Theoretical And Expeimental Study On Dynamic Ating Of HV Single-Core Cable

In recent years, with the rapid development of our nation’s economy, The operation ofhigh voltage overhead lines has been facing transmission bottlenecks, which results in thatexisting high voltage overhead lines are often in a full load or overload operation, andscholars have proposed a way that transmission capacity of high voltage overhead lines isincreased dynamically in order to solve the problem, which have been studied in depth. WhileHV cable transimission lines will confront the same problem. So it is very necessary to studyhow to increase HV cable transmission capacity.So far, cables transmission capacity is calculated based on IEC60287, combined withfield operation of HV cable, which often only offers a steady capacity of HV cable. Andcompared with result from IEC60287, the result calculated by this way is slightly larger,however, it is still inadequate for real capacity of operating cable, especially for emergencyload when the emergency power will be supplied.In this paper, ways to improve the transmission capacity of HV cable at home andabroad were researched in depth, which was on a basis of field operation of HV cable inGuangzhou. Then experiment system for studying how to improve transmission capacity ofHV single core cable was set up; The structures of HV single core cable are analyzed, andtransient thermal circuit model was constructed; In order to increase temporary ampacity ofsingle core cable, the local sensitivity of factors(surroundings thermal resistance and ambienttemperature)affecting the cable was analyzed, and we designed temperature rising test forstep current of110kV XLPE single core cable, and cable was buried in soil, under the waterand laid in the air, and the experimental data was analyzed, and the results show: under thesteady state of the different load current for three kinds of surrounds, conductor temperaturechanges sensitively with the change of surroundings thermal resistance and surroundingsambient temperature; And cable temperature response characteristics with change of load isanalyzed, especially under emergency state such as normal load, full load and over load. Thenexperiments on increasing transmission capacity HV single core cable dynamically undertemporary load and emergency are carried out, and then ways of how to improve transmissioncapacity HV single core cable dynamically are put forward.