Toshiba GRL100-701B Instruction Manual page 153

I B1 , I B2 and I B0 = positive, negative and zero sequence current at terminal B
I d1 ,I d2 and I d0 = positive, negative and zero sequence differential current
Z 11 , Z 12 and Z 10 are expressed by the following equations assuming that Z ab = Z ba , Z bc = Z cb
and Z ca = Z ac :
Z 11 = (Z aa + Z bb + Z cc - Z ab - Z bc - Z ca )/3
Z 12 = (Z aa + a
Z 10 = (Z aa + aZ bb + a
where, Z aa , Z bb and Z cc are self-impedances and Z ab , Z bc and Z ca are mutual impedances.
If Z aa = Z bb = Z cc and Z ab = Z bc = Z ca , then Z 11 is equal to the positive sequence impedance,
and Z12 and Z10 are zero. For setting, the positive-sequence impedance is input using the
expression of the resistive component R1 and reactive component X1.
2.17.4.2 Fault location using the only local end data
The distance to fault x is calculated from equation (1) and (2) using the local voltage and current
1
of the fault phase and a current change before and after the fault occurrence. The current change
before and after the fault occurrence represented by Iβ" and Iα" is used as the reference current.
The impedance imbalance compensation factor is used to maintain high measuring accuracy even
when the impedance of each phase has great variations.
Distance calculation for phase fault (in the case of BC-phase fault)
x =
1 ⋅
{I m (R 1 I bc
where,
V bc = fault voltage between faulted phases = V b − V c
I bc = fault current between faulted phases = I b − I c
Iβ" = change of fault current before and after fault occurrence = (I b -I c ) − (I Lb -I Lc )
I Lb , I Lc = load current
R 1 = resistance component of line positive sequence impedance
X 1 = reactance component of line positive sequence impedance
K bc = impedance imbalance compensation factor
I m ( ) = imaginary part in parentheses
R e ( ) = real part in parentheses
L = line length (km)
2
Z bb + aZ cc + 2(aZ ab + Z bc + a
2 2
Z cc - a Z ab - Z bc - aZ ca )/3
I m (V bc ⋅ I β ") × L
× β ⋅ ⋅ β
I ") + R e (X 1 I bc I ")}
 152 
2
Z ca ))/3 (9)
(1)
×
K bc
6 F 2 S 0 8 5 0