Enable BatteryPriceSOCController to handle multiple battery durations [+bugfix for high/low SOC]

hycon/controllers/battery_controller.py

@@ -145,6 +145,31 @@ def compute_controls(self, measurements_dict):
 class BatteryPriceSOCController(ControllerBase):
     """
     Controller considers price and SOC to determine power setpoint.
+
+    This controller implements a price-arbitrage strategy that uses day-ahead (DA)
+    locational marginal prices (LMPs) and real-time (RT) LMPs to decide when to
+    charge or discharge the battery. The algorithm identifies the top and bottom
+    price hours of the day based on battery duration (e.g., for a 4-hour battery,
+    it targets the "top_d" = 4 highest and "bottom_d" = 4 lowest priced hours).
+
+    The decision logic is as follows:
+        1. If RT price exceeds the highest DA price: discharge at full rate
+           (unconditionally).
+        2. Else if RT price is in the top-d highest DA prices AND SOC > low_soc:
+           discharge at full rate.
+        3. Else if RT price is below the lowest DA price: charge at full rate
+           (unconditionally).
+        4. Else if RT price is in the bottom-d lowest DA prices AND SOC < high_soc:
+           charge at full rate.
+        5. Otherwise: hold (power setpoint = 0).
+
+    The SOC thresholds (high_soc, low_soc) prevent over-charging or over-discharging
+    during moderate price signals, while still allowing full charge/discharge when
+    prices move outside the expected DA range.
+
+    Note:
+        Charging power is represented as negative values, matching the convention
+        used at the Hercules/hybrid_plant level.
     """
 
     def __init__(self, interface, input_dict, controller_parameters={}, verbose=True):
@@ -165,6 +190,27 @@ def __init__(self, interface, input_dict, controller_parameters={}, verbose=True
         self.rated_power_charging = input_dict["battery"]["charge_rate"]
         self.rated_power_discharging = input_dict["battery"]["discharge_rate"]
 
+        # Save the duration rounded to nearest hour
+        self.duration = round(
+            interface.plant_parameters["battery"]["energy_capacity"]
+            / interface.plant_parameters["battery"]["power_capacity"]
+        )
+
+        # Raise if duration makes this controller implausible
+        if self.duration >= 12:
+            raise ValueError(
+                f"Battery duration is {self.duration} hours, which is not "
+                "supported by BatteryPriceSOCController."
+                " This controller is only intended for durations shorter than 12 hours."
+            )
+
+        if self.duration < 1:
+            raise ValueError(
+                f"Battery duration is {self.duration} hours, which is not "
+                "supported by BatteryPriceSOCController."
+                " This controller is only intended for durations of at least 1 hour."
+            )
+
     def set_controller_parameters(
         self,
         high_soc=0.8,
@@ -193,8 +239,8 @@ def compute_controls(self, measurements_dict):
         real_time_lmp = measurements_dict["RT_LMP"]
 
         # Extract limits
-        bottom_4 = sorted_day_ahead_lmps[3]
-        top_4 = sorted_day_ahead_lmps[-4]
+        bottom_d = sorted_day_ahead_lmps[self.duration - 1]
+        top_d = sorted_day_ahead_lmps[-self.duration]
         bottom_1 = sorted_day_ahead_lmps[0]
         top_1 = sorted_day_ahead_lmps[-1]
 
@@ -206,11 +252,11 @@ def compute_controls(self, measurements_dict):
         # will be inverted before passing into the battery modules
         if real_time_lmp > top_1:
             power_setpoint = self.rated_power_discharging
-        elif (real_time_lmp > top_4) & (soc < self.high_soc):
+        elif (real_time_lmp > top_d) & (soc > self.low_soc):
             power_setpoint = self.rated_power_discharging
         elif real_time_lmp < bottom_1:
             power_setpoint = -self.rated_power_charging
-        elif (real_time_lmp < bottom_4) & (soc > self.low_soc):
+        elif (real_time_lmp < bottom_d) & (soc < self.high_soc):
             power_setpoint = -self.rated_power_charging
         else:
             power_setpoint = 0.0

tests/battery_test.py

@@ -18,6 +18,8 @@ def test_BatteryPriceSOCController_init(test_hercules_dict):
 
 
 def test_BatteryPriceSOCController_compute_controls(test_hercules_dict):
+    # This test originally written assuming 4-hour battery
+
     test_interface = HerculesInterface(test_hercules_dict)
 
     # Initialize controller
@@ -30,10 +32,10 @@ def test_BatteryPriceSOCController_compute_controls(test_hercules_dict):
     DA_LMP_test = [i for i in range(24)]  # Price is from 0 to 23
 
     # Test the high soc condition when RT_LMP is below the charge price
-    # but above the low_soc_price
+    # but above the low_soc_price.  SOC is too high to justify charging.
     measurement_dict = {
         "battery": {"state_of_charge": 0.9},
-        "RT_LMP": 3,
+        "RT_LMP": 2.5,
         "DA_LMP_24hours": DA_LMP_test,
     }
     controls_dict = test_controller.compute_controls(measurement_dict)
@@ -44,9 +46,9 @@ def test_BatteryPriceSOCController_compute_controls(test_hercules_dict):
     controls_dict = test_controller.compute_controls(measurement_dict)
     assert controls_dict["power_setpoint"] == -test_controller.rated_power_charging
 
-    # Test the high SOC conditions
+    # Test the high price / low soc condition
     measurement_dict = {
-        "battery": {"state_of_charge": 0.9},
+        "battery": {"state_of_charge": 0.1},
         "RT_LMP": 22,
         "DA_LMP_24hours": DA_LMP_test,
     }
@@ -73,3 +75,37 @@ def test_BatteryPriceSOCController_compute_controls(test_hercules_dict):
     measurement_dict["RT_LMP"] = 10
     controls_dict = test_controller.compute_controls(measurement_dict)
     assert controls_dict["power_setpoint"] == 0.0
+
+
+def test_BatteryPriceSOCController_compute_controls_2_hour_duration(test_hercules_dict):
+    # Set the duration to 2 hours
+    test_hercules_dict["battery"]["energy_capacity"] = 20.0e3
+    test_interface = HerculesInterface(test_hercules_dict)
+
+    # Initialize controller
+    test_controller = BatteryPriceSOCController(test_interface, test_hercules_dict)
+
+    # For testing, overwrite the high_soc and low_soc
+    test_controller.high_soc = 0.8
+    test_controller.low_soc = 0.2
+
+    DA_LMP_test = [i for i in range(24)]  # Price is from 0 to 23
+
+    # Test the in-between bottom 1 and bottom d prices
+    measurement_dict = {
+        "battery": {"state_of_charge": 0.5},
+        "RT_LMP": 0.5,
+        "DA_LMP_24hours": DA_LMP_test,
+    }
+    controls_dict = test_controller.compute_controls(measurement_dict)
+    assert controls_dict["power_setpoint"] == -test_controller.rated_power_charging
+
+    # Now raise the state of charge to 0.85
+    measurement_dict["battery"]["state_of_charge"] = 0.85
+    controls_dict = test_controller.compute_controls(measurement_dict)
+    assert controls_dict["power_setpoint"] == 0.0
+
+    # Now drop the RT_LMP to -.5 (Going below bottom 1 price)
+    measurement_dict["RT_LMP"] = -0.5
+    controls_dict = test_controller.compute_controls(measurement_dict)
+    assert controls_dict["power_setpoint"] == -test_controller.rated_power_charging