Figure shows
the corresponding locus (absolute value and phase) based the coil position.
These three parameters are easily determined from the resonance curve.
Figure Locus zero sequence voltage UNE
The resonance curve healthy grid can described the following parameters:
Ures Maximum zero sequence voltage
Ires Coil position Ipos Ures point; corresponds the momentary grid capacitance ICE
Iw Expected watt-metric current across the faulty section, when low impedance
earth fault occurs.
, ,
1 1
( )
2 1
ne
C W
res
U W
U
j B
U
Y Y
(1.Page 23
Applications
Continuing from the previous chapter, Figure shows the progression the absolute val-
ue the zero sequence voltage UNE based the coil position (Ipos=BLU1N).18)
Multiplying expression
.16)
In order understand IW, have take look the point the resonance curve
where:
1
2
NE
Res
U
U
(1.17)
There, based the assumption that YW, the following equation applies the corre-
sponding coil position Ipos,W=BL,WU1N.
At the resonance point (BC=BL), equation (1.14) simplified to:
1
U
Res N
U W
Y
U U
Y Y
(1
