Improved cost-benefit analysis for reliable long-term transmission planning

The aim of this paper is to incorporate reliability aspects in the transmission planning process presented in previous work. The decision maker has to consider many different aspects during the definition of transmission planning strategy, that sometimes might be contradicting. In the whole planning framework the decision is made by combining economic, environmental, and security of supply criteria in a single pseudo-dynamic algorithm. However, here only the part of security of supply is analyzed. After a sensitivity analysis for identification of critical/important transmission lines, a contingency analysis is performed and the probability of expected unserved energy is calculated together with the costs of expected unserved energy as an indicator. It is also shown that the amount of expected unserved energy is decreasing when additional transmission capacity is added to the connected lines of an unbalanced node. However, this may not be enough to reach zero unserved energy due to limitations of other transmission lines. After all, transmission network reinforcements can be evaluated based on benefits in avoided environmental costs, avoided congestion costs and avoided unserved energy costs in order to provide sufficient information to the decision maker.