invest_nonconvex_flow_examples.diesel_genset_nonconvex_investment

Complexity

Total Complexity

5

Size/Duplication

Total Lines	501
Duplicated Lines	0 %

Importance

Changes

0

1 Function

Rating	Name	Duplication	Size	Complexity
C	main()	0	449	5

# -*- coding: utf-8 -*-

"""
General description
-------------------
This example illustrates the combination of Investment and NonConvex options
applied to a diesel generator in a hybrid mini-grid system.

There are the following components:

    - pv: solar potential to generate electricity
    - diesel_source: input diesel for the diesel genset
    - diesel_genset: generates ac electricity
    - rectifier: converts generated ac electricity from the diesel genset
                 to dc electricity
    - inverter: converts generated dc electricity from the pv to ac electricity
    - battery: stores the generated dc electricity
    - demand_el: ac electricity demand (given as a separate *.csv file)
    - excess_el: allows for some electricity overproduction



Installation requirements
-------------------------
This example requires the version v0.5.x of oemof.solph. Install by:

    pip install 'oemof.solph>=0.5,<0.6'

"""

__copyright__ = "oemof developer group"
__license__ = "MIT"

import numpy as np
import os
import pandas as pd
import time
from datetime import datetime, timedelta
from oemof import solph
import warnings

try:
    import matplotlib.pyplot as plt
except ImportError:
    plt = None


def main():
    ##########################################################################
    # Initialize the energy system and calculate necessary parameters
    ##########################################################################

    # Start time for calculating the total elapsed time.
    start_simulation_time = time.time()

    start = "2022-01-01"

    # The maximum number of days depends on the given *.csv file.
    n_days = 10
    n_days_in_year = 365

    # Create date and time objects.
    start_date_obj = datetime.strptime(start, "%Y-%m-%d")
    start_date = start_date_obj.date()
    start_datetime = datetime.combine(
        start_date_obj.date(), start_date_obj.time()
    )
    end_datetime = start_datetime + timedelta(days=n_days)

    # Import data.
    filename = os.path.join(os.getcwd(), "solar_generation.csv")
    try:
        data = pd.read_csv(filename)
    except FileNotFoundError:
        msg = "Data file not found: {0}. Only one value used!"
        warnings.warn(msg.format(filename), UserWarning)
        data = pd.DataFrame({"pv": [0.3], "wind": [0.6], "demand_el": [500]})

    # Change the index of data to be able to select data based on the time
    # range.
    data.index = pd.date_range(start="2022-01-01", periods=len(data), freq="H")

    # Choose the range of the solar potential and demand
    # based on the selected simulation period.
    solar_potential = data.SolarGen.loc[start_datetime:end_datetime]
    hourly_demand = data.Demand.loc[start_datetime:end_datetime]
    peak_solar_potential = solar_potential.max()
    peak_demand = hourly_demand.max()

    # Create the energy system.
    date_time_index = solph.create_time_index(
        number=n_days * 24, start=start_date
    )
    energysystem = solph.EnergySystem(
        timeindex=date_time_index, infer_last_interval=False
    )

    # -------------------- BUSES --------------------
    # Create electricity and diesel buses.
    b_el_ac = solph.buses.Bus(label="electricity_ac")
    b_el_dc = solph.buses.Bus(label="electricity_dc")
    b_diesel = solph.buses.Bus(label="diesel")

    # -------------------- SOURCES --------------------
    diesel_cost = 0.65  # currency/l
    diesel_density = 0.846  # kg/l
    diesel_lhv = 11.83  # kWh/kg
    diesel_source = solph.components.Source(
        label="diesel_source",
        outputs={
            b_diesel: solph.flows.Flow(
                variable_costs=diesel_cost / diesel_density / diesel_lhv
            )
        },
    )

    # EPC stands for the equivalent periodical costs.
    epc_pv = 152.62  # currency/kW/year
    pv = solph.components.Source(
        label="pv",
        outputs={
            b_el_dc: solph.flows.Flow(
                fix=solar_potential / peak_solar_potential,
                nominal_value=None,
                investment=solph.Investment(
                    ep_costs=epc_pv * n_days / n_days_in_year
                ),
                variable_costs=0,
            )
        },
    )

    # -------------------- TRANSFORMERS --------------------
    # The diesel genset assumed to have a fixed efficiency of 33%.

    # The output power of the diesel genset can only vary between
    # the given minimum and maximum loads, which represent the fraction
    # of the optimal capacity obtained from the optimization.

    epc_diesel_genset = 84.80  # currency/kW/year
    variable_cost_diesel_genset = 0.045  # currency/kWh
    min_load = 0.2
    max_load = 1.0
    diesel_genset = solph.components.Transformer(
        label="diesel_genset",
        inputs={b_diesel: solph.flows.Flow()},
        outputs={
            b_el_ac: solph.flows.Flow(
                nominal_value=None,
                variable_costs=variable_cost_diesel_genset,
                min=min_load,
                max=max_load,
                investment=solph.Investment(
                    ep_costs=epc_diesel_genset * n_days / n_days_in_year,
                    maximum=2 * peak_demand,
                ),
                nonconvex=solph.NonConvex(),
            )
        },
        conversion_factors={b_el_ac: 0.33},
    )

    # The rectifier assumed to have a fixed efficiency of 98%.
    epc_rectifier = 62.35  # currency/kW/year
    rectifier = solph.components.Transformer(
        label="rectifier",
        inputs={
            b_el_ac: solph.flows.Flow(
                nominal_value=None,
                investment=solph.Investment(
                    ep_costs=epc_rectifier * n_days / n_days_in_year
                ),
                variable_costs=0,
            )
        },
        outputs={b_el_dc: solph.flows.Flow()},
        conversion_factor={
            b_el_dc: 0.98,
        },
    )

    # The inverter assumed to have a fixed efficiency of 98%.
    epc_inverter = 62.35  # currency/kW/year
    inverter = solph.components.Transformer(
        label="inverter",
        inputs={
            b_el_dc: solph.flows.Flow(
                nominal_value=None,
                investment=solph.Investment(
                    ep_costs=epc_inverter * n_days / n_days_in_year
                ),
                variable_costs=0,
            )
        },
        outputs={b_el_ac: solph.flows.Flow()},
        conversion_factor={
            b_el_ac: 0.98,
        },
    )

    # -------------------- STORAGE --------------------
    epc_battery = 101.00  # currency/kWh/year
    battery = solph.components.GenericStorage(
        label="battery",
        nominal_storage_capacity=None,
        investment=solph.Investment(
            ep_costs=epc_battery * n_days / n_days_in_year
        ),
        inputs={b_el_dc: solph.flows.Flow(variable_costs=0)},
        outputs={
            b_el_dc: solph.flows.Flow(investment=solph.Investment(ep_costs=0))
        },
        initial_storage_level=0.0,
        min_storage_level=0.0,
        max_storage_level=1.0,
        balanced=True,
        inflow_conversion_factor=0.9,
        outflow_conversion_factor=0.9,
        invest_relation_input_capacity=1,
        invest_relation_output_capacity=0.5,
    )

    # -------------------- SINKS --------------------
    demand_el = solph.components.Sink(
        label="electricity_demand",
        inputs={
            b_el_ac: solph.flows.Flow(
                fix=hourly_demand / peak_demand,
                nominal_value=peak_demand,
            )
        },
    )

    excess_el = solph.components.Sink(
        label="excess_el",
        inputs={b_el_dc: solph.flows.Flow()},
    )

    # Add all objects to the energy system.
    energysystem.add(
        pv,
        diesel_source,
        b_el_dc,
        b_el_ac,
        b_diesel,
        inverter,
        rectifier,
        diesel_genset,
        battery,
        demand_el,
        excess_el,
    )

    ##########################################################################
    # Optimise the energy system
    ##########################################################################

    # The higher the MipGap or ratioGap, the faster the solver would converge,
    # but the less accurate the results would be.
    solver_option = {"gurobi": {"MipGap": "0.02"}, "cbc": {"ratioGap": "0.02"}}
    solver = "cbc"

    model = solph.Model(energysystem)
    model.solve(
        solver=solver,
        solve_kwargs={"tee": True},
        cmdline_options=solver_option[solver],
    )

    # End of the calculation time.
    end_simulation_time = time.time()

    ##########################################################################
    # Process the results
    ##########################################################################

    results = solph.processing.results(model)

    results_pv = solph.views.node(results=results, node="pv")
    results_diesel_source = solph.views.node(
        results=results, node="diesel_source"
    )
    results_diesel_genset = solph.views.node(
        results=results, node="diesel_genset"
    )
    results_inverter = solph.views.node(results=results, node="inverter")
    results_rectifier = solph.views.node(results=results, node="rectifier")
    results_battery = solph.views.node(results=results, node="battery")
    results_demand_el = solph.views.node(
        results=results, node="electricity_demand"
    )
    results_excess_el = solph.views.node(results=results, node="excess_el")

    # -------------------- SEQUENCES (DYNAMIC) --------------------
    # Hourly demand profile.
    sequences_demand = results_demand_el["sequences"][
        (("electricity_ac", "electricity_demand"), "flow")
    ]

    # Hourly profiles for solar potential and pv production.
    sequences_pv = results_pv["sequences"][(("pv", "electricity_dc"), "flow")]

    # Hourly profiles for diesel consumption and electricity production
    # in the diesel genset.
    # The 'flow' from oemof is in kWh and must be converted to
    # kg by dividing it by the lower heating value and then to
    # liter by dividing it by the diesel density.
    sequences_diesel_consumption = (
        results_diesel_source["sequences"][
            (("diesel_source", "diesel"), "flow")
        ]
        / diesel_lhv
        / diesel_density
    )

    # Hourly profiles for electricity production in the diesel genset.
    sequences_diesel_genset = results_diesel_genset["sequences"][
        (("diesel_genset", "electricity_ac"), "flow")
    ]

    # Hourly profiles for excess ac and dc electricity production.
    sequences_excess = results_excess_el["sequences"][
        (("electricity_dc", "excess_el"), "flow")
    ]

    # -------------------- SCALARS (STATIC) --------------------
    capacity_diesel_genset = results_diesel_genset["scalars"][
        (("diesel_genset", "electricity_ac"), "invest")
    ]

    # Define a tolerance to force 'too close' numbers to the `min_load`
    # and to 0 to be the same as the `min_load` and 0.
    tol = 1e-8
    load_diesel_genset = sequences_diesel_genset / capacity_diesel_genset
    sequences_diesel_genset[np.abs(load_diesel_genset) < tol] = 0
    sequences_diesel_genset[np.abs(load_diesel_genset - min_load) < tol] = (
        min_load * capacity_diesel_genset
    )
    sequences_diesel_genset[np.abs(load_diesel_genset - max_load) < tol] = (
        max_load * capacity_diesel_genset
    )

    capacity_pv = results_pv["scalars"][(("pv", "electricity_dc"), "invest")]
    capacity_inverter = results_inverter["scalars"][
        (("electricity_dc", "inverter"), "invest")
    ]
    capacity_rectifier = results_rectifier["scalars"][
        (("electricity_ac", "rectifier"), "invest")
    ]
    capacity_battery = results_battery["scalars"][
        (("electricity_dc", "battery"), "invest")
    ]

    total_cost_component = (
        (
            epc_diesel_genset * capacity_diesel_genset
            + epc_pv * capacity_pv
            + epc_rectifier * capacity_rectifier
            + epc_inverter * capacity_inverter
            + epc_battery * capacity_battery
        )
        * n_days
        / n_days_in_year
    )

    # The only componnet with the variable cost is the diesl genset
    total_cost_variable = (
        variable_cost_diesel_genset * sequences_diesel_genset.sum(axis=0)
    )

    total_cost_diesel = diesel_cost * sequences_diesel_consumption.sum(axis=0)
    total_revenue = (
        total_cost_component + total_cost_variable + total_cost_diesel
    )
    total_demand = sequences_demand.sum(axis=0)

    # Levelized cost of electricity in the system in currency's Cent per kWh.
    lcoe = 100 * total_revenue / total_demand

    # The share of renewable energy source used to cover the demand.
    res = (
        100
        * sequences_pv.sum(axis=0)
        / (sequences_diesel_genset.sum(axis=0) + sequences_pv.sum(axis=0))
    )

    # The amount of excess electricity (which must probably be dumped).
    excess_rate = (
        100
        * sequences_excess.sum(axis=0)
        / (sequences_excess.sum(axis=0) + sequences_demand.sum(axis=0))
    )

    ##########################################################################
    # Print the results in the terminal
    ##########################################################################

    print("\n" + 50 * "*")
    print(
        f"Simulation Time:\t {end_simulation_time-start_simulation_time:.2f} s"
    )
    print(50 * "*")
    print(f"Peak Demand:\t {sequences_demand.max():.0f} kW")
    print(f"LCOE:\t\t {lcoe:.2f} cent/kWh")
    print(f"RES:\t\t {res:.0f}%")
    print(f"Excess:\t\t {excess_rate:.1f}% of the total production")
    print(50 * "*")
    print("Optimal Capacities:")
    print("-------------------")
    print(f"Diesel Genset:\t {capacity_diesel_genset:.0f} kW")
    print(f"PV:\t\t {capacity_pv:.0f} kW")
    print(f"Battery:\t {capacity_battery:.0f} kW")
    print(f"Inverter:\t {capacity_inverter:.0f} kW")
    print(f"Rectifier:\t {capacity_rectifier:.0f} kW")
    print(50 * "*")

    ##########################################################################
    # Plot the duration curve for the diesel genset
    ##########################################################################

    if plt is not None:

        # Create the duration curve for the diesel genset.
        fig, ax = plt.subplots(figsize=(10, 5))

        # Sort the power generated by the diesel genset in descending order.
        diesel_genset_duration_curve = np.sort(sequences_diesel_genset)[::-1]

        percentage = (
            100
            * np.arange(1, len(diesel_genset_duration_curve) + 1)
            / len(diesel_genset_duration_curve)
        )

        ax.scatter(
            percentage,
            diesel_genset_duration_curve,
            color="dodgerblue",
            marker="+",
        )

        # Plot a horizontal line representing the minimum load
        ax.axhline(
            y=min_load * capacity_diesel_genset,
            color="crimson",
            linestyle="--",
        )
        min_load_annotation_text = (
            f"minimum load: {min_load * capacity_diesel_genset:0.2f} kW"
        )
        ax.annotate(
            min_load_annotation_text,
            xy=(100, min_load * capacity_diesel_genset),
            xytext=(0, 5),
            textcoords="offset pixels",
            horizontalalignment="right",
            verticalalignment="bottom",
        )

        # Plot a horizontal line representing the maximum load
        ax.axhline(
            y=max_load * capacity_diesel_genset,
            color="crimson",
            linestyle="--",
        )
        max_load_annotation_text = (
            f"maximum load: {max_load * capacity_diesel_genset:0.2f} kW"
        )
        ax.annotate(
            max_load_annotation_text,
            xy=(100, max_load * capacity_diesel_genset),
            xytext=(0, -5),
            textcoords="offset pixels",
            horizontalalignment="right",
            verticalalignment="top",
        )

        ax.set_title(
            "Duration Curve for the Diesel Genset Electricity Production",
            fontweight="bold",
        )
        ax.set_ylabel("diesel genset production [kW]")
        ax.set_xlabel("percentage of annual operation [%]")

        # Create the second axis on the right side of the diagram
        # representing the operation load of the diesel genset.
        second_ax = ax.secondary_yaxis(
            "right",
            functions=(
                lambda x: x / capacity_diesel_genset * 100,
                lambda x: x * capacity_diesel_genset / 100,
            ),
        )
        second_ax.set_ylabel("diesel genset operation load [%]")

        plt.show()


if __name__ == "__main__":
    main()