Siemens Siprotec 7UM611, Руководство пользователя

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2.20 Jump of Voltage Vector
123
7UM61 Manual
C53000-G1176-C127-3
2.20 Jump of Voltage Vector
Sometimes consumers with their own generating plant feed power directly into a net-
work. The incoming feeder is usually the ownership boundary between the network
utility and these consumers/producers. A failure of the input feeder line for example
due to a three-pole automatic reclosure, can result in a deviation of the voltage or fre-
quency at the feeding generator which is a function of the overall power balance.
When the incoming feeder line is switched on again after the dead time, it may meet
with asynchronous conditions which cause damage to the generator or the gear train
between generator and drive.
One way to identify an interruption of the incoming feeder is to monitor the phase angle
in the voltage. If the incoming feeder fails, the abrupt current interruption causes a
phase angle jump in the voltage. This jump is detected by means of a delta process.
As soon as a preset threshold is exceeded, an opening command for the generator or
bus-tie coupler circuit-breaker is issued.
This means that the vector jump function is mainly used for network decoupling.
2.20.1 Function Description
Frequency Behav-
iour on Load Shed-
ding The following figure shows the evolution of the frequency when a load is disconnected
from a generator. Opening of the generator circuit breaker causes a phase angle jump
that can be observed in the frequency measurement as a frequency jump. The gener-
ator is accelerated in accordance with the power system conditions (see also Section
2.19 Rate-of-Frequency-Change Protection).
Figure 2-38 Change of the Frequency after Disconnection of a Load (Fault recording with the SIPROTEC
®
device- the
figure shows the deviation from the rated frequency)
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