Wavelet Transform and Support Vector Machine- Based Current-Only Directional Overcurrent Relay for Transmission Line Protection

Conventionally, for power protective relay applications, overcurrent relaying is made directional by use of two inputs, the operating current and a reference or polarizing quantity (either voltage or current) that does not change with fault location. This work presents a pattern model, which is capable of providing the characteristic of directionality to a nondirectional overcurrent relay that is installed on a transmission line by monitoring the current signal only, without the reference signal. In addition, a second model which has the ability to identify the type of fault occurred in the protected line is presented. The electrical test system was implemented in ATP/EMTP program, and simulations were driven by a MATLAB program for several short-circuit fault types at different distances. The simulation results constitute the database. These files were processed and analyzed on MATLAB platform mainly using two mathematical tools: Wavelet Transform and Support Vector Machine. Finally, a graphical user interface was implemented for academic purposes, so the user can easily and didactically appreciate the developed methodology, as well as its effectiveness.