Add examples

examples/activity_costs/activity_costs.py

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+# -*- coding: utf-8 -*-
+
+"""
+General description
+-------------------
+This example illustrates the effect of activity_costs.
+
+There are the following components:
+
+    - demand_heat: heat demand (constant, for the sake of simplicity)
+    - fireplace: wood firing, burns "for free" if somebody is around
+    - boiler: gas firing, consumes (paid) gas
+
+Notice that activity_costs is an attribute to NonConvex.
+This is because it relies on the activity status of a component
+which is only available for nonconvex flows.
+
+
+Installation requirements
+-------------------------
+
+This example requires oemof.solph (v0.5.x), install by:
+
+    pip install oemof.solph[examples]
+
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+import pandas as pd
+
+from oemof import solph
+
+
+##########################################################################
+# Calculate parameters and initialize the energy system and
+##########################################################################
+
+periods = 24
+time = pd.date_range('1/1/2018', periods=periods, freq='H')
+
+demand_heat = np.full(periods, 5)
+demand_heat[:4] = 0
+demand_heat[4:18] = 4
+
+activity_costs = np.full(periods, 5)
+activity_costs[18:] = 0
+
+es = solph.EnergySystem(timeindex=time)
+
+b_heat = solph.Bus(label='b_heat')
+
+es.add(b_heat)
+
+sink_heat = solph.components.Sink(
+    label='demand',
+    inputs={b_heat: solph.Flow(fix=demand_heat, nominal_value=1)})
+
+fireplace = solph.components.Source(
+    label='fireplace',
+    outputs={b_heat: solph.Flow(nominal_value=3,
+                                variable_costs=0,
+                                nonconvex=solph.NonConvex(
+                                    activity_costs=activity_costs))})
+
+boiler = solph.components.Source(
+    label='boiler',
+    outputs={b_heat: solph.Flow(nominal_value=10,
+                                variable_costs=1)})
+
+es.add(sink_heat, fireplace, boiler)
+
+##########################################################################
+# Optimise the energy system
+##########################################################################
+
+# create an optimization problem and solve it
+om = solph.Model(es)
+
+# solve model
+om.solve(solver='cbc', solve_kwargs={'tee': True})
+
+##########################################################################
+# Check and plot the results
+##########################################################################
+
+results = solph.processing.results(om)
+
+# plot data
+data = solph.views.node(results, 'b_heat')['sequences']
+ax = data.plot(kind='line', drawstyle='steps-post', grid=True, rot=0)
+ax.set_xlabel('Time')
+ax.set_ylabel('Heat (arb. units)')
+plt.show()