摘要
由于电缆热容的存在,当施加阶跃电流时,电缆温度随时间逐渐变化,经一段时间后达到热稳态,导体温度变化的速度一般用热时间常数来反映。为此,以单芯电缆为研究对象,介绍了电缆热时间常数;建立了电缆本体及周围介质的暂态热路模型并进行简化等效;计算了空气敷设和直埋敷设单芯电缆的热时间常数;并在试验现场进行了阶跃电流下的单芯电缆温升试验,通过对实测导体温度暂态过程的曲线拟合求得了电缆实际的热时间常数,验证了理论计算的正确性。电缆的热时间常数可用于估算阶跃电流作用下的导体暂态温度响应、以及到达最高允许温度所需要的升温时间,为电缆的运行状态监测及故障预警提供理论支持。
Cable conductor temperature in operation is the key factor influencing insulation life, and cable operation state can be monitored through conductor temperature. Not only the value of temperature rise but also the change rate of conductor temperature is concerned. Generally the change rate of cable conductor temperature is represented by its thermal time constant. Consequently, the thermal time constant of single-core cable was introduced, transient thermal circuit models of cable body and its ambient medium were established, and the simplified equivalent ones were given. Moreover, thermal time constants of single-core cable buried in soil and in air were calculated, the onsite temperature rise test under step current was carried out, then the actual thermal time constants were obtained by fitting of the conductor temperature detected in tests. The validity of theoretical calculation was verified by test results. Thermal time constant of cables can be used to roughly estimate the transient response of conductor temperature and to determine the needed time of achieving highest allowable conductor temperature of cables when step current is applied, which provides theoretical support for cable condition monitoring and fault early warming in cable operation.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2009年第11期2801-2806,共6页
High Voltage Engineering
基金
国家重点基础研究发展计划(973计划)(2009CB724507)
广东电网公司重点科技进步项目(JA2006036)~~
关键词
导体温度
热时间常数
单芯电缆
暂态热路模型
计算
试验
升温时间
conductor temperature
thermal time constant
single-core cable
transient thermal circuit model
calculation
test
temperature rising time
