Identifying switched capacitor relative locations and energizing operations

Lao

IEEE Trans. Power Delivery

et al. 2019

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Section: E Comparison To the Discrete Wavelet Transform Methodsmentioning

confidence: 99%

Accurate Identification of Point-on-Wave Inception and Recovery Instants of Voltage Sags and Swells

Lao

IEEE Trans. Power Delivery

et al. 2019

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“…On the other hand, normal de-energizing operations do not result in any voltage or current transient oscillations. These events are characterized by the reduction of system voltage and reactive power support (the latter is applicable only to banks located downstream from the monitoring location) [5].…”

Section: B Capacitor Switching Operationmentioning

confidence: 99%

“…The transients observed during a capacitor energizing operation can be used as signatures for identifying and characterizing these events through a discrete wavelet transform (DWT) [5]. Although this method is very robust and accurate, it requires significant computational effort, as the DWT of the voltage signal must be computed continuously.…”

Section: B Capacitor Switching Operationmentioning

confidence: 99%

“…The detection of an rms voltage step change at index k is based on rms voltage values immediately before and after index k. In order to perform this detection, the sliding window X is divided into 2 subsets: unfiltered rms values before and after index k, respectively, as represented in (5). The number of samples in each subset is at most half of the filter length.…”

Section: B Detection Of Possible Rms Voltage Step Changesmentioning

confidence: 99%

“…On the other hand, these methods are not suitable for triggerless data, due to their inability to detect inconspicuous disturbances. For example, capacitor energizing operations can be identified by the transient in voltage and current waveforms, while the transient-free deenergizing operations must be identified through a step change in the rms voltage profile [5]. Other events that cause an rms voltage step change and may present little to no transients are, for example, transformer tap-changing, voltage regulator operation, and switching of large loads [6].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Novel Moving Average Filter for Detecting RMS Voltage Step Changes in Triggerless PQ Data

Lao

IEEE Trans. Power Delivery

et al. 2018

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The voluminous amount of raw waveform data recorded by triggerless power quality monitors contain conspicuous and inconspicuous disturbance events. Data reduction and detection techniques are needed to efficiently extract useful information hidden in the raw data and identify power quality disturbances. The overall objective of this study is to use step changes in the rms voltage profile as an alternative triggering feature for automatically detecting switching events. The full characterization of the event is based on processing a small portion of the voltage waveform selected around the detected rms voltage step change. A filtering method is proposed to smooth out rapid fluctuations in the rms voltage profile during steady-state operation, while preserving the sharp edges caused by rms voltage step changes. Once the rms voltage profile has been filtered, adaptive limits based on the median absolute deviation are computed for detecting rms voltage step changes. The effectiveness of the proposed technique is evaluated using triggerless voltage waveforms to detect capacitor switching events. The use of the filtered rms voltage profile allows accurate detection of capacitor energizing and de-energizing events, while more than 50% of the detections in the unfiltered profile correspond to false-positives.

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Detection of inconspicuous power quality disturbances through step changes in rms voltage profile

Freitas²,

IET Generation, Transmission & Distribution

et al. 2019

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