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

@@ -12,6 +12,9 @@
 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."""
@@ -110,21 +113,23 @@ def _component_category_from_protobuf(
 class ComponentMetadata:
     """Base class for component metadata classes."""
 
+    fuse: Fuse | None = None
+    """The fuse at the grid connection point."""
+
 
 @dataclass(frozen=True)
 class GridMetadata(ComponentMetadata):
     """Metadata for a grid connection point."""
 
-    max_current: float
-    """maximum current rating of the grid connection point in amps."""
-
 
 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 collections.abc import Iterable
 from dataclasses import dataclass
 
-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
@@ -125,13 +126,16 @@ 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),
+                    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
 
@@ -821,6 +823,9 @@ 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)
+
         # Note: we need to add GriMetadata as a dict here, because that's what
         # the ComponentGraph does too, and we need to be able to compare the
         # two graphs.
@@ -829,7 +834,7 @@ async def test_refresh_from_api(self) -> None:
                 101,
                 ComponentCategory.GRID,
                 None,
-                asdict(GridMetadata(max_current=0.0)),  # type: ignore
+                asdict(GridMetadata(fuse=grid_fuse)),  # type: ignore
             ),
             Component(111, ComponentCategory.METER),
             Component(131, ComponentCategory.EV_CHARGER),
@@ -855,12 +860,13 @@ 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,
-                asdict(GridMetadata(max_current=0.0)),  # type: ignore
+                asdict(GridMetadata(fuse=grid_fuse)),  # type: ignore
             ),
             Component(717, ComponentCategory.METER),
             Component(727, ComponentCategory.INVERTER, InverterType.NONE),

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),
     ]