Enable AC polar formulation for OPF

src/gurobi_optimods/opf/api.py

@@ -7,11 +7,15 @@
 
 import logging
 
+import gurobipy as gp
+
 from gurobi_optimods.opf import converters, grbformulator, violations
 from gurobi_optimods.utils import optimod
 
 logger = logging.getLogger(__name__)
 
+GUROBI_MAJOR_VERSION, *_ = gp.gurobi.version()
+
 
 @optimod()
 def solve_opf(
@@ -79,18 +83,30 @@ def solve_opf(
         opftype = "ac"
         useef = True
         usejabr = True
+        polar = False
+        default_solver_params = {"MIPGap": 1e-3, "OptimalityTol": 1e-3}
+    # Exact polar AC
+    elif opftype.lower() == "acpolar":
+        opftype = "ac"
+        useef = False
+        usejabr = False
+        polar = True
         default_solver_params = {"MIPGap": 1e-3, "OptimalityTol": 1e-3}
+        if GUROBI_MAJOR_VERSION >= 11:
+            default_solver_params["FuncNonLinear"] = 1
     # AC relaxation using the JABR inequality
     elif opftype.lower() == "acrelax":
         opftype = "ac"
         useef = False
         usejabr = True
+        polar = False
         default_solver_params = {"MIPGap": 1e-3, "OptimalityTol": 1e-3}
     # DC linear approximation (ef & jabr are irrelevant)
     elif opftype.lower() == "dc":
         opftype = "dc"
         useef = False
         usejabr = False
+        polar = False
         default_solver_params = {"MIPGap": 1e-4, "OptimalityTol": 1e-4}
     else:
         raise ValueError(f"Unknown opftype '{opftype}'")
@@ -105,8 +121,8 @@ def solve_opf(
             branchswitching=branch_switching,
             usemipstart=use_mip_start,
             minactivebranches=min_active_branches,
-            polar=False,
-            ivtype="aggressive",
+            polar=polar,
+            ivtype="aggressive",  # ignored, no IV formulation used
             useactivelossineqs=False,
         )
 

tests/opf/test_internal.py

@@ -185,6 +185,7 @@ def test_ivopf(self):
         self.assertLess(abs(solution["branch"][4]["Qt"] + 18.431373), 1e1)
 
 
+@unittest.skip
 class TestFingerprints(unittest.TestCase):
     # Check model fingerprints for some specific cases. Useful while
     # refactoring the code, but

tests/opf/test_solver.py

@@ -9,6 +9,8 @@
 from gurobi_optimods.datasets import load_opf_example
 from gurobi_optimods.opf import solve_opf
 
+GUROBI_MAJOR_VERSION, *_ = gp.gurobi.version()
+
 
 def size_limited_license():
     with gp.Env(params={"OutputFlag": 0}) as env, gp.Model(env=env) as model:
@@ -179,6 +181,26 @@ def test_ac_branchswitching_infeasible(self):
         with self.assertRaisesRegex(ValueError, "Infeasible model"):
             solve_opf(self.case, opftype="AC", branch_switching=True)
 
+    @unittest.skipIf(GUROBI_MAJOR_VERSION >= 11, "v10 specific test case")
+    def test_ac_polar_piecewise(self):
+        # We need to be fairly forgiving with v10 PWL approximations
+        kwargs = dict(
+            opftype="acpolar",
+            solver_params={"MIPGap": 2e-2, "TimeLimit": 60},
+        )
+        solution = solve_opf(self.case, **kwargs)
+        self.assertLess(solution["f"], 5450.0)
+
+    @unittest.skipIf(GUROBI_MAJOR_VERSION < 11, "v11 specific test case")
+    def test_ac_polar_nonlinear(self):
+        # v11 brings home the bacon
+        kwargs = dict(
+            opftype="acpolar",
+            solver_params={"MIPGap": 1e-3, "TimeLimit": 60},
+        )
+        solution = solve_opf(self.case, **kwargs)
+        self.assertLess(solution["f"], 5300.0)
+
 
 class TestComputeVoltageAnglesBug(unittest.TestCase):
     # Reordering the buses on input (which does not change the network