Allow lower limit for generic_integral_limit

src/oemof/solph/constraints/integral_limit.py

@@ -12,6 +12,7 @@
 SPDX-License-Identifier: MIT
 
 """
+import warnings
 
 from pyomo import environ as po
 
@@ -29,7 +30,7 @@ def emission_limit(om, flows=None, limit=None):
 
     """
     generic_integral_limit(
-        om, keyword="emission_factor", flows=flows, limit=limit
+        om, keyword="emission_factor", flows=flows, upper_limit=limit
     )
 
 
@@ -49,7 +50,9 @@ def emission_limit_per_period(om, flows=None, limit=None):
     )
 
 
-def generic_integral_limit(om, keyword, flows=None, limit=None):
+def generic_integral_limit(
+    om, keyword, flows=None, upper_limit=None, lower_limit=None, limit=None
+):
     r"""Set a global limit for flows weighted by attribute named keyword.
     The attribute named keyword has to be added
     to every flow you want to take into account.
@@ -69,8 +72,10 @@ def generic_integral_limit(om, keyword, flows=None, limit=None):
         used.
     keyword : string
         attribute to consider
-    limit : numeric
-        Absolute limit of keyword attribute for the energy system.
+    upper_limit : numeric
+        Absolute upper limit of keyword attribute for the energy system.
+    lower_limit : numeric
+        Absolute lower limit of keyword attribute for the energy system.
 
     Note
     ----
@@ -80,7 +85,10 @@ def generic_integral_limit(om, keyword, flows=None, limit=None):
     **Constraint:**
 
     .. math:: \sum_{i \in F_E} \sum_{t \in T} P_i(p, t) \cdot w_i(t)
-               \cdot \tau(t) \leq M
+               \cdot \tau(t) \leq UB
+
+    .. math:: \sum_{i \in F_E} \sum_{t \in T} P_i(p, t) \cdot w_i(t)
+               \cdot \tau(t) \geq LB
 
 
     With `F_I` being the set of flows considered for the integral limit and
@@ -95,7 +103,8 @@ def generic_integral_limit(om, keyword, flows=None, limit=None):
     :math:`P_n(p, t)` V    power flow :math:`n` at time index :math:`p, t`
     :math:`w_N(t)`    P    weight given to Flow named according to `keyword`
     :math:`\tau(t)`   P    width of time step :math:`t`
-    :math:`L`         P    global limit given by keyword `limit`
+    :math:`UB`        P    global limit given by keyword `upper_limit`
+    :math:`LB`        P    global limit given by keyword `lower_limit`
     ================= ==== ====================================================
 
     Examples
@@ -124,6 +133,20 @@ def generic_integral_limit(om, keyword, flows=None, limit=None):
     flows = _check_and_set_flows(om, flows, keyword)
     limit_name = "integral_limit_" + keyword
 
+    if limit is not None:
+        msg = (
+            "The keyword argument 'limit' to generic_integral_limit has been"
+            "renamed to 'upper_limit'. The transitional wrapper will be"
+            "deleted in a future version."
+        )
+        warnings.warn(msg, FutureWarning)
+        upper_limit = limit
+
+    if upper_limit is None and lower_limit is None:
+        raise ValueError(
+            "At least one of upper_limit and lower_limit needs to be defined."
+        )
+
     setattr(
         om,
         limit_name,
@@ -138,11 +161,18 @@ def generic_integral_limit(om, keyword, flows=None, limit=None):
         ),
     )
 
-    setattr(
-        om,
-        limit_name + "_constraint",
-        po.Constraint(expr=(getattr(om, limit_name) <= limit)),
-    )
+    if upper_limit is not None:
+        setattr(
+            om,
+            limit_name + "_upper_limit",
+            po.Constraint(expr=(getattr(om, limit_name) <= upper_limit)),
+        )
+    if lower_limit is not None:
+        setattr(
+            om,
+            limit_name + "_lower_limit",
+            po.Constraint(expr=(getattr(om, limit_name) >= lower_limit)),
+        )
 
     return om
 

tests/constraint_tests.py

@@ -904,6 +904,29 @@ def test_flow_without_emission_for_emission_constraint_no_error(self):
 
         self.compare_lp_files("emission_limit_no_error.lp", my_om=om)
 
+    def test_flow_without_emission_for_emission_constraint_lower(self):
+        """Test that no error is thrown if no flows are explicitly passed"""
+        bel = solph.buses.Bus(label="electricityBus")
+        source1 = solph.components.Source(
+            label="source1",
+            outputs={
+                bel: solph.flows.Flow(
+                    nominal_value=100,
+                    custom_attributes={"emission_factor": 0.8},
+                )
+            },
+        )
+        source2 = solph.components.Source(
+            label="source2", outputs={bel: solph.flows.Flow(nominal_value=100)}
+        )
+        self.energysystem.add(bel, source1, source2)
+        om = self.get_om()
+        solph.constraints.generic_integral_limit(
+            om, keyword="emission_factor", lower_limit=777
+        )
+
+        self.compare_lp_files("emission_limit_lower.lp", my_om=om)
+
     def test_equate_variables_constraint(self):
         """Testing the equate_variables function in the constraint module."""
         bus1 = solph.buses.Bus(label="Bus1")

tests/lp_files/emission_budget_limit.lp

@@ -6,7 +6,7 @@ objective:
 
 s.t.
 
-c_u_integral_limit_emission_factor_constraint_:
+c_u_integral_limit_emission_factor_upper_limit_:
 +0.5 flow(source1_electricityBus_0)
 -1.0 flow(source1_electricityBus_1)
 +2.0 flow(source1_electricityBus_2)

tests/lp_files/emission_limit.lp

@@ -6,7 +6,7 @@ objective:
 
 s.t.
 
-c_u_integral_limit_emission_factor_constraint_:
+c_u_integral_limit_emission_factor_upper_limit_:
 +0.5 flow(source1_electricityBus_0)
 -1.0 flow(source1_electricityBus_1)
 +2.0 flow(source1_electricityBus_2)

tests/lp_files/emission_limit_lower.lp

@@ -0,0 +1,38 @@
+\* Source Pyomo model name=Model *\
+
+min 
+objective:
++0 ONE_VAR_CONSTANT
+
+s.t.
+
+c_l_integral_limit_emission_factor_lower_limit_:
++0.8 flow(source1_electricityBus_0)
++0.8 flow(source1_electricityBus_1)
++0.8 flow(source1_electricityBus_2)
+>= 777
+
+c_e_BusBlock_balance(electricityBus_0)_:
++1 flow(source1_electricityBus_0)
++1 flow(source2_electricityBus_0)
+= 0
+
+c_e_BusBlock_balance(electricityBus_1)_:
++1 flow(source1_electricityBus_1)
++1 flow(source2_electricityBus_1)
+= 0
+
+c_e_BusBlock_balance(electricityBus_2)_:
++1 flow(source1_electricityBus_2)
++1 flow(source2_electricityBus_2)
+= 0
+
+bounds
+   1 <= ONE_VAR_CONSTANT <= 1
+   0 <= flow(source1_electricityBus_0) <= 100
+   0 <= flow(source1_electricityBus_1) <= 100
+   0 <= flow(source1_electricityBus_2) <= 100
+   0 <= flow(source2_electricityBus_0) <= 100
+   0 <= flow(source2_electricityBus_1) <= 100
+   0 <= flow(source2_electricityBus_2) <= 100
+end

tests/lp_files/emission_limit_no_error.lp

@@ -6,7 +6,7 @@ objective:
 
 s.t.
 
-c_u_integral_limit_emission_factor_constraint_:
+c_u_integral_limit_emission_factor_upper_limit_:
 +0.8 flow(source1_electricityBus_0)
 +0.8 flow(source1_electricityBus_1)
 +0.8 flow(source1_electricityBus_2)

tests/test_constraints_module.py

@@ -1,9 +1,10 @@
 import pandas as pd
+import pytest
 
 from oemof import solph
 
 
-def test_special():
+def test_integral_limit_wrapper():
     date_time_index = pd.date_range("1/1/2012", periods=5, freq="h")
     energysystem = solph.EnergySystem(
         timeindex=date_time_index,
@@ -22,9 +23,24 @@ def test_special():
     flow_with_keyword = {
         (src1, bel): flow1,
     }
-    solph.constraints.generic_integral_limit(
-        model, "my_factor", flow_with_keyword, limit=777
+    with pytest.warns(FutureWarning):
+        solph.constraints.generic_integral_limit(
+            model, "my_factor", flow_with_keyword, limit=777
+        )
+
+
+def test_limetless_limit():
+    date_time_index = pd.date_range("1/1/2012", periods=5, freq="h")
+    energysystem = solph.EnergySystem(
+        timeindex=date_time_index,
+        infer_last_interval=True,
     )
+    model = solph.Model(energysystem)
+    with pytest.raises(
+        ValueError,
+        match="At least one of upper_limit and lower_limit",
+    ):
+        solph.constraints.generic_integral_limit(model, "my_factor")
 
 
 def test_something_else():