Power System Adequacy With Variable Resources: A Capacity Credit Perspective

The concept of capacity credit (CC) has been proposed to evaluate the contribution of generators for system adequacy since the 1960s. CC determines the extent to which the added unit affects the generation adequacy of the system. The equivalent reliability builds the bridge between the evaluated unit and the virtual firm capacity. This article firstly summarizes the reliability equivalent criteria for CC of generators and lists various CC definitions. Second, the methodologies for evaluating CC are categorized into three parts in terms of the modeling of the reliability function and the solving strategies. Then, a theoretic expression from several analytical methods is proposed to better interpret the characteristics of the CC function. Some discussions of CC are conducted afterwards. The applications of CC on power system planning and capacity market are presented. Finally, we propose four aspects of future work well worth further investigations.