ABB 615 Series - Page 446

consideration of possible network topology changes, compensation coil and parallel
resistor switching status and compensation degree variations.
As an alternative for internal residual zero-sequence overvoltage based pickup-condition,
67YN function can also be externally released by utilizing the RELEASE input. In this
case, the external release signal overrides the Voltage pickup 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
V
G j B
o o0
1
0
1
0
1
1 1
3
=
⋅
−
= + ⋅
GUID-24706434-ECF8-40C5-8F88-27DD2BB84699 V1 EN (Equation 55)
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
V
0
1
The fundamental frequency zero-sequence voltage phasor
= + +V V V
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
V
j B
n
n
n
o
n
0
0
0
3




=
⋅
−








= ⋅
GUID-67114C57-781D-4665-A69A-5E43C9E19937 V1 EN (Equation 56)
Section 4 1MAC059074-MB A
Protection functions
440 615 series ANSI
Technical Manual