There is no way of representing vehicle charging and discharging processes

[areleu]

Description of the issue

Currently in the ontology we have Charging which is the process of transmitting energy from the grid to a battery. This is insufficient to describe particulars associated with electric vehicles.

Ideas of solution

Plug-in capacity

First we need to expand the definition of power capacity or add a parallel term for objects that are not generators. #1492

After that we can implement a term for plug-in capacity that covers both charging and dischargingof a battery:

• plug-in capacity: A connection capacity is a rated(power?) capacity between a battery and a grid.
  • rated charging capacity : A rated charging capacity is a plug-in capacity directed from grid to battery.
  • rated discharging capacity : A rated discharging capacity is a plug-in capacity directed from battery to grid.

Plug-in Modes

A definition of “Modes” is probably hard to implement. But we can still enrich the ontology with information about vehicle-to-grid (V2G) and grid-to-vehicle (G2V) using the existing model. Currently we have charging

• charging: Charging is an electrical energy transfer where the transferred energy is stored in a battery

Analogously to it we can define discharging :

• discharging: Discharging is an electrical energy transfer where the transferred energy is transmitted from a battery to a grid.

We can define based on this vehicle charging and vehicle-to-grid (I am not sure about the implementation, proably will need to use a owl file axiom)

• vehicle charging: Vehicle charging is a charging whose participant battery is part of an electric vehicle.
• vehicle-to-grid: Vehicle-to-grid is a discharging whose participant battery is part of an electric vehicle.

This is where it gets tricky. Since the EVs are mobile, the modes in which they transfer energy vary depending on their operation. In the case of vehicle charging/vehicle-to-grid the processes can only happen when the vehicle is connected to a charging station, so it must be sitting idle. This means that there is either a parallel process of a vehicle being connected or we allow a energy transfer with no actual energy being transferred ( plug-in process) . See diagram.

Workflow checklist

• I discussed the issue with someone else than me before working on a solution
• I already read the latest version of the workflow for this repository
• The goal of this ontology is clear to me

I am aware that

• every entry in the ontology should have a definition
• classes should arise from concepts rather than from words

[areleu]

@l-emele or @Ludee can you add @fabmio to the group so she can post here if necessary.

[areleu]

@OpenEnergyPlatform/oeo-general-expert-formal-ontology if we were to define a energy transfer process where not actual energy is being transferred. Could this lead to issues?

[stap-m]

I added @fabmio

[l-emele]

@OpenEnergyPlatform/oeo-general-expert-formal-ontology if we were to define a energy transfer process where not actual energy is being transferred. Could this lead to issues?

We already have an issue for this question, see the following issue:

• Usage of participates in #1350

We already discussed this general problem a while ago but decided that for the moment ignore this participates only sometimes for the moment in specific classes until we have developed a general solution.

[areleu]

@OpenEnergyPlatform/oeo-general-expert-formal-ontology if we were to define a energy transfer process where not actual energy is being transferred. Could this lead to issues?

We already have an issue for this question, see the following issue:

* [Usage of `participates in` #1350](https://github.com/OpenEnergyPlatform/ontology/issues/1350)

We already discussed this general problem a while ago but decided that for the moment ignore this participates only sometimes for the moment in specific classes until we have developed a general solution.

In general having has participant seems to be a good general solution but I think this is addressing half of the problem in this case. Being able to express that vehicle is in stand-by and connected to the grid is relevant for mobility scientists, according to @fabmio.

So I was wondering if it would be valid to add a stand-by, waiting or idle process. This would be something like:

stand-by: Stand-by is a process in which a continuant does not change state. (?)

or

stand-by: Stand-by is a process in which a continuant does not participate(is not participant) in any other process. (!?)

The latter kind of implies that this is a special process with maximal one participant. I would call it the null pointer of processes in BFO.

The reason I think this can be a process (or an ocurrent at least) is becasue we can describe it with temporal parts. In a wider sense this process fits good when trying to decribe the History¹ of an object:

At time x power plant A does nothing
At time x + 1 power plant A does nothing
At time x + 2 power plant A does nothing
...
At time x + n power plant A participates in power generation

The exact definition is something that I would extensively discuss because I think this touches on the realm of Foundational ontology. We would be either extending BFO or working around what we have in there. @fabianneuhaus is this something that we could discuss at one of the meetings?

Footnotes

1. BFO_0000182 history elucidation "A history is a process that is the sum of the totality of processes taking place in the spatiotemporal region occupied by a material entity or site, including processes on the surface of the entity or within the cavities to which it serves as host. (axiom label in BFO2 Reference: [138-001])." ↩

[stap-m]

Plug-in Modes

A definition of “Modes” is probably hard to implement. But we can still enrich the ontology with information about vehicle-to-grid (V2G) and grid-to-vehicle (G2V) using the existing model. Currently we have charging: Charging is an electrical energy transfer where the transferred energy is stored in a battery

Analogously to it we can define discharging : Discharging is an electrical energy transfer where the transferred energy is transmitted from a battery to a grid.

We can define based on this vehicle charging and vehicle-to-grid (I am not sure about the implementation, proably will need to use a owl file axiom)

• vehicle charging: Vehicle charging is a charging whose participant battery is part of an electric vehicle.
• vehicle-to-grid: Vehicle-to-grid is a discharging whose participant battery is part of an electric vehicle.

This is also discussed in #1622 and provides a useful extension.

[stap-m]

So I was wondering if it would be valid to add a stand-by, waiting or idle process.

To me these sound like process attributes, e.g. "process states" with individuals stand-by, waiting or idle.

[chrwm]

I ran into the same problem of a missing discharging process.

Your discussion seems leaning towards electrical charging and discharging processes and is already deep-diving into the axioms.
Taking one step back, I'd like to share some thougts on a class hierarchy level, without touching upon the axioms yet.
I see three options:

1. revisit charging definition. In doing so I'd genarelise the charging object from battery to energy storage object, since all other storage types under energy storage object are able to store or release energy.

Move charging directly under energy transfer

Definition proposal:
Charging is an electrical energy transfer where the transferred energy is stored in or removed from a battery an energy storage object.

This solution has the benefit that no charging and discharging processes for heat transfer storage objects and chemical energy transfer storage objects need to be defined.

2. introduce new process discharging under electrical energy transfer: Discharging is an electrical energy transfer where the energy is removed from a battery.

3. Combine 1 and 2: Introduce discharging and charging generally under energy transfer.

charging: Charging is an energy transfer where the transferred energy is stored in an energy storage object.

discharging: Discharging is an energy transfer where the transferred energy is removed from an energy storage object.

[stap-m]

@chrwm charging is currently also discussed in #1622. I think it would be useful to align the discussions. My suggestion is to discuss the general concept first in #1622 and come back to these more specific topics afterwards in this issue.