GAME THEORY Project Phase I1. IntroductionDecisions regarding the expansion of the electricity transmission grid have become more difficult over the past two decades. In fact, the energy sector has been decentralized and the electricity market is now a competitive market. Therefore a transmission expansion plan can no longer follow traditional planning criteria. As a result, new techniques are developed to solve the TEP transmission expansion problem. Different optimization methods are usually used to solve the TEP: genetic algorithm (GA), Tabu search (TS) and different heuristic and metaheuristic techniques. Those are called static scenarios. Dynamic scenarios are those based on game theory that represent the behavior of the different participants in the electricity market. Different games and models like Cournot, Stackelberg, bargaining etc. have recently been used to obtain an optimal decision regarding the TEP. This paper presents a non-cooperative game theory approach to solving the TEP. First, the transmission expansion problem is formulated in Section II so as to minimize the cost of expansion subject to voltage, power flow, and other constraints. In Section III, the expansion plans proposed by investors are subject to the following steps: evaluation of the expansion plan, determination of the optimal effort using a principle-agent model, and competitive bidding to obtain the efficient bid. Section IV presents a numerical application using the classic six-bus Garver system. Conclusions are finally drawn in Section V.2. Review of previous worksIn the literature, there are examples of transmission expansion problems solved by cooperative and non-cooperative games....... half of the article......7] J.D. Molina, J. Contreras, H. Rudnick, “A Principal-Agent Approach to Transmission Expansion: Part I: Regulatory Framework,” Power Systems, IEEE Transactions vol. 28, pp 256-263, 2013.[8] M. Jenabi, S. Mohammad, T.F. Ghomi, and Y.Smeers "Bi-level game approaches for coordination of generation and transmission expansion planning within a market environment", Power Systems, IEEE Transactions vol . 28, pp. 2639 – 2650, 2013[9] M.R. Hesamzadeh, D.R. Biggar, N.Hosseinzadeh, and P.J. Wolfs, “Increasing Transmission with Mathematical Models of Market Power and Strategic Generation Expansion: Part I,” Power Systems, IEEE Transactions Vol. pp. 26, pp 2040-2048, 2011[10] L.Xiaotong, L.Yimei, Z. Xiaoli and Z.Ming “Generation and transmission expansion planning based on game theory in power engineering” Systems Engineering Procedia 4 (2012) 79 – 86.