直埋电缆群载流量和稳态温度场计算新方法

New Method to Calculate Ampacity and the Steady-state Temperature Field of Direct Buried Cable System

在人口稠密的城市,电能通常通过直埋电力电缆来传输。为确保电缆能够安全和经济的运行,采用精确的方法预计地下电缆的载流量和温度场是很有意义的。因而提出场路结合的新方法,在电缆区域采用等值热路法,而在土壤区域采用有限容积法,并将两者有效地结合起来。该新方法具有比等值热路法计算准确,比坐标组合法计算快速的优点。通过与均匀土壤中的等值热路法和不均匀土壤中的坐标组合法计算结果比较,证明该新方法可以满足实际需要。

For the safety and economy of the transmission,it is meaningful to accurately predict the steady state thermal field and ampacity of underground cables.Based on the method of field-circuit coupling theory,a new numerical calculation method of cable temperature field is presented.The thermal circuit is used to model the temperature rise of cable in cable areas.The finite volume method is used to model the temperature rise of the cable in soil areas.The thermal circuit and finite volume method are combined effectively by the new method.The unrealistic simplifying assumptions,used in the published models for calculating the heat dissipation from the underground cable system,are not needed in the proposed model.Compared with thermal circuit mothod,the new method is accurate and can be coped with any complicated soil structure.Compared with finite volume method or combinatorial coordinates,the new method calculates quickly.The calculation results are compared with those of thermal circuit in uniform soil and those of combinatorial coordinates in nonuniform soil,and it is revealed that the new method can provide enough precision for engineering use.