摘要
为模拟真实雷电冲击电流在接地装置及其周围土壤中的散流过程,准确掌握接地装置的冲击特性,研制了接地装置的冲击大电流试验系统。在大量仿真计算和系统方案论证的基础上,提出了围绕直径40m圆环形回流电极均匀对称布置的4台分体式冲击大电流发生器的技术方案,其中单台冲击电流发生器的充电电压可达1 000kV,该系统可在负载大于4Ω的情况下产生峰值为100kA、波形为8μs/20μs的标准雷电冲击电流。测量得到的地表、回流电极地电位升分布均匀,证实了试验冲击电流地中分布与真实雷电流地中分布的等效性。针对该系统提出了工频、冲击接地电阻的修正公式。通过试验得到了典型杆塔接地装置在8μs/20μs、2.6μs/50μs冲击电流作用下的冲击特性曲线。该曲线表明在低电阻率土壤中该装置的冲击接地电阻随冲击电流峰值的变化并不显著。
An impulse current testing system of grounding devices is needed to be built so as to simulate the diffusing course of impulse current on grounding devices and in the soil around the devices, and to know well the impulse characteristics of grounding devices. By simulating and project demonstrating, we put forward a technological scheme including four split style impulse current generators arranged uniformly around returning electrodes of circular current whose diameter is 40 meters, in which the charging voltage of single impulse current generator could reach 1 000 kV. The testing system can generate standard lightning impulse current of peak value 100 kA and waveform 8μs/20μs on the load whose impedance is larger than 4 g. Moreover, equivalency of distribution of impulse current and actual lightning current is expounded and proved by the distribution uniformity of ground potential rise of ground surface and returning electrode of current, and a modified formula of power frequency grounding resistance and impulse grounding resistance is presented according to the testing system. The curve of impulse characteristics of the typical grounding device under the action of impulse current of waveform 8 /xs/20 /is and 2.6 μs/50μs is obtained, indicating that impulse grounding resistance of the device varies insignificantly with the peak value of impulse current.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2013年第6期1527-1535,共9页
High Voltage Engineering
基金
国家电网公司科技项目(SG0911)~~
关键词
接地装置
冲击大电流发生器
圆环形回流电极
标准雷电冲击电流
电流分布等效性
冲击特性
互阻抗
grounding devices
impulse high current generator
circular current＇s returning electrode
standardlightning impulse current
equivalency of current distribution
impulse characteristic
mutual impedance
