Dynamic Load Capacity Forecast Of Buried Transmission Cable Considering Rainfall

New cable lines have become increasingly difficult due to the increasing supply of urban power supply.Therefore,it is necessary to consider how to tap the cables' transmission potential.When the parameters of the cable are invariable,the dynamic load capacity of the transmission cable is mainly determined by the surrounding soil thermal parameters(thermal resistance coefficient,specific heat capacity,temperature).At present,the influence of rainfall and moisture content on the thermal characteristics of the soil around the transmission cable is seldom considered.Therefore,it is necessary to evaluate dynamically load capability of transmission cables in summer in Guangzhou because of the rainy summer and heavy load in this area.Based on the above analysis,this paper includes the following contents:The transient thermal analysis model of cable system was studied.The expression of transient conductor temperature response was obtained by comparing the circuit principle.The dynamic load forecasting model of transmission cable was studied.And the correctness of the transient thermal circuit model of emergency was verified by comparing the calculated values of the conductor temperature with the measured values.The soil thermal resistance coefficient and specific heat capacity were measured repeatedly in Guangzhou,and the soil moisture content,soil temperature and rainfall were recorded without interruption.The soil temperature,soil moisture in different depth were compared and analyzed.The effects of rainfall on soil temperature and soil moisture were studied.And the effects of rainfall and soil moisture content on soil thermal resistance coefficient and specific heat capacity were studied.Based on the dynamic load forecasting model of transmission cable and the correlational studies of soil thermal parameters,the emergency load capacity in different initial conditions was calculated.Finally,considering the effect of rainfall,the influence of rainfall and sustained duration of the rainfall on the emergency load capacity was analyzed.The research content of this paper will be helpful to study the problem of conductor heating when the cable is short-term emergency capability or short-circuit fault,and can provide theoretical support for electric power operators.