Research On Temperature Field Analysis And Calculation Method Of Ampacity Of 10kV Distribution Network Buried Power Cable

Most of the distribution of power distribution cables is made of direct burial,compared to other methods,buried directly because of its lower cost,shorter installation cycle and widely used.It is not conducive to maintenance and inspection because of the power cable laying in the ground,so the power cable line operation and load monitoring is of great significance.At present,the power cable line load monitoring purposes have been become by giving full play to the cable line load capacity.For the complex and large distribution cable network load monitoring system,the rapidity and accuracy of the current carrying capacity calculation has become one of the measurement standards.For the load monitoring system,the load capacity of the cable is a very important reference factor for load monitoring and adjustment.The thermal circuit method is one of the methods to calculate the cable load capacity(ampacity),but most of the calculations are carried out under certain conditions(such as the depth of embedment,the range of backfill and the temperature of the environment).The numerical calculation method is more accurate,but its modeling and calculation is complex,which is not suitable for online system.Test and on-line monitoring are not suitable for complex distribution network because of the high cost.In fact,there are deviation between the calculation ampacity by one of above methods and the actual value.For the distribution cable line,it is based on the IEC standard for the analysis of the thermal path by comprehensiving cost,computational complexity and other factors.In this paper,using statistical methods,propose a new thermal model to solve the problem of universal buried cable model,using the combination of analytical method and numerical analysis to solve the problem of computing speed and accuracy.The heat path model is regarded as a function to be identified,taking the cable body and the external environment as the input parameters,numerical simulation of the flow data as the output,a series of empirical parameters of the formula in the improved heat path are obtained by using the statistical method.The single core cable burying is calculated and verified,and the calculating formula for multi loop buried cable ampacity is proposed.The results show that the deviation between the calculated load of the model and the numerical simulation can meet the requirement of Engineering application.This method not only overcomes the shortcomings of the specific conditions in the IEC standard,but also improves the accuracy.Avoid the use of more complex computing methods in on-line system.