Multi-national transmission planning using joint and disjoint solutions

Transmission systems have a critical role in well-functioning of liberalised electricity markets. Diversity in generation portfolio and improving system reliability are the main incentives for significant cross-border trades between Transmission System Operators (TSOs) in Europe. Nowadays, two ways are discussed for investment in additional transmission capacity by multiple TSOs: (1) Cooperative approach and (2) non-cooperative approache. In cooperative planning, the governing body looks for the highest overall social welfare while in non-cooperative approach, each TSO decides on his own transmission system based on his social welfare. The problem is that the outcome of these two approaches might be different. Each TSO tries to maximise his own social welfare and they are reluctant to act in a joint solution where they are losing some of their social welfare. In the context, they prefer to act strategically in order to maximise their social welfare. This paper evaluates the joint and disjoint solutions of the multi-national transmission planning. We propose a simultaneous-move game between the involved TSOs. The game is formulated as a one-shot mixed-integer linear programming problem. Then the joint solution is developed by merging all TSOs in one TSO responsible for transmission planning in all TSOs´ regions. The joint solution is formulated as a mixed-integer linear programming and used as the benchmark in our studies.