高压直流线路开路试验的控制原理及保护分析

Control Principle and Protection Analysis of the HVDC Open Line Test

高压直流线路开路试验是一种检测手段,主要是对换流站直流侧进行加压,其控制理念和相关保护全然不同。若控制保护异常,直流电压会异常升高或者不变,最终导致试验失败。结合常规直流系统线路开路试验,介绍了线路开路试验的控制原理,比较了理论计算与实际工程中的母线电压最大值,得出直流线路电压参考值和实际电压测量值可以同步变化,差值不超过10kV。为了在试验不成功时闭锁换流器,采用了ABB公司Mach2系统中的电压差值保护、过流保护、过流后备保护和保护性触发等保护技术。通过保护分析得出:在原理上、工程上、保护上,直流系统的正常运行和开路试验有所不同。

The HVDC open line test is a means of detection which a DC voltage is presented to the DC side of a converter station to test the insulate level, and the related control and protection philosophy is entirely different to the normal operation. If the control and protection is abnormal, the DC voltage will be elevated abnormally or remained unchanged, eventually lead to the test failed. Combined with the conventional DC system open line test, the control principle of open line test is described, and the difference of bus voltage is not more than 10 kV by comparison of theoretical calculation and actual engineering. It is derived that the DC line vohage reference value and the actual voltage measured value can synchronize change. In order to ensure the equipment＇s security the convertor will be blocked if the test is unsuccessful, control and protection technologies such as the voltage difference protection, overcurrent protection, overcurrent backup protection and protective trigger are used in the ABB company＇s Mach2 system. Differences are drawn： the principle, the control, the protection of the normal operation of the DC system and the open line test.