ABB HiPerGuard MV UPS User Manual page 26

In this configuration, typically one generator first livens the generator bus and the other generators
synchronize and connect to this bus. Generators are in isochronous frequency-control mode, also known
as Island Forming mode. In this mode, for multiple parallel generators to share load equally they typically
employ frequency droop and have an overriding controller which adjusts the generators' frequency
reference to regulate the frequency to nominal.
The MV UPS adaptive walk-in is designed to work with this configuration. As soon as the first generator
livens the generator bus once the voltage and frequency are within specification the UPS(s) will connect
to the bus. Once the MV UPSs are connected, their adaptive walk-in algorithm will support the generator
bus by not letting the frequency drop below 98% of the nominal frequency. As individual generators
continue to connect to the bus, they will ramp in load to regulate the frequency back to the nominal.
Once enough generators are supplying load then the bus will eventually regulate to the nominal
frequency.
3.2.6. Automatic bypass operation
In case of an expected or unexpected HiPerGuard MV UPS shutdown, the load current is transferred to
the automatic bypass breaker. The MV switchgear acts as the primary system bypass, and its operation
is fully controlled by the MV UPS, while the MV UPS control switch located on the switchgear is in "UPS
Control" mode.
The rated current for the automatic bypass breaker will be the same as the rated current of the MV
switchgear (rating is project dependent, please refer to specific project switchgear documentation for
more information). During the bypass operation, the MV UPS synchronizes the load output voltage to
the MV UPS input voltage and then closes the automatic bypass breaker. After confirming that the
automatic bypass breaker is closed, the MV UPS opens the input and output breakers.
In the very unlikely event where the UPS is not capable of synchronizing the output voltage to the input
voltage, the bypass will still automatically close, as the closing logic is embedded in the switchgear.
When this occurs, a slight phase shift between the input and output voltages is expected during the
operation. This phase shift is unlikely to have an impact on the load.
3.2.7. Power Exchanger interface
This section defines the MV UPS system controller interface towards a third-party Demand Response
Controller (DRC). The Power Exchanger functionality is an optional feature, identified by a number on the
order code. Please refer to chapter 4 for more information. Always refer to the local grid
standards/regulations before implementing Power Exchanger controls.
The next sub-chapters will also provide a guideline to what a third-party DRC must consider and how the
system will operate in different scenarios. The Power Exchanger functionality is only available when the
MV UPS is operating in Power Conditioning Mode. The Power Exchanger related settings is preferrable
transmitted over Modbus TCP communications, alternatively an I/O device can be used.
HI PE RG UA RD M V UP S U S E R M A N UA L
P RO DU C T D ES C R IP T I ON
26/103