PhD Thesis - Energy Systems Research Unit - University of Strathclyde

The i value is checked to see if it corresponds with either of the recharge start
times. If not, the vehicle battery is discharged in a similar manner to the other
vehicles. If the battery charge goes below zero, and fast recharging is not
allowed, the transport demand that can be met with the available charge is
calculated and the available battery charge is set to zero. If fast refueling is
allowed, the electricity required to fully recharge the battery is calculated in kW
rather than kWh, using Equation 5.14. This gives the electricity supply rate
required to fully recharge the battery over the available timestep interval in kW,
which can be directly compared to the available supply.
required (kW) = (maxkWh – tank) x timesteps per hour (5.14)
Likewise, when this electricity supply is used to add charge to the battery, the
electricity supply in kW must be divided by the timesteps per hour to find the
storage value (kWh) that can be added to the tank in that timestep interval, as
shown in Equation 5.15.
tank (kWh) = tank + (fuel supply / timesteps per hour) (5.15)
In reality, the recharge would probably take less time than the full timestep
interval, but in dealing with, mainly, half-hourly timesteps, there is a necessary
averaging out of all supply data [4]. To avoid this, a greater number of
timesteps per hour may be chosen, but this only makes sense if other electricity
supply profiles and climate data are also available at that frequency.
If the slow recharge is to start, or continue as the level has not reached 100%
and there is no demand, the percentage charge of the battery must be checked.
If this is below the bulk percentage level, the percentage charge increases at a
constant rate, and this does not vary with the percentage charge in the battery.
Therefore, the required energy supply rate is constant, and calculated using
Equation 5.16.
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