Add support for inequality instead of equality

Author: staadecker

switch_model/energy_sources/fuel_costs/markets.py

@@ -204,6 +204,10 @@ def define_components(mod):
     become non-linear.
 
     """
+    # When this variable is True we only allow positive fuel costs
+    # This simplifies the model since we can set some of our constraints
+    # as greater than instead of equals.
+    ONLY_POSITIVE_RFM_COSTS = False
 
     mod.REGIONAL_FUEL_MARKETS = Set(dimen=1)
     mod.rfm_fuel = Param(mod.REGIONAL_FUEL_MARKETS, within=mod.FUELS)
@@ -234,7 +238,8 @@ def zone_rfm_init(m, load_zone, fuel):
         dimen=3, validate=lambda m, r, p, st: (
             r in m.REGIONAL_FUEL_MARKETS and p in m.PERIODS))
     mod.rfm_supply_tier_cost = Param(
-        mod.RFM_SUPPLY_TIERS, within=Reals)
+        mod.RFM_SUPPLY_TIERS,
+        within=PositiveReals if ONLY_POSITIVE_RFM_COSTS else Reals)
     mod.rfm_supply_tier_limit = Param(
         mod.RFM_SUPPLY_TIERS, within=NonNegativeReals, default=float('inf'))
     mod.min_data_check(
@@ -333,12 +338,16 @@ def GENS_FOR_RFM_PERIOD_rule(m, rfm, p):
     enforce_fuel_consumption_scaling_factor = 1e-2
 
     def Enforce_Fuel_Consumption_rule(m, rfm, p):
-        return m.FuelConsumptionInMarket[rfm, p] * enforce_fuel_consumption_scaling_factor \
-               == enforce_fuel_consumption_scaling_factor * sum(
-            m.GenFuelUseRate[g, t, m.rfm_fuel[rfm]] * m.tp_weight_in_year[t]
-            for g in m.GENS_FOR_RFM_PERIOD[rfm, p]
-            for t in m.TPS_IN_PERIOD[p]
-    )
+        lhs = m.FuelConsumptionInMarket[rfm, p] * enforce_fuel_consumption_scaling_factor
+        rhs = enforce_fuel_consumption_scaling_factor * sum(
+            m.GenFuelUseRate[g, t, m.rfm_fuel[rfm]] * m.tp_weight_in_year[t] for g in m.GENS_FOR_RFM_PERIOD[rfm, p] for
+            t in m.TPS_IN_PERIOD[p])
+        # If we have only positive costs, FuelConsumptionInMarket will automatically
+        # try to be minimized in which case we can use a one-sided constraint
+        if ONLY_POSITIVE_RFM_COSTS:
+            return lhs >= rhs
+        else:
+            return lhs == rhs
     mod.Enforce_Fuel_Consumption = Constraint(
         mod.REGIONAL_FUEL_MARKETS, mod.PERIODS,
         rule=Enforce_Fuel_Consumption_rule)