Operating principle
Depending on the configuration, 1 or 2 "synchronization contactors" are used to disconnect or connect an energy storage unit from or to the DC link. These contactors must be installed in the supply cable to the negative or positive pole.
If the load-break switch is opened, e.g. to perform service work on the DC link, the MOVI-C® CONTROLLER automatically opens the synchronization contactors. The storage can now be switched on again via the load-break switch after completed service work. The final connection via the synchronization contactor can be taken over by the "DC synchronization" operating mode. In this process, the DC link voltage is first adjusted to the storage voltage to prevent any current flow during the switching process. The contactors are then closed so that the storage is now permanently connected to the DC link.
The operating mode can be activated only if the energy storage unit is explicitly selected to be disconnectable in the configuration of the software module. If the energy storage unit cannot be separated from the DC link but is permanently installed, the xStorageConnected output is always "TRUE".
The operating mode checks the switching state of the storage unit using test procedures. The energy storage status reported to the user can have the following states:
- Energy storage unit connected: The energy storage is now connected to the DC link. The result is reliable because a charge test has been performed.
- Energy storage unit not connected: The energy storage unit is not connected to the DC link. The result is reliable because a charge test has been performed.
- State of energy storage unit unknown: The energy storage unit is either connected or disconnected. No charge test has been carried out, therefore the switching state of the contactors cannot be reliably indicated.
INFORMATION
In order to be able to connect storage units with any state of charge, the minimum voltage of the side on which the energy storage unit is located (parameter "Application limit – Minimum voltage A‑side" or "Application limit – Minimum voltage B‑side") must be set to 0 V in the State of charge control configuration menu.
A possible connection topology is illustrated and symbolized in the following figure:
In addition, the connection variant is supported in which an additional synchronization contactor is installed in the positive supply cable of the energy storage unit. This must be configured separately in MOVISUITE®.
The additional contactor is especially necessary if the energy storage unit is to be disconnected from the DC link in all poles (e.g. if a modular residual current device is installed).
