Relay coordination and protection failure effects on reliability indices in an interconnected sub-transmission system

Protection system failure is the main cause of cascading outages. It has been shown that the hidden failures lead to cascading outages. However, the effects of the coordination method as well as the hidden failure of the protection systems have not been investigated yet. In this paper, an algorithm based on sequential Monte Carlo simulation is proposed to find the reliability indices for different overcurrent relay coordination methods. The proposed algorithm is applied to the results of different relay coordination methods of a real network. The indices SAIFI, CAIDI, CAM and ENS for the results of different relay coordination methods are obtained strictly based on the contribution of the protection failure issues. Then, a comparison is made between the results of the different relay coordination methods in order to show how the coordination methods affect the reliability indices. (C) 2008 Elsevier B.V. All rights reserved.