GSYE-835: Adapt TankEnergyParameters.get_min_energy_consumption so th…

…e storage temperature can drop to its mininum

src/gsy_e/models/strategy/energy_parameters/heatpump/tank.py

@@ -79,8 +79,22 @@ def get_max_energy_consumption(self, cop: float, time_slot: DateTime):
         return max_temp_diff * self._Q_specific / cop
 
     def get_min_energy_consumption(self, cop: float, time_slot: DateTime):
-        """Calculate min energy consumption that a heatpump with provided COP can consume."""
-        return self._state.get_temp_decrease_K(time_slot) * self._Q_specific / cop
+        """
+        Calculate min energy consumption that a heatpump with provided COP has to consume in
+        order to only let the storage drop its temperature to the minimum storage temperature.
+        - if current_temp < min_storage_temp: charge till min_storage_temp is reached
+        - if current_temp = min_storage_temp: only for the demanded energy
+        - if current_temp > min_storage: only trade for the demand minus the heat
+                                         that can be extracted from the storage
+        """
+        diff_to_min_temp_C = self._state.get_current_diff_to_min_temp_K(time_slot)
+        temp_diff_due_to_consumption = self._state.get_temp_decrease_K(time_slot)
+        min_temp_diff = (
+            temp_diff_due_to_consumption - diff_to_min_temp_C
+            if diff_to_min_temp_C <= temp_diff_due_to_consumption
+            else 0
+        )
+        return min_temp_diff * self._Q_specific / cop
 
     def current_tank_temperature(self, time_slot: DateTime) -> float:
         """Get current tank temperature for timeslot."""

src/gsy_e/models/strategy/state/heat_pump_state.py

@@ -66,6 +66,14 @@ def get_temp_decrease_K(self, time_slot: DateTime) -> float:
         """Return the temperature decrease for a given time slot."""
         return self._temp_decrease_K.get(time_slot, 0)
 
+    def get_current_diff_to_min_temp_K(self, time_slot: DateTime) -> float:
+        """
+        Return the temperature difference between the current storage temp and the minimum
+        storage temperature
+        """
+        min_temp_decrease_K = self.get_storage_temp_C(time_slot) - self._min_storage_temp_C
+        return min_temp_decrease_K
+
     def get_temp_increase_K(self, time_slot: DateTime) -> float:
         """Return the temperature increase for a given time slot."""
         return self._temp_increase_K.get(time_slot, 0)

tests/strategies/energy_parameters/test_heat_pump.py

@@ -110,7 +110,9 @@ def test_event_market_cycle_populates_state(energy_params):
         energy_params.event_market_cycle(CURRENT_MARKET_SLOT)
         assert isclose(tank_state._temp_decrease_K[CURRENT_MARKET_SLOT], 56.4, abs_tol=1e-3)
         assert tank_state._storage_temp_C[CURRENT_MARKET_SLOT] == 20
-        assert isclose(heatpump_state._min_energy_demand_kWh[CURRENT_MARKET_SLOT], 5, abs_tol=1e-3)
+        assert isclose(
+            heatpump_state._min_energy_demand_kWh[CURRENT_MARKET_SLOT], 4.113, abs_tol=1e-3
+        )
         assert isclose(
             heatpump_state._max_energy_demand_kWh[CURRENT_MARKET_SLOT], 8.546, abs_tol=1e-3
         )
@@ -141,11 +143,34 @@ def test_event_traded_energy_updates_temp_increase(energy_params):
         assert isclose(tank_state._temp_increase_K[CURRENT_MARKET_SLOT], 1.1280172413793106)
 
     @staticmethod
-    def test_get_min_energy_demand_kWh_returns_correct_value(energy_params):
+    @pytest.mark.parametrize(
+        "current_temp, expected_demand",
+        [
+            [10, 2],  # storage too cold, charging with _max_energy_consumption_kWh reached
+            [20, 1.739],  # storage too cold, charging
+            [30, 0.58],  # storage at min temp, only trade for heat demand
+            [32, 0.348],  # storage does not need to be charged, can drop to min
+            [35, 0.0],  # temp decrease due to demand is equal to drop to min, do not trade
+            [37, 0.0],  # temp decrease due to demand is higher than the drop to min, do not trade
+        ],
+    )
+    def test_get_min_energy_demand_kWh_returns_correct_value(
+        energy_params, current_temp, expected_demand
+    ):
+        energy_params._max_energy_consumption_kWh = 2
+        temp_decrease_consumption = 5
+        energy_params._state.heatpump.get_cop = Mock(return_value=5)
+        for tank_states in energy_params._state.tanks._tanks_energy_parameters:
+            tank_states._state._min_storage_temp_C = 30
+            tank_states._state.get_storage_temp_C = Mock(return_value=current_temp)
+            tank_states._state.get_temp_decrease_K = Mock(return_value=temp_decrease_consumption)
         energy_params.event_market_cycle(CURRENT_MARKET_SLOT)
         assert isclose(
-            energy_params.get_min_energy_demand_kWh(CURRENT_MARKET_SLOT), 5, abs_tol=1e-3
+            energy_params.get_min_energy_demand_kWh(CURRENT_MARKET_SLOT),
+            expected_demand,
+            abs_tol=1e-3,
         )
+        # assert False
 
     @staticmethod
     def test_get_max_energy_demand_kWh_returns_correct_value(energy_params):

tests/strategies/energy_parameters/test_tank_energy_parameters.py

@@ -80,7 +80,7 @@ def test_get_max_energy_consumption(self, cop):
     def test_get_min_energy_consumption(self, cop):
         self._tanks.decrease_tanks_temp_from_heat_energy(2000, self._datetime)
         min_energy_consumption = self._tanks.get_min_energy_consumption(cop, self._datetime)
-        assert isclose(min_energy_consumption, 0.55555 / cop, rel_tol=0.0001)
+        assert isclose(min_energy_consumption, 0.1851851 / cop, rel_tol=0.0001)
 
     def test_get_average_tank_temperature(self):
         self._tanks._tanks_energy_parameters[0]._state._storage_temp_C[self._datetime] = 30