Computational And Experimental Research On Conductor Temperature Of Power Cable Based On Thermal Circuit Model

Power cable is one of the important equipments for power transmission, and it is of great significance to calculate temperature field accurately and determine the cable rated carrying capacity for engineering application. At present, the rated carrying capacity of the power cables is based on the most conservative safety parameters, excavating transmission capability deficiently and causing unnecessary waste. Because of varied cable laying methods and variable factors influencing the load flow, it can cause larger errors to determine the carrying capacity only with the reference of IEC standard. In this paper, the equivalent thermal circuit model of single core cable is established based on the thermal circuit method, and the temperature of the conductor is calculated by the optical fiber. This paper verifies the correctness of the numerical calculation by using high-current tests, and this calculation method can guide the cable operation safely and economically.Firstly, according to IEC-60287 standard for power cable of rated load flow and periodic load flow calculation of a brief introduction to the principles and methods. To equivalent the heat capacity of power cable by distribution ratio coefficient that proposed by IEC60853 method, and equivalent and simplified the complete transient thermal circuit model. By this way, we can get a thermal time constant of the cable and derived conductor transient temperature rise formula by the optical fiber measuring temperature.Secondly, building an high current test platform of distributed optical fiber power cable in the air to monitor the temperature of the cable conductor and surface by the thermocouple sensor and the fiber temperature in the water blocking buffer by optical transmitter and receiver. In this way, collecting data and verifying the correctness of the model.Finally, according to the current in the cable and the the temperature measured by the optical fiber proposing an equivalent external thermal resistance method. Based on the known optical fiber temperature, the temperature of the conductor can be obtained and the external thermal resistance of the cable can be modified. The method by the mutual heat effect between the cable optical fiber increase temperature caused by the mutual heat effect between the cable added to the cable external thermal resistance, using simple single cable thermal circuit equivalent model to derive the temperature of the conductor, and forecasting and managing the load.