Hossien Askarian Abyaneh - Electrical Energy and Control System, School of Electrical and Computer Systems Engineering RMIT University,Australia, Electrical Eng. Dept., Amirkabir University of Technology, Hafez Ave., Tehran, Iran Tehran Regional Electric Company(TREC),Tehran, Iran
Majid Al-Dabbagh - Electrical Energy and Control System, School of Electrical and Computer Systems Engineering RMIT University,Australia
Hossien Karegar - Electrical Eng. Dept., Amirkabir University of Technology, Hafez Ave., Tehran, Iran Tehran Regional Electric Company(TREC),Tehran, Iran
Abachi - Department of Electrical & Computer Systems Engineering, Monash University, Australia

In this paper a new method for optimal co-ordination of overcurrent relays is proposed. In the existing optimal coordination of overcurrent relays methods, relay models that the operating times of the relays are proportional to their time dial settings (TDS) are used. Such characteristic model is referred to as L.P (Linearly proportional) to TDS. Most of the relays do not have such characteristics i.e they are nonlinearly proportional to TDS (N.L.P). The proposed method considers both L.P and N.L.P models. The method is based on increasing the lower part of the boundary constraints, which are using a simple technique. The method does not need any initial solution. In this paper, the optimal settings of overcurrent relays for the IEEE 8-BUS network are obtained and comparison between the new method and existing methods is made. From the results, the advantages of the new method can be concluded.

Optimal Co-ordination, Simplex, Dual Simplex, Linear Programming, Overcurrent Relay