Woodward HighPROTEC - Page 644

Protective Elements
Automatic Calculations: Amplitudes, Vector Groups, and Zero Sequence Removal
The calculations performed can be done by matrix calculations. Three steps have to be completed.
1. Adjust the amplitude according to all transformation ratios (Stepup transformer and CTs).
2. Adjust the vector group angle by rotating the three-phase system accordingly.
3. Remove the zero sequence current where necessary (this being valid for winding 1 and winding 2).
Re. 1.: Amplitude Adjustment:

I
W2
'
=

I
W2
⋅ k
r
k
r
=
CT
pri , W2
I
B , W2
⋅
I
b , W1
CT
pri ,W1
=
CT
pri ,W2
CT
pri ,W1
⋅
V
LL,W2
V
LL,W1
⋅ (1 + Tap Changer )
Re. 2.: Vector Group Adjustment:
The vector group adjustment is calculated using the following formulas and transformation matrices:

I
W2
' '
=
[
T
Phase Shift
]
∗

I
W2
'
[
T
Phase Shift
]
→
[
T
0,1,2...11
]
Even Connection Groups Odd Connection Groups
T
0
=
[
1 0 0
0 1 0
0 0 1
]
T
2
=
[
0 −1 0
0 0 −1
−1 0 0
]
T
4
=
[
0 0 1
1 0 0
0 1 0
]
T
6
=
[
−1 0 0
0 −1 0
0 0 −1
]
T
8
=
[
0 1 0
0 0 1
1 0 0
]
T
10
=
[
0 0 −1
−1 0 0
0 −1 0
]
T
1
=
1
√
3
⋅
[
1 −1 0
0 1 −1
−1 0 1
]
T
3
=
1
√
3
⋅
[
0 −1 1
1 0 −1
−1 1 0
]
T
5
=
1
√
3
⋅
[
−1 0 1
1 −1 0
0 1 −1
]
T
7
=
1
√
3
⋅
[
−1 1 0
0 −1 1
1 0 −1
]
T
9
=
1
√
3
⋅
[
0 1 −1
−1 0 1
1 −1 0
]
T
11
=
1
√
3
⋅
[
1 0 −1
−1 1 0
0 −1 1
]
Re. 3.: Zero sequence removal (elimination of the ground current if this can only flow through one winding at the
external asymmetrical faults and will not be transformed to the other winding).
644 MCDGV4 DOK-HB-MCDGV4-2E