Table of Contents
Conference Papers in Engineering
Volume 2013 (2013), Article ID 198021, 7 pages
Conference Paper

Prevention of Cascaded Events of Distance Relay Zone Three Using Logic Controls

1Middle Delta Electricity Production Company, Ministry of Electricity and Energy, Cairo, Egypt
2Department of Electrical Power Engineering, University of Al-Azhar, Cairo, Egypt

Received 7 February 2013; Accepted 29 April 2013

Academic Editors: M. Elmusrati, A. Gaouda, and H. Koivo

This Conference Paper is based on a presentation given by Mohamed Younes E. Henna at “International Conference on Electrical and Computer Engineering” held from 26 March 2013 to 28 March 2013 in Benghazi, Libya.

Copyright © 2013 Mohamed Younes E. Henna and Sayed A. Nagy. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper presents a new method to prevent cascaded events caused by zone 3 elements of distance relays due to transmission line overload by using logic controls. A proposed adaptive distance relay algorithm provides a new concept to distinguish between actual faults and flow transfers and secures time to perform remedial controls by a defense system during cascaded events. Maloperation of distance relay is a very critical situation, leading to more operation of other distance relays and finally partial or total blackout. Logic controls are used to insure the operating decision through observing the system parameters and compare it with a setting already being input to the system. When distance relay is activated and the logic controls find that the system is healthy (unfaulted) and that the activation resulted from transmission line overload not real fault, the operation signal will be blocked to protect the system from maloperation.