Majlesi Journal of Electrical Engineering Reliability Indices Utlization in Combined Heat and Power ( CHP ) Optimal Operation Volume 8 (2014) Issue 4, November 2014 2024 02 21 Reliability Indices Utlization in Combined Heat and Power ( CHP ) Optimal Operation EN Hamed Hosseinnia Dariush Nazarpour Department of Electrical Engineering, Urmia university, Urmia, Iran Masoud Rezaei Benam Department of Electrical Engineering, Sharif university, Tehran, Iran Journal Article 2024 02 21 The reason that cogeneration is being used more compared to separate heat and power is because it is more efficient.  In this paper the goal is finding the optimized CHP system utility size and thermal storage considering reliability limits of boiler and grid connected bus. Loss of Load Expectation (LOLE) and Expected energy not supplied (EENS) are considered as two reliability indices to insure the security of operation. non-sequentional Monte carlo simulation method is introduced to the reliability assessment of CHP,and a normal distribution electrical load model is built to simulate the hourly electrical load.CHP model combined with a two-state reliability model is applied to monte carlo simulation method, and results show that the CHP reliability model works well with non-sequential monte carlo simulation. Non-Sequential Monte Carlo method is used to generate scenarios. Also in order to reduce computation time and due to the large number of scenarios, a scenario reduction technique is used. GAMS software is used for optimization object.