跨电压等级不接地故障时低电压系统的过电压评估

发生跨电压等级不接地故障时,低电压等级系统出现电压升高的特征变异.针对这个问题,建立了跨电压等级不接地故障的模型,以此为基础探究各关键运行与设计参数对低电压等级系统过电压的影响,并在实际电网中对过电压倍数进行数值评估.研究表明,跨电压等级单相不接地故障时,低电压等级系统过电压情形最严重,此过电压倍数与高电压等级系统电源强度呈正相关,与低电压等级系统电源强度呈负相关;同塔架设位置对过电压倍数影响大,线间互感对过电压倍数影响小.综合以上规律,给出系统安全运行方面的建议.

Overvoltage evaluation of low voltage system when cross-voltage ungrounded fault

A characteristic variation of voltage rise in a low voltage level system occurs when cross-voltage ungrounded fault. In response to this problem, this paper establishes a model of cross-voltage ungrounded fault, based on which to explore the impact of various critical operating and design parameters on the overvoltage of low voltage level systems, and numerically evaluate the overvoltage multiples in the actual grid. The research shows that the overvoltage condition of the low voltage level system is the most serious when single-phase cross-voltage ungrounded fault. This overvoltage multiple is positively correlated with the high voltage level system power supply strength and negatively correlated with the low voltage system power supply strength; The erection position of the same tower has a great influence on the overvoltage multiple, and the mutual inductance between the lines has little influence on the overvoltage multiple. Based on the above rules, suggestions for the design of the same tower and the safe operation of the system are given.