Communication Between Mv Ups Units In Parallel Configuration - ABB HiPerGuard MV UPS User Manual

6.7. Communication between MV UPS units in parallel
configuration
It is possible to connect two or more MV UPS units in a parallel configuration. The medium voltage input
and output connections of the group are paralleled via the medium voltage switchgear. This enables the
MV UPS system total output power capacity to be increased according to the number of units in parallel,
and to achieve redundancy in the event of a fault with one of the units.
To achieve the required load sharing and fault handling in the parallel group, it is necessary to set up a
communications link between the System Controllers of each of the paralleled units. The APS enclosure
of each MV UPS unit has Ethernet couplers XF2, XF3 installed (Figure 6.12), to enable setup of the parallel
machine communications network. Refer to Figure 6.13.
Figure 6.13: Parallel machine communications network
Figure 6.13 shows 10 HiPerGuard MV UPS units connected in parallel. Note that two network switches
are required (not included on MV UPS scope of supply), each with enough Ethernet ports to support the
number of units in parallel. The "redundant star" network topology is chosen to give a high level of
integrity and enable operation to continue in the event of a single network failure.
The control of the MV UPS units uses a peer-to-peer protocol, which eliminates the possibility of a single
machine failure bringing down the system, which is possible with a master-slave protocol. If any of the
parallel units develops a fault and trips off, the others will seamlessly take over the load.
The two network switches will typically be powered from 24Vdc. It is recommended that they receive
power from separate no-break DC power supplies. This helps to improve the integrity of the system,
enabling communications to continue, even after failure of the power to one of the switches.
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