A wavelet transform-based method for improved modeling of transmission lines

This paper is concerned about the accurate representation of transmission lines for electromagnetic transients simulation studies. The frequency dependent (FD) line model (also known as the J. Marti model) which is currently used in most electromagnetic transient programs [1], has been a major contribution to the power system transient simulations. However, despite its accuracy and computational efficiency for most simulation cases, it still requires improvement due to the approximation it makes in choosing the modal transformation matrix T-v. This matrix is, in general, frequency dependent and used in transforming variables between the phase and modal domains at each simulation time step. Currently, it is approximated as a constant matrix which may not hold true for certain tower configurations and/or conductor types where line parameters vary drastically with frequency. In this paper, a wavelet-based alternative solution, which incorporates frequency dependence of transformation matrices into the simulation process, is proposed. Simulation results, illustrating the effects of using the proposed model versus the existing FD line model, are also presented.