Allow for fixing investments

src/oemof/solph/_models.py

@@ -368,7 +368,9 @@ class Model(BaseModel):
  InvestNonConvexFlowBlock,
  ]
 
- def __init__(self, energysystem, discount_rate=None, **kwargs):
+ def __init__(
+ self, energysystem, discount_rate=None, **kwargs
+ ):
  if discount_rate is not None:
  self.discount_rate = discount_rate
  elif (
@@ -383,6 +385,7 @@ def __init__(self, energysystem, discount_rate=None, **kwargs):
  self._set_discount_rate_with_warning()
  else:
  pass
+ self._fix_investments = False
  super().__init__(energysystem, **kwargs)
 
  def _set_discount_rate_with_warning(self):
@@ -521,3 +524,16 @@ def _add_parent_block_variables(self):
  if (o, i) in self.UNIDIRECTIONAL_FLOWS:
  for p, t in self.TIMEINDEX:
  self.flow[o, i, p, t].setlb(0)
+
+ def fix_investments(self):
+ """Fix investment results of an already solved model"""
+ if self.solver_results is None:
+ msg = (
+ "Cannot fix investments as model has not yet been solved!\n"
+ "You have to first solve your model and then call method "
+ "`fix_investments()` on your model instance."
+ )
+ raise ValueError(msg)
+ self._fix_investments = True
+ if hasattr(self, "InvestmentFlowBlock"):
+ self.InvestmentFlowBlock.fix_investments_results()

src/oemof/solph/flows/_investment_flow_block.py

@@ -87,6 +87,7 @@
  attribute investment and the associated source (s) and target (t)
  of flow e.g. groups=[(s1, t1, f1), (s2, t2, f2),..]
  """
+ m = self.parent_block()
  if group is None:
  return None
 
@@ -1175,3 +1176,15 @@
  self.maximum_rule_build = BuildAction(rule=_max_invest_rule)
 
  return self.maximum_rule
+
+ def fix_investments_results(self):
+ """Fix investments if `_fix_investments` is set to True for model"""
+ m = self.parent_block()
+ for (i, o) in self.INVESTFLOWS:
+ for p in m.PERIODS:
+ self.invest[i, o, p].fix()
+ self.total[i, o, p].fix()
+ if m.es.periods is not None:
+ self.old[i, o, p].fix()
+ self.old_end[i, o, p].fix()
+ self.old_exo[i, o, p].fix()

tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_fixed.py

@@ -0,0 +1,22 @@
+from oemof.solph import processing
+from test_multi_period_investment_model import (
+ set_up_multi_period_investment_model,
+)
+
+
+def test_multi_period_investment_fixed(solver="cbc"):
+ """test fixing investments in a repeated solve"""
+ om = set_up_multi_period_investment_model(approach="DLR")
+ om.receive_duals()
+ om.solve(solver=solver)
+
+ assert om.solver_results is not None
+ om.fix_investments()
+ om.solve(solver=solver)
+ for (i, o) in om.InvestmentFlowBlock.INVESTFLOWS:
+ for p in om.PERIODS:
+ assert om.InvestmentFlowBlock.invest[i, o, p].fixed
+ assert om.InvestmentFlowBlock.total[i, o, p].fixed
+ assert om.InvestmentFlowBlock.old[i, o, p].fixed
+ assert om.InvestmentFlowBlock.old_end[i, o, p].fixed
+ assert om.InvestmentFlowBlock.old_exo[i, o, p].fixed