Fix exclusion-bound target direction

Signed-off-by: Mathias L. Baumann <mathias.baumann@frequenz.com>

Author: Marenz

RELEASE_NOTES.md

@@ -11,3 +11,6 @@ This release updates the microgrid component graph library to v0.6.0, which stop
   - Producer power used to clamp each producer at zero. A producer that draws power now adds a positive value instead of zero, so the total can be positive. For example, PV producing 10 kW and a CHP drawing 2 kW used to give -10 kW and now give -8 kW. There is one exception: when the two share a meter below the grid meter, that meter sends data, and `disable_fallback_components` is off, the meter measures them together, so they gave -8 kW before too. `producer.power.min(Power.zero()).build("producer_power")` clamps the total at zero, but it still differs from the old result when one producer draws power while another produces.
   - With `ComponentGraphConfig(include_phantom_loads_in_consumer_formula=True)`, consumer power is unchanged: it still clamps each of its terms at zero.
 
+## Bug Fixes
+
+* Make the PowerManager fall back to zero instead of changing the requested power direction when a target is snapped outside asymmetric exclusion bounds.

src/frequenz/sdk/microgrid/_power_managing/_shifting_matryoshka.py

@@ -40,9 +40,14 @@ def _get_nearest_possible_power(
         case (None, p) | (p, None) if p:
             return p
         case (low, high) if low and high:
-            if high - power < power - low:
-                return high
-            return low
+            # The exclusion bounds are a region where the system cannot operate.
+            nearest = high if high - power < power - low else low
+            # Never turn a request into power in the opposite direction.
+            if (power > Power.zero() and nearest < Power.zero()) or (
+                power < Power.zero() and nearest > Power.zero()
+            ):
+                return Power.zero()
+            return nearest
         case _:
             return Power.zero()
 
@@ -197,9 +202,10 @@ def _calc_targets(  # pylint: disable=too-many-branches,too-many-statements
 
         if allocations:
             _logger.info(
-                "PowerManager allocations for component IDs: %s: %s",
+                "PowerManager allocations for component IDs: %s: %s, target power: %s",
                 sorted(component_ids),
                 allocations,
+                target_power,
             )
 
         return target_power, Bounds[Power](lower=lower_bound, upper=upper_bound)

tests/actor/_power_managing/test_shifting_matryoshka.py

@@ -6,6 +6,7 @@
 # pylint: disable=duplicate-code
 
 import asyncio
+import logging
 import re
 from datetime import datetime, timedelta, timezone
 
@@ -397,6 +398,45 @@ async def test_matryoshka_with_excl_3() -> None:
     tester.bounds(priority=0, expected_power=-50.0, expected_bounds=(-60.0, 5.0))
 
 
+@pytest.mark.parametrize(
+    ("requested_power", "exclusion_bounds", "expected_power"),
+    [
+        (-3.0, (-35.0, 7.0), 0.0),
+        (3.0, (-7.0, 35.0), 0.0),
+        (-30.0, (-35.0, 7.0), -35.0),
+    ],
+)
+async def test_matryoshka_avoids_opposite_direction_outside_exclusion_bounds(
+    caplog: pytest.LogCaptureFixture,
+    requested_power: float,
+    exclusion_bounds: tuple[float, float],
+    expected_power: float,
+) -> None:
+    """Avoid targets that would snap to the opposite direction."""
+    batteries = frozenset({ComponentId(2), ComponentId(5)})
+    system_bounds = _base_types.SystemBounds(
+        timestamp=datetime.now(tz=timezone.utc),
+        inclusion_bounds=timeseries.Bounds(
+            lower=Power.from_watts(-200.0), upper=Power.from_watts(200.0)
+        ),
+        exclusion_bounds=timeseries.Bounds(
+            lower=Power.from_watts(exclusion_bounds[0]),
+            upper=Power.from_watts(exclusion_bounds[1]),
+        ),
+    )
+    tester = StatefulTester(batteries, system_bounds)
+
+    with caplog.at_level(logging.INFO):
+        tester.tgt_power(
+            priority=1,
+            power=requested_power,
+            bounds=(-200.0, 200.0),
+            expected=expected_power,
+        )
+
+    assert f"target power: {expected_power:g} W" in caplog.messages[-1]
+
+
 async def test_matryoshka_drop_old_proposals() -> None:
     """Tests for the power managing actor.