过程中引发的自励磁现象,结论可为规划阶段送端电源组织方式和投产后系统运行方式的制定提供参考。

HVDC power transmission system is a rapid response system and in which the minimal startup power corresponding to minimal DC current operation mode exists to ensure normal commutation of HVDC system and nonoccurrence of setting off; however, thermal power generation system is a slow response system and it needs a long time to reach normal power; thus it is necessary to coordinate the de-blocking process of DC system under islanded operation mode at sending system with unit characteristics of power plants. In this paper, the results of detailed analysis on the selection of minimal startup power and its impacting factors as well as the de-blocking process of ±660 kV DC power transmission system from China to Mongolia under the islanded operation mode at sending system are given, and it is proposed to pay special attention to the self-excitation caused by the de-blocking process of DC system. The conclusion of this research is available for reference in the organization of power sources at sending end in the planning stage and in the drafting of operation modes of HVDC system after its putting into operation to offer assurance for the planning, construction and operation of subsequent HVDC power transmission project.