Numerical distance protection of power transmission lines

The electrical energy demand of our country is rising very fast every day due to thedevelopments in industry, technology and growing population. Therefore it is very importantto sustain continuity within the process beginning with electrical power generation until itstransmission to urban areas. In this context power transmission lines, being the mostimportant part of the system, and distance relays that protect these lines have very importantresponsibilities. Instead of the electromechanical or static (analog technology) relays thatwere being used in the past years, nowadays fast, selective, reliable, user-friendly and mostimportantly completely microprocessor based numerical distance protection relays are beingused which are capable of making numerical calculations.In this work; numerical (digital) distance protection and numerical relays have been inspectedthoroughly; comparisons have been made with the old electromechanical-static relays wherenecessary. Investigations in Atışalanı and Davutpaşa Switchgear Substations belonging toTurkish Electricity Transmission Company First Region in Istanbul have been made, andinformation has been gathered about the switchgear and distance protection. Taking intoconsideration the information from electrical transmission utility and the experience that Ihave gathered in the Siemens Company for which I have been working more than five years,the switchgear substations in Turkey and distance protection of power transmission lines hasbeen examined in details. In the numerical applications section, a numerical distanceprotection relay which is widely used for protecting transmission lines has been examined andnecessary setting values of this relay for the protection of the power transmission line with154 kV rated voltage between Beylikdüzü-Bahçeşehir-Habipler in İstanbul have beencalculated. The transmission line has been modeled in computer with SINCAL packetsoftware developed by Siemens Company; three-phase simulation of the system for variousfault cases on the line has been realized; behaviour of the numerical distance relays for eachfault has been investigated.Keywords: Distance protection, numerical distance protection relay, power transmissionlines, digital distance protection relay.xv