System Manual
10 MV Station Functions
73
10.10
GFDI Function
The DC Cabinet is equipped with the GFDI (Ground Fault Detection and Interruption)
function. The GFDI fuse, with a certain cutoff limit, is installed on the negative pole of DC
input side.
10.11
Vs-U Curve
The relationship between the MPPT lower limit Vs reactive power and AC voltage Uac is
shown in the figure below.
Fig. 10-5
Vs-U Curve
10.12
Protection Function
The MV Station has complete protection functions to protect itself when input voltage or
grid is abnormal until the anomaly is removed and the MV Station can operate normally.
10.12.1
DC over-voltage protection
When the DC voltage of the PV array exceeds the max. DC voltage, MV Station will stop
operating, send warning signal and display the fault type on the LCD screen.
MV Station can detect the abnormal voltage and respond quickly.
10.12.2
AC over/under-voltage protection
When the MV Station AC output voltage exceeds the allowable range, MV Station will stop
feeding the grid, send warning signal and display the fault type on the LCD screen.
MV Station can detect the abnormal voltage and respond quickly.
10.12.3
Frequency anomaly protection
When the grid frequency exceeds the allowable range, MV Station will stop feeding the grid,
send warning signal and display the fault type on the LCD screen.
MV Station can detect the abnormal frequency and respond quickly.
10.12.4
Islanding protection
Islanding is a condition that can occur if the utility grid is disconnected while the MV Station
