en Power Systems Reliability Power Systems Reliability Research Paper Research Paper <div style="text-align: justify;"><span style="font-family:times new roman;"><span style="font-size:14px;"><span style="color:#000000;">In this paper, the new approach for the transmission reliability cost allocation&nbsp;(TRCA) problem is proposed. In the conventional TRCA problem, for calculating the contribution of each user (generators & loads or contracts) in the reliability margin of each transmission line, the outage analysis is performed for all system contingencies. It is obvious that this analysis is very time-consuming for large power systems. This paper suggests that this calculation should be done only for major contingencies. To do this, at first, the contingency filtering technique (CFT) is introduced based on the new economic indices that quantify the severity of each contingency to determine the critical contingencies. Then the results of contingency filtering are used in the TRCA problem. The simulation results are reported for the IEEE 118-bus test system. The obtained results show that by application of CFT in TRCA problem, the simulation time is greatly reduced, but the percentage of error remains within an acceptable limit.​</span></span></span></div> Transmission Cost Allocation,Reliability Cost,Large Power System,Contingency Ranking,Filtering,Critical Contingency,Economic Index, 556 564 http://ijeee.iust.ac.ir/browse.php?a_code=A-10-262-4&slc_lang=en&sid=1 M. Ghayeni m_ghayeni@sadjad.ac.ir 180031947532846008307 180031947532846008307 Yes Department of Electrical Engineering, Sadjad University of Technology, Mashhad, Iran.