Power Model
All methods for constructing powermodels should be defined on the following type:
PowerModels.AbstractPowerModel — Typeroot of the power formulation type hierarchy
which utilizes the following (internal) functions:
PowerModels.build_ref — Functionused for building ref without the need to build a initialize an AbstractPowerModel
PowerModels.calc_buspair_parameters — Functioncompute bus pair level data, can be run on data or ref data structures