ABB Relion 670 Series Applications Manual page 304

Section 13
System protection and control
The following figure shoes typical configuration connections required to utilize this filter in
conjunction with multi-purpose function as non-directional overcurrent protection.
IEC13000179 V1 EN-US
Figure 135: Required ACT configuration
Such overcurrent arrangement can be for example used to achieve the subsynchronous
resonance protection for turbo generators.
13.1.3 Setting guidelines
13.1.3.1 Setting example
A relay type used for generator subsynchronous resonance overcurrent protection shall be
replaced. The relay had inverse time operating characteristic as given with the following
formula:
=
t T
op 01
EQUATION13000029 V1 EN-US
Where:
• t
op
• T
01
• K is a constant (setting)
• I is measured subsynchronous current in primary amperes
S
The existing relay was applied on a large 50Hz turbo generator which had shaft mechanical
resonance frequency at 18.5Hz. The relay settings were T
and minimal subsynchronous current trip level was set at I
Solution:
First the IED configuration shall be arranged as shown in
SMAI HPAC filter and multipurpose function shall be derived from existing relay settings in the
following way:
The subsynchronous current frequency is calculated as follows:
=
50
f
s
EQUATION13000030 V1 EN-US
298
K
+
I
s
is the operating time of the relay
is fixed time delay (setting)
- =
Hz 18.5 Hz 31.5 Hz
© Copyright 2017 Hitachi Power Grids. All rights reserved
1MRK 511 401-UEN Rev. K
IEC13000179-1-en.vsd
GUID-5A3F67BD-7D48-4734-948C-01DAF9470EF8 v2
01
= 0.64 seconds, K= 35566 Amperes
=300 Amperes primary.
S0
Figure 135. Then the settings for
Bay control REC670
Application manual
(Equation 173)
(Equation 174)