Setting Guidelines; Figure 131: Frequency Supervised Rate Of Change Of Frequency Protection - GE MiCOM P40 Agile Technical Manual

P14x
Frequency

Figure 131: Frequency supervised rate of change of frequency protection

6.3.2

SETTING GUIDELINES

We recommend that the frequency supervised rate of change of frequency protection (f+df/dt) element be used in
conjunction with the time delayed frequency protection (f+t) elements.
A four stage high speed load shedding scheme may be configured as indicated below, noting that in each stage,
both the "f+t" and the "f+df/dt" elements are enabled.
Frequency "f+t [81U/81O]" Elements
Frequency Setting
Stage
(Hz)
1 49
2 48.6
3 48.2
4 47.8
It may be possible to further improve the speed of load shedding by changing the frequency setting on the f+df/dt
element. In the settings outlined below, the frequency settings for this element have been set slightly higher than
the frequency settings for the f+t element. This difference will allow for the measuring time, and will result in the
tripping of the two elements at approximately the same frequency value. Therefore, the slow frequency decline
and fast frequency decline scenarios are independently monitored and optimised without sacrificing system
security.
Frequency "f+t [81U/81O]" Elements
Frequency Setting
Stage
(Hz)
1 49
2 48.6
3 48.2
4 47.8
P14xEd1-TM-EN-1
Rapid decay
Frequency Supervised Rate of Change of Frequency "f+df/dt
Time Setting (Sec.) Frequency Setting (Hz)
20 49
20 48.6
10 48.2
10 47.8
Frequency Supervised Rate of Change of Frequency "f+df/dt
Frequency Setting
Time Setting (Sec.)
20 49.2
20 48.8
10 48.4
10 48.0
Chapter 11 - Frequency Protection Functions
[81RF]" Elements
Rate of Change of Frequency Setting (Hz/
1.0
1.0
1.0
1.0
[81RF]" Elements
Rate of Change of Frequency Setting (Hz/
(Hz)
1.0
1.0
1.0
1.0
fn
f
1
Slow decay
f
2
Time
E00858
sec.)
sec.)
247