Measurement-based Estimation of Transmission Line Parameters

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Dr. Raisz Dávid Márk
Department of Electric Power Engineering

In this thesis, methods for computing or estimating transmission line parameters will be discussed and their results will be analyzed. As the transmission line parameter values are used for designing new lines, adjusting protections and in various other tasks, it is crucial to determine them accurately.

The thesis discusses methods that can be found in papers relevant to this field of science. It mentions classic approaches that can calculate the values of line parameters using the transmission line’s geometrical data. Newer methods (like the Finite Element Method) will be discussed as well, including those that rely heavily on computer calculating capacity but provide very accurate results in a broad (up to 1 MHz) range of frequencies. Also, other methods shall be discussed, methods that measure phasors (voltage or current phasors) or powers at both ends of the transmission line, and estimate the line parameters using these measured data.

It also discusses in depth and evaluates one particular method of the relevant literature. The method uses the parameter estimation based on measured voltage and current phasors. This method is used in several cited papers. One of the papers describes the how its Author implemented the mathematical algorithm. I have implemented the algorithm by following the steps detailed in the paper, but the results were not the expected ones. Real measured data were used as input.

There is another modified algorithm proposed, and its results and accuracy on real, measured field data are analyzed. The same measured data were used as input for this method, too. This thesis discusses the results yielded for inputs of different sizes, and it analyzes the influence of different initial values for approximation.

The thesis also discusses briefly the Dynamic Line Rating and the different models that DLR uses. It also mentions a possible way to use the line parameter estimation method in the field of DLR.


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