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Evaluation of Different Methods for Voltage Sag Source Detection

Boštjan Polajžer orcid.org/0000-0001-5022-7391 ; University of Maribor, Faculty of Electrical Engineering and Computer Science Slovenia
Gorazd Štumberger ; University of Maribor, Faculty of Electrical Engineering and Computer Science Slovenia
Sebastijan Seme ; University of Maribor, Faculty of Electrical Engineering and Computer Science Slovenia

Sažetak

This paper compares and evaluates three different methods for voltage sag source detection.
First method (method I) is based on the assumption, that the energy flow at the monitoring
point increases during downstream events and decreases during upstream events. Second and
third method (methods II and III) are both based on the assumption that currents measured at
the monitoring point increase during downstream events and decrease during upstream events.
The slope of a current-voltage trajectory is investigated in method II, while a real current
component is observed within method III. Both current-based methods (II and III) require
fundamental harmonic components of sampled voltages and currents, which are extracted
using discrete orthogonal series expansion, such as Fourier or Walsh. Algorithms of this type
are especially appropriate for studying steady-state and periodically repeating conditions.
Voltage sags are, on the contrary, transient disturbance events. Thus, usage of the discussed
algorithms may not be appropriate. Furthermore, criteria within methods II and III are
checked for each phase individually. In the cases of asymmetrical voltage sags exact
interpretation of the obtained results, therefore, might not be possible. Method I is, on the
contrary, based on instantaneous values of line voltages and currents, while three-phase
criterion is used. An exact interpretation of the results obtained by this method is, therefore,
also possible in cases of asymmetrical voltage sags. All the discussed methods for voltage sag
source detection have been tested by applying extensive simulations and field tests. The
results for ground faults, asymmetrical voltage sags, upstream events and motor starting have
been analyzed in order to evaluate all the discussed methods. The obtained results show that
all discussed methods are very successful in cases of heavy motor starting and other
symmetrical voltage sags. In cases of asymmetrical voltage sags the methods II and III do not
work well, especially for those originating from the upstream side, while the method I is not
successful only in particular cases of voltage sags due to upstream ground faults. Based on the
performed evaluation it can be concluded, that further development is still needed to increase
the degree of confidence in the discussed methods.

Ključne riječi

Power – System; Power – Quality; Voltage Sag; Source; Detection

Hrčak ID:

198384

URI

https://hrcak.srce.hr/198384

Datum izdavanja:

19.6.2017.

Posjeta: 743 *