Rate-Of-Change Of Frequency Protection Sapfrc; Identification; Application; Setting Guidelines - ABB RET650 Applications Manual

Section 9
Frequency protection
9.3
9.3.1
9.3.2
9.3.3
166

Rate-of-change of frequency protection SAPFRC

Identification

Function description
Rate-of-change of frequency protection

Application

Rate-of-change of frequency protection (SAPFRC) is applicable in all situations,
where reliable detection of change of the fundamental power system voltage
frequency is needed. SAPFRC can be used both for increasing frequency and for
decreasing frequency. SAPFRC provides an output signal, suitable for load
shedding or generator shedding, generator boosting, HVDC-set-point change, gas
turbine start up and so on. Very often SAPFRC is used in combination with a low
frequency signal, especially in smaller power systems, where loss of a fairly large
generator will require quick remedial actions to secure the power system integrity.
In such situations load shedding actions are required at a rather high frequency
level, but in combination with a large negative rate-of-change of frequency the
underfrequency protection can be used at a rather high setting.

Setting guidelines

The parameters for Rate-of-change frequency protection SAPFRC are set via the
local HMI or or through the Protection and Control Manager (PCM600).
All the frequency and voltage magnitude conditions in the system where SAPFRC
performs its functions should be considered. The same also applies to the
associated equipment, its frequency and time characteristic.
There are two application areas for SAPFRC:
1. to protect equipment against damage due to high or too low frequency, such as
generators, transformers, and motors
2. to protect a power system, or a part of a power system, against breakdown by
shedding load or generation, in situations where load and generation are not in
balance.
SAPFRC is normally used together with an overfrequency or underfrequency
function, in small power systems, where a single event can cause a large imbalance
IEC 61850 IEC 60617

identification

identification
SAPFRC
df/dt > <
SYMBOL-N V1 EN-US
Transformer protection RET650 2.2 IEC
1MRK 504 169-UEN A
IP15748-1 v4
M14868-1 v4
ANSI/IEEE C37.2
device number
81
M14966-3 v5
M14971-3 v7
Application manual