ABB Relion 650 Series Technical Manual page 127

1MRK 506 326-UUS B
The current and voltage samples for each phase passes through a notch filter that filters out the
fundamental components. Under steady state load conditions or when no fault is present, the
output of the filter is zero or close to zero. When a fault occurs, currents and voltages change
resulting in sudden changes in the currents and voltages resulting in non-fundamental waveforms
being introduced on the line. At this point the notch filter produces significant non-zero output.
The filter output is processed by the delta function. The algorithm uses an adaptive relationship
between phases to determine if a fault has occurred, and determines the faulty phases.
The current and voltage delta based phase selector gives a real output signal if the following
criterion is fulfilled (only phase A shown):
Max(ΔVA,ΔVB,ΔVC)>
Max(ΔIA,ΔIB,ΔIC)>
where:
ΔVA, ΔVB and ΔVC
DeltaVMinOp and
DeltaIMinOp
The delta voltages ΔVA(B,C) and delta current ΔIA(B,C) are the voltage and current between
sample t and sample t-1.
The delta phase selector employs adaptive techniques to determine the fault type. The logic
determines the fault type by summing up all phase values and dividing by the largest value. Both
voltages and currents are filtered out and evaluated. The condition for fault type classification for
the voltages and currents can be expressed as:
FaultType
EQUATION1808-ANSI V1 EN-US
FaultType
EQUATION1809-ANSI V1 EN-US
The value of FaultType for different shunt faults are as follows:
Under ideal conditions: (Patent pending)
Single phase-to-ground;
Phase-to-phase fault
Three-phase fault;
Line distance protection REL650
Technical manual
DeltaVMinOp
DeltaIMinOp
are the voltage change between sample t and sample t-1
are the minimum harmonic level settings for the voltage and
current filters to decide that a fault has occurred. A slow evolving
fault may not produce sufficient harmonics to detect the fault;
however, in such a case speed is no longer the issue and the
sequence components phase selector will operate.
å D D D
( VA VB , , VC
=
D D D
Max IA IB ( , , IC
å D D D
( IA IB , , IC )
=
D D D
Max IA IB ( , , IC
FaultType=1
FaultType=2
FaultType=3
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)
)
)
Section 5
Impedance protection
(Equation 21)
(Equation 22)
121