±800kV糯扎渡直流输电工程孤岛运行过电压水平

The Overvoltage Level of ±800 kV Nuozhadu DC Transmission Project in Islanded Operation Mode

孤岛运行作为±800 kV糯扎渡直流输电工程设计运行方式之一,能够提高系统的稳定水平,但必须以解决过电压问题为前提。对糯扎渡直流工程孤岛方式下的过电压水平进行了计算,结果表明:各种故障工况下操作过电压水平均满足规程要求,最大仅为1.62 p.u.;交流滤波器-电容器断路器断口暂态恢复电压最大值不超过1 305 kV,可选择双断口断路器;靠直流站控分时切除滤波器-电容器功能,各种工况下的最大工频暂态过电压达1.39 p.u.,此值较大但持续时间不超过500 ms,在设备可耐受能力之内;A型避雷器最大吸收能量99 kJ,占标称设计值的2.2%。因此,糯扎渡直流输电工程孤岛运行方式下的过电压水平在完全可控范围之内。

Islanded operaton is one of the normal operation modes designed for ±800 kV Nuozhadu DC project.It can effectively enhance the stability level of China Southern Power Grid（CSG） base on a premise of overvoltage being controled.The overvoltage levels in islanded operation models of the projec are calculated in this paper,and the results are as follows： The switching overvoltage in various fault conditions is less than 1.62 p.u so that it meets the demands of regulations.The maximum transient recovery voltage across AC filter/capacitor circuit breakers is less than 1 305 kV so that double-fracture circuit breakers can be chosen.For the function of tripping AC filter/SC one by one in DC station control,the maximum transient overvoltage of 1.39 p.u.is somehow larger but with a duration time less than 500 ms and it can be withstood by the equipments.The maximum absorption energy of A-type arrester in various fault conditions is 99 kJ,only 2.2% of the nominal value.Hence,the overvoltage levels in islanded operation models of Nuozhadu DC project are all in control.