ElectricVehicle¶

An ElectricVehicle models a vehicle in a fleet: a Battery that leaves on trips. While it's parked and plugged in, it charges, and with vehicle-to-grid (V2G) it can also feed power back, always through a Charger. The optimizer decides when each vehicle charges and discharges, so that every trip leaves with enough charge at the lowest cost.

A fleet is a much smaller scale than the site the other pages build, so this page and the Charger page use a depot of two delivery vans over a 12-hour shift, in hourly steps from 06:00. Powers and energies are still in MW and MWh, so a 22 kW charger is 0.022.

Basic usage¶

from datetime import timedelta

from odys import Battery, ElectricVehicle, ElectricVehicleFinalState, ElectricVehicleInitialState, Trip

van_1 = ElectricVehicle(
    name="van_1",
    battery=Battery(
        capacity=0.100,  # 100 kWh
        max_charge_power=0.022,  # 22 kW
        max_discharge_power=0.011,  # 11 kW V2G
        efficiency_charging=0.95,
        efficiency_discharging=0.95,
    ),
    trips=(
        Trip(
            name="morning_delivery",
            start_time=timedelta(hours=2),  # leaves at 08:00
            end_time=timedelta(hours=4),  # back at 10:00
            energy_consumption=0.030,  # 30 kWh
            min_soc_at_departure=0.8,
        ),
    ),
)
initial_conditions = (ElectricVehicleInitialState(vehicle=van_1, soc=0.5),)
final_conditions = (ElectricVehicleFinalState(vehicle=van_1, soc=0.5),)

van_1 starts the shift half charged, has to leave at 08:00 with at least 80 %, and has to be back at 50 % at the end of the shift. Both states go to the EnergySystem, with initial_conditions=... and final_conditions=... (see Initial and final state).

Fields¶

Vehicle-to-grid (V2G)¶

The battery's max_discharge_power decides whether a vehicle can feed power back. Above 0, it can discharge, at up to that power; at 0.0, it can only charge. Either way, power flows only while the vehicle is connected to a charger, so V2G goes through the charger too. van_1 above can give back up to 11 kW. See B-2 and CH-4.

Trips¶

A Trip says when the vehicle is away, how much energy it uses, and how full it has to be when it leaves:

Trip times count from the start of the run, not from a clock time. With the shift starting at 06:00, a second van's afternoon route from 12:00 to 15:00 starts 6 hours in and ends 9 hours in:

van_2 = ElectricVehicle(
    name="van_2",
    battery=Battery(
        capacity=0.100,
        max_charge_power=0.022,
        max_discharge_power=0.011,
        efficiency_charging=0.95,
        efficiency_discharging=0.95,
    ),
    trips=(
        Trip(
            name="afternoon_route",
            start_time=timedelta(hours=6),
            end_time=timedelta(hours=9),
            energy_consumption=0.040,
            min_soc_at_departure=0.7,
        ),
    ),
)

Here's what a trip means for the plan:

• The vehicle is away from start_time until end_time. In that time it can't charge, discharge, or hold a charger, and it can charge again from the step that starts at end_time.
• The trip's energy leaves the battery evenly over the steps it's away: van_2's 40 kWh over three steps is 0.133 of its capacity per step.
• The battery has at least min_soc_at_departure when the vehicle leaves, before the trip uses any energy. It also stays above soc_min while driving, so a trip has to fit in the charge the vehicle can leave with.
• Trips of one vehicle can't overlap; building the vehicle raises an OdysValidationError if they do. Trip times also have to fall on a step and end within the run, which is checked when you create the EnergySystem: with 15-minute steps, a trip can leave at 45 minutes but not at 50.

See EV-1 to EV-3 and CH-3.

Initial and final state¶

A vehicle takes an ElectricVehicleInitialState, which is required, and optionally an ElectricVehicleFinalState. They work like any battery's, under State of charge.

One check is particular to vehicles: a trip that leaves at the very start of the run (start_time=timedelta(0)) has no step before it to charge in. So creating the ElectricVehicleInitialState raises an OdysValidationError when the starting charge can't serve that trip, because it's below the trip's min_soc_at_departure, or holds less energy above soc_min than the trip uses.

Their fields are on the Battery page, under State of charge.

Results¶

A vehicle's results are in result.electric_vehicles: net_power, soc and charge_mode, one pandas.Series each, indexed by vehicle and time. They read like any battery's, under Results. The vans can't charge yet, so the depot is solved on the Charger page, once it has one. The Depot Charging with V2G example runs three vans and two chargers over a full day.

How it's modelled¶

A vehicle is a battery, B-1 to B-7, plus its trips: EV-1 takes the trip's energy out of the battery, EV-2 stops charging on the road, and EV-3 checks the charge at departure. Its power reaches the bus only through a charger (CH-1 to CH-4). Every rule and its limitations are on the Electric vehicles and chargers formulation page.

Next steps¶

The vans can't charge yet: they need a charger. Next, see how a Charger connects them to the grid, and solve the depot's day.