V2G Control / Bi-directional Charging

[junknik]

Hi,

Firstly a quick thank you to all of those involved in the project; I just installed the OCPP add-on and it appears that my charger has connected to it :)

After the installation of OCPP I noticed that the amount of data available is quite comprehensive. In particular I was interested by charger.Energy.Active.Export.register and charger.Power.Active>Export, which seemed to indicate that bi-directional chargers may be supported? We have a Quasar bi-directional charger and so this looked promising. It appears as though the current flowing to(from) the charger is set by charger.Maximum_Current. In the Wallbox app for the Quasar this figure can be set between -32A and 32A to allow control of discharging as well as charging. In the OCPP control the values are from 0 to 32A (understandably!) I am not sure but wondered whether modification of this control to allow a negative current to be set would allow me to set discharging on the Quasar. Would it be difficult to modify this?
I am happy to try out any modifications or debug things, but before I started exploring the code I thought I would ask in case such feature was already a WIP.

Thank you!

Neil

[drc38]

It'll be interesting to see what is supported with V2X use and the Quasar charger, change the min_value=0 in number.py

When you have it working we can look at how we include in the codebase, perhaps an if statement based on whether an export measurand is selected on setup.

[junknik]

I have been using the Quasar for quite a while through the app and as part of a trial. My experience with it so far is that you can set the discharge rate that you would like through the app and it gets actioned straight away. Will take a look at the logs ......

[junknik]

Hi, I don't think that the discharge current is related to a battery temperature or conditioning issue - using the Wallbox app the desired discharge current is reached almost immediately. I turned on a higher level of debugging for the OCPP component, and think that I can see at least part of the issue. When setting a positive current (6A) two messages are sent, the first failing and the second one is accepted thus

2022-06-03 15:08:05 DEBUG (MainThread) [custom_components.ocpp] Get Configuration for ChargeProfileMaxStackLevel: 1
2022-06-03 15:08:05 INFO (MainThread) [ocpp] WallboxQuasar: send [2,"430cb035-144c-461a-b56c-52bbd9c26153","SetChargingProfile",{"connectorId":0,"csChargingProfiles":{"chargingProfileId":8,"stackLe
vel":1,"chargingProfileKind":"Relative","chargingProfilePurpose":"ChargePointMaxProfile","chargingSchedule":{"chargingRateUnit":"A","chargingSchedulePeriod":[{"startPeriod":0,"limit":6.0}]}}}]
2022-06-03 15:08:05 INFO (MainThread) [ocpp] WallboxQuasar: receive message [3,"430cb035-144c-461a-b56c-52bbd9c26153",
{
"status": "Rejected"
}]
2022-06-03 15:08:05 DEBUG (MainThread) [custom_components.ocpp] ChargePointMaxProfile is not supported by this charger, trying TxDefaultProfile instead...
2022-06-03 15:08:05 INFO (MainThread) [ocpp] WallboxQuasar: send [2,"c0df942f-288a-409b-bbd1-cae0c53a755a","SetChargingProfile",{"connectorId":0,"csChargingProfiles":{"chargingProfileId":8,"stackLe
vel":0,"chargingProfileKind":"Relative","chargingProfilePurpose":"TxDefaultProfile","chargingSchedule":{"chargingRateUnit":"A","chargingSchedulePeriod":[{"startPeriod":0,"limit":6.0}]}}}]
2022-06-03 15:08:05 INFO (MainThread) [ocpp] WallboxQuasar: receive message [3,"c0df942f-288a-409b-bbd1-cae0c53a755a",
{
"status": "Accepted"
}]

When I send a negative current (-6A) they both get rejected

2022-06-03 15:09:02 INFO (MainThread) [ocpp] WallboxQuasar: send [2,"e8a83593-8a9f-46e3-b230-bd389e687cdb","SetChargingProfile",{"connectorId":0,"csChargingProfiles":{"chargingProfileId":8,"stackLe
vel":1,"chargingProfileKind":"Relative","chargingProfilePurpose":"ChargePointMaxProfile","chargingSchedule":{"chargingRateUnit":"A","chargingSchedulePeriod":[{"startPeriod":0,"limit":-6.0}]}}}]
2022-06-03 15:09:02 INFO (MainThread) [ocpp] WallboxQuasar: receive message [3,"e8a83593-8a9f-46e3-b230-bd389e687cdb",
{
"status": "Rejected"
}]
2022-06-03 15:09:02 DEBUG (MainThread) [custom_components.ocpp] ChargePointMaxProfile is not supported by this charger, trying TxDefaultProfile instead...
2022-06-03 15:09:02 INFO (MainThread) [ocpp] WallboxQuasar: send [2,"55da52d8-ca5c-4370-b321-a1ebe5ed7081","SetChargingProfile",{"connectorId":0,"csChargingProfiles":{"chargingProfileId":8,"stackLe
vel":0,"chargingProfileKind":"Relative","chargingProfilePurpose":"TxDefaultProfile","chargingSchedule":{"chargingRateUnit":"A","chargingSchedulePeriod":[{"startPeriod":0,"limit":-6.0}]}}}]
2022-06-03 15:09:03 INFO (MainThread) [ocpp] WallboxQuasar: receive message [3,"55da52d8-ca5c-4370-b321-a1ebe5ed7081",
{
"status": "Rejected"
}]
2022-06-03 15:09:03 WARNING (MainThread) [custom_components.ocpp] Failed with response: Rejected

However it has some affect on the charger as it does start to discharge, albeit at the -6A rate no matter what current limit I specify. I know that the discharge rate can at least be set to -32A, and I believe controlled as the charger is being controlled via OCPP on the trial that I am part of. Perhaps I need to investigate the OCPP spec?

[drc38]

Worth seeing if you can "sniff" a successful message from the official app or look at its ocpp documentation. Otherwise it will be a process of trial and error based on the official ocpp spec.

Also look through the configuration keys in case a custom key is being used for setting the V2X current. It could also be set through a custom data transfer message.

[drc38]

You can also try changing the ChargingingProfileKind to TxProfile.

[junknik]

Hi, Thanks for the ideas. I don't think that the official app uses OCPP to communicate with the charger; though I guess it is still worth checking. The URL for the OCCP 'server' on the trial starts WSS, so I am assuming that that is a secure (encrypted) link, though I could still take a look. Will also ask about any official documentation!

[desolina-nz]

Hi @junknik , just wondering if you got any further with this? I'm about to start on the same journey. I have a Quasar with the latest firmware and about to try to connect to my local HA server over OCPP. Did you fix the issue with discharging past -6A?

[desolina-nz]

Yes that works. Setting a number between 6 and 32 will result in a successful discharge at that rate. If I try to set a negative number, I get the warning "Warning: Set charging profile failed with response Rejected"

[desolina-nz]

(I just made the first change you suggested ChargingProfilePurposeType.tx_profile.value I have not tried the second change of relative to absolute)

[desolina-nz]

Do I need to put an if statement in there to switch between tx_profile and charge_point_max_profile depending if the inputed max charge rate is negative or positive? Sorry, I'm not much of a software engineer!

[drc38]

You can do, are you sure it is as simple as changing the profile to switch between charging and discharging?

[desolina-nz]

yeah not really sure! I've got modbus control working pretty well now so might stick to that. Thanks for your help though! Happy to test any changes in the future to the OCPP integration for V2G.