A Council model for evaluating costs and risks associated with different regional strategies over many future power system environments is the Regional Portfolio Model (RPM)[1]. While it performs the tasks of a more traditional capital expansion model, it does so while explicitly accounting for risk of future uncertainty, and thus imperfect decision making in the planning process. 

The RPM uses methods first developed for the 5th Power Plan. While the version of the model used to develop the 2021 Power Plan differs in some respects from this methodology, the rationale behind the core logic and analytical approaches taken in the RPM is documented in the 5th, 6th and 7th Power Plans. For more detail on the model development throughout time, see appendices L and P in the 5th Power Plan, appendix J in the 6th Power Plan and appendix L in the 7th Power Plan. This previous RPM documentation does not capture the exact implementation of the current model, but is an important part of understanding the evolution of this model. Additionally, the model was redeveloped before the 7th Power Plan using the Analytica as a platform, and much of the individual logic is documented in detail in the model itself.

While in past plans the RPM has been used successfully as the primary analytical tool for understanding strategy tradeoffs, in the 2021 Power Plan, many of the previous assumptions that made its underlying structure convenient and efficient for understanding regional risks were challenged. Through the advisory committee process it became clear that there were some limitations to the RPM structure that made it difficult to rely on the model without the context of the other Council power system models due to effects on regional operations due to policies both internal and external to the region. Significant model enhancements and assumption changes were implemented to try and incorporate information necessary to make reasonable regional resource strategy decisions.

[1] This model was documented in detail in the 7th Power Plan appendix L.