Account for the capacity credit of wind explicitly in the LOLE calculation

[ChaelKruip]

In conjunction with https://github.com/quintel/merit/issues/122 we could rid the ETM of the use of a capacity credit for wind. The capacity credit is a measure for the reliable fraction of the installed capacity of wind turbines. The capacity credit is only used in the LOLE calculation.

The current modeling of capacity credit for wind has several disadvantages:

• The value for the capacity credit is modeled as a function of the installed capacity of wind. In reality, however, it is the relative installed capacity of wind and dispatchable production that determines the capacity credit.
• The data that the modeling is based on is limited in range (of installed capacities) so extrapolation is needed making the results less trustworthy.
• The fitting function used to describe the capacity credit requires several constants that are stored int the country.ad files. These numbers are not very easily explained to outsiders or researched for new countries.

The proposed solution is to model the reliable explicitly by subtracting the production-curve for wind from the demand curve and do the LOLE calculation on the resulting curve.

In addition we could also subtract the solar production curve from the demand. This will likely not have a big impact on the LOLE outcome as the peaks in demand are expected to occur predominantly in the winter-evenings.

Whether we should subtract the must-run CHPs from the demand curve depends on how we model them. Currently, the must-run CHPs are not dispatchable, even if they are not running according to their must-run profiles (see https://github.com/quintel/etengine/issues/706). In the current case, we would need to subtract their production because they behave similarly to volatiles. If https://github.com/quintel/etengine/issues/706 is closed, we can add their total available capacity to the reliable capacity used in the LOLE calculation.

[ChaelKruip]

Including @jorisberkhout @dennisschoenmakers @AlexanderWirtz

[ChaelKruip]

Closing.