Recording Systems In Power Plants - Siemens SIMEAS R-PMU Manual

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2.1 Recording Systems in Power Plants

2.1 Recording Systems in Power Plants
The operating personnel in power plants want to analyze and understand the following problems:
A short-circuit occurs on the generator during the start-up phase before the generator has
reached the nominal frequency of the system voltage. During this period, the generator
frequency ranges from 0 Hz up to the nominal value
function is required during this phase.
The generator's circuit breaker is closed. Possible faults such as a wrong phase sequence
or insufficient synchronization must be recorded during this period. The Transient Analog
Recorder function is also necessary in this case.
A short-circuit occurs on the generator or in the communications system, after the generator
has been connected to the system and has been in operation without any problems. In this
case, the Transient Analog Recorder function is also required. The records must be used to
analyze the cause of the short-circuit at the generator.
Local or inter-area oscillations occur: These oscillations can put an enormous load on the
generator shaft, e. g., if no electronic stabilization measures (Power System Stabilizer, PSS)
are provided or this electronic unit has not been adjusted appropriately. Such malfunctions
can be recorded precisely with the Transient Phasor Recorder (TPR) and the Continuous
Phasor Recorder (CPR). The process signal inputs are a special feature that can be used to
record the electronic signals of the PSS and further important variables such as the
generator's excitation current, the steam pressure etc. Afterwards, these signals can be
compared to the rms value curves for voltage and current and an analysis can be performed.
Oscillations between the power plant and the communications system can cause enormous
damage to the generator, if they are not recognized and eliminated well in time. This is
usually the field of application for distance protection devices. The "Transient Phasor
Recorder (TPR)" function can be used to exactly record the system condition prior to, during
and after the oscillation event. If the Transient Analog Recorder has also been activated, it
can be clarified, e. g., whether a local or a distant short-circuit in the system caused the
oscillation, or whether a load or generator shedding led to this system condition.
The Phasor Measurement Unit function is used to monitor large communications systems.
The system voltage, system current and system frequency phasors are calculated precisely
and provided with a time stamp. Via a communication channel, the calculated data is
continuously sent to a computer that is called the Phasor Data Concentrator (PDC). The data
of several PMUs is processed in the PDC thus ensuring that bottlenecks in the
communications system, line overloads etc. can be detected.
In order to enable a detailed analysis of problems such as the long-term stability of the
system voltage and system frequency, the functions Continuous Phasor Recorder (CPR),
Continuous Frequency Recorder (CFR), Continuous RMS-value Recorder (CRR) and
Continuous Power Recorder (CQR) must be used. These functions facilitate the recording of
long-term curves for currents and voltages, active and reactive power curves, system
frequency curves and curves of other important system variables. Recording functions such
as Continuous Process Signal Recorder (CDR) and Event Recorder (ER) provide more
extensive and detailed records.
As described above, the use of a modern recording device and the correct application of the
corresponding functions allows for a most precise recording and subsequent analysis of the
electrical events in and around the power plant.
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f n . Only the Transient Analog Recorder
Digital Fault Recorder, SIMEAS R-PMU, Manual
E50417-H1076-C360-A5, Release 10.2012