Calliope

Version 0.6.0 is an almost complete rewrite of most of Calliope's internals. See [New in v0.6.0](https://calliope.readthedocs.io/en/v0.6.0/user/whatsnew.html) for a more detailed description of the many changes.

Major changes

|changed| |backwards-incompatible| Substantial changes to model configuration format, including more verbose names for most settings, and removal of run configuration files.

|new| |backwards-incompatible| Complete rewrite of Pyomo backend, including new various new and improved functionality to interact with a built model (see :doc:`user/ref_05_to_06`).

|new| Addition of a ``calliope convert`` CLI tool to convert 0.5.x models to 0.6.0.

|new| Experimental ability to link to non-Pyomo backends.

|new| New constraints: ``resource_min_use`` constraint for ``supply`` and ``supply_plus`` techs.

|changed| |backwards-incompatible| Removal of settings and constraints includes ``subset_x``, ``subset_y``, ``s_time``, ``r2``, ``r_scale_to_peak``, ``weight``.

|changed| |backwards-incompatible| ``system_margin`` constraint replaced with ``reserve_margin`` constraint.

|changed| |backwards-incompatible| Removed the ability to load additional custom constraints or objectives.

* |fixed| Allow `r_area` to be non-zero if either of `e_cap.max` or `e_cap.equals` is set, not just `e_cap.max`.
* |fixed| Ensure static parameters in resampled timeseries are caught in constraint generation
* |fixed| Fix time masking when set_t.csv contains sub-hourly resolutions

Major changes

* |fixed| `r_area_per_e_cap` and `r_cap_equals_e_cap` constraints have been separated from r_area and r_cap constraints to ensure that user specified `r_area.max` and `r_cap.max` constraints are observed.

* |changed| technologies and location subsets are now communicated with the solver as a combined location:technology subset, to reduce the problem size, by ignoring technologies at locations in which they have not been allowed. This has shown drastic improvements in Pyomo preprocessing time and memory consumption for certain models.

Other changes

* |fixed| Allow plotting carrier production using `calliope.analysis.plot_carrier_production` if that carrier does not have an associated demand technology (previously would raise an exception).
* |fixed| Define time clustering method (sum/mean) for more constraints that can be time varying. Previously only included `r` and `e_eff`.
* |changed| storage technologies default `s_cap.max` to `inf`, not 0 and are automatically included in the `loc_tech_store` subset. This ensures relevant constraints are not ignored by storage technologies.
* |changed| Some values in the urban scale MILP example were updated to provide results that would show the functionality more clearly
* |changed| technologies have set colours in the urban scale example model, as random colours were often hideous.
* |changed| ruamel.yaml, not ruamel_yaml, is now used for parsing YAML files.
* |fixed| e_cap constraints for unmet_demand technologies are ignored in operational mode. Capacities are fixed for all other technologies, which previously raised an exception, as a fixed infinite capacity is not physically allowable.
* |fixed| stack_weights were strings rather than numeric datatypes on reading NetCDF solution files.

Major changes

* |new| (BETA) Mixed integer linear programming (MILP) capabilities, when using ``purchase`` cost and/or ``units.max/min/equals`` constraints. Integer/Binary decision variables will be applied to the relevant technology-location sets, avoiding unnecessary complexity by describing all technologies with these decision variables.

Other changes

* |changed| YAML parser is now ruamel_yaml, not pyyaml. This allows scientific notation of numbers in YAML files (57)
* |fixed| Description of PV technology in urban scale example model now more realistic
* |fixed| Optional ramping constraint no longer uses backward-incompatible definitions (55)
* |fixed| One-way transmission no longer forces unidirectionality in the wrong direction
* |fixed| Edge case timeseries resource combinations, where infinite resource sneaks into an incompatible constraint, are now flagged with a warning and ignored in that constraint (61)
* |fixed| e_cap.equals: 0 sets a technology to a capacity of zero, instead of ignoring the constraint (63)
* |fixed| depreciation_getter now changes with location overrides, instead of just checking the technology level constraints (64)
* |fixed| Time clustering now functions in models with time-varying costs (66)
* |changed| Solution now includes time-varying costs (costs_variable)
* |fixed| Saving to NetCDF does not affect in-memory solution (62)

* |changed| Calliope now uses Python 3.6 by default. From Calliope 0.6.0 on, Python 3.6 will likely become the minimum required version.
* |fixed| Fixed a bug in distance calculation if both lat/lon metadata and distances for links were specified.
* |fixed| Fixed a bug in storage constraints when both ``s_cap`` and ``e_cap`` were constrained but no ``c_rate`` was given.
* |fixed| Fixed a bug in the system margin constraint.

|new| |backwards-incompatible| Better coordinate definitions in metadata. Location coordinates are now specified by a dictionary with either lat/lon (for geographic coordinates) or x/y (for generic Cartesian coordinates), e.g. ``{lat: 40, lon: -2}`` or ``{x: 0, y: 1}``. For geographic coordinates, the ``map_boundary`` definition for plotting was also updated in accordance. See the built-in example models for details.

|new| Unidirectional transmission links are now possible. See the [documentation on transmission links](https://calliope.readthedocs.io/en/v0.5.1/user/configuration.html#transmission-links).

Other changes

* |fixed| Missing urban-scale example model files are now included in the distribution
* |fixed| Edge cases in ``conversion_plus`` constraints addressed
* |changed| Documentation improvements