IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 2377 Attribution of Responsibility for Short-Duration Voltage Variations in Power Distribution Systems via QGIS, OpenDSS, and Python Language Arthur Gomes de Souza , Luiz Arthur Tarralo Passatuto , Wellington Maycon Santos Bernardes , Luiz Carlos Gomes Freitas , and Ênio Costa Resende Abstract— Short-Duration Voltage Variations (SDVVs) are phe- nomena that significantly impact power quality. Although they typically last no longer than three minutes, such events can disrupt load operations and cause substantial production losses. This study presents an enhanced methodology for determining whether an SDVV event originates upstream or downstream of the point of common coupling between two agents interconnected through a transformer. Building upon the work of Ferreira et al., whose origi- nal approach was applied to a circuit using MATLAB/Simulink, this research advances the methodology by applying it to both real and benchmark distribution systems using open-source tools, namely QGIS, OpenDSS, and PythonTM. The well-known IEEE 34-Bus Test System has been used to verify the methodology’s generaliz- ability. The method was also further validated through tests con- ducted on two actual Brazilian distribution feeders in Uberlândia, Minas Gerais: one supplying large industrial consumers such as a rice mill and a carbonated beverages factory, and the other serving a municipal wastewater treatment plant and a large photovoltaic plant. By using real, detailed and georeferenced data, the approach ensures an accurate representation of both the network topology and the installed equipment. The results confirm that the proposed methodology reliably identifies the origin of SDVV events. A key contribution of this study is that the attribution of responsibility remains robust regardless of variations in transformer winding Received 4 May 2025; revised 20 August 2025; accepted 31 August 2025. Date of publication 7 October 2025; date of current version 10 February 2026. Paper 2025-PSEC-0778.R1, presented at the 2024 International Work- shop on Artificial Intelligence and Machine Learning for Energy Transfor- mation (AIE), Vaasa, Finland, May 20–22, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Power Systems Engineering Committee of the IEEE Industry Applications Society [DOI: 10.1109/AIE61866.2024.10561325]. This work was supported in part by Minas Gerais Research Funding Foundation (FAPEMIG) through Demanda Universal under Grant APQ-02176-22 and Grant APQ-04929-22, in part by Conselho Nacional de Desenvolvimento Científico e Tecnológico through CNPq under Grant 406881/2022-7, and in part by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil through CAPES - Finance Code 001, ROR: 00x0ma614. (Corresponding author: Wellington Maycon Santos Bernardes.) Arthur Gomes de Souza, Luiz Arthur Tarralo Passatuto, Wellington May- con Santos Bernardes, and Luiz Carlos Gomes Freitas are with the Depart- ment of Electric Power Systems (DEPSEE), Faculty of Electrical Engineering (FEELT), Federal University of Uberlândia (UFU), Uberlândia 38400-902, Brazil (e-mail: arthurgs@ufu.br; tarralo@ufu.br; wmsbernardes@ufu.br; lcgfre- itas@ufu.br). Ênio Costa Resende is with the Department of Electric Power Systems (DEPSEE), Faculty of Electrical Engineering (FEELT), Federal University of Uberlândia (UFU), Uberlândia 38400-902, Brazil, and also with the School of Technology and Innovations, Electrical Engineering, University of Vaasa, 65200 Vaasa, Finland (e-mail: eniocostaresende@ufu.br). Color versions of one or more figures in this article are available at https://doi.org/10.1109/TIA.2025.3618601. Digital Object Identifier 10.1109/TIA.2025.3618601 configurations, fault resistance, circuit topology, load character- istics, or the presence of distributed generation. These findings demonstrate the accessibility, robustness and practical applicabil- ity, offering a valuable tool for utilities and researchers aiming to enhance power quality and accountability in distribution networks. Index Terms—OpenDSS, phenomenon responsibility, power quality, QGIS, short-duration voltage variation (SDVV). NOMENCLATURE ANEEL Brazilian Electricity Regulatory Agency. ANN Artificial Neural Networks. BDGD Geographic Database of the Distribution Company. CLVR Critical Load Voltage Regulator. DG Distributed Generation. DVR Dynamic Voltage Restorer. FFT Fast Fourier Transformer. GIS Geographic Information System. HV High Voltage. LL Line-to-Line. LLL Three-phase. LLG Double-Line-to-Ground. LG Single-Line-to-Ground. MV Medium Voltage. PRODIST Electric Power Distribution Procedures in the Na- tional Electric System. SDVV Short-Duration Voltage Variation. STFT Short-Time Fourier Transform. UF Unbalance Factor. I. INTRODUCTION A CONSUMER, whether an industry, a commercial com- pany, or even a residential home, is exposed to challenges associated with the quality of electrical energy that may signifi- cantly impact their processes and operations [1], [2], [3]. One of these problems is the SDVV. According to the Brazilian Electric- ity Regulatory Agency (ANEEL) [4], SDVV refers to significant deviations in the voltage rms value, that occur in time intervals of less than three minutes. These phenomena are the main causes of power quality loss, caused by short circuits, switching of large loads that require high starting currents, or intermittent disconnection of cable within the electrical system. SDVVs are divided into voltage surges, voltage sags, and short interruptions, depending on the duration of the occurrence [5], [6]. © 2025 The Authors. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ https://orcid.org/0000-0003-2025-2988 https://orcid.org/0009-0002-5577-118X https://orcid.org/0000-0001-7401-3478 https://orcid.org/0000-0002-1036-2801 https://orcid.org/0000-0002-5110-6791 mailto:arthurgs@ufu.br mailto:tarralo@ufu.br mailto:wmsbernardes@ufu.br mailto:lcgfreitas@ufu.br mailto:lcgfreitas@ufu.br mailto:eniocostaresende@ufu.br https://doi.org/10.1109/TIA.2025.3618601 2378 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 SDVV often lead to increased consumer complaints, mal- function or shutdown of sensitive equipment across residential, commercial, and industrial sectors. These disturbances may also interrupt production processes, cause economic losses, and compromise both facility and public safety [7], [8]. This article proposes a generalized methodology for accurately assigning responsibility in SDVV events, independent of the electrical system’s specific configurations. The method is designed to be broadly applicable, enhancing the precision and reliability of dis- turbance source identification. The proposed approach enhances electrical network reliability and facilitates the integration of advanced analytical techniques. As a result, energy data can be managed more efficiently and interpreted with greater clarity. Module 8 of Electric Power Distribution Procedures in the National Electric System (PRODIST) from Brazil evaluates the SDVVs, and these contingencies are stratified based on their duration and amplitude. After this stratification, the events are divided into nine sensitivity regions. The aim is to establish a correlation between the importance of each SDVV event and the sensitivity levels of the different loads connected to distribution systems, in Medium Voltage (MV) or High Voltage (HV). Next, the Unbalance Factor (UF) indicator is calculated, which characterizes the severity of the SDVV event [4]. It is important to highlight that the calculation of UF does not lead to any form of penalization or allocation of responsibility between the electricity companies and/or consumers. Instead, it merely assesses the event. Given the frequent occurrence of SDVV in power grids, a straightforward and practical method for attributing responsibility is essential. The startup of large motors may require mitigation strategies, such as the use of soft-start devices or pre-scheduled operations, to prevent volt- age sags and ensure compliance with power quality standards. By defining clear responsibilities, this methodology facilitates efficient problem-solving and ensures the reliability of the grid. Ferreira et al. [9] introduced a methodology for allocating responsibilities based on the analysis of voltage unbalances at the primary and secondary sides of the service transformer. Their original implementation was carried out using MAT- LAB/Simulink, a proprietary platform widely used for simu- lation in Electrical Engineering. Notably, their validation was performed using a simplified and fully controlled laboratory circuit, which limits its applicability to real-world conditions. In contrast, the present study revisits and expands upon the original methodology by applying it to both real-world dis- tribution feeders and a standardized IEEE benchmark circuit, using only open-source tools. This extension demonstrates the method’s robustness and applicability in practical, large-scale scenarios. Particularly, the study proposes adaptations and im- provements that enhance the applicability and scalability of the original method. The revised methodology is initially tested on the test circuit from the reference [9], a simplified system used to validate foundational aspects. Following this, in sequence, it is applied to the IEEE 34-Bus System, a widely recognized benchmark for distribution network analysis. Subsequently, a more ro- bust validation is conducted using two real feeders operated by CEMIG Distribuição S/A in the city of Uberlândia, Minas Gerais, Brazil. These feeders supply large industrial consumers and critical infrastructure, which are especially vulnerable to process disruptions caused by SDVV. The first feeder serves two major industrial facilities: a carbonated beverage factory and a rice processing plant. The second feeder supplies a municipal wastewater treatment plant and a large photovoltaic plant, under- scoring the growing integration of distributed generation (DG), which has been rapidly expanding in Brazil and worldwide. In addition, the network used for the simulations was obtained from the Geographic Database of the Distribution Company (BDGD), incorporating data on distribution lines (length, re- sistance, and reactance per kilometer), transformers, and loads, using QGIS [10] (previously known as Quantum Geographic Information System (GIS)). It is a full-featured, free and open source tool to perform different species of spatial analysis, al- lowing to create, edit, visualize, analyze and publish mapping in- formation on Windows, Mac OS, Linux and others. Previously, it was challenging to find libraries that could automatically model feeders into files compatible with OpenDSS, and this process was done entirely manually. The analyzed feeders, ULAE714 and ULAU13, were fully modeled based on the BDGD using BDGD2DSS1, a custom PythonTM library developed by two of the authors [11]. This tool converts data from the BDGD into files for simulation and analysis of electric distribution feeders in the OpenDSS environment. Alternatively, the modeling can also be performed using the library developed by Radatz et al. [12]. Once the complete network has been assembled, simulations were carried out in OpenDSS, and a PythonTM routine was developed for processing. It is well-known that OpenDSS is an open-source software widely used in both academic and commercial contexts to sim- ulate electrical distribution networks [13], [14], [15]. Several research studies have used OpenDSS for various purposes, such as: (a) using chatbots to generate distribution network models, specifically for educational applications [16]; (b) optimizing with MATLAB the integration of Distributed Generation (DG) systems into the distribution network [17]; and (c) evaluation of the impact of the integration of charging stations for electric vehicles into a real network [18]. The versatility and widespread use of OpenDSS make it a valuable tool for energy system study. It also has an interface to PythonTM via the py-dss-interface package [19] enabling seamless communication between script and software. As is evident, a comprehensive explanation of the work’s originality and specific contributions has been aforementioned to the reader. Other papers summarising the related studies are described in Table I. In general, these are studies that focus solely on the detection and measurement of SDVV, while others com- pare international reference standards. Only one study employs a methodology for the attribution of a SDVV, which served as reference for the present work. Attention should be drawn to the fact that this article is an updated version of Passatuto et al. [1], enhancing the explanation 1Available in https://pypi.org/project/bdgd2dss/. The user should use the command ‘pip install bdgd2dss’ for package installation. Release on: July 31, 2025. The first commits found on Github are from September 2nd, 2024. https://pypi.org/project/bdgd2dss/ DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2379 TABLE I SUMMARY OF STUDIES ON SHORT-DURATION VOLTAGE VARIATION (SDVV) of methodology, as well as incorporating additional feeders with distinct characteristics and applying more computational simulations. While the previous study focused on an only single feeder, this work extends the analysis to the electrical circuit designed by Ferreira et al. [9], to the IEEE 34-Bus Test System, as well as two real feeders, ULAE714 and ULAU13, providing a broader assessment of the proposed work across different network configurations. The paper is divided as follows: Primarily, Section II discusses the methodology applied and explains the mathematical and computational tools used, as well as elucidates the acquisition and modeling of the electrical circuit with OpenDSS software and PythonTM language. In Section III, the results are pre- sented and critically analyzed. The validity of this investigation is corroborated through the testing of several aforementioned electrical networks. Finally, Section IV concludes the study and provides recommendations for future research. II. METHODOLOGY The SDVV events are rms voltage changes, namely interrup- tion, swell, and sags. These phenomena represent momentary voltage variations in power systems: a sag is a temporary drop below a specified threshold, typically caused by short circuits or large load startups; a swell is a brief increase above the nominal level, often due to load switching or grounding issues; and an interruption occurs when the voltage falls below 5% of the reference value, indicating a near or total loss of supply. The duration is determined by the elapsed time interval in which the signal exceeds a certain threshold value [4], [31]. Most SDVV events are caused by short circuits [32]. According to Furse et al. [33], the most common causes of short circuits in power grids are: faulty equipment, human error, vehicle accidents, falling trees, strong winds, and storms. It is observed that most of these events are temporary, either due to the nature of the anomaly or due to protective measures, causing a voltage sag in the network. According to Bordalo et al. [34] and Martins [35], the fol- lowing average values for the short-circuits occurrence were determined by statistical analysis: � Three-phase (LLL) short circuit: 3%; � Double-Line-to-Ground (LLG) short circuit: 6%; � Line-to-Line (LL) short circuit: 10% and 2380 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 � Single-Line-to-Ground (LG) short circuit: 81%. In other words, 97% of short circuits are asymmetric. There- fore, the analysis presented in this article to assign responsibility for SDVV is based on the propagation of UF between the primary and secondary sides of the transformer [9]. Unbalanced three-phase voltages and currents can be decomposed into their positive, negative, and zero sequence components, among other analysis techniques. The relationship between the original com- ponents A, B and C and the subsequent components is given by (1). ⎡ ⎢⎣ V̇a V̇b V̇c ⎤ ⎥⎦× ⎡ ⎢⎣ 1 1 1 1 a2 a 1 a a2 ⎤ ⎥⎦ = ⎡ ⎢⎣ ˙Va0 ˙Va1 ˙Va2 ⎤ ⎥⎦ (1) Once the sequence components of the voltages are obtained, the UF can be calculated using (2) and (3). UF%V2 = Va2 Va1 × 100% (2) UF%V0 = Va0 Va1 × 100% (3) The methodology is based on the evaluation of the propaga- tion behavior of negative sequence voltage unbalance in the transformer when a short circuit happens, and consequently a SDVV. For the evaluation, several short circuits were applied on the primary and secondary sides of the transformer, observing whether the type of fault influences the results. Another variation has been the type of connection of the primary and secondary windings. The zero sequence UF will be not analyzed because this com- ponent may not be present depending on the type of connection, for example, if one of the windings is connected in a Δ design, making it impossible to use (3). A further change, compared to the proposal of Ferreira et al. [9] is that the relationship between the UF, here denoted as URPS , of the primary and secondary sides is evaluated for the attribution of responsibility for the SDVV (4). The values on the primary and secondary sides are compared qualitatively in the reference, but no explicit factor or quantitative relationship between these values has been defined. URPS = UFprimary UFsecundary (4) This work proposes that in case of a short circuit occurs on the primary side of the substation, i.e. on the electric utility side, regardless of its type or the number of phases involved in the fault or the fault resistance value, the relationship defined by (4) will be � 0.95 (threshold) and the responsibility for the SDVV can be attributed to the electric utility. If, on the other hand, the fault occurs on the secondary side, i.e. on, the consumer side, the relationship defined by (4) is < 0.95, which means that the responsibility for SDVV lies with consumer connected to substation transformer. Fig. 1. Circuit from Ferreira et al. [9]. Fig. 2. IEEE 34-Bus System [39]. A. Case Studies The test circuit from the [9] is considered in first. This benchmark system serves as a foundation for validating the proposed methodology. Following this, the study analyzes a benchmark power distribution system from IEEE, as well as two real distribution feeders, both located in the city of Uberlândia, Minas Gerais, Brazil. Each case presents distinct characteristics and contributes to a comprehensive evaluation of the proposed methodology. The analyzed systems are described as follows: � Circuit from Ferreira et al. [9] – The test system used in Ferreira et al. [9] consists of a simple circuit with three transformers and two load groups, as shown in Fig. 1. The methodology proposed in this article will initially be tested on this electrical network, with Transformer 1 (T1) being the primary focus of the study. � IEEE 34-Bus System – It models a 34-node, 24.9 kV medium-voltage radial distribution system with unbal- anced loads and long, high-impedance lines, making it ideal for voltage drop and power loss studies. The sys- tem incorporates various load types, capacitor banks, and voltage regulators, providing a realistic representation of real-world distribution networks. Due to its complexity, it is extensively used in studies on voltage control, fault analysis, and the integration of distributed generation [36], [37], [38] (Fig. 2). DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2381 Fig. 3. Feeder ULAE714 region. A rice mill and a carbonated drink industry in highlight [40]. � Feeder ULAE714 – Originating from the Uberlândia 7 Substation, this 13.8 kV distribution circuit supplies electricity to consumers in the Custódio Pereira neighbor- hood. The feeder delivers power to both medium and low voltage consumers, encompassing residential areas, com- mercial establishments, and industrial facilities. Among the industrial loads connected to this feeder are a rice processing plant and a carbonated beverage factory, both of which contribute significantly to the feeder’s demand due to their continuous and energy-intensive operations. Fig. 3 illustrates the layout and coverage of this feeder within the distribution network, highlighting the substation transformer and the loads of interest with their respective bus numbers (note that this numbering originates from the database in use). � Feeder ULAU13 – Originating from the Uberlândia 1 Sub- station, this 13.8 kV distribution circuit supplies electricity to consumers in the Guarani and Tocantins neighborhoods. It serves medium and low voltage loads, including resi- dential, commercial, and institutional consumers. A key feature of this feeder is its connection to a large-scale photo- voltaic farm, which contributes to the local distributed gen- eration capacity. Additionally, the feeder supplies power to the municipal wastewater treatment plant, an essential infrastructure facility. Fig. 4 shows the layout and area of coverage of this feeder within the distribution system, highlighting the substation transformer and the loads of interest with their respective bus numbers (note that this numbering originates from the database used). The test circuit from the [9], along with these feeders and the IEEE 34-Bus System, were selected to evaluate the proposed methodology in different operational scenarios, considering both industrial and infrastructure-critical loads, as well as a standardized benchmark for comparison. This approach evaluates the methodology across different scenarios, considering load typology variations along the feeder. Both circuits were modeled using BDGD data, a public database with detailed electrical and geographical feeder information. These data are processed in QGIS following Module 10 of PRODIST, which standardizes Brazilian regulatory geographic information, ensuring consistency in network modeling [41], [42]. The BDGD contains comprehensive information about a vast region served by the utility, potentially covering an entire state. To simplify the studies, filters must be applied to delimit the analysis area. Fig. 3 illustrates feeder ULAE714, and Fig. 4 shows feeder ULAU13, both adding a layer with a visualization of the regions using the Google Satellite plug-in for QGIS [40]. In Figs. 3 and 4, the transmission lines responsible for supplying electrical power to the high-voltage substation are represented in pink. The green square indicates the substation, where the substation transformer is located and which will be the focus of this investigation for attributing responsibility, either upstream or downstream, while the white line represents the medium-voltage network. Regarding the points, red markers in- dicate distribution transformers, whereas yellow markers denote reclosers, which identify the connection points for consumers supplied by the medium-voltage network. Additionally, in Fig. 3, 2382 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 Fig. 4. Feeder ULAU 13 region. Photovoltaic farm and a municipal wastewater treatment plant in highlight [40]. the green diamond highlights the rice milling industry, while the black diamond represents the carbonated beverage industry. In Fig. 4, the yellow symbol marks the photovoltaic farm, and the blue diamond corresponds to the municipal wastewater treatment plant. For the feeder modeling, the BDGD2DSS library, which is already publicly available [11], has been employed. A complete description of its design and functionalities will be presented in future works due to space constraints. This library processes the BDGD layers and converts them into . dss files, enabling the complete modeling of the system, including both medium- and low-voltage sections, as well as loads and distributed generation. The generated files can then be simulated within the OpenDSS environment. By automating data conversion, the library facili- tates the integration of real-world network information into com- putational simulations, enhancing the accuracy of this analysis. The modeled feeders are in a public repository from GitHub, Inc© , available by the researchers in [43]. The BDGD layers used in the modeling can be grouped according to their function: 1) Electrical Infrastructure: � SUB – Substations of the system; � CTMT – Medium voltage circuits, used to identify the feeder; � UNTRAT – Substation transformers; � UNTRMT – Medium voltage transformers along the circuit. 2) Electrical Network and Conductors: � SEGCON – Detailed conductor data, including resis- tance and reactance. � SSDMT, SSDBT, and RAMLIG – Lengths of medium and low voltage segments, and connection branches. 3) System Loads: � UCMT and UCBT – Medium and low voltage consumer units, respectively, from which the load powers are extracted. � PIP – Public lighting points. � CRVCRG – Load curves associated with different types of consumers. 4) Distributed Generation: � UGBT and UGMT – Low and medium voltage gener- ation units. 5) Control and Protection Equipment: � UNSEMT and UNSEBT – Medium and low voltage disconnect switches, essential to avoid improper inter- ruptions in the modeling. � EQRE and UNREMT – Voltage regulators of the net- work. � UNCRMT – Capacitor banks used to correct the voltage level at certain feeder buses. Thus, the developed model accurately represents the feeder’s structure, ensuring that the simulation in OpenDSS properly reflects the electrical characteristics of the studied network. The modeling process followed the standard set by ANEEL [44], [45], [46]. The short-circuit level at the substation input was set to 100 MVA. The simulations were configured in daily mode, considering a 24-hour period. The one-line diagram presented in Fig. 5 provides a simplified schematic representation of the feeders illustrated in Figs. 3 and 4. Transformer T1, which represents the one located at the DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2383 Fig. 5. Single-line diagram. Transformer T1 connection type will be changed interactively in the simulations (from Δ− Yn, to Yn −Δ, Δ−Δ and Yn − Yn). substation, has its data extracted from the UNTRAT layer and will be the object of study in this analysis. Short-circuit tests are conducted on both the primary and secondary windings of this transformer, as illustrated in Fig. 5. During the simulation, the connection type will be adjusted accordingly in order to validate the proposed method and ensure accurate results for each configuration. Transformers T2, T3, T4, and Tn represent the medium- voltage transformers from the UNTRMT layer, which may cor- respond to both the distribution network transformers and those of consumers supplied with medium voltage. Among these consumers, those in feeders ULAE714 and ULAU13, highlighted in Figs. 3 and 4, are of particular importance. Information about these consumers is extracted from the UCMT and UCBT layers. The white lines represent the medium-voltage circuit, with data extracted from the SEGCON and SSDMT layers, while the gray lines correspond to the low-voltage circuits from the SSDBT layer. Additionally, the presence of distributed generation (DG) is indicated at both medium and low voltage buses, reflecting its distribution along the circuit, as recorded in the UGMT and UGBT layers. B. Computational Modeling and Analysis To validate the proposed method, computational simula- tions of the electrical circuits have been performed using the OpenDSS software, also utilizing an interface script written in the PythonTM language [47] with the py-dss-interface library. This package was used to facilitate direct communication and easy manipulation and to allow the export of data to more suitable formats or the creation of diagrams as desired. To better understand the simulation, a flowchart is shown in Fig. 6. Basically, an instance is created between PythonTM and Fig. 6. Flowchart of the proposed intelligent algorithm. OpenDSS using the mentioned package, reading the . dss file with the data of the circuit under study. Within the same script, a list of the twenty four fault cases to be studied was created. The four connection schemes of the transformer are then run through, and the faults contained in the list of cases are simulated for each of these schemes. After compiling the circuit file with py-dss-interface, the simulation is run in daily mode for one day, with short circuits applied at noon, when solar incidence and DG contribution are highest. The PythonTM script is used to extract the data of interest. This includes the unbalances of the negative sequence voltages in relation to the positive sequence voltages, on the primary and secondary sides of the transformer (supplier and load, respectively), each one in percent. By calculating the ratio between these unbalances, the responsibility is assigned to one of the parties involved in the system. Subsequently, the data is organized in a data frame using Pandas library [48] for further analysis. In the end, when all connection schemes have been run through, the graphs are plotted using matplotlib [49] for better visualization by the user. The proposed flowchart can be used for different types of analyses related to the assignment of responsibility when SDVV occurs. The electrical system can be modelled directly with the. dss file. Much of the extracted data have the default settings from OpenDSS itself, and this may be checked directly via the manual [50], following the same standard procedures in Brazil. The proposed script simulates 24 different fault cases, con- sidering up to four transformer connection schemes, based 2384 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 on the most commonly used configurations in the ANEEL database [41] and the schemes available in OpenDSS. However, not all connection schemes are tested in every case. When all four transformer connections are considered, the total number of simulations reaches 96 (4 connection schemes × 24 fault cases). For each fault type, i.e., LG, LLG, or LL, simulations are conducted with short-circuit resistances of 0 Ω, 5 Ω, 10 Ω, and 20 Ω. The inclusion of these resistance values ensures a more comprehensive analysis, preventing extreme variations in fault currents and aligning with numerical values used in [51]. It can be observed that the simulations in OpenDSS consider a common reference for all elements of the circuit. Therefore, the application of LG and LLG faults on the Δ transformer side, will occur in one of the phases and the ground. III. RESULTS AND DISCUSSIONS The simulations provide the desired data, with the most relevant being the ratio URPS between the UF on the pri- mary (supplier) and secondary (consumer) sides of Transformer T1 during the fault, as defined by (4). This ratio determines which side is responsible for the SDVV, validating the proposed methodology. Voltage plots are not presented since the studies are conducted in DSS, a frequency-domain simulation engine specifically designed for power distribution systems. The tests were carried out on the circuit from [9], the IEEE 34-Bus System, and the feeders ULAE714 and ULAU13. In the IEEE 34-Bus System, different transformer connection config- urations were tested to assess their influence on the proposed methodology. For the first feeder, all possible configurations of the substation transformer (Transformer T1) were analyzed, applying various types of short circuits to both the primary and secondary sides of the transformer while considering different short-circuit resistance values, as previously described. For the second feeder, an additional analysis was conducted to evaluate the impact of distributed generation (DG) by comparing sce- narios with and without its presence. This comparison aimed to determine whether the introduction of DG affects the method- ology’s effectiveness. A. Case 1 - Circuit From [9] Table II presents the single-phase voltages at both the primary and secondary sides of transformer T1 (Δ-Yn), corresponding to buses B1 and B2 in the circuit. Five scenarios are considered: 1) Pre-fault single-phase voltages at buses B1 and B2; 2) Single-phase voltages during LG fault at bus B1 (primary side of the transformer) with Rfault = 0 Ω; 3) Single-phase voltages during LG fault at bus B2 (sec- ondary side of the transformer) with Rfault = 0 Ω; 4) Single-phase voltages during LL fault at bus B1 (primary side) with Rfault = 20 Ω and; 5) Single-phase voltages during LL fault at bus B2 (sec- ondary side) with Rfault = 20 Ω. From these values, the unbalanced three-phase system is decomposed into three balanced sequence components (posi- tive, negative, and zero sequence) using (1). Subsequently, the unbalance factors for both the primary and secondary sides TABLE II PRE-FAULT AND FAULT VOLTAGES AND ANGLES FOR THE CIRCUIT IN [9] (TRANSFORMER: Δ-Yn) are determined using (2) and (3). Finally, (4) is applied to compute the ratio between the primary and secondary unbalance factors, enabling the assessment of unbalance propagation. It is important to note that Table II presents results only for the short-circuit conditions corresponding to cases 1, 5, 20 and 24 of Table III, due to limitation of space. Building upon this initial analysis for theΔ-Yn configuration, the study extends to evaluate transformerT1 under four different possible winding connections: Δ-Yn, Δ-Δ, Yn-Yn, and Yn-Δ. Additionally, different short-circuit resistances are applied to both the primary and secondary windings to assess their influ- ence on system behavior. The results, presented in Table III, illustrate how variations in transformer connections and fault conditions impact the propagation of unbalances and voltage deviations within the network. Analyzing Table III, there is minimal variation due to trans- former winding configurations or the applied short-circuit resis- tance. This indicates that, in a smaller, simplified, and controlled circuit, such changes do not significantly affect the results. As a final point, the same Table III shows that primary-side faults yield an unbalance ratio near 1, while secondary-side faults cause a significant drop below 0.95. According to Fig. 6, this threshold distinguishes responsibility attribution. These re- sults confirm that the unbalance ratio reliably indicates whether voltage disturbance originates on the primary or secondary side. B. Case 2 - IEEE 34-Bus System Table IV presents the pre-fault and during-fault voltages for a LG short circuit, as well as for a LL fault applied to both the primary and secondary sides of the transformer (SourceBus and Bus 800), with a fault resistance of 20 Ω. As in the previous case, these single-phase voltage values are used to calculate the unbalance factors and analyze their propagation throughout the system. It is important to note that Table IV includes only cases 1, 5, 20 and 24 from Table V. DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2385 TABLE III SIMULATION RESULTS FOR DIFFERENT CONNECTIONS T1 IN CIRCUIT FROM [9] TABLE IV PRE-FAULT AND FAULT VOLTAGES AND ANGLES FOR THE CASE IEEE 34-BUS SYSTEM (TRANSFORMER: Δ-Yn) In the IEEE 34-Bus System, the propagation of unbalance was analyzed considering two different configurations for the supply transformer, originally connected in Δ-Yn at bus 800 in Fig. 2. Initially, tests were conducted with the original configuration, and subsequently, the transformer connection was modified to TABLE V SIMULATION RESULTS FOR DIFFERENT FAULT TYPES CASE IEEE 34-BUS SYSTEM Yn-Yn to assess the impact of this change on the propagation of unbalance throughout the system. The results obtained for both configurations are presented in Table V, highlighting the 2386 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 TABLE VI PRE-FAULT AND FAULT VOLTAGES AND ANGLES FOR THE ULAE714 FEEDER (TRANSFORMER: Δ-Yn) variations in voltages and unbalances recorded at different points in the electrical network. Analyzing the results in Table V, it is clear that for faults on the primary side, the URPS values remain close to 1in both transformer configurations. The greatest variation occurs in case 12. In this scenario, the URPS value changes from 0.9993 in the Yn-Yn configuration to 1.0012 in the Δ-Yn configuration. The absolute difference between these values is 0.0019, while the relative difference, considering the Yn-Yn configuration as a reference, is approximately 0.19%. This indicates that the impact of the transformer connection on the fault response on the primary side is minimal, with variations that are practically negligible in most practical applications. On the other hands, for faults on the secondary side, it is observed that the unbalance ratio does not remain close to 1, indicating that the unbalance does not propagate in the same way as when the fault occurs on the primary side. As ratio < 0.95, the responsibility is assigned to the consumer according to Fig. 6. Therefore, these outcomes support the methodology’s premise that, when the SDVV occurs on the primary side, the unbalance ratio between the primary and secondary is close to 1. And it will be otherwise, in case the SDVV occurs on the secondary side. C. Case 3 - Feeder ULAE714 Table VI presents the pre-fault and during-fault voltages for a LG short circuit, as well as for a line-to-line fault with a fault resistance of 20Ω applied to both primary and secondary sides of the transformer (SourceBus and Bus 126355009). Repeating the previous process, these single-phase voltage values are used to calculate the unbalance factors and analyze their propagation throughout the system. It is important to note that Table VI includes only cases 1, 5, 20 and 24 from Table VII. Table VII presents the simulation results for the four trans- former connection schemes:Δ-Yn,Yn-Δ,Δ-Δ, andYn-Yn. The results include different short circuit resistance values and the URPS ratios obtained for each configuration. It is observed that the variation in resistance has little influence on the URPS ratio when comparing cases with the same transformer and fault type. The most significant difference occurs in the Δ-Yn connection for an LG fault on the secondary side (cases 5 and 6), showing an absolute variation of 0.1202. However, this variation does not significantly impact the overall analysis, as the URPS ratio remains far from unity in all cases. When comparing different connection schemes, the results remain consistent across configurations. Even with variations in transformer connection, the URPS ratio stays close to unity when the fault occurs on the primary side. The largest observed difference appears in an LG fault on the secondary side, consid- ering a fault resistance of 0 Ω, for the Δ-Yn and Δ-Δ connec- tions, resulting in a value of 0.2442. However, this difference does not affect the final conclusions, as the URPS ratio re- mains far from unity, reinforcing the robustness of the proposed methodology. Thus, the study concludes that, in these cases, the URPS ratio is minimally influenced by the type of transformer winding connection, regardless of the presence or absence of a nonzero fault resistance. This finding is crucial for the assignment of responsibility in the occurrence of a SDVV, as the URPS ratio provides an objective criterion: when it exceeds a defined thresh- old, the fault is attributed to the primary side of the transformer (supplier). Given that the lowest observed value was 0.9985 and the highest was 1.0006, the established threshold of 0.95, as defined in the script according to Fig. 6, proves to be not only appropriate but could potentially be set even more restrictively, reinforcing the robustness of the methodology. It is important to highlight that when a fault occurs on the sec- ondary side, where the consumer is connected, the measurement of the UF at this location has minimal influence on the observed value at the primary side. Conversely, when the fault occurs on the primary side, the resulting unbalance directly impacts the UF on both sides, causing their values to become nearly identical. D. Case 4 - Feeder ULAU13 Table VIII presents the pre-fault and during-fault voltages for a LG short circuit, as well as for a LL fault with a fault resis- tance of 20 Ω, applied to both primary and secondary sides of the transformer (SourceBus and Bus 126438617). Additionally, Table VIII shows the voltage behavior at the bus (179454784) of the photovoltaic farm. Following the same procedure as before, these voltages serve as the basis for calculating unbalance indi- cators and analyzing their propagation throughout the system. Note that only cases 1, 5, 20, and 24 from Table IX are included in Table VIII. Observe that Table IX presents the values of the unbalance ratio URPS for the feeder, considering scenarios with and DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2387 TABLE VII SIMULATION RESULTS FOR DIFFERENT CONNECTIONS FEDDER ULAE714 TABLE VIII PRE-FAULT AND FAULT VOLTAGES AND ANGLES FOR THE ULAU13 FEEDER (TRANSFORMER: Δ-Yn) without DG, as well as variations in the transformer winding connection (Δ-Yn and Yn-Yn) and short circuit resistance. The analysis of Table IX confirms that both the variation in short circuit resistance and the configuration of the transformer windings do not significantly influence the unbalance ratios, as observed in Case 1 and 2, leading to the same decisions. Furthermore, when comparing the results with and without the presence of DG, the largest absolute difference observed was 0.0021 for the Δ-Yn connection in a line-to-line fault on the primary side with RFault = 0 Ω, corresponding to a relative variation of approximately 0.21%. This minimal impact confirms that the presence of DG has a negligible effect on the URPS ratios and, consequently, does not influence the assignment of responsibility in a SDVV. It is again confirmed, in another feeder, that when the SDVV occurs on the transformer’s primary side, the ratio URPS is close to a unit value, while this is not the case on the sec- ondary side. Thus, if URPS is close to 1, the responsibility lies with the supplier; otherwise, the responsibility is with the consumer. For better visualization, the script produces a scatter plot as presented in Fig. 7, showing the ratio between primary and secondary UF for each case considering the two connection schemes. The data used corresponds to the values presented in Table IX. To enhance interpretation, different markers are used to distinguish between faults occurring on the primary and secondary sides of the transformer. Visually, there is little difference between the points of the two connection cases. There is a noticeable distance between the cases where responsibility lies with the supplier and those one where the consumer is responsible. This observation further confirms the earlier find- ing regarding the minimal impact of the type of transformer connection. The threshold used for attribution is indicated in the figure and proves to be satisfactory for distinguishing between responsibilities. 2388 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 62, NO. 2, MARCH/APRIL 2026 TABLE IX SIMULATION RESULTS FOR DIFFERENT CONNECTIONS FEDDER ULAU13 WITH AND WITHOUT DGS Fig. 7. Connection schemes with UF ratios between primary and secondary sides of transformer in cases of SDVV. This study was conducted using a computer with the following specifications: an Intel(R) Core(TM) i5-8500 CPU @ 3.00 GHz processor, 8 GB of RAM, a 500 GB SSD, running Windows 10 Pro (version 22H2, 64-bit), with PythonTM version 3.11.0 and installed OpenDSS version 9.6.1.3. The simulation time for feeder ULAE714 was 793,33 seconds, while for feeder ULAU13, it was 1275,97 seconds. Meanwhile, the IEEE 34-Bus System simulation took less than 10 seconds. IV. CONCLUSION This paper demonstrates that the methodology proposed by Ferreira et al. [9], initially applied to simplified circuits, can also be successfully extended to complete and complex real distribution feeders. By implementing the approach in both actual utility networks and the IEEE 34-Bus Test System, this study confirms its applicability in more realistic and opera- tionally relevant scenarios. The use of OpenDSS, combined with PythonTM, enhances the simulation and analysis process, while offering an accessible and open-source alternative to commercial tools. Additionally, the integration of real network data from the BDGD strengthens the practical value and reliability of the improved methodology. This study contributes to the field of responsibility attribu- tion for SDVV by analyzing various factors that may impact unbalance propagation, including transformer winding config- urations, fault resistance variations, different circuit types with diverse load compositions, and the presence of DG. The re- sults indicate that when the ratio between unbalance factors is below 0.95, the responsibility is attributed to the consumer side, highlighting this threshold as a key indicator. Conversely, values equal to or greater than 0.95 suggest that the disturbance originated on the supplier side. The analysis also revealed that regardless of minor variations introduced by transformer con- nections and fault resistances, the overall trend remained con- sistent. Furthermore, despite the rapid expansion of distributed DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2389 generation (DG) in modern distribution networks, the proposed methodology remains robust and unaffected. The evaluation of multiple circuit configurations with varying load conditions further confirms its reliability and adaptability. It is important to note that this work does not aim to pinpoint the exact physical location of the event within the network or to numerically allocate responsibility for it, which is a limitation of the study and could be addressed in future research. Instead, its purpose is to determine whether the disturbance occurred upstream or downstream of the analysis point, providing a methodology for responsibility attribution. Thus, the proposed methodology contributes to regulatory standards for events such as SDVV, relying on widely acces- sible software and real data from electric utilities. The data were obtained from a public repository. However, it should be emphasized that computational simulations may not fully reflect the current state of the grid, as the utility company frequently makes unannounced updates to the database. One of the main challenges faced during the research was the accurate modeling of the circuit and the development of the simulation code using PythonTM. The first difficulty has been the limited availability of modeling tools, which was overcome through the use of a custom library developed by two of the authors and released to the public, available in [11]. This library will be described in detail in future works. The second challenge involved to create a script capable of simulating various types of faults, which was greatly facilitated by the py-dss-interface library [19]. Another significant difficulty was the potential presence of incorrect or incomplete information in the publicly available BDGD data, which required careful verification during the modeling process. The current results offer significant contributions to the en- ergy transformation sector, providing a method that combines computational analysis with relevant power system data to evaluate recurring power quality events in the electrical grid. Future work will aim to incorporate battery banks and addi- tional consumers, refining the responsibility attribution to in- dividual consumers or groups, rather than just identifying the responsible side. Additionally, future investigations involving Neural Networks [52], [53], [54], [55], [56], [57], [58] may be explored as a means to enhance classification accuracy and automate the attribution process, enabling more adaptive and intelligent analysis of complex power quality patterns in modern distribution networks. 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Appl., vol. 60, no. 6, pp. 9227–9236, Nov./Dec. 2024, doi: 10.1109/TIA.2024.3444744. https://pypi.org/project/py-dss-interface/ https://dx.doi.org/10.1109/ICHQP.2016.7783308 https://dx.doi.org/10.1109/ECCE-Asia49820.2021.9479387 https://dx.doi.org/10.1109/SPEEDAM61530.2024.10609106 https://www.sciencedirect.com/science/article/pii/S0378779625003657 https://www.sciencedirect.com/science/article/pii/S0378779625003657 https://www.mdpi.com/2411-5134/9/1/12 https://www.sciencedirect.com/science/article/pii/S0142061525004181 https://www.sciencedirect.com/science/article/pii/S0142061525004181 https://dx.doi.org/10.1109/EDM.2018.8434940 https://dx.doi.org/10.1016/j.epsr.2020.106811 https://dx.doi.org/10.1109/JSEN.2020.2987321 https://dx.doi.org/10.1109/TPWRS.2006.873055 https://dx.doi.org/10.11606/D.18.2021.tde-24032021-102152 https://dx.doi.org/10.1109/ICCCNT61001.2024.10725909 https://dx.doi.org/10.1109/ICCCNT61001.2024.10725909 https://dx.doi.org/10.1109/SMC42975.2020.9283083 https://dx.doi.org/10.1109/SBSE.2018.8395588 https://dx.doi.org/10.1109/SBSE.2018.8395588 https://dx.doi.org/10.1109/PES.2006.1709506 https://www.google.com/earth/ https://dadosabertos-aneel.opendata.arcgis.com/search{?}collection$=$Dataset https://dadosabertos-aneel.opendata.arcgis.com/search{?}collection$=$Dataset https://www.gov.br/aneel/pt-br/centrais-de-conteudos/procedimentos-regulatorios/prodist https://www.gov.br/aneel/pt-br/centrais-de-conteudos/procedimentos-regulatorios/prodist https://github.com/ArthurGS97/Attribution-SDVV-feeders https://github.com/ArthurGS97/Attribution-SDVV-feeders https://www2.aneel.gov.br/cedoc/aren2021956_2_6.pdf https://www2.aneel.gov.br/cedoc/aren2021956_2_6.pdf https://www2.aneel.gov.br/cedoc/aren2021956_2_9.pdf https://www2.aneel.gov.br/aplicacoes/audiencia/arquivo/2014/026/documento/nota_tecnica_0057_srd.pdf https://www2.aneel.gov.br/aplicacoes/audiencia/arquivo/2014/026/documento/nota_tecnica_0057_srd.pdf https://www.python.org/ https://dx.doi.org/10.25080/Majora-92bf1922-00a https://dx.doi.org/10.25080/Majora-92bf1922-00a https://dx.doi.org/10.1109/MCSE.2007.55 https://www.epri.com/pages/sa/opendss https://dx.doi.org/10.1016/j.epsr.2023.109871 https://www.sciencedirect.com/science/article/pii/S0378779623007599{?}viaLY1 extbackslash %3Dihub https://www.sciencedirect.com/science/article/pii/S0378779623007599{?}viaLY1 extbackslash %3Dihub https://dx.doi.org/10.1109/ISGT-LA.2013.6554422 https://dx.doi.org/10.1109/ISGT-LA.2013.6554422 https://dx.doi.org/10.1109/ISGT-LA.2013.6554453 https://dx.doi.org/10.1016/j.neucom.2015.02.090 https://www.sciencedirect.com/science/article/abs/pii/S0925231215009285 https://www.sciencedirect.com/science/article/abs/pii/S0925231215009285 https://dx.doi.org/10.17648/sbai-2019-111138 https://proceedings.science/p/111138 https://dx.doi.org/10.1109/TIA.2025.3529804 https://dx.doi.org/10.1109/TIA.2024.3430270 https://dx.doi.org/10.1109/TIA.2024.3444744 DE SOUZA et al.: ATTRIBUTION OF RESPONSIBILITY FOR SHORT-DURATION VOLTAGE VARIATIONS 2391 Arthur Gomes de Souza was born in Correntina, Bahia, Brazil. He received the bachelor’s degree in electrical engineering and the M.Sc. degree in elec- trical engineering with a focus on power system pro- tection from the Federal University of Uberlândia, Uberlândia, Brazil, in 2021, He is currently working toward the Ph.D. degree. His graduate studies are financially supported by Coordination for the Im- provement of Higher Education Personnel. As a Re- searcher with the Laboratory of Alternative Energies and Power System Protection, he has worked on a range of topics, including feeder modeling and simulation, and the optimization of protection systems in electrical networks. He is proficient in tools such as OpenDSS, PythonTM and QGIS, with several publications demonstrating his expertise in these areas. His research interests include electrical system modeling, protection coordination, and the application of advanced optimization techniques—such as evolutionary algorithms for coordinating protective devices in distribution networks. Luiz Arthur Tarralo Passatuto was born in Colina, São Paulo, Brazil. He received the B.Sc. and M.Sc. degrees in electrical engineering in 2021 and 2025, re- spectively, from the Federal University of Uberlândia, Uberlândia, Brazil„ where he is currently working toward the Ph.D. degree. As a Researcher with the Laboratory of Alternative Energies and Power System Protection, he has worked with optimization in elec- tric power system protection using metaheuristics, developing software tools that use Blockchain and power system modeling with distributed energy re- sources. He has good knowledge in programming with PythonTM and OpenDSS tool. His research interests include power system analysis, protection studies, solving engineering problems with optimization techniques, and incorporation of distributed energy resources in the electrical network. Wellington Maycon Santos Bernardes was born in Goiânia - Goiás, Brazil. He received the B.Sc. degree in electrical engineering from Federal Uni- versity of Uberlândia (UFU), Uberlândia, Brazil, in 2010, and the M.Sc. and Ph.D. degrees in electrical engineering from São Carlos School of Engineering, University of São Paulo, São Paulo, Brazil, in 2013 and 2018, respectively. He has undertaken a mobility period (Sandwich Ph.D.) supported by the prestigious scholarship of the European Commission’s Erasmus Mundus Programme with the Faculty of Engineering, University of Porto, Porto, Portugal. He was a Professor with UFU in 2019, a Coordinator with the Laboratory of Alternative Energies and Power System Protection, an ad hoc Consultant for the State Funding Agency of Distrito Federal, and the National Institute of Educational Studies and Research Aní- sio Teixeira, Brasília - DF. Extensive experience in academic administration, serving as Coordinator with the Department of Electric Power Systems, and a Undergraduate Coordinator of the Electrical Engineering Program. He also has expertise in power systems projects, funded by Brazilian research foundations (CNPq, CAPES, FAPEMIG, FAPESP) and utility companies. His research interests include power system protection, alternative energies, measurement and uncertainty analysis, optimization and applications of artificial intelligence in electrical networks, energy efficiency, and power quality. Luiz Carlos Gomes Freitas was born in Uberlân- dia, Brazil, in 1976. He received an undergraduate degree in electrical engineering with emphasis on power systems, and the M.Sc. and Ph.D. degrees in electrical engineering with emphasis on power electronics from the Federal University of Uberlândia (UFU), Uberlândia, Brazil, in 2001, 2003, and 2006, respectively. In his doctoral thesis, he developed an innovative topological design of a three-phase hybrid rectifier for high power drive systems. In 2008, he joined as the Faculty Member with the UFU, where he is developing teaching and research activities in the area of power electronics and power systems. Since 2010, he is the Coordinator of the Power Electronics Research Center, Faculty of Electrical Engineering, UFU. His research interests include electrical engineering, conversion and rectification of electric energy, working on various topics related to power electronics, electric power quality, and renewable energy. In 2012, he was th recipient of the Second Prize Paper Award of the IEEE-IAS-Industrial Automation and Control Committee for his contribution to the development of hybrid rectifier structures. Since 2013, he is a Researcher recognized by the National Council for Scientific and Technological Development (CNPq) with a Research Productivity Grant. Ênio Costa Resende received the bachelor’s degree in electrical engineering from the Federal University of Uberlândia (UFU), Uberlândia, Brazil, including an exchange period through the CsF / CAPES Pro- gram with Sacramento State University (SAC-State), Sacramento, CA, USA, in 2018, the M.Sc. degree in electrical engineering with a specialization in power electronics from Power Electronics Research Center, UFU, Postgraduate Program, in 2020, and the Ph.D. degree in electrical engineering in 2024. During his doctoral studies, he was a Visiting Researcher with the University of Vaasa, Vaasa, Finland, from 2023 to 2024, where he worked on Neural Networks and Fuzzy Logic, focusing on islanding detection techniques, synchronization strategies, and maximum power point tracking (MPPT) meth- ods. He is currently a Postdoctoral Researcher with UFU, working on hybrid microgrids, battery charging systems, and electric vehicle charging stations. His research interests include islanding detection, distributed generation, renewable energies, MPPT, control methods, power quality, microgrids, embedded control, and dual-active-bridge converters. << /ASCII85EncodePages false /AllowTransparency false /AutoPositionEPSFiles true /AutoRotatePages /None /Binding /Left /CalGrayProfile (Gray Gamma 2.2) /CalRGBProfile (sRGB IEC61966-2.1) /CalCMYKProfile (U.S. Web Coated \050SWOP\051 v2) /sRGBProfile (sRGB IEC61966-2.1) /CannotEmbedFontPolicy /Warning /CompatibilityLevel 1.4 /CompressObjects /Off /CompressPages true /ConvertImagesToIndexed true /PassThroughJPEGImages true /CreateJobTicket false /DefaultRenderingIntent /Default /DetectBlends true /DetectCurves 0.0000 /ColorConversionStrategy /sRGB /DoThumbnails true /EmbedAllFonts true /EmbedOpenType false /ParseICCProfilesInComments true /EmbedJobOptions true /DSCReportingLevel 0 /EmitDSCWarnings false /EndPage -1 /ImageMemory 1048576 /LockDistillerParams true /MaxSubsetPct 100 /Optimize 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