Flexibility from the demand side

The stochastic nature of renewable energy sources such as wind and sun introduces a new form of uncertainty in power system operation. The standard answer to the concerns that this increase in uncertainty raises is that the system should become more “flexible”. However, there is as yet no agreement on exactly how much flexibility is needed or even a commonly accepted measure of flexibility. There is agreement however on the fact that flexibility has a cost and that this cost should be minimized in a way that does not affect reliability to facilitate the integration of these renewable energy sources. This presentation will explore how flexibility from demand-side resources compares with the flexibility that fast ramping generating units can provide. In order to take into account the associated investment costs, this comparison relies on an extended unit commitment optimization that considers both short- and long-term aspects.