ABB RELION 620 Series Technical Manual page 477

1MRS757644 F
620 series
Technical Manual
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)
1
3 I
⋅
1 1
0
Y G j B
= = + ⋅
0 o
1
U
−
0
GUID-565B235E-04DA-4AC2-93A8-FE327A53424F V1 EN
The fundamental frequency neutral admittance phasor.
1
Y
0
The fundamental frequency zero-sequence current phasor
1
I
0
1 1 1
( ( I I I
= + +
A B C
The fundamental frequency zero-sequence voltage phasor
1
U
0
1 1
( ( U U U
= + +
A B
The fundamental frequency conductance,
1
G
o
( ) 1
Re Y
0
The fundamental frequency susceptance,
1
B
o
( ) 1
Im Y
0
Harmonic susceptance
n
 
3 I
⋅
n
0
 
Im Y Im
=
 
0
 
n
U
−
 
 
0
GUID-FEC1F705-F45C-4C56-9A74-AC4EDFC7FC4C V1 EN
where n = 2, 3, 5, 7 and 9
The nth harmonic frequency neutral admittance phasor.
n
Y
0
The nth harmonic frequency zero-sequence current phasor.
n
I
0
The nth harmonic frequency zero-sequence voltage phasor.
n
U
0
n
B
o
The nth harmonic frequency susceptance,
1
o
) / ) 3
1
) / ) 3
C
n
j B
= ⋅
o
( )
Im Y
Section 4
Protection functions
n
0
(Equation 46)
(Equation 47)
471