solve: add option for post-discretization of lines and links

config/config.default.yaml

@@ -770,11 +770,20 @@ solving:
     # io_api: "direct"  # Increases performance but only supported for the highs and gurobi solvers
     # options that go into the optimize function
     track_iterations: false
-    min_iterations: 4
-    max_iterations: 6
+    min_iterations: 2
+    max_iterations: 3
     transmission_losses: 2
     linearized_unit_commitment: true
     horizon: 365
+    post_discretization:
+      enable: false
+      line_unit_size: 1700
+      link_unit_size:
+        DC: 2000
+        H2 pipeline: 1200
+        gas pipeline: 1500
+      line_threshold: 0.3
+      link_threshold: 0.3
 
   constraints:
     CCL: false

doc/configtables/post_discretization.csv

@@ -1,10 +0,0 @@
-,Unit,Values,Description
-post-discretization,,,
--- AC,int,1700,Minimum capacity of discrete "AC" line expansion steps.
-links,,,
--- DC,int,2000,Check
--- gas pipeline,int,1500,Minimum capacity of discrete "gas pipeline".
--- gas pipeline new,int,1500,Minimum capacity of discrete "new gas pipeline".
--- H2 pipeline,int,1200,Minimum capacity of discrete "H2 pipeline".
--- H2 pipeline (Kernnetz),int,1200,Minimum capacity of discrete "H2 pipeline (Kernnetz)".
--- H2 pipeline retrofitted,int,1200,Minimum capacity of discrete "retrofitted H2 pipeline".

doc/configtables/solving.csv

@@ -14,6 +14,13 @@ options,,,
 -- transmission_losses,int,[0-9],"Add piecewise linear approximation of transmission losses based on n tangents. Defaults to 0, which means losses are ignored."
 -- linearized_unit_commitment,bool,"{'true','false'}",Whether to optimise using the linearized unit commitment formulation.
 -- horizon,--,int,Number of snapshots to consider in each iteration. Defaults to 100.
+-- post_discretization,,,
+-- -- enable,bool,"{'true','false'}",Switch to enable post-discretization of the network. Disabled by default.
+-- -- line_unit_size,MW,float,Discrete unit size of lines in MW.
+-- -- link_unit_size,MW,float,Discrete unit size of links in MW by carrier (given in dictionary style.
+-- -- -- {carrier},,,
+-- -- line_threshold,,float,The threshold relative to the discrete line unit size beyond which to round up to the next unit. Defaults to 0.3.
+-- -- link_threshold,,float,The threshold relative to the discrete link unit size beyond which to round up to the next unit. Defaults to 0.3.
 constraints ,,,
 -- CCL,bool,"{'true','false'}",Add minimum and maximum levels of generator nominal capacity per carrier for individual countries. These can be specified in the file linked at ``electricity: agg_p_nom_limits`` in the configuration. File defaults to ``data/agg_p_nom_minmax.csv``.
 -- EQ,bool/string,"{'false',`n(c| )``; i.e. ``0.5``-``0.7c``}",Require each country or node to on average produce a minimal share of its total consumption itself. Example: ``EQ0.5c`` demands each country to produce on average at least 50% of its consumption; ``EQ0.5`` demands each node to produce on average at least 50% of its consumption.

doc/release_notes.rst

@@ -43,7 +43,10 @@ Upcoming Release
 
 * Allow dictionary for the config aviation_demand_factor.
 
-* Post discretize network infrastructure like lines and links.
+* Add option to post-discretize line and link capacities based on unit sizes and
+  rounding thresholds specified in the configuration under ``solving: options:
+  post_discretization:`` when iterative solving is enables (``solving: optiosn:
+  skip_iterations: false``). This option is disabled by default.
 
 * Group existing capacities to the earlier grouping_year for consistency with optimized capacities.
 

envs/environment.yaml

@@ -11,7 +11,7 @@ dependencies:
 - pip
 
 - atlite>=0.2.9
-- pypsa>=0.26.1
+- pypsa>=0.28
 - linopy
 - dask
 

scripts/solve_network.py

@@ -45,7 +45,6 @@ from _helpers import (
 )
 from pypsa.descriptors import get_activity_mask
 from pypsa.descriptors import get_switchable_as_dense as get_as_dense
-from pypsa.optimization.abstract import optimize_transmission_expansion_iteratively
 
 logger = logging.getLogger(__name__)
 pypsa.pf.logger.setLevel(logging.WARNING)
@@ -923,9 +922,11 @@ def solve_network(n, config, solving, **kwargs):
         kwargs["track_iterations"] = cf_solving["track_iterations"]
         kwargs["min_iterations"] = cf_solving["min_iterations"]
         kwargs["max_iterations"] = cf_solving["max_iterations"]
-        kwargs["lines_disc"] = config["post-discretization"]["lines"]
-        kwargs["links_disc"] = config["post-discretization"]["links"]
-        status, condition = optimize_transmission_expansion_iteratively(n, **kwargs)
+        if cf_solving["post_discretization"].pop("enable"):
+            kwargs.update(cf_solving["post_discretization"])
+        status, condition = n.optimize.optimize_transmission_expansion_iteratively(
+            **kwargs
+        )
 
     if status != "ok" and not rolling_horizon:
         logger.warning(