Papers by Victor A Barrera Nunez
2010 IEEE ANDESCON, 2010
Abstract This paper proposes a segmentation method to analyze waveforms based on tensor analysis.... more Abstract This paper proposes a segmentation method to analyze waveforms based on tensor analysis. The method directly identifies the non-stationary parts of the waveforms from the instantaneous voltage and current values instead of using the rms sequence values. ...
Ingenieria e Investigación
This article presents an analysis of voltage sag propagation. The ATPDraw tool was selected for s... more This article presents an analysis of voltage sag propagation. The ATPDraw tool was selected for simulating the IEEE 34 node test feeder. It takes into account both voltage sags caused by electrical fault network, as well as voltage sag propagation characteristics caused by induction motor starting and transformer energising. The analysis was aimed at assessing the influence of transformer winding connections, the impedance of these transformers, lines and cables, summarising the effects on disturbance magnitude and phase. The study shows that the influence of an induction motor on voltage sag propagation results in increased voltage sag severity. Voltage sags caused by induction motor starting and transformer energising have no zero-sequence component, so they are only affected by type 3 transformers. The influence of fault resistance on voltage sag magnitude and phase characteristics is examined and some aspects of interest in characterising these electromagnetic disturbances is identified.
The origin of outages occurring in a power distribution network are highly related with the weath... more The origin of outages occurring in a power distribution network are highly related with the weather conditions existing during its apparition. Wind, rain and lightnings usually are the trigger causes of power network outages, hence the analysis of the relationship between weather and network outage information plays an important role for forecasting the impact of future weather conditions in the power distribution network. In this paper, weather information and distribution-network outages collected during three years are studied and statistically analyzed. From the analysis some useful relationships between weather conditions and network outages were extracted.
2009 IEEE International Conference on Communications, 2009
In this paper the issue of improving the performance of iterative decoders based on sub-optimal c... more In this paper the issue of improving the performance of iterative decoders based on sub-optimal calculation of the messages exchanged during iterations (L-values) is addressed. It is well known in the literature that a simple-yet very effectiveway to improve the performance of suboptimal iterative decoders is based on applying a scaling factor to the L-values. In this paper, starting with a theoretical model based on the so-called consistency condition of a random variable, we propose a methodology for correcting the L-values that relies only on the distribution of the soft information exchanged in the iterative process. This methodology gives a clear explanation of why the well-known linear scaling factor provides a very good performance. Additionally, the proposed methodology allows us to avoid the exhaustive search required otherwise. Numerical simulations show that for turbo codes the scaling factors found closely follow the optimum values, which translates to a close-to-optimal BER performance. Moreover, for LDPC codes, the proposed methodology produces a better BER performance compared with the known method in the literature.
2008 IEEE/PES Transmission and Distribution Conference and Exposition: Latin America, 2008
This paper aims to survey the techniques and methods described in literature to analyse and chara... more This paper aims to survey the techniques and methods described in literature to analyse and characterise voltage sags and the corresponding objectives of these works. The study has been performed from a data mining point of view.
Proceedings of 14th International Conference on Harmonics and Quality of Power - ICHQP 2010, 2010
This paper proposes the application of support vector machines (SVM) to classify overhead distrib... more This paper proposes the application of support vector machines (SVM) to classify overhead distribution faults according to their general root causes; they are faults due to animal contacts, tree contacts, and lightning-induced events. The SVM method uses unique features buried in voltage and/or current waveforms. Seven unique features based on time and electrical quantities are presented. The performance of support
Artificial Intelligence Research and Development, 2008
ABSTRACT This work presents a set of rules to determine the voltage sag source location in electr... more ABSTRACT This work presents a set of rules to determine the voltage sag source location in electric power systems. The rule set is extracted using subgroup discovery (SD). The SD objective is to discover characteristics of subgroups with respect to a specific property of interest. Our interest is to obtain the origin of sag events, upstream or downstream from the measurement point. Voltage sag features registered in electric substations are used as input data to SD algorithm. The SD algorithm used is CN2-SD to learn descriptive rules. Results show the rules extracted can be easily interpreted by a domain expert, allowing the formulation of heuristic classification rules with high accuracy.
... This paper appears in: Power and Energy Society General Meeting, 2010 IEEE Issue Date: 25-29 ... more ... This paper appears in: Power and Energy Society General Meeting, 2010 IEEE Issue Date: 25-29 July 2010 On page(s): 1 - 8 Location: Minneapolis, MN ISSN: 1944-9925 E-ISBN: 978-1-4244-8357-0 Print ISBN: 978-1-4244-6549-1 INSPEC Accession Number: 11570743 ...
2008 IEEE/PES Transmission and Distribution Conference and Exposition: Latin America, 2008
Three multivariate statistical tools (Principal Component Analysis, Factor Analysis, Analysis Dis... more Three multivariate statistical tools (Principal Component Analysis, Factor Analysis, Analysis Discriminant) have been tested to characterize and model the sags registered in distribution substations. Those models use several features to represent the magnitude, duration and unbalanced grade of sags. They have been obtained from voltage and current waveforms. The techniques are tested and compared using 69 registers of sags. The advantages and drawbacks of each technique are listed. Index Terms-discriminant analysis, factor analysis, power quality monitoring, principal component analysis, voltage sag (dip).
2008 IEEE/PES Transmission and Distribution Conference and Exposition: Latin America, 2008
A statistical method for classification of sags their origin downstream or upstream from the reco... more A statistical method for classification of sags their origin downstream or upstream from the recording point is proposed in this work. The goal is to obtain a statistical model using the sag waveforms useful to characterise one type of sags and to discriminate them from the other type. This model is built on the basis of multi-way principal component analysis
2008 13th International Conference on Harmonics and Quality of Power, 2008
This paper presents and compares two approaches to estimate the origin (upstream or downstream) o... more This paper presents and compares two approaches to estimate the origin (upstream or downstream) of voltage sag registered in distribution substations. The first approach is based on the application of a single rule dealing with features extracted from the impedances during the fault whereas the second method exploit the variability of waveforms from an statistical point of view. Both approaches have been tested with voltage sags registered in distribution substations and advantages, drawbacks and comparative results are presented. . Index Terms-Fault location, position measurement, power quality monitoring, voltage sag (dip) source detection.
2009 10th International Conference on Electrical Power Quality and Utilisation, 2009
Proceedings of 14th International Conference on Harmonics and Quality of Power - ICHQP 2010, 2010
This paper addresses the problem of extracting effective features for the analysis of underlying ... more This paper addresses the problem of extracting effective features for the analysis of underlying causes of power quality (PQ) disturbances. For each underlying cause, we define and extract a set of features based on analysis of voltage/current waveforms or the combination of them. The proposed feature sets are then used for building a rule-based classification framework for automatic identification of
2010 IEEE ANDESCON, 2010
Abstract In this paper Kalman filter and Wavelet transform (DWT) are compared in voltage event se... more Abstract In this paper Kalman filter and Wavelet transform (DWT) are compared in voltage event segmentation. The waveform segmentation is required to detect stationary and non-stationary stages throughout the voltage event waveforms. This detection plays an ...
Revista Iberoamericana de Automática e Informática Industrial RIAI, 2013
ABSTRACT This paper focuses on diagnosis of voltage events collected in power distribution networ... more ABSTRACT This paper focuses on diagnosis of voltage events collected in power distribution networks. Fault networks, induction motor starting, transformer energization and capacitor bank switching cause voltage events. A characterization of voltage events using attributes directly extracted from the voltage and current waveforms is done in this paper. The used attributes are highly related with the event root-cause as well as the relative location of the event source with respect to the measurement point. The relevance of each attribute has been assessed applying a statistical analysis of variance (MANOVA). The most relevant attributes have been used as input to rule-extraction algorithms in order to extract classification rules. The results were obtained using 484 real-world and 38 synthetic voltage events.
Lecture Notes in Computer Science, 2009
In the recent years, there is an increasing interest of the use of case-based reasoning (CBR) in ... more In the recent years, there is an increasing interest of the use of case-based reasoning (CBR) in medicine. CBR is an approach to problem solving that is able to use specific knowledge of previous experiences. However, the efficiency of CBR strongly depends on the similarity metrics used to recover past experiences. In such metrics, the role of attribute weights is
2010 IEEE ANDESCON, 2010
Abstract This paper proposes a segmentation method to analyze waveforms based on tensor analysis.... more Abstract This paper proposes a segmentation method to analyze waveforms based on tensor analysis. The method directly identifies the non-stationary parts of the waveforms from the instantaneous voltage and current values instead of using the rms sequence values. ...
European Transactions on Electrical Power, 2010
Electric Power Systems Research, 2012
Waveform segmentation algorithms to determine non-stationary stages of events are analyzed in thi... more Waveform segmentation algorithms to determine non-stationary stages of events are analyzed in this paper. Disturbances caused by four different types of voltage events (single and multi stage short-circuits, transformer saturation, and fuse operation events) have been used in the study. Performance of three different segmentation algorithms has been analyzed against these disturbances. Two of them are based on Kalman filter and the third one uses a Tensor theory based approach. One of the Kalman-based algorithm uses the residual model concept to identify non-stationary stages, whereas the other one takes advantage of second order harmonic components flowing during nonstationary stages. Tensor-based algorithm uses the geometric analysis of instantaneous power and its variation through time to identify non-stationary stages. Performance of these algorithms has been assessed using both, synthetic and real-world events. Accuracy of the s is analyzed with respect to the remaining voltage and the fault insertion phase angle. Advantages and drawbacks of each algorithm according to the different causes of events are identified and discussed. In general, the tensor-based algorithm has shown to be the fastest and more accurate identifying non-stationary stages in power quality events.
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Papers by Victor A Barrera Nunez