Study On Forecasting System Of Current Loading Capability For Power Cable Induty

More and more power cables are used in power transmission system in city. During the cable running time, heat produced by the conductor current and dielectric loss would accelerate the insulation aging, shorten the cable life, even arise accidents. So, it is important to monitor the temperature of cables and research its character of heat, which will ensure the safe operation of power system.This paper presents some studying about on-line forecasting system for power cable current carrying capability based on the electrical power engineering application background, for the purpose of developing an on-line system to monitor power cable running condition and load status. It includes distributed temperature measuring unit, temperature measuring controlling unit, upper-computer signal sampling and analyzing system. The system can forecast power cable carrying capability on-line and alarm when cable runs abnormally. So it makes the power department work easier and helpful to optimize transmission circuits of the substation, such as cable, overhead line and so on.At first, the theory for forecasting cable carrying capablities is studed. The factor of carrying ability is analyzed by investigating the relation between cable temperature, conductor temperature and current carrying capacity, as well as the method of calculating current carrying capacity, to lay a foundation for calculating the real-time current carrying capacity. Secondly, according to different conditions and performance requirements, the relation of cable carrying capability and relative factors is obtained by experiment, in order to measure the current carrying capacity precisely. Finally, a complete on-line forecasting system for power cable current carrying capability is developed, including the simulating and the selection of temperature sensor and communication mode, the design of sortware and hardware and so on. The error between calculating value and experiment one is limited within 5%, to meet the real-time monitoring requirement of running cable.