40 FDUL/VFXR/FDUG/VFXG/AFR/AFG Main features CG Drives & Automation, 01-7318-01r1
7.17 Grid code functionality
AFG offers grid code functionality for generation applications where AFG is connected to the utility grid.
It includes:
• Grid monitoring or Protective functions (voltage and frequency protections)
• Reactive power support.
• Grid fault ride through and Anti-Islanding
7.17.1 Grid monitoring or protective functions
Grid voltage and frequency monitoring and protective functions are standard requirements for fulfilling the basic grid codes for
distributed renewable generation systems (DRGS) connected to either the low-voltage (200-690 V) or medium voltage networks
(1-25 kV), i.e. IEEE 1547, IEC 50438/50549, BDEW etc. This section gives a detailed description of the monitoring and
protective functions with respect to voltage and frequency implemented in the CG/Emotron Active Front-End (AFE) intended
for renewable energy sources (RES). The protective function features are implemented in AFE SW option version 97.09 and
later, and requires the SVMB version 2, see section 7.16 for grid voltage measurement.
7.17.1.1 Grid voltage and frequency protection
The grid voltage and frequency protective functions operate on the extracted information of the phase voltages (or line-line
voltages) and the frequency from the SVMB, see the block-diagram of the grid protection functionality in
Fig. 33.
Fig. 33 Block diagram of voltage and frequency protection functionality in the AFE.
The over- and under-voltage protection contains two stages (3U>, 3U>> and 3U<, 3U<<), each with independently settable trip
levels and trip times, see Fig. 34. The voltage protections are all of three phase type and contain one common hysteresis limit and
reset timer. The source for voltage protection can be the phase voltages or line to line voltages.
3U<<
3U>>
U+>
U->
U0>
U(10)>
U(10)<
F<<
F>>
dF/dt
F<
F>
U+<
3U<
3U>
>
<
>1
_
>1
_
>1
_
U 123 Ф 123
ph ph
U 123 Ф 123
LL LL
U+
U-
F
dF/dt
U0
Source [G111]
AFE.TRIP.U
AFE.
TRIP
AFE.
TRIP.F
U
mean
(10min)
AFE.TRIP.dF/dt
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