Add tests for startup and shutdown costs

tests/test_flows/test_non_convex_flow.py

@@ -1,60 +1,100 @@
+# -*- coding: utf-8 -*-
+
+"""Tests for Flows with NonConvex attribute
+
+SPDX-FileCopyrightText: Deutsches Zentrum für Luft- und Raumfahrt e.V.
+SPDX-FileCopyrightText: Patrik Schönfeldt
+
+SPDX-License-Identifier: MIT
+"""
+
 import pandas as pd
 
 from oemof import solph
 
 
-def test_initial_status_off():
+def _run_model(flow):
     date_time_index = pd.date_range("1/1/2012", periods=10, freq="h")
     energysystem = solph.EnergySystem(
         timeindex=date_time_index,
         infer_last_interval=True,
     )
-    bus = solph.buses.Bus(label="electricityBus", balanced=False)
+    bus = solph.buses.Bus(label="bus", balanced=False)
     energysystem.add(bus)
 
+    bus.inputs[bus] = flow
+
+    model = solph.Model(energysystem)
+    model.solve()
+
+    return solph.processing.results(model)[(bus, bus)]["sequences"]
+
+
+def test_initial_status_off():
     # negative costs but turned off initially
     flow = solph.flows.Flow(
         nominal_value=10,
         nonconvex=solph.NonConvex(initial_status=0, minimum_downtime=5),
         variable_costs=-1,
     )
-    bus.inputs[bus] = flow
-
-    model = solph.Model(energysystem)
-
-    model.solve()
+    flow_result = _run_model(flow)
 
-    results = solph.processing.results(model)
-
-    assert (
-        results[(bus, bus)]["sequences"]["flow"][:-1] == 5 * [0] + 5 * [10]
-    ).all()
+    assert (flow_result["flow"][:-1] == 5 * [0] + 5 * [10]).all()
 
 
 def test_initial_status_on():
-    date_time_index = pd.date_range("1/1/2012", periods=10, freq="h")
-    energysystem = solph.EnergySystem(
-        timeindex=date_time_index,
-        infer_last_interval=True,
-    )
-    bus = solph.buses.Bus(label="electricityBus", balanced=False)
-    energysystem.add(bus)
-
     # positive costs but turned on initially
     flow = solph.flows.Flow(
         nominal_value=10,
         min=0.5,
         nonconvex=solph.NonConvex(initial_status=1, minimum_uptime=3),
         variable_costs=1,
     )
-    bus.inputs[bus] = flow
+    flow_result = _run_model(flow)
 
-    model = solph.Model(energysystem)
+    assert (flow_result["flow"][:-1] == 3 * [5] + 7 * [0]).all()
+
+
+def test_startup_costs_start_off():
+    price_pattern = [1, 1, 1, -4, 1, 1, 1, -4, 1, 1]
+
+    # startup costs higher then effect of shutting down
+    flow = solph.flows.Flow(
+        nominal_value=10,
+        min=0.1,
+        nonconvex=solph.NonConvex(startup_costs=5, initial_status=0),
+        variable_costs=price_pattern,
+    )
+    flow_result = _run_model(flow)
+
+    assert (flow_result["flow"][:-1] == [0, 0, 0, 10, 1, 1, 1, 10, 0, 0]).all()
 
-    model.solve()
 
-    results = solph.processing.results(model)
+def test_startup_costs_start_on():
+    price_pattern = [1, 1, 1, -4, 1, 1, 1, -4, 1, 1]
+
+    # startup costs higher then effect of shutting down
+    flow = solph.flows.Flow(
+        nominal_value=10,
+        min=0.1,
+        nonconvex=solph.NonConvex(startup_costs=5, initial_status=1),
+        variable_costs=price_pattern,
+    )
+    flow_result = _run_model(flow)
+
+    assert (flow_result["flow"][:-1] == [1, 1, 1, 10, 1, 1, 1, 10, 0, 0]).all()
+
+
+def test_shutdown_costs_start_on():
+    price_pattern = [1, 1, 1, -4, 1, 1, 1, -4, 1, 1]
+
+    # shutdown costs higher then effect of shutting down
+    flow = solph.flows.Flow(
+        nominal_value=10,
+        min=0.1,
+        nonconvex=solph.NonConvex(shutdown_costs=5, initial_status=1),
+        variable_costs=price_pattern,
+    )
+    flow_result = _run_model(flow)
 
-    assert (
-        results[(bus, bus)]["sequences"]["flow"][:-1] == 3 * [5] + 7 * [0]
-    ).all()
+    assert (flow_result["flow"][:-1] == [1, 1, 1, 10, 1, 1, 1, 10, 1, 1]).all()