Heating zone improvements

[MPavicevic]

Model could be generalized a bit further because variables such as commitment, ramping rates, min on/off times etc. dont work for heat only units (they work only on u(au) set).

Storage units can also be attached to heating zone, now this is not possible because set s(u) instead of s(au).

For this to work storage balance equation needs to be expanded with Heat(hu,i) parameter but some creativity is necessary to avoid conflicts with other heat units who supply heat directly into their own storage and then storage supplies heat to the heating zone (this is also a bit fishy because even when heat storage capacity is set to 0 storage charging is recorded in OutputsStorageInput which complicates plotting of storage units linked to one heating zone). One of the solutions would be introduction of StorageDischarge variable that would bypass heat storage in hours when it is to expensive and supply heat directly into the heating zone (same as in electricity zones).

[MPavicevic]

Resolved