Variable energy resource capacity contributions consistent with reserve margin and reliability

This paper presents a study case of the impact of Variable Energy Resources (VERs) on the Reserve Margin of the ERCOT region. Wind and solar are projected to provide a large contribution in generation capacity for the North American Bulk Power System (BPS). The increasing penetration of VERs makes it important to define “best practices” for quantifying the contribution of these energy-limited resources when evaluating resource adequacy. Calculating the capacity values of VERs can be challenging because they interact with each other in a nonlinear and dependent manner. The approach taken in this paper is part of a larger effort that the North American Electric Reliability Corporation (NERC) is taking to ensure reliable operation of the North American BPS. A loss of load probability model is used to determine VER capacity contributions. Over or under assigning the VER percentage capacity credits is shown to affect the reserve margin (RM) percentage needed to maintain the same level of reliability. The authors recommend a method for maintaining RM consistency.