# Minimal and maximal runtime¶

## Constraining uptime and downtime of plants¶

### General description¶

Example that illustrates how to model min and max runtimes.

### Code¶

Download source code: `min_max_runtimes.py`

Click to display code
```from matplotlib import pyplot as plt

from oemof import solph

def main():
# Create demand data
demand_el = [0] * 24
for n in [10, 15, 19]:
demand_el[n] = 1

# create an energy system
idx = solph.create_time_index(2017, number=24)
es = solph.EnergySystem(timeindex=idx, infer_last_interval=False)

# power bus and components
bel = solph.Bus(label="bel")

demand_el = solph.components.Sink(
label="demand_el",
inputs={bel: solph.Flow(fix=demand_el, nominal_value=10)},
)

dummy_el = solph.components.Sink(
label="dummy_el", inputs={bel: solph.Flow(variable_costs=10)}
)

pp1 = solph.components.Source(
label="plant_min_down_constraints",
outputs={
bel: solph.Flow(
nominal_value=10,
min=0.5,
max=1.0,
variable_costs=10,
nonconvex=solph.NonConvex(
minimum_downtime=4, initial_status=0
),
)
},
)

pp2 = solph.components.Source(
label="plant_min_up_constraints",
outputs={
bel: solph.Flow(
nominal_value=10,
min=0.5,
max=1.0,
variable_costs=10,
nonconvex=solph.NonConvex(minimum_uptime=2, initial_status=1),
)
},
)

# create an optimization problem and solve it
om = solph.Model(es)

# debugging
# om.write('problem.lp', io_options={'symbolic_solver_labels': True})

# solve model
om.solve(solver="cbc", solve_kwargs={"tee": True})

# create result object
results = solph.processing.results(om)

# plot data
data = solph.views.node(results, "bel")["sequences"]
data[[(("bel", "demand_el"), "flow"), (("bel", "dummy_el"), "flow")]] *= -1
exclude = ["dummy_el", "status"]
columns = [
c
for c in data.columns
if not any(s in c[0] or s in c[1] for s in exclude)
]
data = data[columns]
fig, ax = plt.subplots(figsize=(10, 5))
data.plot(ax=ax, kind="line", drawstyle="steps-post", grid=True, rot=0)
ax.set_xlabel("Hour")
ax.set_ylabel("P [MW]")
plt.legend(loc="upper center", bbox_to_anchor=(0.5, 1.3), ncol=1)
plt.show()

if __name__ == "__main__":
main()
```

### Installation requirements¶

This example requires oemof.solph (v0.5.x), install by:

```pip install oemof.solph[examples]
```