Need to note extenuating circumstances when IFRs may be modified

[alanccai]

We should note somewhere, maybe in the study limitations section, that there are extenuating circumstances that allow project operators to temporarily modify the IFRs.

Below is an example of this language: "Equipment malfunction, emergency or law enforcement activity, agency requirements, or electric system emergencies beyond the control of the Licensee".

Language describing ramping rate restrictions below Donnells Dam (Beardsley/Donnells Hydroelectric Project P-2005)

Originally posted by @alanccai in https://github.com/vicelab/sierra-pywr/issues/43#issuecomment-554652907

[alanccai]

Another example: under conditions of extreme drought, some facilities can request variances of the MIFs. See attached docs:

P-1061_Pheonix_2015_VarianceRequest.pdf

P-1061_Pheonix_2015_ModifyingContinuingTemporaryVarianceMIF.pdf

But the internal deliberations of the operator/consulted agencies / FERC that would determine the nature of the variance request, the duration of the variance request, and whether the variance is granted in full or in part, are too complex to code, I would think.

Instead, we would say "this modelling assumes no extenuating circumstances occur that trigger a modification or variance of the IFRs".

[alanccai]

Unrelated note: should also provide a cutoff date for IFRs. Something like:

"The IFRs our model incorporate represent the IFRs in effect as of November 15, 2019."

[drheinheimer]

@alanccai Thanks for pointing this out. I'm not sure this is something we can model per se, other than to note that, say, PG&E would typically request a variation under predictable circumstances (e.g., particularly low flows)