Hybrid Electric Vehicle Chargers

In December 2008 the residential module received a preliminary implementation of all-electric and plug-in hybrid-electric vehicle charger loads for inclusion in Diablo (Version 2.0).

EV/PHEV Model

There are only two types of electric vehicles supported:

• ELECTRIC pure electric vehicle with limited range based on battery capacity

• HYBRID hybrid electric vehicle with longer range based on fuel capacity The evcharger simulation is based on demand state profile of the vehicle. When the vehicle is at home, it has a probability of leaving on one of 3 trips, as shown in Figure 1.

• WORK trip to work (standard distance defined by trip.d_work)

• SHORTTRIP random trip up to 50 miles (battery will not be fully discharged)
• LONGTRIP random trip over 50 miles (battery will be discharged up to 25%) but only possible for HYBRID vehicles

When away, the probability of a return is used to determine when the vehicle returns, as shown in Figure 2.

The charger power can have one of three levels:

• LOW 120V/15A charger
• MEDIUM 240V/30A charger
• HIGH 240V/60A charger

The trip distances are used to estimate the battery charge upon return according to the following rules:

1. A work trip discharges the battery depending on whether charge_at_work is defined. If charging at work is allowed, the battery will discharge for 1 trip (back only), otherwise it will discharge for 2 trips (there and back). The assumption at this time is that there is enough charging capacity at work to make the time at work inconsequential.
2. A short trip discharges the battery based on the distance traveled.
3. A long trip discharges the battery to 25%, but is only possible with hybrids.

In all cases, if the trip distance is greater than 50 miles and the car is a hybrid, the discharge will be down to 25%.

Heat fraction ratio is used to calculate the internal gain from plug loads during the heating phase. Note that this heat gain is to the residential indoor air, not the garage air. So the fraction must account for the very weak coupling between the two, if any.

Demand profiles

The format of the demand profile is as follows:

DAYTYPE
DIRTRIP ,DIRTRIP ,...
#.###,#.###,...
#.###,#.###,...
.
.
.
#.###,#.###,...

where

• DAYTYPE is either WEEKDAY or WEEKEND ,
• DIR is either ARR or DEP , and
• TRIP is either HOME , WORK , SHRT , or LONG.

There must be 24 rows of numbers, the numbers must be positive numbers between 0 and 1, and each column must be normalized (they must add up to 1.000 over the 24 hour period).

You may introduce as many DAYTYPE blocks as are supported simultaneously (2 max at this time).

Synopsis

class evcharger {
       (class residential_enduse;)
       enumeration {HIGH=2, MEDIUM=1, LOW=0} charger_type;
       enumeration {HYBRID=1, ELECTRIC=0} vehicle_type;       
       enumeration {WORK=1, HOME=0, UNKNOWN=4294967295} state;       
       double p_go_home[unit/h];
       double p_go_work[unit/h];
       double work_dist[mile];
       double capacity[kWh];
       double charge[unit];
       bool charge_at_work;
       double charge_throttle[unit];
       char1024 demand_profile;
}

Properties

Table 1: Hybrid Electric Vehicle Charger Parameters

Property name	Type	Unit	Description
charger_type	enumeration	none	Charge rate (HIGH, MEDIUM, or LOW)
vehicle_tpe	enumeration	none	Specify if vehicle is hybrid or all electric.
state	enumeration	none	Initial location of the vehicle.
p_go_home	double	unit/h	Probability of vehicle returning home.
p_go_work	double	unit/h	Probability of vehicle leaving to work.
work_dist	double	mile	One way distance traveled between home and work.
capacity	double	kWh	Battery capacity
charge	double	unit	Current battery state of charge, fraction of capacity.
charge_at_work	bool	none	Specify if work charging is available.
charge_throttle	double	unit	Sets fraction of full charge rate.
demand_profile	char1024	none	Demand profile of the vehicle.

Default Evcharger

The minimum definition for an evcharger object is

object evcharger {
}

Evcharger Schedule

The evcharger object can be put on a schedule to control when it is at home, work, or on a trip. This can be done by using a schedule for the p_go_home and p_go_work properties (only control when it is at home or work) or by using the demand_profile property.

Example

module residential;
module tape;

clock {
    timezone PST+8PDT;
    timestamp '2001-07-10 00:00:00';
    stoptime  '2001-07-18 00:00:00'; 
};

object house {
    object evcharger {
        object recorder {
            file charge.csv;
            property charge;
            interval 600;
        };
    };              
}