Operation Principle: Droop Speed Control Mode; Operation Principle: Isochronous Speed Control Mode - Danfoss Vacon NXP Applications Manual

General
1.3.1

Operation principle: Droop Speed Control Mode

When the power demand increases, all generators on the grid allow frequency to droop. This will
balance the load between all the generators on the grid. Then the power management system gives
all generators a command to increase frequency so that the grid frequency is maintained at its
nominal value.
When the load is reducing on the grid, the frequency of the generators will increase, and the power
management system gives a command to decrease frequency.
Freq. Change
52,0 Hz +4%
51,5 Hz +3%
51,0 Hz
+2%
50,5 Hz
+1%
50,0 Hz
49,5 Hz -1%
-2%
49,0 Hz
-3%
48,5 Hz
-4%
48,0 Hz
1.3.2

Operation principle: Isochronous Speed Control Mode

In the isochronous speed control mode, the Micro Grid frequency reference is kept the same as the
grid frequency with help of OPT-D7. This will keep power at zero regardless of grid frequency. While
drive operates in drooping mode, the actual power is controlled by base current reference. This
reference needs to be controller by power management system (PMS) that will handle power
sharing between different machines on the grid.
24-hour support: +358 (0)201 212 575 • Email: vacon@vacon.com
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Figure 4.
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