Vsi Vs Virtual Generator - ABB SureWave SFC User Manual

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11.3.1.2 VSI-V/F droop enable
Additionally, the SureWave can operate in parallel and share the load with other energy sources
by enabling the frequency and voltage droops.
Note, when droop enable the frequency and the voltage will change depending on the load.
This is not a recommended operation. VGen with droop is the recommended mode of operation
when running is parallel with other systems.
11.3.2 Virtual generator (VGen) operation mode
The ABB virtual generator mode is a unique operating mode for a power electronic converter
whereby the converter emulates the behavior of a rotary generator and thus interacts with the
power system in the same way as a traditional synchronous machine. This behavior is achieved
purely through power electronic control and there are no large spinning masses.
When set to virtual generator mode, the SureWave SFC ca be operated in two control modes:
11.3.2.1 VGen-V/F
When operated in virtual generator V/F mode, the SFC run as a standalone power source by
tightly controlling its own voltage and frequency. In this setting the SureWave supports the local
loads with minimal disturbance.
In this mode, physical inertia is modeled in the SureWave SFC control system providing a damp-
ing response to the grid frequency via the energy provided by the incoming supply.
Note, the modelled inertia artificially limits the speed of the SFC, thus this mode is not recom-
mended for applications where fast control is required.
11.3.2.2 VGen-V/F droop
The recommended mode when in parallel with other energy sources.
Note, when droop enable the frequency and the voltage will change and depending on the load.
11.3.2.3 VGen fix power (P/Q)
When operated in VGen fix power, the SFC has the ability to control power flow on the output .
This is typically used when interfacing generators to a grid where power flow to and from the
grid must be controlled. The SureWave SFC operates with setpoints for both real power (P) and
reactive power (Q).
Note, switching between V/F and fix power control modes can be done while the system is run-
ning, which is particularly interesting for micro-grid applications.
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VSI vs virtual generator

VSI mode is the simplest mode and can provide 'stiff' voltage and frequency. This has the fastest
transient response. Although it can be used with droop it is not recommended.
Virtual generator mode is the most powerful when it comes to load sharing. It can be tuned to
emulate the transient behavior of almost any type and size of generator. This allows even load
SUREWAVE SFC USER MANUAL