云广特高压直流工程是世界上第1个±800 kV特高压直流输电工程。列出了单、双12脉动换流阀组不带直流线路、带直流线路的空载加压试验电压的计算公式。以穂东换流站单阀组和双阀组空载加压试验为例，分析了试验过程中开路电压实测值与公式计算值之间的关系和误差。结果表明，可以不采用电压原理的保护作为判断空载加压试验失败的依据。

Yunnan-Guangdong UHVDC project is the first ultra high voltage DC transmission project with ±800 kV in the world. In this paper, the voltage calculation formulas are presented of single valve group and double valve groups with and without DC line in the open line test (OLT). Taking the open line test of single valve group and double valve groups in Suidong converter station as an example, the relationship and the error between the measured and the calculated results of open circuit voltage are analyzed. It is concluded that the voltage protection should not be applied in open line test.