Research On The LMS-Based Experimental Method To Analyze The Characteristic Parameters Of The Thermal Model For Power Cable

As the rapid development of global economy, the energy shortage and environment pollution problems become serious increasingly.Green power is being developed rapidly. However, it’s strong Paroxysm and randomness characteristics lead to the current Electric power transmission under the static standard faces the problem that the power can’t be sent out and amount of the energy is wasted. Therefore dynamic standard should be used to transmit the power and the correct estimation of cable core temperature is the key to the transmission way. As for the estimation, accurate thermal physical model is important.Under the support from the projects, Research On Highly Efficient Delivery Of Power With Strong Intermittency(No.Z2012015), Research On Highly Efficient Delivery Of Power With Randomness(No.13ZA0025) and another project(N0.CHUANCAIJIAO[2013]203), I present the method to obtain characteristics parameters for power cable thermal model accurately based on the experimental analysis of LMS method.According to cable structure and material characteristics, I analyze cable temperature field, and the cable consists of 4 layers. The layers are core layer, insulating layer, inner-sheath layer and outer-sheath layer from cable inside to outside. Thermal models of single core cable and multi-core cable in the steady state and transient state are set up. The Fourier’s law is used to calculate the temperature of cable core. IEC standard method and the shape factor method,which are taken to calculate cable loss and thermal characteristic parameters, are analyzed in detail. According to differential equations of the cable temperature, four calculation methods are put forward to calculate cable thermal characteristic parameters. The methods are discrete recursive LMS method, regression method, the trapezoidal discrete LMS method and trapezoidal discrete recursive regression method based on the LMS. In the Matlab integrated development environment,the calculation algorithms and implementations are explored based on above methods.I have set up the power transfer system experimental platform. The temperature acquisition system platform consists of thermocouple, TC-08 temperature recorder and PC, which can perform temperature acquisition of various structural layers in the cable on line. According to the cable structure and temperature, the thermal characteristic parameters of the cable have been analyzed respectively based on the above methods. The parameters are taken into the model equations, and iterative method is adopted to the calculation the temperature of the cable core and the armor layer.And then the results are compared with the measured temperature. The experimental results show that the cable temperature calculation error based on the trapezoidal discrete LMS method and difference quotient discrete LMS method is lower than that of IEC standard method,and the above methods have higher accuracy than that of the IEC method. The results indicate that analysis precision of thermal characteristic parameters based on the LMS methods is higher than that of IEC standard method.