Figure 113: Virtual Current Polarization; Negative Sequence Polarizing - GE MiCOM P40 Agile Technical Manual

P543i/P545i
V03522

Figure 113: Virtual Current Polarization

The Polarizing voltage (VNpol) is as per the table below and RCA is the relay characteristic angle defined by the
DEF Char. Angle setting.
Phase selector pickup
A Phase Fault
B Phase Fault
C Phase Fault
No Selection
5.3.2

NEGATIVE SEQUENCE POLARIZING

In certain applications, residual voltage polarization of Aided DEF may not be possible, or it may be problematic.
Example cases are:
Where a 3-limb voltage transformer is fitted, which has no path for residual flux.
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Where the application features a parallel line and zero sequence mutual coupling may exist.
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The problems in these applications can be alleviated using negative phase sequence (nps) voltage for polarization.
The nps voltage threshold must be set in the cell DEF V2pol Set.
Note:
The current quantity used for operation of the Aided DEF when it is nps Polarized is the residual current not the nps current.
The directional criteria with negative sequence polarization are as follows:
Directional forward
-90° < [(angle(V2) +180°) - (angle(I2) - RCA) ] < 90°
P54x1i-TM-EN-1
For a forward direction , -VN hs to be in the shaded area
For a reverse direction, -VN has to be in unshaded area
Chapter 8 - Carrier Aided Schemes
IN angle -RCA
VB + VC
VA + VC
VA + VB
VN = VA + VB + VC
IN
VNpol
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