Impact of wind generation intermittency on transmission expansion models

This paper presents fundamentals of modelling wind generation for a probabilistic Cost-Benefit Analysis (CBA) for transmission planning. As known, wind generation exhibits intermittency as one of its main characteristics. This attribute of wind adds to the computational burden when planning the transmission system since the number of potential generation backgrounds sharply increases with respect to a pure conventional generation case. In order to tackle computational burden problems, simplifications in modelling become an important issue. Therefore, the impact of these simplifications on the overall result of transmission investment must be assessed. Basic concepts about transmission investment under the market perspective with (high) wind penetration are presented along with transmission distortions that may arise when making simplifications to model wind generation. We conclude that bundling similar wind scenarios into limited generation output possibilities leads to under/overestimate transmission investment without a clear pattern. In addition, the right number of minimum scenarios to consider so as to meaningfully estimate transmission investment depends not only on the amount of wind capacity installed but also on the nodal supply functions and demand.