Storage level constraint¶

Constrain inflows and outflows to storage level¶

General description¶

Example that shows the storage_level_constraint.

Code¶

Download source code: storage_level_constraint.py

Click to display code

import pandas as pd
from oemof.solph import Bus, EnergySystem, Flow, Model
from oemof.solph.components import GenericStorage, Source, Sink
from oemof.solph.processing import results

import matplotlib.pyplot as plt
import pandas as pd

from oemof.solph import Bus
from oemof.solph import EnergySystem
from oemof.solph import Flow
from oemof.solph import Model
from oemof.solph.components import GenericStorage
from oemof.solph.components import Sink
from oemof.solph.components import Source
from oemof.solph.constraints import storage_level_constraint
from oemof.solph.processing import results


def storage_level_constraint_example():
    es = EnergySystem(
        timeindex=pd.date_range("2022-01-01", freq="1H", periods=24),
        infer_last_interval=True,
    )

    multiplexer = Bus(
        label="multiplexer",
    )

    storage = GenericStorage(
        label="storage",
        nominal_capacity=3,
        initial_storage_level=1,
        balanced=True,
        loss_rate=0.05,
        inputs={multiplexer: Flow()},
        outputs={multiplexer: Flow()},
    )

    es.add(multiplexer, storage)

    in_0 = Source(
        label="in_0",
        outputs={multiplexer: Flow(nominal_capacity=0.5, variable_costs=0.15)},
    )
    es.add(in_0)

    in_1 = Source(
        label="in_1", outputs={multiplexer: Flow(nominal_capacity=0.1)}
    )
    es.add(in_1)

    out_0 = Sink(
        label="out_0",
        inputs={multiplexer: Flow(nominal_capacity=0.25, variable_costs=-0.1)},
    )
    es.add(out_0)

    out_1 = Sink(
        label="out_1",
        inputs={multiplexer: Flow(nominal_capacity=0.15, variable_costs=-0.1)},
    )
    es.add(out_1)

    model = Model(es)

    storage_level_constraint(
        model=model,
        name="multiplexer",
        storage_component=storage,
        multiplexer_bus=multiplexer,
        input_levels={in_1: 1 / 3},  # in_0 is always active
        output_levels={out_0: 1 / 6, out_1: 1 / 2},
    )
    model.solve()

    my_results = results(model)

    df = pd.DataFrame(my_results[(storage, None)]["sequences"])
    df["in1_status"] = my_results[(in_1, None)]["sequences"]
    df["out1_status"] = my_results[(out_1, None)]["sequences"]
    df["out0_status"] = my_results[(out_0, None)]["sequences"]

    df["in1"] = my_results[(in_1, multiplexer)]["sequences"]
    df["in0"] = my_results[(in_0, multiplexer)]["sequences"]
    df["out0"] = my_results[(multiplexer, out_0)]["sequences"]
    df["out1"] = my_results[(multiplexer, out_1)]["sequences"]

    plt.step(df.index, df["in0"], where="post", label="inflow (<= 1)")
    plt.step(df.index, df["in1"], where="post", label="inflow (< 1/3)")
    plt.step(df.index, df["out0"], where="post", label="outflow (> 1/6)")
    plt.step(df.index, df["out1"], where="post", label="outflow (> 1/2)")

    plt.grid()
    plt.legend()
    plt.ylabel("Flow Power (arb. units)")
    plt.ylim(0, 0.5)

    plt.twinx()

    plt.plot(df.index, df["storage_content"], "k--", label="storage content")
    plt.ylim(0, 3)
    plt.legend(loc="center right")
    plt.ylabel("Stored Energy (arb. units)")

    print(df)

    plt.show()


if __name__ == "__main__":
    storage_level_constraint_example()

Installation requirements¶

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

pip install oemof.solph[examples] matplotlib

License¶