The Open Smart Charging Protocol (OSCP) determines very precisely which messages can be sent by the distribution system operator to the operator and what form these messages should take. When all parties agree about the form taken by these messages, everyone knows which requirements must be met in order to participate in the Smart Charging process. This can be compared to language: if people don’t all speak the same language it’s hard for them to work together, even if they want to achieve the same goal.
How does the Smart Charging Protocol work?
- The distribution system operator (DSO) knows the maximum load of the cable used to charge the electric vehicles. On the basis of weather forecasts and statistical data, the DSO can predict 24 hours in advance how much energy the households and other energy consumers connected to the cable will use every quarter of an hour. Any remaining capacity on the cable can be used to charge electric vehicles. For each cable, the DSO informs the operators that have charging stations on this cable how much capacity they have available per quarter of an hour for the coming 24 hours.
- The operators then decide how they wish to distribute the capacity among the various vehicles. Here they can, for instance, take into account that some vehicles have an almost empty battery or have to continue their journey quickly, while others don’t. They could also take the electricity prices into account. Using many different input sources, they do the calculations to decide the capacity distribution. Then they inform each Local Controller on the cable in question how the vehicles should be controlled.
(NB: The basic principle of Smart Charging is that the operator can always do the calculations in such a way that all vehicles can be recharged in time. If the amount of available power is too small to do this, the DSO must ensure that more cables are laid).
- The Local Controller has been told by the operator how it should control the charging stations and then ensures that this is carried out locally. However, at some moments the Local Controller might not have a link to the operator. In this case the controller must do its own calculations to decide how the vehicles should be controlled. This calculation may be a little less intelligent because the Local Controller does not have all the data available to the operator, but the vehicles will still certainly be charged.
- Finally the vehicle can still make its own plan within the range assigned to it by the Local Controller. If for instance a battery is almost full then a vehicle will usually charge less intensively because this is better for the battery. So at this moment the vehicle does not use all the capacity available to it. In such situations the vehicle can inform the Local Controller that the latter can assign some of this capacity to another vehicle.