Constrain flow count to avoid cycling flows

- use new constraint feature from oemof 0.4
- make Battery flows nonconvex to be able to use its status of activity
- add the limited flow count constraint to the oemof model

Resolves simultanious in and out flow of #218

smooth/components/component_battery.py

@@ -238,9 +238,11 @@ def create_oemof_model(self, busses, _):
         battery = solph.components.GenericStorage(
             label=self.name,
             inputs={busses[self.bus_in_and_out]: solph.Flow(
-                    nominal_value=self.p_in_max, variable_costs=self.current_vac[0])
-                    },
+                nonconvex=solph.NonConvex(), exclusive_flow=True,
+                nominal_value=self.p_in_max, variable_costs=self.current_vac[0]),
+            },
             outputs={busses[self.bus_in_and_out]: solph.Flow(
+                nonconvex=solph.NonConvex(), exclusive_flow=False,
                 nominal_value=self.p_out_max, variable_costs=self.current_vac[1])
             },
             loss_rate=self.loss_rate,

smooth/framework/run_smooth.py

@@ -127,6 +127,7 @@
 """
 
 import oemof.solph as solph
+from oemof.solph.constraints import limit_active_flow_count
 
 from smooth.framework.simulation_parameters import SimulationParameters as sp
 from smooth.framework.functions.debug import get_df_debug, show_debug
@@ -200,6 +201,23 @@ def run_smooth(model):
         # Do the simulation for this time step.
         model_to_solve = solph.Model(oemof_model)
 
+        # Add constraints to the oemof model
+        # - Only one Battery flow should be active per timestep
+        # TODO: specify constrained flow within model description file (maybe using keyword),
+        #  so it does not apply for all Generic Storages, but e.g. only batteries
+        my_constraint_flows = []
+        for flow in model_to_solve.flows:
+            for in_or_out in flow:
+                if isinstance(in_or_out, solph.components.GenericStorage):
+                    my_constraint_flows.append(flow)
+        model_to_solve = limit_active_flow_count(model_to_solve,
+                                                 'in_or_out_flow',
+                                                 my_constraint_flows,
+                                                 lower_limit=0,
+                                                 upper_limit=1)
+
+
+
         for this_comp in components:
             this_comp.update_constraints(busses, model_to_solve)