The Impact of Various Upgrade Strategies on the Long-Term Dynamics and Robustness of the Transmission Grid

We use the OPA global complex systems model of the power transmission system to investigate the effect of a series of different network upgrade scenarios on the long time dynamics and the probability of large cascading failures. The OPA model represents the power grid at the level of DC load flow and LP generation dispatch and represents blackouts caused by randomly triggered cascading line outages and overloads. This model represents the long-term, slow evolution of the transmission grid by incorporating the effects of increasing demand and engineering responses to blackouts such as upgrading transmission lines and generators. We examine the effect of increased component reliability on the long-term risks, the effect of changing operational margins and the effect of redundancy on those same long-term risks. The general result is that while increased reliability of the components decreases the probability of small blackouts, depending on the implementation, it actually can increase the probability of large blackouts. When we instead increase some types of redundancy of the system there is an overall decrease in the large blackouts with a concomitant increase of the smallest blackouts. As some of these results are counter intuitive these studies suggest that care must be taken when making what seem to be logical upgrade decisions.