Dynamic load balancing

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Required:

The installation must be set to Default Charging Mode.

To implement load balancing effectively, the installation must be set to Default Charging Mode. The current charging mode can be determined using the AvailableCurrentMode value in the installation response:

• 0 indicates Default Charging.
• 1 indicates Scheduled Charging.
• 2 indicates APM (Automatic Power Management).

This guide covers essential topics, including:

• Tracking charger state in real-time
• Retrieving charger and installation data
• Subscribing to the Service Bus for real-time updates
• Adjusting charger current dynamically
• Managing phase switching between 3-phase and 1-phase charging

By following these best practices, integrators can ensure stable, efficient, and optimized charging operations within a Zaptec installation.

Tracking charger state

To effectively manage charging based on energy production, you need to track the chargers state in realtime

Store charger state locally

1. Retrieve charger and installation data

   • Use the Zaptec API to get a list of installations and chargers available to your integration:
     • /api/installation (retrieves installations)
     • /api/chargers (retrieves chargers)
     • /api/installation/{id}/hierarchy (retrieves the hierarchy of chargers within an installation)

2. Connect to the Service Bus for real-time updates

   • Connect to the user group service bus where real-time updates for charger state in your installations/chargers will be provided (Accessible by your user group)
   • Connection details must be retrieved from Zaptec API

info: Service Bus subscriptions expire after 14 days of inactivity.

3. Retrieve charger state from API

   • Use /api/chargers/{id}/state to get the latest charger state.

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   The /chargers/{id}/state endpoint is cached for 15 seconds, meaning real-time tracking should rely on Service Bus events to maintain synchronization.

4. Maintain local state synchronization

   • Use the Service Bus events to update your local system with real-time state changes.

To optimize current control as an integrator you should track below key observations. (list of additional observations)

Subscribing to the service bus

Zaptec offers a message subscription service to keep track of charger state changes dynamically. You can subscribe to charger related messages to receive.

• Charging status updates
• Power consumption data
• session details

To subscribe and set up to service bus please follow the instructions in Zaptec API Message Subscriptions.

Adjusting the charger current

To control the charger's current dynamically, you can use the Zaptec API to update installation settings. This will allow the Zaptec load balancer to act based on the values set.

Refer to the official documentation for API endpoints: Zaptec API Documentation.

To dynamically control the charger’s current based on available current:

1. Use /api/installation to update installation settings.
2. Adjust the Available Charging Current dynamically.
3. The Zaptec Load Balancer will regulate the charging current based on the configured values.

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The available current update will immediately trigger phase balancing and load adjustments for the installation. As a result, charging stations will adapt their phase and current settings, with vehicles responding within approximately five seconds. All chargers in the Zaptec hierarchy are contained within an installation, we advise making changes at the installation level this allows the Zaptec load balancer to allocate current based on values set

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To ensure a stable charging experience, we recommend updating this setting no more than once every 15 minutes. Frequent changes to the charge current and phase may cause the vehicle to interrupt the charging session. Additionally, the available current is always capped at the installation’s configured maximum limit.

3-to-1 Phase switching in zaptec chargers

Zaptec chargers handle phase switching and load balancing differently based on the product type:

• Zaptec Pro supports automatic phase switching between three-phase and single-phase charging, optimizing power allocation dynamically.
• Zaptec Go does not support phase switching and will always deliver the configured phase rotation.
• Zaptec Go 2 can switch from three-phase to wired L1 terminal charging, allowing more flexibility in power allocation.

Phase switching behavior

• Zaptec Pro dynamically adjusts between three-phase and single-phase based on the available current. You can read more here on "3- to 1 phase balancing with Zaptec Pro"
• Zaptec Go 2 will switch phases if required based on wiring and power availability.
• Zaptec Go remains fixed to the configured phase rotation.

Zaptec Pro and Zaptec Go 2 chargers support phase switching between single-phase and three-phase charging to enhance load balancing. This feature helps optimize power allocation in scenarios where total available current fluctuates.

By adjusting the Installation Available current via the API, this will switch between 3 or 1 phase charging depending on availability in Zaptec Pro.

To configure the value at which this switches, the owner of the installation can adjust this via the Zaptec Portal

If the charging current drops below the 3 to 1-phase switch current, the system will switch from three phase to one phase. This can be set by the installer.

You will also see a 'Switches allowed before locking to a single phase' slider, this should also be adjusted depending on how many switches should be allowed in a charging session.