高海拔地区高压直流屏蔽金具电晕特性

Corona Characteristics of HVDC Shielding Fittings in High Altitude Area

随着高压直流屏蔽金具国产化的推进,越来越多的国产金具如屏蔽环等逐渐应用到换流站中,而屏蔽环电晕起始特性随自身尺寸变化规律目前尚不清楚。为研究屏蔽环的电晕特性,依据±500 k V木家换流站和昭通换流站阀厅典型屏蔽环的尺寸,设计了环径分别为600、800、1 000 mm的3组屏蔽环,在昆明南网特高压试验基地(海拔约为2 100 m)开展试验,采用阶梯升压方式对屏蔽环加载电压,通过紫外成像仪判断屏蔽环是否发生电晕,以确定对应的电晕起始电压,并根据试验布置建立3D电场仿真模型,采用有限元数值仿真方法,计算出各屏蔽环对应的电晕起始场强。通过对屏蔽环电晕特性的分析研究得出屏蔽环电晕起始电压与场强随环径、管径的变化趋势,并给出各典型尺寸屏蔽环在高海拔地区的电晕起始控制场强,其中最小的起晕场强控制值>21k V/cm,这为实际工程提供了校核参考数据,并为屏蔽金具的国产化设计和选型提供参考。

With the advance of the localization of HVDC shielding fittings, more and more domestic shielding fittings such as shielding rings are gradually applied to the converter station, and the corona onset characteristics of the shielding ring with its own size is not clear yet. In order to study the corona characteristics of domestic shielding ring, we designed three groups of shielding ring with the diameter 600, 800, and 1 000 mm, according to the typical shielding ring dimensions in±500 k V Mujia converter station and Zhaotong converter station valve hall. The experiments were carried out in Kunming South Network EHV test base（about 2 100 m elevation）, loading DC voltage step by step.The ultraviolet imaging instrument was used to determine whether shielding ring had corona discharge and to measure the corresponding corona inception voltage. According to the layout of the test, a 3D simulation model was established to calculate the corresponding corona inception field strength of the shielding ring with the finite element method. The variation tendency between corona inception voltage and electric field with ring diameter and pipe diameter was obtained according to the analysis of corona characteristics of shielding ring, and the corona inception control field strength of typical-size domestic-shielding ring in high altitude area was also obtained.The minimum control value of the field strength is above 21 k V/cm, which can provide the checking reference data for practical engineering and a reference for the design and selection for the advance of the localization valve hall shielding fittings.