Hitachi Relion 670 Series Applications Manual page 191

1MRK511407-UUS Rev. N
In order to properly extract the weak subsynchronous signal in presence of the dominating 50Hz signal
the SMAI HPAC filter shall be set as given in the following table:
Table 23:
I_HPAC_31_5Hz: SMAIHPAC:1
ConnectionType
SetFrequency
FreqBandWidth
FilterLength
OverLap
Operation
Now the settings for the multi-purpose overcurrent stage one shall be derived in order to emulate the
existing relay operating characteristic. To achieve exactly the same inverse time characteristic the
programmable IDMT characteristic is used which for multi-purpose overcurrent stage one, which has the
following equation (for more information see Section "Inverse time characteristics" in the TRM).
æ
ç
[ ]
ç
=
s
t
ç
ç
è
EQUATION13000031 V1 EN-US
In order to adapt to the previous relay characteristic the above equation can be re-written in the following
way:
æ
ç
ç
[ ]
=
s
t
ç
ç
ç
è
EQUATION13000032 V1 EN-US
Thus if the following rules are followed when multi-purpose overcurrent stage one is set:
•
in >
•
=
A
•
=
B
Phasor measurement unit RES670
Application manual
Proposed settings for SMAIHPAC
Filterlength of SMAIHPAC shall be properly coordinated with the operate times of the
functions that are consuming SMAIHPAC data, in order to prevent inadvertent operation.
ö
÷
A
÷
+ ×
B k
p ÷
æ i ö
-
C
÷
ç ÷
>
è in ø
ø
ö
K
÷
I ÷
+ ×
T 1
so
÷
01
1
æ ö
I
÷
-
s 0
ç ÷
÷
I
è ø
ø
so
= I = 300A
S0
K 35566
= =
118.55
I 300
so
=
0.64
T
01
© 2017 - 2023 Hitachi Energy. All rights reserved
Ph — N
31.5
0.0
1.0 s
75
On
Section 12
System protection and control
(Equation 97)
(Equation 98)
185