ABB Relion 620 Series - Page 483

Fundamental frequency admittance (conductance and susceptance)
Y
I
U
G j B
o o0
1
0
1
0
1
1 1
3
=
⋅
−
= + ⋅
(Equation 47)
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 48)
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
( )
For fault direction determination, the fundamental frequency admittance and
harmonic susceptances are summed together in phasor format. The result is the
sum admittance phasor defined as below.
Y Y j Y Y G j B
osum
n
n
o osum
=




+ ⋅ +






= + ⋅
=
∑
Re Im
0
1
0
1
0
2
9
1
(Equation 49)
1MRS757644 H
Protection functions
620 series
Technical Manual
483