Congested flowgates ranking analysis and a potential new approach

Congested flowgate ranking is a process to rank flowgates by the potential benefits associated with each flowgate when it is relieved. The rank can be used to help identify top congested flowgates for full evaluation and planning. Ideally, congested flowgates should be ranked by their potential benefits when congestion is relieved individually. This approach however requires one change case simulation for each flowgate and creates significant computation burden. It is desirable to develop metrics solely based on information from base case simulation and use the metrics to get approximate rank. Two metrics, annual shadow price and annual congestion cost, are used in the industry to rank the congested flowgates. No analysis has yet been done to compare these two metrics. This paper compares these two metrics by using different measures. Measures such as data correlation, rank correlation, rank correctness count and percentage are proposed to evaluate the goodness-of-fit of the ranks produced by the two metrics with respect to the actual rank. Sample data from MISO Top Congested Flowgates Study are used in this analysis. As neither of the metrics has been justified in producing a good rank, a new approach is explored. The feasibility is exemplified through a 5-bus test system study. The new approach is potentially capable of estimating actual benefit in a more accurate and computational efficient manner.