RELEASE
input. In this case, the external release signal overrides the
Voltage start
value setting and sets the internal limit to minimum value.
Multi-frequency admittance calculation
Multi-frequency admittance calculation module calculates neutral admittances
utilizing fundamental frequency and the 2nd, 3rd, 5th, 7th and 9th harmonic
components of residual current and zero-sequence voltage. The following
admittances are calculated, if the magnitude of a particular harmonic in residual
current and zero-sequence voltage are measurable by the protection relay.
Fundamental frequency admittance (conductance and susceptance)
Y
I
U
G
j B
o
o
0
1
0
1
0
1
1
1
3
=
⋅
−
=
+ ⋅
(Equation 32)
Y
0
1
The fundamental frequency neutral admittance phasor.
I
0
1
The fundamental frequency zero-sequence current phasor
( (
) / )
=
+
+
I
I
I
A
B
C
1
1
1
3
U
0
1
The fundamental frequency zero-sequence voltage phasor
( (
) / )
=
+
+
U
U
U
A
B
C
1
1
1
3
G
o
1
The fundamental frequency conductance,
Re
Y
0
1
( )
B
o
1
The fundamental frequency susceptance,
Im
Y
0
1
( )
Harmonic susceptance
Im
Im
Y
I
U
j B
n
n
n
o
n
0
0
0
3
=
⋅
−
= ⋅
(Equation 33)
where n = 2, 3, 5, 7 and 9
Y
n
0
The nth harmonic frequency neutral admittance phasor.
I
n
0
The nth harmonic frequency zero-sequence current phasor.
U
n
0
The nth harmonic frequency zero-sequence voltage phasor.
B
o
n
The nth harmonic frequency susceptance,
Im
Y
n
0
( )
1MRS758755 C
Protection functions
REC615 & RER615
Technical Manual
391
Содержание Relion REC615
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