Implementation Of The Reverse-Power Protection - Siemens siprotec SJ62 User Manual

2.18.2 Implementation of the Reverse-Power Protection

General
Determination of
the Reverse Power
Functional Logic
Pickup Value,
Dropout Ratio
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
2.18 Reverse-Power Protection Application with Flexible Protection Function
The names of the indications can be edited in DIGSI and were tailored to this example.
The parameter names are fixed.
The reverse-power protection evaluates the active power from the symmetrical funda-
mental components of voltages and currents. Evaluation of the positive-sequence
systems secures reverse-power detection against asymmetries occurring in the volt-
ages and currents and reflects the real load of the drive side. The calculated active
power value corresponds to the total active power. The relay measures the power in
direction of the busbar as being positive for the connection shown in the example.
The following logic diagram depicts the functional logic of the reverse-power protec-
tion.
Figure 2-93 Logic diagram of the reverse-power determination with flexible protection func-
tion
The reverse-power protection picks up once the configured pickup threshold has been
exceeded. If the pickup condition persists during the equally settable pickup delay, the
pickup message P.rev.PU is generated and starts the trip delay time. If the pickup con-
dition does not drop out while the trip delay time is counting down, the trip indication
P. rev. TRIP and the timeout indication P. rev. timeout are generated. The picked up
element drops out when the value falls below the dropout threshold. The blocking input
>P rev. block blocks the entire function, i.e. pickup, trip and running times are reset.
After the blocking has been released, the reverse power must exceed the pickup
threshold and both times must run out before the protective function trips.
The pickup value of the reverse-power protection is set to 10% of the generator
nominal output. In this example, the setting value is configured as secondary power in
watts. The following relationship exists between the primary and the secondary power:
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