Keywords— cumulants, Edgeworth series, equivalent load duration curve, expected energy not supplied, generation expansion, gram-charlier series, loss of load probability, transmission expansion Abstract— In this paper generation and transmission expansion planning of IEEE 300-BUS TEST SYSTEM using equivalent load duration curve is studied. To this end, equivalent load duration curve for each electricity region is calculated for years 1991 and 1996 using the expansion of the probability random distribution series. The criteria loss of load probability, expected energy not supplied, and capacity shortage are computed using equivalent load duration curves. Equivalent load duration curves and the above-mentioned criteria are calculated using convolution method to validate the results. Finally, generation and transmission expansion planning of the system is studied considering the computed criteria. I. INTRODUCTION T o supply electric energy consumption, generation and transmission should be developed while consumption increases. Expansion costs, reliability, uncertainties, and risk should be taken into account in expansion planning. Generation and transmission expansion planning methods can be classified from different viewpoints. From the viewpoint of uncertainties, expansion planning methods are classified into deterministic and nondeterministic ones [1]- [2]. In deterministic methods expansion is planned only for the worst system operating point without considering its occurrence probability. In nondeterministic methods, expansion is planned for all possible system operating points considering their occurrences probability. Therefore, nondeterministic methods can take past experiences and future expectations into account. Probabilistic load flow models [3], and probabilistic based reliability criteria [4], take lack of nonrandom reliabilities into account. Analyzing the decision is a suitable way for dynamic planning. Fuzzy decision making takes ambiguous data into account. From the viewpoint of expansion horizon, expansion planning methods are classified into static and dynamic methods [1]-[2]. In static planning, planners attempt to find the optimal expansion plans for a given year in planning horizon. From the viewpoint of power system structures, planning methods can be classified into methods for regulated power systems and methods for deregulated power systems. The main objective of generation and transmission expansion in regulated power systems is to supply the load while maintaining the system reliability. Uncertainties are much more in deregulated power systems than regulated power systems. Probabilistic production simulation is one of the methods used for generation and transmission expansion planning [5]. Equivalent load duration curve (ELDC) is the most important concept in generation expansion. This curve integrates random outage capacity of generation units with random load. In fact ELDC is the same as load duration curve (LDC) in which the effect of forced outage of generators has been taken into consideration. Expansion criteria such as loss of load probability (LOLP), and expected energy not supplied (EENS) can be calculated using ELDC [5]-[6]. In this paper generation and transmission expansion planning of IEEE 300-BUS TEST SYSTEM [8] is investigated. In section II, computing ELDC using the expansion of random distribution series is described. In section III, ELDC is computed for all of the three electricity regions of IEEE 300-BUS TEST SYSTEM. To validate the results, ELDCs are calculated using convolution method [5] in section IV. In section V, expansion planning of IEEE 300-BUS TEST SYSTEM is investigated. Conclusion in section VI closes the paper. II. COMPUTING THE ELDC USING THE EXPANSION OF RANDOM DISTRIBUTION SERIES Random variables in power system are mostly dependent on load changes and random outage of generators. Random phenomena can be modeled by their distribution functions. Each probability distribution function can be described using its moments, central moments, or cumulants. We can suppose that random variable x is equal to x i with probability  . , order moment of random variable x, is defined as follows:         (1) Cumulants of different orders of random variable x can be calculated from the following recursive relation [5]:                            (2) Generation expansion planning in IEEE power system using probabilistic production simulation Abdolazim Yaghooti 1 , Ghafur Ahmad Khanbeigi 2 Mohammad Esmalifalak 3 Amirkabir University of Technology 1 , Member, IEEE 2 University of Houston 3 Tehran, Iran 1, 2 Texas, USA 3 E-mail 1, 2 : ayaghooti@aut.ac.ir , gh_khanbeigi@yahoo.com E-mail 3 : mesmalif@mai.uh.edu 2010 IEEE International Energy Conference 978-1-4244-9380-7/10/$26.00 ©2010 IEEE 769