ABB Relion REG670, Техническое руководство

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The phasor filter is frequency adaptive in the sense that its coefficients are changed
based on the estimated power system frequency.
A half cycle filter will not be able to reject both even and odd harmonics. So, while odd
harmonics will be completely attenuated, accuracy will be affected by even
harmonics. Even harmonics will not cause the distance zones to overreach however;
instead there will be a slightly variable underreach, on average in the same order as the
magnitude ratio between the harmonic and fundamental component.
7.3.7.2 Distance measuring zones
Th different fault loops within the IED are of full scheme type, which means that earth
fault loop for phase-to-earth faults and phase-to-phase faults for forward and reverse
faults are executed in parallel.
Figure 81 presents an outline of the different measuring loops for the six distance
zones.
IEC05000458-2-en.vsd
L1-N L2-N L3-N
L1-N L2-N L3-N
L1-N L2-N L3-N
L1-N L2-N L3-N
L1-L2 L2-L3 L3-L1
L1-L2 L2-L3 L3-L1
L1-L2 L2-L3 L3-L1
L1-L2 L2-L3 L3-L1
L1-N L2-N L3-N L1-L2 L2-L3 L3-L1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
L1-N L2-N L3-N L1-L2 L2-L3 L3-L1
Zone RV
IEC05000458 V2 EN
Figure 81: The different measuring loops at phase-to-earth fault and phase-to-
phase fault
Each distance protection zone performs like one independent distance protection
function with six measuring elements.
Tansients from CVTs may have a significant impact on the transient overreach of a
distance protection. At the same time these transients can be very diverse in nature
from one type to the other; in fact, more diverse than can be distinguished by the
algorithm itself in the course of a few milliseconds. So, a setting (
CVTtype ) is
introduced in order to inform the algorithm about the type of CVT applied and thus
providing the advantage of knowing how performance should be optimized, even
during the first turbulent milliseconds of the fault period.
There are basically two types of CVTs from the function point of view, the passive and
the active type, which refers to the type of ferro-resonance suppression device that is
employed. The active type requires more rigorous filtering which will have a negative
1MRK502052-UEN B
Section 7
Impedance protection
213
Technical manual