Dynamic thermal analysis of a power line by simplified RC model networks: Theoretical and experimental analysis

摘要

The dynamic thermal analysis of a power line is commonly based on its temperature response to a power step input. In practice, instead of a power step input, an electric current step is usually used. Note that in the latter case the power input is no longer a step. This could lead to the misleading conclusion that the system is non-linear. In this paper, a simple theoretical analysis is carried out to develop a mathematical correction that can relate the two cases. In the electric current step input case, the input and output variables are transformed in order to be linearly related. A new power input variable is created by taking the product of the dissipated electric current and the voltage drop. This leads to the definition of a linear model that can describe the relationship between power and temperature. Experiments are conducted implementing the two different forms of heat dissipation. The experimental results are further processed and juxtaposed with the theoretical ones in terms of the dynamic thermal characterisation tools: thermal impedance, time constant distribution and cumulative structure function.