Add SIPM inference

pvfit/modeling/ac/sipm/inference.py

@@ -0,0 +1,54 @@
+"""
+Sandia Inverter Performance Model (SIPM) inference.
+
+https://energy.sandia.gov/wp-content/gallery/uploads/Performance-Model-for-Grid-Connected-Photovoltaic-Inverters.pdf
+
+WARNING: This code is experimental and not subject to semantic versioning.
+"""
+
+import numpy
+from scipy.optimize import least_squares
+
+
+def fit(*, Vdc, Pdc, Pac, Vdco, Paco, Pnt):
+    """
+    Use least squares to fit the parameters of the Sandia Array Performance Model.
+    """
+    efficiency = numpy.amax(Pac / Pdc)
+
+    # Construct IC vector for fit. [C0, C1, C2, C3, Pdco, Pso]
+    x0 = numpy.array([0, 0, 0, 0, Paco / efficiency, 0.1 * Paco])
+
+    # Inline these functions here for transformed model, with closures over data.
+    def fun(x):
+        deltaV = Vdc - Vdco
+        A = x[4] * (1 + x[1] * deltaV)
+        B = x[5] * (1 + x[2] * deltaV)
+        C = x[0] * (1 + x[3] * deltaV)
+        AminusB = A - B
+        PdcminusB = Pdc - B
+        return ((Paco / AminusB) - C * AminusB) * PdcminusB + C * PdcminusB**2 - Pac
+
+    # Compute fit.
+    sol = least_squares(
+        fun,
+        x0,
+        method="dogbox",
+        jac="3-point",
+        max_nfev=10000 * x0.size,
+        bounds=([-numpy.inf, -numpy.inf, -numpy.inf, -numpy.inf, 0.0, 0.0], numpy.inf),
+    )
+
+    model_params_fit = {
+        "Paco": Paco,
+        "Pdco": sol.x[4],
+        "Vdco": Vdco,
+        "Pso": sol.x[5],
+        "C0": sol.x[0],
+        "C1": sol.x[1],
+        "C2": sol.x[2],
+        "C3": sol.x[3],
+        "Pnt": Pnt,
+    }
+
+    return {"model_params_fit": model_params_fit, "sol": sol}

pvfit/modeling/ac/sipm/inference_test.py

@@ -0,0 +1,5 @@
+"""Sandia Inverter Performance Model (SIPM) inference tests."""
+
+
+def test_package_import():
+    import pvfit.modeling.ac.sipm.inference

pvfit/modeling/ac/sipm/simulation.py

@@ -1,5 +1,5 @@
 """
-Sandia Inverter Performance Model (SIPM)
+Sandia Inverter Performance Model (SIPM) simulation.
 
 https://energy.sandia.gov/wp-content/gallery/uploads/Performance-Model-for-Grid-Connected-Photovoltaic-Inverters.pdf
 

pvfit/modeling/ac/sipm/simulation_test.py

@@ -0,0 +1,5 @@
+"""Sandia Inverter Performance Model (SIPM) simulation tests."""
+
+
+def test_package_import():
+    import pvfit.modeling.ac.sipm.simulation