Setting Guidelines; Setting Example - ABB Relion REC670 Applications Manual

Section 11
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 86: Required ACT configuration
Such overcurrent arrangement can be for example used to achieve the subsynchronous
resonance protection for turbo generators.
11.1.3

Setting guidelines

11.1.3.1

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
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
214
K
+
I
s
is the operating time of the relay
is fixed time delay (setting)
- =
Hz 18.5 Hz 31.5 Hz
IEC13000179-1-en.vsd
GUID-5A3F67BD-7D48-4734-948C-01DAF9470EF8 v2
01
= 0.64 seconds, K= 35566 Amperes
=300 Amperes primary.
S0
Figure 86. Then the settings for SMAI
Application manual
1MRK 511 358-UEN A
(Equation 107)
(Equation 108)