Instruction manual
–
AQ G3x7 Generator protection IED
153 (211
)
As overexcitation is a phenomenon which is typical if the generator or the generator
transformer unit is not connected to the network, the voltage drop does not need any
compensation. If the voltage is measured at the supply side of the unit transformer, then the
voltage
is higher then the voltage of the magnetization branch of the transformer’s
equivalent circuit. Thus the calculated flux cannot be less then the real flux value. The
protection operates with increased security.
3.2.24.3
Structure of the overexcitation protection function
Figure below shows the structure of the overexcitation protection (VPH24) algorithm.
Figure 3-92: Structure of overexcitation protection function.
The inputs are
•
The sampled values of a line-to-line voltage (ULL),
•
Parameters,
•
Status signals.
The outputs are
•
The binary output status signals.
The software modules of the overexcitation protection function: