ABB Relion, Техническое руководство

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1 2 3
2 2
_ 2 1 1 _ 1 1 0 1 _ 2
1 _ 2 1
_ 1 2 1 _ 1 1 1 0 _ 2
3 _ 1
3
_ 1 1 2 0 1 1
_ 1 _ 2
IDNS A INS W INS W
Vn W
IDNS B a INS W a INS W
Vn W
IDNS C
a INS W a INS W
- - -
= × - - × × + × × - × ×
- - -
× ×
é ù é ù
é ù é ù é ù
ê ú ê ú
ê ú ê ú ê ú
ê ú ê ú
ê ú ê ú ê ú
ê ú ê ú
ê ú ê ú ê ú
ë û ë û ë û
ë û ë û
EQUATION1560 V1 EN
(Equation 23)
where:
1.
is the Negative Sequence Differential Current per phase
2. is Negative Sequence current contribution from the W1 side
3. is the Negative Sequence current contribution from the W2 side
and where:
IDNS_A
is the negative sequence differential current in phase A (in
W1 side primary amperes)
IDNS_B is the negative sequence differential current in phase B (in
W1 side primary amperes)
IDNS_C is the negative sequence differential current in phase C (in
W1 side primary amperes)
INS_W1 is the negative sequence current on the W1 side in primary
amperes (phase A reference)
INS_W2 is the negative sequence current on the W1 side in primary
amperes (phase A reference)
Vn_W1 is the transformer rated phase-to-phase voltage on the W1
side (setting parameter)
Vn_W2 is transformer rated phase-to-phase voltage on W2 side
(setting parameter)
a is the complex operator for sequence quantities, for example,
120
1 3
2 2
j
a e j
× = = - + ×
o
EQUATION1248 V1 EN
(Equation 24)
Because the negative sequence currents always form a symmetrical three phase system
(negative sequence currents in every phase will always have the same magnitude and a
120 degrees phase rotation compared to each other), it is only necessary to calculate the
first negative sequence differential current that is, IDNS_A. This value is then reported as
IDNSMAG
.
Section 6
1MRK 502 048-UUS A
Differential protection
102
Technical manual