Setting Guidelines; Setting Example - Hitachi Relion 670 Series Applications Manual

Section 12
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 78:
Such overcurrent arrangement can be for example used to achieve the subsynchronous resonance
protection for turbo generators.
12.1.3

Setting guidelines

12.1.3.1

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 is the operating time of the relay
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
subsynchronous current trip level was set at I
Solution:
First the IED configuration shall be arranged as shown in
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
184
Required ACT configuration
K
+
I
s
is fixed time delay (setting)
- =
Hz 18.5 Hz 31.5 Hz
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IEC13000179-1-en.vsd
01
= 0.64 seconds, K= 35566 Amperes and minimal
=300 Amperes primary.
S0
Figure 78. Then the settings for SMAI HPAC
1MRK511407-UUS Rev. N
GUID-5A3F67BD-7D48-4734-948C-01DAF9470EF8 v3
(Equation 95)
(Equation 96)
Phasor measurement unit RES670
Application manual