# Transmission line

This section describes transmission line

The component parameters can be defined in three ways, changing the Model definition parametar. If Geometry is selected, the component parameters are geometric arrangement of the transmission line and cable’s data. User has to define in the properties window the Cartesian coordinates of each of the transmission line cables along with the cable’s GMR, radius, resistance and length. It is possible to change the earth resistivity and frequency to be used at the calculation. If RLC is selected, the user defines the R, L and C (if PI model is selected) per length matrices in the phase domain and the line length. If Sequence is selected, the user needs to define the R, L and C (if PI model is selected) per length matrices in the sequence domain and line length. The property Number of phases defines the number of phases of the component, which can range from 2 to 4. The Sequence model definition only supports three phases. This is why the number of phases has to be set to three if the user wants to switch to this model definition.

Definition of R, L and C matrices in phase domain will be shown on L matrix, the same way can be applied to R, and C matrix. Transmission line component for RLC parameters definition requires nested python list (matrix) [[Laa, Lab, Lac], [Lba, Lbb, Lbc], [Lca, Lcb, Lcc]], where diagonal elements Laa, Lbb, Lcc represent self-inductances of each phase, and off-diagonal elements represent mutual coupling inductances between phases.

Definition of R, L and C matrices in sequence domain will be shown on L matrix, where the same way can be applied to R, and C matrix. Transmission line component for sequence parameters definition requires nested python list (matrix) [[L00, L01, L02], [L10, L11, L12], [L20, L21, L22]], where diagonal elements L00, L11, L22 represent inductances of zero, positive and negative sequence, respectively. Off-diagonal elements represent mutual couplings between sequences.

Properties window of transmission line for all cases of Model definition parametaris shown in Figure 1, on Geometry properties window, Figure 2 on RLC properties window and Figure 3 on Sequence properties window.

Transmission line has two configurations, with capacitances neglected or included. This can be set in the properties window selecting RL coupled or PI in the Model combo box. By default it is set to RL coupled.

Symbol and Schematic diagrams of the three phase Transmission line in Typhoon schematic editor are shown in Figure 4 and Figure 5, while Figure 6 is of a three phase transmission line with PI configuration.