Add information if a unit transformation was performed for the composite schedule calculation

[Matthias-NIDEC]

OCPP Version

OCPP1.6

Describe the problem

1. On business logic site there is no information if the resulting period.limit is converted, meaning query unit != resulting profile.limit.unit

In order to query get_all_composite_charging_schedules a unit information is required or if optional it is [A] selected.

If a transformation was performed it is on business logic not clear, if the resulting period.limit is modified:
e.g.

• query with unit [A]: underlying winning period is [W], result is period.limit/Internal.SupplyVoltage and transformation happened
• query with unit [W]: underlying winning period is [A], result is profile*Internal.SupplyVoltage and transformation happened

If on return it is cleared that a transformation happened, the query can be reperformed with the winning profile unit.

Use Case:
With this modification it is possible to do Current [A] based limitation on business logic site.

Describe your solution

1. Discussion in the weekly call identified:
   Add the limit.unit to the EnhancedChargingSchedulePeriod as additional information. On return compare the winning.limit.unit to the query.unit, if both are the same, return true, otherwise false.

See PR: #909

2. Extend the call interface get_all_composite_charging_schedules with a Vector of the acting Voltages [V] present for each Connector.

Optional:

Additional context

No response

[Matthias-NIDEC]

Explanation:
In order to limit the charging power by a charging profile TxProfile/DefaultProfile, there are two possibilities from CSMS site w.r.t. Unit:

1) The CSMS set charging profile with chargingRateUnit [W]. A query from business logic with Watt, will deliver the limitation. The information can be used onwards, to limit the Current [A] by knowing the charging Voltage [V] car vice.

2) The CSMS set charging profile with chargingRateUnit [A]. A query from business logic with unit [W], will transform the profile information to [W], using the Internal.SupplyVoltage [V] value. This value does not reflect the charging Voltage [V] car vice, and thus, the [W] limitation is wrong if used with another Voltage [V], then the conversion Internal.SupplyVoltage [V] and can not be used.
A workaround [WA1] would be set the Internal.SupplyVoltage [V] to the charging Voltage [V] car vice before the query to result in the [W] profile.
Another change would be to use as proposed a boolean indicator, that the profile result is based on a transformation. With this information, the business logic can decide, if it queries again with the alternate Unit [A]. Then, it can continue and recalculate w.r.t. its charging Voltage [V] to a power [W] limitation value.
With the help of the bool indicator, it can be returned that a conversion happened, and the original profile unit can be queried again. The conversion responsible is then moved to the business logic.