An Essential Combination
As large fleet operators convert their assets to electric, an increasing need to manage how the fleet is charging is going to be required. For example, in British Columbia, Canada, a fleet of 100 vehicles using “slow chargers” will result in a power demand charge of close to $9,000 per month under the BC Hydro Large General Service (LGS) Rate, while the energy cost can be as low as 20% of that. The energy is what is used by the vehicle to perform its duty, the charging power is only a constraint that needs to be managed.
This article explains smart charging as a simple concept that can be adapted to a specific operation to reduce installation capital costs and reduce operating costs by lowering the peak power demand.
Fleet Electrification is not only about the vehicles
One of our previous article touched on the many parameters to consider when decarbonizing a fleet. In most situations, battery electric vehicles will be the best long term solution. In addition to drafting a vehicle transition plan, including a right-sizing strategy, the supporting infrastructure required to enable this electrification is a very important piece of the process. While this is not the main concern during a pilot program due to the small number of electric vehicles, a complete fleet electrification without a charging strategy could potentially increase operating costs to a point it does not make economical sense.
What is smart charging for?
The fundamental reason why unmanaged charging will drive operating cost up is because of the peak power demand. Most utilities will charge industries for the power demand creating an incentive to keep the peak as low as possible.
The example below shows the power demand for a fleet of 35 vehicles charging overnight. In this scenario and under BC Hydro LGS Rate, the cost of power is approximately $3,100 per month while the energy (i.e. the only useful component) cost is $1,400 per month.
Smart charging is a model that can intelligently control the chargers to minimize the peak power. A variety of techniques exists and consists in reducing the power of specific chargers or even switch certain chargers off for a certain period of time.
Reducing Capital Cost – Load Sharing
A peak power demand requires sufficient electrical capacity to supply this peak even if it is for a short period of time. Proper planning of the future needs will help minimize the initial capital cost by reducing the installation capacity. Optimizing the electrical installation will be dependent on the local codes and regulations with regards to software controlled load.
The example below shows how the main feeder cable and potentially the upstream transformer size is reduced by limiting the current capacity. The smart charging system therefore needs to be programmed to model the installation layout to make appropriate decisions in limiting the current. This configuration is often called load sharing and ensure that a group of chargers does not exceed a certain limit.
Reducing Operating Cost – Dynamic Load Management
Smart charging can lower operating costs by reducing the power demand charge from the utility. If smart charging is implemented to charge the fleet of 35 electric vehicles (from the example above) overnight, the cost of power can be reduced by 68% for the same amount of energy delivered. As stated above, only the energy matters for the vehicle to perform its duty. This results in nearly a 50% reduction to the total cost of energy. The larger the fleet, the greater the value smart charging can deliver.
The strategy can go beyond load sharing and specifically assign a charging profile per charger/vehicle depending on a variety of criteria (time of departure, energy needs forecast, battery state of charge, etc.). This is often named dynamic load management.
A very customized solution
In order to effectively minimize peak demand, the intelligence behind the smart charging algorithm needs to include a detailed model of the industry operation. It is easy to reduce the power of a charger, it is more complicated to ensure the vehicle has sufficient energy stored in the battery to operate the next day.
Picea Hoa Technologies Ltd has experts in smart charging who can develop optimized smart charging strategies by leveraging the power of the Hoa Platform.