摘要
在变电站接地网设计中,考虑到切合站场母线会对通信设备产生强大的电磁干扰,通常会将电缆屏蔽层两端接地。然而,在变电站受到雷击或发生短路故障情况下,电缆芯线与屏蔽层之间会产生巨大的转移电位差。这种电位差一方面可能会破坏电缆芯线与屏蔽层之间的主绝缘,形成电树枝或介质击穿,另一方面转移电位差会在铠装层形成回路,产生很大的暂态电流,干扰通信设备导致设备误操作。因此,转移电位差对变电站设备的影响亟待更深入的分析。笔者针对发生对地短路故障的变电站,建立铠装电缆的电气模型,给出变电站短路故障下芯线和屏蔽层之间的转移电位差解析式,分析电缆参数对转移电位差的影响,并且通过接地工程软件CDEGS分析接地网、土壤等参数对转移电位差的变化规律,提出抑制转移电位差的措施,为实际施工和建设提供理论依据。
To reduce the interference on communication equipment caused by transient electromagnetic field of switching operation, the shielding layer of cable is connected to grounding grid on both terminals in the substations grounding designs. However, when the substation is stricken by lightning or short-circuit occurred, the great potential difference called diverting potential difference between the cable core and the shielding is generated, which can easily destroy the insulation of cables, even can cause electrical tree or dielectric breakdown in insulation material. Moreover, the large current flowing through the shield of cables will cause personnel accidents and equipment damages. In this paper, the electric model of cables is established when line-to-ground short-circuit occurs in substation. Formula of cable＇s diverting potential difference is obtained, and influencing factors of diverting potential difference are discussed by changing cable parameters. Using grounding grid simulation software-CDEGS, the way diverting potential difference changes influenced by grounding grids, soil and other parameters is analyzed. Measures to reduce diverting potential difference are proposed for providing a theoretical basis of construction in practice.
出处
《高压电器》
CAS
CSCD
北大核心
2014年第10期43-48,55,共7页
High Voltage Apparatus
关键词
接地网
接地电阻
转移电位差
铠装电缆
屏蔽层
CDEGS
grounding grid
ground resistance
diverting potential difference
shielded cable
shielding layer
CDEGS
