分层接入式特高压换流站1000 kV换流变区域空气间隙放电特性

Air Gap Discharge Characteristics of 1 000 k V Transformer Area of Converter Station with Hierarchical Connection Mode

随着分层接入800 kV特高压换流变网侧电压等级从750 kV上升到1 000 kV,特高压换流站对网侧设备的绝缘要求也随之升高,网侧1 000 kV空气间隙的优化,对控制阀厅长度、确保换流站安全可靠运行、降低换流站占地和减少工程成本有重要意义。该文对换流站低端阀厅网侧1 000 kV换流变区域内各种带电导体之间的空气间隙在长波前操作冲击电压进行了放电试验研究,得到了相应空气间隙的50%操作冲击放电电压试验曲线。根据换流站不同类型下的交流侧1 000 kV操作过电压计算结果,分析了相应情况下交流侧1 000 kV换流变区域空气间隙相对地和相间的50%操作冲击放电电压。根据空气间隙试验曲线和最大的相间和相地操作50%放电电压,得出换流站网侧关键空气间隙的取值。计算表明:套管均压环对阀厅墙的最小空气间隙为7.1m,套管均压环对阀厅墙压顶的最小空气间隙为6.6 m,套管均压环–避雷器均压环不被击穿的最小空气间隙为8.2 m,管母–分裂导线和管母–套管最小空气间隙均为7.8 m。研究结果对网侧1 000 kV空气间隙的选取具有指导意义。

As the voltage level of 800 kV UHV converter station network side increases from 750 kV to 1 000 kV, the insulation requirements for UHV converter station on network equipment should also be increased. The optimization of 1 000 kV air gap on network side is of great significance to controlling the length of valve hall, ensuring safe and reliable operation of converter station, reducing the occupancy of converter station, and reducing project cost. Consequently, we experimentally investigated the discharge of air gap between various charged conductors in the 1 000 kV converter area of the low voltage valve hall network of station. The 50% operating impulse discharge voltage test curve of the corresponding air gap was obtained. Moreover, according to the calculation results of 1 000 kV switching overvoltage on the network side of converter station under different types of conditions, the 50% switching impulse discharge voltage of air gap in 1 000 kV converter area on the network side was analyzed. According to the air gap test curve and the maximum 50% discharge voltage of phase-to-phase and phase-to-ground operation, the value of the key air gap at the network side of the converter station was obtained. The calculation shows that the minimum air clearance of the casing equalizing ring is 7.1 m for the valve hall wall, the minimum air clearance of the casing equalizing ring for the roof of the valve hall wall is 6.6 m, the minimum air clearance of the casing equalizing ring-lightning arrester equalizing ring is 8.2 m, and the minimum air clearance of the pipe bus to split conductor and the casing equalizing ring is 7.8 m. The research results have guiding significance for the selection of the 1 000 kV air clearance on the network side.