Use fuse in GridMetadata

This commit uses a Fuse object to represent the max current limit in
component metadata in the internal layer that parses component objects
obtained directly from the Microgrid API. This makes the abstraction of
fuses one level deeper, increasing the chances of the `grid_connection.py`
file being more stable in the future if/when further changes are
introduced in the Microgrid API.

Signed-off-by: Tiyash Basu <[email protected]>

Author: tiyash-basu-frequenz

src/frequenz/sdk/microgrid/component/_component.py

@@ -6,13 +6,17 @@
 from __future__ import annotations
 
 import typing
+from abc import ABC
 from dataclasses import dataclass
 from enum import Enum
 
 import frequenz.api.common.components_pb2 as components_pb
 import frequenz.api.microgrid.grid_pb2 as grid_pb
 import frequenz.api.microgrid.inverter_pb2 as inverter_pb
 
+from ...timeseries import Current
+from ..fuse import Fuse
+
 
 class ComponentType(Enum):
     """A base class from which individual component types are derived."""
@@ -107,29 +111,41 @@ def _component_category_from_protobuf(
     return ComponentCategory(component_category)
 
 
-class ComponentMetadata:
+class ComponentMetadata(ABC):
     """Base class for component metadata classes."""
 
+    @property
+    def fuse(self) -> Fuse | None:
+        """Get the fuse associated with this component.
+
+        Returns:
+            The fuse associated with this component.
+        """
+        return None
+
 
 class GridMetadata(ComponentMetadata):
     """Metadata for a grid connection point."""
 
-    def __init__(self, max_current: float) -> None:
+    def __init__(self, fuse: Fuse) -> None:
         """Create a new instance.
 
         Args:
-            max_current: maximum current rating of the grid connection point in amps.
+            fuse: The fuse at the grid connection point.
         """
-        self._max_current = max_current
+        self._fuse = fuse
 
     @property
-    def max_current(self) -> float:
-        """Get the maximum current rating of the grid connection point.
+    def fuse(self) -> Fuse | None:
+        """Get the fuse at the grid connection point.
 
         Returns:
-            Maximum current rating in amps.
+            None, by default.
         """
-        return self._max_current
+        if not isinstance(self, GridMetadata):
+            return None
+
+        return self._fuse
 
     def __eq__(self, other: typing.Any) -> bool:
         """Check if this instance is equal to another.
@@ -138,21 +154,23 @@ def __eq__(self, other: typing.Any) -> bool:
             other: object to compare to.
 
         Returns:
-            `True` if `other` is a `GridMetadata` instance and `max_current` is equal,
+            `True` if `other` is a `GridMetadata` instance and `fuse` is equal,
                 `False` otherwise.
         """
         if not isinstance(other, GridMetadata):
             return False
 
-        return self.max_current == other.max_current
+        return self.fuse == other.fuse
 
 
 def _component_metadata_from_protobuf(
     component_category: components_pb.ComponentCategory.ValueType,
     component_metadata: grid_pb.Metadata,
 ) -> GridMetadata | None:
     if component_category == components_pb.ComponentCategory.COMPONENT_CATEGORY_GRID:
-        return GridMetadata(float(component_metadata.rated_fuse_current))
+        max_current = Current.from_amperes(component_metadata.rated_fuse_current)
+        fuse = Fuse(max_current)
+        return GridMetadata(fuse)
 
     return None
 

src/frequenz/sdk/microgrid/grid.py

@@ -11,7 +11,6 @@
 from dataclasses import dataclass
 from typing import Iterable, Optional
 
-from ..timeseries import Current
 from .component import Component
 from .component._component import ComponentCategory
 from .fuse import Fuse
@@ -36,7 +35,8 @@ def initialize(components: Iterable[Component]) -> None:
 
     Raises:
         RuntimeError: If there is more than 1 grid connection point in the
-            microgrid.
+            microgrid, or if the grid connection point is not initialized,
+            or if the grid connection point does not have a fuse.
     """
     global _GRID  # pylint: disable=global-statement
 
@@ -57,8 +57,14 @@ def initialize(components: Iterable[Component]) -> None:
             f"Expected at most one grid connection, got {grid_connections_count}"
         )
     else:
-        max_current = grid_connections[0].metadata.max_current  # type: ignore
-        fuse = Fuse(Current.from_amperes(max_current))
+        if grid_connections[0].metadata is None:
+            raise RuntimeError("Grid metadata is None")
+
+        fuse = grid_connections[0].metadata.fuse
+
+        if fuse is None:
+            raise RuntimeError("Grid fuse is None")
+
         _GRID = Grid(fuse)
 
 

tests/microgrid/test_client.py

@@ -26,6 +26,7 @@
     InverterType,
     MeterData,
 )
+from frequenz.sdk.microgrid.fuse import Fuse
 from frequenz.sdk.timeseries import Current
 
 from . import mock_api
@@ -125,10 +126,13 @@ async def test_components(self) -> None:
                 Current.from_amperes(123.0),
             )
 
+            grid_max_current = Current.from_amperes(123.0)
+            grid_fuse = Fuse(grid_max_current)
+
             assert set(await microgrid.components()) == {
                 Component(100, ComponentCategory.NONE),
                 Component(
-                    101, ComponentCategory.GRID, None, GridMetadata(max_current=123.0)
+                    101, ComponentCategory.GRID, None, GridMetadata(fuse=grid_fuse)
                 ),
                 Component(104, ComponentCategory.METER),
                 Component(105, ComponentCategory.INVERTER, InverterType.NONE),

tests/microgrid/test_graph.py

@@ -24,6 +24,8 @@
     GridMetadata,
     InverterType,
 )
+from frequenz.sdk.microgrid.fuse import Fuse
+from frequenz.sdk.timeseries import Current
 
 from .mock_api import MockGrpcServer, MockMicrogridServicer
 
@@ -821,8 +823,11 @@ async def test_refresh_from_api(self) -> None:
         servicer.set_connections([(101, 111), (111, 131)])
         await graph.refresh_from_api(client)
 
+        grid_max_current = Current.zero()
+        grid_fuse = Fuse(grid_max_current)
+
         expected = {
-            Component(101, ComponentCategory.GRID, None, GridMetadata(max_current=0.0)),
+            Component(101, ComponentCategory.GRID, None, GridMetadata(fuse=grid_fuse)),
             Component(111, ComponentCategory.METER),
             Component(131, ComponentCategory.EV_CHARGER),
         }
@@ -847,8 +852,9 @@ async def test_refresh_from_api(self) -> None:
         )
         servicer.set_connections([(707, 717), (717, 727), (727, 737), (717, 747)])
         await graph.refresh_from_api(client)
+
         expected = {
-            Component(707, ComponentCategory.GRID, None, GridMetadata(max_current=0.0)),
+            Component(707, ComponentCategory.GRID, None, GridMetadata(fuse=grid_fuse)),
             Component(717, ComponentCategory.METER),
             Component(727, ComponentCategory.INVERTER, InverterType.NONE),
             Component(737, ComponentCategory.BATTERY),

tests/microgrid/test_grid.py

@@ -31,9 +31,12 @@ async def test_grid() -> None:
 
     # validate that the microgrid initialization fails when there are multiple
     # grid connection points.
+    fuse_current = Current.from_amperes(123.0)
+    fuse = Fuse(fuse_current)
+
     components = [
-        Component(1, ComponentCategory.GRID, None, GridMetadata(123.0)),
-        Component(2, ComponentCategory.GRID, None, GridMetadata(345.0)),
+        Component(1, ComponentCategory.GRID, None, GridMetadata(fuse)),
+        Component(2, ComponentCategory.GRID, None, GridMetadata(fuse)),
         Component(3, ComponentCategory.METER),
     ]
 
@@ -48,7 +51,7 @@ async def test_grid() -> None:
 
     # validate that microgrids with one grid connection are accepted.
     components = [
-        Component(1, ComponentCategory.GRID, None, GridMetadata(123.0)),
+        Component(1, ComponentCategory.GRID, None, GridMetadata(fuse)),
         Component(2, ComponentCategory.METER),
     ]