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2.2 Recording Systems in Communications Systems
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Digital Fault Recorder, SIMEAS R-PMU, Manual
E50417-H1076-C360-A5, Release 10.2012
2.2 Recording Systems in Communications Systems
Most of the digital recording systems are installed in the substations for communications
systems. Although the main field of application is still the fault analysis and thus the use of the
Transient Analog Recorder (TAR) function, the other functions are also used to an increasing
degree, in order to understand stability problems of the power supply system and to work out
appropriate countermeasures:
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Capacitor voltage dividers are used in several communications systems. In the event of a
short-circuit in the line, high-frequency signals can occur in the voltage path that may cause
failures to operate or unwanted operations of protection devices. Such transient events and
the behavior of the protection devices can be analyzed in detail with the Transient Analog
Recorder (TAR) function.
‰
Compensating reactors installed at the beginning and end of transmission lines form a
resonant circuit with the line capacitance and/or a series capacitor. Sympathetic oscillations
that last for several cycles can occur when a line is switched off. With single-pole auto-
reclosings, these oscillations can significantly corrupt the measured values of protection
devices and thus cause false trippings. This is why sympathetic oscillations that occur after
the line has been switched off must be recorded and analyzed using a Transient Analog
Recorder (TAR).
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Inductances of voltage transformers and stray capacitances in the substations (busbars,
lines) may lead to ferromagnetic resonance effects. Under normal circumstances, these
problems are not recorded by the protection devices. If such problems are not recognized in
time and countermeasures are not taken, however, they may cause considerable damage to
the substation such as, e. g., the explosion of voltage transformers. A Transient Analog
Recorder (TAR) is required to record such events.
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Wide area measurements can be performed with the Transient Phasor Recorder (TPR) and
the Phasor Measurement Unit (PMU). The purpose of the measurements is to recognize
power oscillations, oscillation events, voltage and frequency stability problems.
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The use of Continuous Recorders is gaining more and more importance. These functions
facilitate the detailed analysis of long-term stability problems. Such measurements provide a
solid basis for expensive investments such as the purchase of compensation systems (SVC)
etc.