ABB Relion RER615 - Page 391

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 o0
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 ImY
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