Question About Sequential ESS Operation Using ESS Cluster

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Hello OpenEMS Community,

I am working on an EMS project for my master thesis using OpenEMS with two ESS modules (ess0 and ess1).

My project requirement is:

  1. ess1 should discharge first (discharge priority)

  2. ess0 should charge first (charge priority)

  3. Only one ESS should discharge at a time

  4. Both ESS modules should not share discharge power simultaneously

  5. When ess1 reaches reserve SoC, ess0 should start discharging

I currently use:

  • ESS Cluster

  • Shared grid meter

  • CSV Direct simulation for load and production

  • ESS power strategy: OPTIMIZE_BY_MOVING_TOWARDS_TARGET

However, from the logs I observe behavior like:

  • initially ess1 discharges,

  • then both ESS modules share power,

  • later ess0 becomes dominant.

This seems to behave more like a virtual aggregated battery, which is not aligned with my requirement.

Is there any way to configure ESS Cluster for:

  • discharge/charge priority,

  • preventing simultaneous discharge,

  • sequential ESS operation?

I would appreciate any suggestions or recommended architecture for implementing this behavior in OpenEMS.

Thank you.