Distance Elements Analysis - GE D30 Instruction Manual

DISTANCE ELEMENTS
The same desirable effect of memory polarization applies to the directional comparator of the quadrilateral characteristic.
Mutual zero-sequence compensation can raise concerns regarding directional integrity on reverse faults in the situation
when the relay gets "overcompensated." This problem does not affect the D30 because its ground distance elements use
zero-sequence and negative-sequence currents in extra directional comparators. Both the currents are from the protected
line and are not affected by any compensation as the latter applies only to the reach defining comparators: the mho,
reactance, and blinder characteristics.

9.1.6 Distance elements analysis

9
9.1.6.1 Description
This subsection shows how to analyze the operation of the distance elements in steady states using the results of short
circuit studies. All quantities are secondary ohms, volts, and amperes. Ground phase A and phase AB distance elements
are analyzed.
Assume that the following settings have been entered:
Phase Rotation: ABC
9-8
Figure 9-2: Dynamic shift of the mho characteristic
Figure 9-3: Dynamic shift of the memory-polarized directional characteristic
Self-polarized
837724A1.CDR
X
(Reverse fault)
R
Memory-
polarized
(Forward fault)
D30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 9: THEORY OF OPERATION
Memory-
polarized