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the VSG function. During off-grid operation, the PCS can activate the VSG function to pro-
vide an AC voltage source to support the load. In this case, the amplitude and frequency of
the AC voltage source are automatically adjusted according to the load attributes.
The VSG function has a commanding advantage in commercial micro grid with multiple
kinds of energies. Particularly, in the micro grid with many rotating equipment such as a die-
sel engine, the VSG function can stabilize the system operation well.
Black Start
In a system with black start application, the PCS and the isolation transformer are connected
in parallel to the plant by the MV BUS, which is connected to the power grid through the main
boost transformer of the plant. The entire plant will be in a state of no electricity after it is dis-
connected from the grid if the grid suffers a major accident. Black start is defined as the
process in which the major power generation unit in the plant reboots out of no electricity
and is connected to the grid or establishes a grid.
Fast On/Off-grid Switching
After the plant is disconnected from the grid, the PCS will switch from grid-connected mode
to off-grid mode after receiving an external switching signal.
P-f Curve
figure 10-1 P(f) curve
table 10-1 Description of P-f curve Parameters
Parameter
Desciptions
Default
Range
Function switch Enable/Disable P(f) 0 0-1
Deadband Deadband (fdead) of P(f) curve 0.0Hz 0~5Hz
10 PCS Functions System Manual
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