Computer-aided coordination of power system protection

In electrical power networks, faults can occur for various reasons. The task of the protection devices in electrical power systems (EPS) is to detect these faults and to eliminate the faulty parts of an EPS. In order to minimize the fault's consequences, different protection devices have to be coordinated. In this article, a computer-aided approach is described that should help project-planning engineers with this task and reduce the very time-consuming procedure of protection-strategy development and documentation preparation to a minimum. The main goal of the proposed concept is to make the tool as user-friendly as possible. The user communicates with a program system and device databases via a graphical user interface (GUI), which enables the visualization of a network. The clear graphical representation of the problem reduces the possibility of human errors. In this paper, the concept of the tool for overcurrent, overload and distance-protection coordination, its main features, and a typical example are presented.

I. Introduction

Coordination of protection can be defined as the systematic application of multiple protection devices in electrical power systems (EPSs). The objective of this coordination is to disconnect the faulty or overloaded parts of an EPS in order to minimise any equipment damage, process-outage costs and risks to personnel. Depending on the voltage level, the type of network, and the importance of the operation in various parts of an EPS or the characteristics of the load, various protection devices are used in order to realize the desired protection philosophy.