Hitachi Relion 670 Series Applications Manual page 141

1MRK511407-UUS Rev. N
=
3I
0
2 Z
EQUATION2023-ANSI V1 EN-US
Where
V is the phase voltage in the fault point before the fault
phase
Z is the total positive sequence impedance to the fault point. Z
1
Z is the total zero sequence impedance to the fault point. Z
0
R is the fault resistance.
f
The residual voltages in stations A and B can be written:
=
V 3I (Z
0 A
EQUATION2024-ANSI V1 EN-US
=
V 3I (Z
OB
EQUATION2025-ANSI V1 EN-US
The residual power, measured by the sensitive ground fault protections in A and B will be:
=
S 3V
0A
EQUATION2026-ANSI V1 EN-US
=
S 3V
0B
EQUATION2027-ANSI V1 EN-US
The residual power is a complex quantity. The protection will have a maximum sensitivity in the
characteristic angle RCA. The apparent residual power component in the characteristic angle, measured
by the protection, can be written:
S
0 A ,prot
EQUATION2028-ANSI V1 EN-US
=
S
0 B,prot
EQUATION2029-ANSI V1 EN-US
The angles φ
station compensated with the characteristic angle RCA.
The protection will use the power components in the characteristic angle direction for measurement, and
as base for the inverse time delay.
The inverse time delay is defined as:
Phasor measurement unit RES670
Application manual
3V
phase
× + + ×
Z 3 R
1 0 f
× +
3R )
0 T ,0 N
× + +
3R Z
0 T ,0 N lineAB,0
×
3I
0A 0
×
3I
0B 0
= × × j
3V 3I cos
0 A 0 A
× × j
3V 3I cos
0 B 0 B
and φ are the phase angles between the residual current and the residual voltage in the
A B
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= Z
1
= Z +3R
0 T,0
)
+Z +Z +Z
sc T,1 lineAB,1 lineBC,1
+Z +Z
N lineAB,0 lineBC,0
Section 8
Current protection
(Equation 48)
(Equation 49)
(Equation 50)
(Equation 51)
(Equation 52)
(Equation 53)
(Equation 54)
135