Add terse links for gradient-based calculation using graph-based collection definition

ard/collection/optiwindnet_wrap.py

@@ -4,13 +4,23 @@
 import numpy as np
 
 from optiwindnet.mesh import make_planar_embedding
-from optiwindnet.interarraylib import L_from_site
+from optiwindnet.interarraylib import L_from_site, calcload
 from optiwindnet.heuristics import EW_presolver
 from optiwindnet.MILP import OWNWarmupFailed, solver_factory, ModelOptions
 
 from . import templates
 
 
+def _S_from_terse_links(terse_links, **kwargs):
+    T = terse_links.shape[0]
+    S = nx.Graph(T=T, R=abs(terse_links.min()), **kwargs)
+    S.add_edges_from(tuple(zip(range(T), terse_links)))
+    calcload(S)
+    if "capacity" not in kwargs:
+        S.graph["capacity"] = S.graph["max_load"]
+    return S
+
+
 def _own_L_from_inputs(inputs: dict, discrete_inputs: dict) -> nx.Graph:
     # get the metadata and data for the OWN warm-starter from the inputs
     T = len(inputs["x_turbines"])
@@ -122,6 +132,9 @@ class OptiwindnetCollection(templates.CollectionTemplate):
     -------
     total_length_cables : float
         the total length of cables used in the collection system network
+    terse_links : np.ndarray
+        a 1D numpy int array encoding the electrical connections of the collection
+        system (tree topology), with length `N_turbines`
 
     Discrete Outputs
     -------
@@ -134,9 +147,6 @@ class OptiwindnetCollection(templates.CollectionTemplate):
         length `N_turbines`
     max_load_cables : int
         the maximum cable capacity required by the collection system
-    terse_links : np.ndarray
-        a 1D numpy int array encoding the electrical connections of the collection
-        system (tree topology), with length `N_turbines`
     """
 
     def initialize(self):
@@ -156,6 +166,13 @@ def setup_partials(self):
             ["x_turbines", "y_turbines", "x_substations", "y_substations"],
             method="exact",
         )
+        self.declare_partials(
+            ["terse_links"],
+            ["x_turbines", "y_turbines", "x_substations", "y_substations"],
+            method="exact",
+            val=0.0,
+            dependent=False,
+        )
 
     def compute(
         self,
@@ -254,14 +271,14 @@ def compute(
         # pack and ship
         self.graph = G
         discrete_outputs["graph"] = G  # TODO: remove for terse links, below!
-        discrete_outputs["terse_links"] = terse_links
         discrete_outputs["length_cables"] = length_cables
         discrete_outputs["load_cables"] = load_cables
         discrete_outputs["max_load_cables"] = S.graph["max_load"]
         # TODO: remove this assert after enough testing
         assert (
             abs(length_cables.sum() - G.size(weight="length")) < 1e-7
         ), f"difference: {length_cables.sum() - G.size(weight='length')}"
+        outputs["terse_links"] = terse_links
         outputs["total_length_cables"] = length_cables.sum()
 
     def compute_partials(self, inputs, J, discrete_inputs=None):

ard/collection/templates.py

@@ -108,8 +108,8 @@ def setup(self):
 
         # set up outputs for the collection system
         self.add_output("total_length_cables", 0.0, units="m")
+        self.add_output("terse_links", np.full((self.N_turbines,), -1))
         self.add_discrete_output("length_cables", np.zeros((self.N_turbines,)))
-        self.add_discrete_output("terse_links", np.full((self.N_turbines,), -1))
         self.add_discrete_output("load_cables", np.zeros((self.N_turbines,)))
         self.add_discrete_output("max_load_cables", 0.0)
         self.add_discrete_output("graph", None)

ard/cost/orbit_wrap.py

@@ -12,11 +12,13 @@
 from ORBIT.core.library import default_library
 from ORBIT.core.library import initialize_library
 
+from ard.collection.optiwindnet_wrap import _S_from_terse_links
+from ard.collection.optiwindnet_wrap import _own_L_from_inputs
 from ard.cost.wisdem_wrap import ORBIT_setup_latents
 
 
 def generate_orbit_location_from_graph(
-    graph,  # TODO: replace with a terse_links representation
+    terse_links,
     X_turbines,
     Y_turbines,
     X_substations,
@@ -57,6 +59,10 @@ def generate_orbit_location_from_graph(
         if the recursive setup seems to be stuck in a loop
     """
 
+    # create graph from terse links
+    tlm = np.astype(terse_links, np.int_)
+    graph = _S_from_terse_links(tlm)
+
     # get all edges, sorted by the first node then the second node
     edges_to_process = [edge for edge in graph.edges]
     edges_to_process.sort(key=lambda x: (x[0], x[1]))
@@ -209,7 +215,9 @@ def initialize(self):
         super().initialize()
 
         self.options.declare("case_title", default="working")
-        self.options.declare("modeling_options")
+        self.options.declare(
+            "modeling_options", types=dict, desc="Ard modeling options"
+        )
         self.options.declare("approximate_branches", default=False)
 
     def setup(self):
@@ -287,7 +295,7 @@ def setup(self):
         self.N_substations = self.modeling_options["layout"]["N_substations"]
 
         # bring in collection system design
-        self.add_discrete_input("graph", None)
+        self.add_input("terse_links", np.full((self.N_turbines,), -1))
 
         # add the detailed turbine and substation locations
         self.add_input("x_turbines", np.zeros((self.N_turbines,)), units="km")
@@ -359,7 +367,7 @@ def compile_orbit_config_file(
 
         # generate the csv data needed to locate the farm elements
         generate_orbit_location_from_graph(
-            discrete_inputs["graph"],
+            inputs["terse_links"],
             inputs["x_turbines"],
             inputs["y_turbines"],
             inputs["x_substations"],
@@ -430,7 +438,7 @@ def setup(self):
                 "total_capex_kW",
                 "bos_capex",
                 "installation_capex",
-                "graph",
+                "terse_links",
                 "x_turbines",
                 "y_turbines",
                 "x_substations",
@@ -443,3 +451,17 @@ def setup(self):
         # connect
         for key in variable_mapping.keys():
             self.connect(key, f"orbit.{key}")
+
+    def setup_partials(self):
+
+        self.declare_partials(
+            "*",
+            "*",
+            method="fd",
+            step=1.0e-5,
+            form="central",
+            step_calc="rel_avg",
+        )
+        self.declare_partials(
+            "terse_links", "*", method="exact", val=0.0, dependent=False
+        )

test/ard/unit/collection/test_optiwindnet.py

@@ -129,6 +129,7 @@ def test_modeling(self, subtests):
             # make sure that the outputs in the component match what we planned
             output_list = [k for k, v in self.collection.list_outputs()]
             for var_to_check in [
+                "terse_links",
                 "total_length_cables",
             ]:
                 assert var_to_check in output_list
@@ -141,7 +142,6 @@ def test_modeling(self, subtests):
                 "length_cables",
                 "load_cables",
                 "max_load_cables",
-                "terse_links",
             ]:
                 assert var_to_check in discrete_output_list
 

test/ard/unit/collection/test_templates.py

@@ -78,6 +78,7 @@ def test_setup(self):
             for var_to_check in [
                 "length_cables",
                 "load_cables",
+                "terse_links",
                 "total_length_cables",
                 "max_load_cables",
             ]:
@@ -87,9 +88,7 @@ def test_setup(self):
             discrete_output_list = [
                 k for k, v in self.coll_temp._discrete_outputs.items()
             ]
-            for var_to_check in [
-                "terse_links",
-            ]:
+            for var_to_check in []:
                 assert var_to_check in discrete_output_list
 
     def test_compute(self):

test/ard/unit/cost/test_orbit_wrap.py

@@ -144,7 +144,7 @@ def test_raise_error(self):
                 "y_substations",
             ],
         )
-        model.connect("collection.graph", "orbit.graph")
+        model.connect("collection.terse_links", "orbit.terse_links")
 
         model.set_input_defaults(
             "x_turbines", modeling_options["layout"]["x_turbines"], units="km"
@@ -328,7 +328,7 @@ def test_baseline_farm(self, subtests):
                 "y_substations",
             ],
         )
-        model.connect("collection.graph", "orbit.graph")
+        model.connect("collection.terse_links", "orbit.terse_links")
 
         model.set_input_defaults(
             "x_turbines", modeling_options["layout"]["x_turbines"], units="km"
@@ -525,7 +525,7 @@ def setup_method(self):
                 "y_substations",
             ],
         )
-        self.model.connect("collection.graph", "orbit.graph")
+        self.model.connect("collection.terse_links", "orbit.terse_links")
 
         self.model.set_input_defaults(
             "x_turbines", self.modeling_options["layout"]["x_turbines"], units="km"