Teses em Engenharia Elétrica (Doutorado) - PPGEE/ITEC
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2317
O Doutorado Acadêmico inicio-se em 1998 e pertence ao Programa de Pós-Graduação em Engenharia Elétrica (PPGEE) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).
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Item Acesso aberto (Open Access) Análise magnética e mecânica em transformadores sob correntes de energização e energização solidária(Universidade Federal do Pará, 2019-10-01) LIMA, Diorge de Souza; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813The power transformer is one of the most important equipment in the electric power system, allowing the feasibility of connecting the generating centers to the consumer centers, even over long distances. Reliable and continuous operation is of fundamental importance for service maintenance and is subject to various types of disturbances that can lead to failures. In this perspective, studies of the dynamic behavior of transformer windings through computer simulations have been widely used to safely and accurately evaluate their operation. Therefore, this paper presents the methodology for research on a 50 MVA power transformer using the finite element method for static and time domain analysis. Thus, the study was performed by means of magnetic-mechanical couplings. In the first analysis (circuit study), the ATPDraw software was used to obtain the behavior of the inrush current and solidarity energization during the transformer bank energization. Therefore, in the ANSYS MAXWELL software magnetic studies were performed. For this, a real 3D model was used (taking into account the characteristics of the lamination core and windings, being in disc). Thus, the results of the behavior of magnetic induction and magnetic forces in the windings of the equipment are presented. Finally, in the ANSYS STRUCTURAL software, structural (mechanical) studies were performed. Also, as before, a close-to-real 3D model was used, presenting as results the behavior of the total deformation in the winding, the mechanical stress suffered and the degree of safety during the occurrence of energization. The static studies were considered three operating conditions: nominal condition, sympathetic inrush and inrush current. For the nominal condition, the equipment's plate data was used, for the energizing condition (sympathetic inrush and inrush current) the largest amplitude obtained during the simulation was used. It is noteworthy that for the time domain analysis, only the condition of the inrush current was analyzed, both for the high computational cost required and for being the worst condition in the static analysis.Item Acesso aberto (Open Access) Aplicações de controle preventivo baseadas em árvore de decisão para aumentar a capacidade de sobrevivência a afundamentos de tensão dos geradores de indução duplamente excitados em sistemas de potência(Universidade Federal do Pará, 2018-09-21) VIEIRA, Dione Jose Abreu; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447The development of a preventive control methodology to increase the capacity of voltage sag recovery (Fault Ride Through Capability (FRTC)) of a doubly-fed induction generator (DFIG) connected in an electrical network is presented. This methodology, which is based on the decision trees (DT) technique, assists with monitoring and support for security and preventive control, ensuring that wind systems remain connected to the power system even after the occurrence of disturbances in the electric system. Based on offline studies, DT discovers inherent attributes of the FRTC scenario related to electrical system behavior and provides a quick prediction model for real-time applications. From the obtained results, it is possible to check that the DFIG is contributing to a system’s operation security from the availability of power dispatch and participation in the voltage control. It is also noted that the use of DT, in addition to classifying the system’s operational state with good accuracy, also significantly facilitates the operator´s task, by directing him to monitor the most critical variables of the monitored operation state for a given system’s topological configuration.Item Acesso aberto (Open Access) Avaliação da distorção harmônica total de tensão no ponto de acoplamento comum industrial usando o processo KDD baseado em medição(Universidade Federal do Pará, 2018-03-27) OLIVEIRA, Edson Farias de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148In the last decades, the transformation industry has provided the introduction of increasingly faster and more energy efficient products for residential, commercial and industrial use, however these loads due to their non-linearity have contributed significantly to the increase of distortion levels harmonic of voltage as a result of the current according to the Power Quality indicators of the Brazilian electricity distribution system. The constant increase in the levels of distortions, especially at the point of common coupling, has generated in the current day a lot of concern in the concessionaires and in the consumers of electric power, due to the problems that cause like losses of the quality of electric power in the supply and in the installations of the consumers and this has provided several studies on the subject. In order to contribute to the subject, this thesis proposes a procedure based on the Knowledge Discovery in Database - KDD process to identify the impact loads of harmonic distortions of voltage at the common coupling point. The proposed methodology uses computational intelligence and data mining techniques to analyze the data collected by energy quality meters installed in the main loads and the common coupling point of the consumer and consequently establish the correlation between the harmonic currents of the nonlinear loads with the harmonic distortion at the common coupling point. The proposed process consists in analyzing the loads and the layout of the location where the methodology will be applied, in the choice and installation of the QEE meters and in the application of the complete KDD process, including the procedures for collection, selection, cleaning, integration, transformation and reduction, mining, interpretation, and evaluation of data. In order to contribute, the data mining techniques of Decision Tree and Naïve Bayes were applied and several algorithms were tested for the algorithm with the most significant results for this type of analysis as presented in the results. The results obtained evidenced that the KDD process has applicability in the analysis of the Voltage Total Harmonic Distortion at the Point of Common Coupling and leaves as contribution the complete description of each step of this process, and for this it was compared with different indices of data balancing, training and test and different scenarios in different shifts of analysis and presented good performance allowing their application in other types of consumers and energy distribution companies. It also shows, in the chosen application and using different scenarios, that the most impacting load was the seventh current harmonic of the air conditioning units for the collected data set.Item Acesso aberto (Open Access) Avaliação da segurança de sistemas de potência para múltiplas contingências usando árvore de decisão multicaminhos(Universidade Federal do Pará, 2017-09-15) OLIVEIRA, Werbeston Douglas de; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913The search for effective ways to promote the secure operation of power systems and to increase its understanding by operators has encouraged continuous research for new techniques and methods that can help in this task. In this paper, it is proposed an approach to assess power system operation security for multiple contingencies using a multiway decision tree (MDT). The MDT differs from other decision tree techniques for establishing, in the training step, one value of the categorical attributes by branch. This approach proposes the use of topologies (contingencies) as categorical attributes. In this way, it improves interpretability regarding the power system operational state, as the operator can see clearly the critical variables for each topology, such that the MDT rules can be used in aiding the decision-making. This proposal was used for security assessment of two test systems, the IEEE 39-bus system and the Northern part of the Brazilian Interconnected Power System (BIPS), and BIPS was tested with real data from one day operation. The proposed MDT-based technique demonstrated superior performance, with a set of simple and clear rules. It was also performed a comparison of the obtained results with other techniques based on DT and it turned out that MDT has resulted in a simpler procedure for power system security classification with good accuracy.Item Acesso aberto (Open Access) Avaliação do impacto da produção eólica na reserva operativa de curto e longo prazo utilizando séries temporais(Universidade Federal do Pará, 2019-05-30) SANTOS, Fernando Manuel Carvalho da Silva; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; BRANCO, Tadeu da Mata Medeiros; http://lattes.cnpq.br/8911039344594817One of the main concerns of a system planner is to size generation equipment, mainly for meeting the load growth and to achieve certain spinning reserve requirements. In general, generation systems must be sized with sufficient capacity, flexibility and robustness to respond to several operational challenges. However, the volatility and variability that comes from renewable generation is a relatively recent concern for the system planners. This thesis evaluates the potential of diverse wind power patterns to balance the global power output of wind farms using the concept of operating reserve assessment. To achieve this, operating reserve assessment models are utilized to evaluate bulk generation systems under several conditions of wind power geographic distribution. Different wind behavior patterns and wind power penetration levels are tested using a modified configuration of the IEEE RTS-96 and a planning configuration of the Portuguese Generation System. The results highlight that on a large country scale system with different wind characteristics, the diversification of wind behavior might be conducive to a compensation of wind power fluctuations, which may significantly decrease the need for system operating reserves. This effect is verified using probability distribution functions of reserve needs estimated by sequential Monte Carlo simulations (SMCS), such that useful information regarding generation capacity flexibility is drawn from the evaluations.Item Acesso aberto (Open Access) Avaliação probabilística do impacto da recarga rápida de veículos elétricos nos sistemas de distribuição de energia elétrica(Universidade Federal do Pará, 2024-11-13) HERNÁNDEZ GÓMEZ, Oscar Maurício; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913The mass adoption of electric vehicles (EVs) is transforming the automotive sector, driven by environmental concerns and technological advancements. Governments and companies are investing in the expansion of charging networks, focusing on fast charging to meet the growing demand. Developing a robust infrastructure of charging stations is essential to eliminate “range anxiety” and encourage the transition to EVs. Fast charging is crucial for the success of vehicle electrification. It allows batteries to be charged much more quickly than conventional charging, increasing convenience for users and improving the overall user experience. As more fast-charging stations are installed, consumer confidence in EVs grows, paving the way for a more sustainable future. With a well-distributed fast-charging network, EVs become a practical alternative to fossil fuel-powered vehicles, accelerating the transition to greener mobility. However, fast charging of EVs can cause technical impacts on medium voltage networks. The high current demand can result in voltage drops, especially in areas with weaker distribution infrastructure. Transformers can be overloaded, reducing their lifespan and increasing the risk of failures. Excessive heating of conductors due to high current can also cause losses and damage cables. These challenges highlight the need for proper planning and investments in electrical infrastructure to support the increase in fast charging. A probabilistic analysis of the impact of fast charging on medium voltage networks is crucial. Energy demand varies throughout the year due to seasonal factors, such as the use of air conditioning in summer and heaters in winter. Fast charging adds a considerable load to the network, which can coincide with these demand peaks, exacerbating management challenges. The installation of multiple charging points can cause voltage fluctuations and overloads. Probabilistic analysis helps predict these impacts and develop mitigation strategies by simulating charging scenarios and user behaviors. This allows for more precise infrastructure planning, including network reinforcements and improvements to ensure supply reliability. This thesis proposes a probabilistic methodology to evaluate the impact of fast charging of electric vehicles on medium voltage distribution networks, considering voltage drops, network element loading, and regulator tap changes. Using the Power Factory software by DIgSILENT©, a real feeder in Brazil is simulated, analyzing different case studies. Three fast charging stations (FCS) are connected, each with six charging points of 100 kVA, totaling 600 kVA per EP. The charging profile of the EPs is programmed with stochastic variables. Finally, a Volt/Var control strategy is presented to mitigate the impact on voltage drops and regulator tap changes, allowing reactive power injection without the need for communication between charging points.Item Acesso aberto (Open Access) Contribuição do controle secundário de tensão aplicado em um parque eólico composto de aerogeradores dfig à estabilidade de tensão de longo-prazo(Universidade Federal do Pará, 2019-08-30) MATOS, Kayt Nazaré do Vale; AFFONSO, Carolina de Mattos; http://lattes.cnpq.br/2228901515752720; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913This thesis investigates the use of secondary voltage control (SVC) in a wind park based on doubly fed induction generator (DFIG) and its effect on long-term voltage stability. The wind park consists of several wind turbines is modeled as an DFIG equivalent model. Initially, the performance of the SVC applied to wind park is compared with the case when only the primary voltage control (PVC) is adopted. A detailed analysis is conducted with time-domain simulations, considering high and low wind speed regimes, control variable limits of wind generators, static and dynamic loads, as well as dynamic models of overexcitation limiter (OEL) and load tap changing (LTC) transformer. Based on the results, the use of secondary voltage control in a DFIG-based wind park can postpone long-term voltage collapse of power system. Further, an adverse situation was observed showing that SVC can lead the grid-side converter (GSC) of DFIG to absorb reactive power from the electric grid and lose the capability of injecting reactive power in the grid. Thus, two novel auxiliary control strategies inserted in the GSC control loop are presented to prevent reactive reverse flow in the GSC, as well as forcing the provision of reactive power to the system via the GSC. The results indicate the effectiveness of the auxiliary control strategies in postponing the voltage collapse and increase the voltage stability margin of the system.Item Acesso aberto (Open Access) Desempenhos térmico e energético de uma edificação na região amazônica brasileira(Universidade Federal do Pará, 2018-09-06) AGUILAR, Heliana Maria Ceballos; PINHO, João Tavares; http://lattes.cnpq.br/0847897516772421This work presents an innovative proposal of integration of several strategies to reduce energy consumption, where the impact of each one of them is evaluated individually, and all together, in the thermal, energetic and economic performance of a building located in the Brazilian Amazon Region. High temperature and humidity characterize this region climatically, where achieving adequate comfort conditions implies a high demand for energy for air conditioning systems. Different Energy Conservation Measures are evatuated in order to achieve a better use of daylighting; and to reduce thermal loads for cooling, with the installation of a thermal insulation material in the eastern and western walls, and a thermal insulation and air chamber in the roof, which are the external surfaces that receive higher solar radiation in the building. Additionally, various photovoltaic generation systems are considered, one of which is integrated as an architectural element and another adapted on the roof of the building. In the building, two types of analysis are conducted: dynamic and static. For the dynamic analysis, the EnergyPlus software is used to know its thermal and energy consumption performances, analyzed for the entire year and for the design day, and the Daysim/Radiance software to know the autonomy of daylighting attained, using data measured with an on-site meteorological station. Concerning the static analysis, the level of energy efficiency is evaluated by the prescriptive method according to the current national regulations. Subsequently, the same building is simulated for the nine capital cities of the states of the Legal Brazilian Amazon Region, with the aim of knowing its energetic performance and the economic feasibility depending on the climatic characteristics and electrical energy tariffs of each city. With the assessments performed, it is determined that the ECM have a direct and significant influence on the reduction of the thermal load for cooling, through the reduction of radiation effects, the shading in the eaves and the reduction of the transmittance of the surfaces treated. The possibility of maximizing the daylight in internal spaces, to improve the comfort of the users is also verified, allowing better performance and energy savings with artificial lighting. In terms of energy consumption and economic feasibility, the ECM achieve an annual energy savings of 52 % in the building taken as a case study, and the solutions adopted show a good return on financial investment, and are also suitable for energy saving and economically feasible in regions with similar climatic characteristics.Item Acesso aberto (Open Access) Desenvolvimento a eventos discretos de um controlador de balanceamento de fases para sistemas legados de baixa tensão e microgrids(Universidade Federal do Pará, 2019-06-10) VILCHEZ, José Ruben Sicchar; SILVA, José Reinaldo; http://lattes.cnpq.br/9317869378701106; COSTA JÚNIOR, Carlos Tavares da; http://lattes.cnpq.br/6328549183075122In the up-grading of the legacy low-voltage system as urban microgrids, phase - balance algorithm development becomes useful and important to ensures robust and reliable load balancing, establish an efficient automation workflow among consumers, the legacy lowvoltage grid and the supervision center of the distribution network of electrical power. It constituting an alternative. This may constitute an alternative phase-balancing control system based on consumer units dynamic switching rather than electrical current injection by microgrids. Formal automation design of these algorithms become an interesting milestone for performance evaluation and properties validation for their insertion in the new microgrid architecture. This may evaluate the system's reliable performance when verifying dynamic properties as well as, the univocal solutions that ensure load transfer and load stability robustness of low-voltage grid, without operation interruptions neither conflicting events. This work, proposes a new phase-load- balancing control system based on combined algorithms resulting from a Hierarchical Petri net system design. Through this model it was obtained an optimized and reliable automated workflow of load balance in the low-voltage grid phases, with an efficient choice of consumer units for the switching process, aiming to obtain a robust steady state of load against unbalances between phases, and neutral current minimized. From the model obtained called “Transformer- Phase Balancing Controller” (T-PBC) were developed four integrated algorithms: the Load Transfer Algorithm, that calculates the load imbalance level and power to be transferred in the transformer phases; the Consumption Diagnose Algorithm, that identifies the load levels margins in each consumer unit; the Consumption Forecast Algorithm, that forecast the monthly energy future states in consumers; and the Switch Selection Algorithm, that selects the consumers units to switch based on the future state of energy consumption, the load level margins and the average of the energy future states. Based on the performance results, it was obtained, the efficient reduction of the neutral current and the load average unbalance in the low-voltage grid phases, with load stability robustness about three months, making it an efficient alternative system against load unbalances in the legacy low-voltage grid and the microgrids.Item Acesso aberto (Open Access) Estimação das parcelas de contribuição de cargas não lineares na distorção harmônica de tensão de um barramento de interesse do sistema elétrico de potência utilizando rede neural artificial(Universidade Federal do Pará, 2019-09-06) MANITO, Allan Rodrigo Arrifano; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813This work presents a methodology to estimate the non-linear loads contribution on voltage harmonic distortion at a bus of interest in the electric power system. The estimation process is carried out through the development of a model based on artificial neural networks (ANN) added to a sensitivity analysis in neural network input. The ANN model input is constituted by the non-linear loads harmonic currents considered in the studied system, and the ANN output corresponds to the harmonic voltage values in the bus under study, for the same harmonic frequency. The study is carried out for each harmonic order individually and the data required for the construction of the model as well as for the results validation have been obtained from synchronized measurement campaigns and by computational simulation, using harmonic load flow studies. Comparisons between reference results through computational simulation with the results obtained by neural model are carried out and it is observed that the developed methodology is able to classify correctly the impact of non-linear loads in the voltage distortion at a bus of interest of the electric system. Additionally, the effectiveness of the methodology is tested in two real systems in order to verify the good performance of this methodology considering real data obtained during measurement campaigns.Item Acesso aberto (Open Access) Estimador de estado harmônico trifásico incorporando Saturação de transformadores(Universidade Federal do Pará, 2019-06-28) SOARES, Thiago Mota; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813Item Acesso aberto (Open Access) Estrutura de redes neurais auto-associativas aplicadas ao processo de identificação de equipamentos elétricos em sistemas de monitoramento não intrusivo de cargas(Universidade Federal do Pará, 2019-10-23) MORAIS, Lorena dos Reis; CASTRO, Adriana Rosa Garcez; http://lattes.cnpq.br/5273686389382860The pursuit of reducing and rationalizing electricity consumption is increasingly becoming a priority for all consumers worldwide. Residential environments are responsible for a large part of electricity consumption. Non-intrusive load monitoring systems were created with the aim of helping consumers, providing the possibility of obtaining information about the individual consumption of equipment and thus allowing a monitored consumption and the consequent increase in energy efficiency. In a Non-Intrusive Load Monitoring System, four steps are critical: acquiring aggregate data through a single sensor, detecting equipment on / off events from the aggregate load, extracting disaggregated signal characteristics and the identification of equipment based on the characteristics extracted from the disaggregated signal. In this context, this work proposes a new methodology for identification of electrical equipment in a residential environment employing a competitive structure of Auto-Associative Neural Networks. The proposed system is based on power signal measurements obtained from equipment on / off events. To test the proposed methodology 3 scenarios were developed using 3 different public databases. Due to the good results achieved, analyzed using statistical metrics, it is evaluated that the proposed methodology is able to efficiently perform the task of identifying electrical equipment, thus contributing to the development of future non-intrusive monitoring systems. meet market demands.Item Acesso aberto (Open Access) Ferramentas de apoio à tomada de decisão ao problema de alocação ótima de bancos de capacitores em redes de distribuição de energia considerando cargas não lineares(Universidade Federal do Pará, 2017-12-14) ONAKA, José Henrique Dias; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148The use of properly allocated capacitor banks has long been one of the main strategies used to maintain electrical variables such as voltage, power factor and feeder loading within acceptable levels. However, the constant presence of harmonics in the grid limits the applicability of this strategy. In this context, this work proposes an a posteriori evaluation of the Resonance Index to support the decision making process, in conjunction with the multiobjective evolutionary algorithm, SPEA2, to solve the Optimal Capacitor Allocation Problem (OCAP) in three-phase radial distribution networks considering the harmonic resonance and amplification phenomena due to the presence of non-linear loads. A study of the variation of the equivalent impedance of the network (driving point impedance) seen from the allocation point of the respective capacitor bank, either by the variation of load during the day or by the numerous maneuvers to which the system is subjected. The results presented here were obtained from the IEEE 34-bus three-phase radial distribution network and the IEEE 123- bus network, in which the models from three different harmonic sources commonly found in real case scenarios were inserted. Finally, the convenience of the use of multiobjective routines in solving the OCAP and the importance of the evaluation of resonance scenarios in order to guarantee an adequate and safe operation of the system are highlighted.Item Acesso aberto (Open Access) Identificação de sistemas multiforças a partir de dados de vibração e técnicas de aprendizado de máquinas(Universidade Federal do Pará, 2024-11-07) PINHEIRO, Giovanni de Souza; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447The emergence of defects in dynamic components tends to produce changes in the forces generated, which can be detected through alterations in the vibration response spectrum of the equipment. Understanding the forces acting on a structure is extremely important, especially in cases where measurement points are limited or inaccessible, as it allows for assessing, among other things, whether the component's lifespan is compromised by the current condition of the machine. In such cases, an inverse problem needs to be solved. Machine Learning techniques have been standing out as a powerful tool for prediction among the solutions developed for this type of problem, being increasingly applied to engineering problems. Therefore, this work aims to evaluate different machine learning models for the identification of a system, composed of a suspended plate with one or more applied forces, based on measured vibration data. In this regard, a computational model was generated and calibrated using vibration responses measured in the laboratory. A robust database was created using Response Surface Methodology together with the Design of Experiment (DOE) and then used to assess the ability of machine learning models to predict the location, excitation frequency, magnitude, and number of forces acting on the structure. Among the six machine learning models evaluated, k-NN was able to predict with an error of 0.013%, and random forests showed a maximum error of 0.2%. Finally, a database, containing a line of experimental data, was used to evaluate the k-NN and Random Forest models, obtaining a score of 0.96 and 0.93, respectively. The innovation of the study lies in the application of the proposed method for parameter identification in multiforce systems.Item Acesso aberto (Open Access) Identificação em malha fechada para controle tolerante a falta passivo aplicado a um sistema industrial de bombeamento hidráulico(Universidade Federal do Pará, 2019-08-30) ROCHA, Erick Melo; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608Fluid pumping systems are part of many industrial applications. From the traditional water supply, to the cooling systems of thermonuclear power plants and the complex aircraft maneuvering system, using pneumatic actuators, we find examples of application of these systems. As any physical system, fluid pumping systems may also be subject to anomalous behaviors or failures that can lead to malfunction or even loss of stability of an entire process. Such faults may cause permanent damage due to the effect of undesirable phenomena such as cavitation and water hammer, for example. Thereby, this work proposes the development of a Fault Tolerant Control System (FTCS) aiming at to mitigate the undesirable effects of pressure oscillation and speed variation that may affect this type of system. This research assumes that, for economic and safety reasons, industrial systems operate by default in closed-loop to ensure stability and desired performance. Therefore, a methodology is introduced to identify the open-loop transfer function of industrial plants, based on data obtained by signal measurement, of the industrial process operating in closed-loop, denominated Two-Stage Method. The identified model is used to design a controller that meets the performance criteria defined by the FTCS instead of the traditional control system, designed for a specific operating point regardless of the fault acting in the system. For experimental evaluation, an industrial fluid pumping bench was used, developed at the Automation and Control Laboratory of Federal University of Pará (UFPA). A passive FTCS was designed using robust control technique based on parametric uncertainties. For that end, it was used a set of uncertain models, obtained by parametric identification, considering a desired operating range for the test plant, with the system operating under both normal and fault conditions. Performance indices were calculated in order to quantitatively evaluate the performance of the FTCS monitored system, with the results obtained for the system operating without the FTCS (using classical controller). The results show the good performance of the proposed methodology.Item Acesso aberto (Open Access) Inibidor bidirecional de eventos de runaway no comutador de tap de reguladores de tensão em redes de distribuição reconfiguráveis com geração distribuída(Universidade Federal do Pará, 2024-06-25) SOUZA, Vanderson Carvalho de; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913Climate change has intensified over the years, especially as a result of the global energy model that is predominantly based on the use of fossil fuels. Thus, there is an urgent need to boost a low-carbon economy as a response to the climate crisis. In this context, renewable energy sources emerge as the main alternative to fossil fuels. However, the integration of these sources into distribution networks can cause voltage control problems resulting from bidirectional power flow in such networks. An important voltage control problem is the phenomenon known as tap changer runaway condition in step-voltage regulators (SVRs). Nowadays, the problem is further challenging in reconfigurable distribution networks with renewable energy sources connected to both the source-side and load-side of the SVR. This problem occurs when the SVR control cannot adequately distinguish the origin of the active power flow through the SVR and tries to control the voltage on the side of the network with the highest short circuit capacity (strong side), causing under or overvoltage on the side of the network with the lowest short circuit capacity. short circuit (weak side). Current solutions to mitigate the runaway problem are mainly based on three categories: 1) voltage control support by distributed generation (DG); 2) use of remote measurements/information; and 3) use of local measurements/information. However, considering practical aspects, only solutions in the third category are feasible. Even so, these solutions are restricted to application for inhibiting the runaway condition caused exclusively by reverse power flow. In this Thesis, an algorithm is proposed for robust local bidirectional on-line inhibition of the runaway condition based only on a test tap switching with robustness guarantees and without the need for switching of tap test coordinate in cascaded SVRs. The main contributions of the Thesis are the innovative application of the algorithm in robust local bidirectional on-line inhibition of the runaway condition in the tap switch and the introduction to industrial insights. The accuracy and robustness of the proposed algorithm are verified through time series power flow simulations carried out on two test networks, with noise and gross errors in measurements, using extensive Monte Carlo simulations. The uncoordinated operation of test tap switching in cascaded SVRs is examined through case studies on a long real rural distribution network. Finally, the effect of photovoltaic (PV) source variability on the performance of the proposed algorithm is evaluated. The results obtained confirmed the effectiveness of the proposed algorithm in bidirectional inhibition of the runaway conditionItem Acesso aberto (Open Access) Investigação de estratégias de controle de ordem fracionárias aplicadas a sistemas elétricos e industriais(Universidade Federal do Pará, 2018-11-14) AYRES JÚNIOR, Florindo Antonio de Carvalho; LENZI, Marcelo Kaminski; http://lattes.cnpq.br/8471869055654497; COSTA JÚNIOR, Carlos Tavares da; http://lattes.cnpq.br/6328549183075122The use of control techniques is of great importance to maintain competitive performance for electrical and industrial systems suitable to trace behavior adjustment points as close as possible to a desired set point of operation for deviation and oscillation reduced. In this work, fractional automatic control techniques are investigated to improve the performance of industrial systems. Two fractional-order control techniques are studied: one of the Lead-Lag based fractional order (FOLL) type based on the frequency response method and applied to the improvement of power system stabilizers (ESP). Control laws are implemented in the form of digital control in an embedded system, based on microcontroller. The performance of the compensators is evaluated by performing several experimental tests on a 10 kVA reduced scale power system located at the UFPA Electrical Engineering Laboratory. Variation tests are carried out at one pulse in the generator voltage reference at various power operation points of the micro generator system, in addition to the robustness analysis of the system using a robust plot tool from the Bode diagram known as RBode. Second, there is an investigation of a fractional pole allocation technique (FOPP) which takes into account temporal response criteria of fractional systems to three terms, which, in this work, are overtime, settlement time, applied in a coupled tanks system, and in a Buck DC / DC converter, where the FOPP technique is compared with two other techniques: these are the classical technique of integer pole allocation (IOPP), and a tuning technique of FOPID controllers based on Gain Margins and Phase Margins (GMPM). The results are corroborated by simulations in Matlab / Simulink Environment. The results show a reduction of approximately 15% at least in the ITAE and ISE indexes related to the dynamic performances of the systems addressed in this study associated with the controlled variable, with the insertion of the fractional controllers based on both the topology using the FOLL and using the FOPP and GMPM techniques, compared to the values obtained from these indexes of the controllers tuned by conventional whole order techniques.Item Acesso aberto (Open Access) Investigação de estratégias de controle robusto multivariável descentralizado aplicadas à melhoria do desempenho de um conversor de potência CC/CC do tipo buck com estrutura single inductor multiple output(Universidade Federal do Pará, 2018-02-05) MEDEIROS, Renan Landau Paiva de; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608The DC/DC power converter systems are important devices to use in several applications in many sectors of the society. For this reason, several DC/DC converter topologies are developed to improve the performance of devices, aiming at reducing losses and improving the converter energy quality. However, such improvements should assess the control strategies that enable the correct functioning of the power converters. This works covers experimental assessment of the design of robust decentralized multivariable controller applied to a specific topology of the multivariable step-down power converter, where a single inductor element is shared by multiples outputs. Furthermore, it is important to ensure the system stability, as well as the multiple outputs regulations, however some difficulties remains, e.g., hard coupling between system’s outputs, non-linearities due to the inductive element and uncertainties due to imprecision of mathematical models and/or variation of nominal values of the discrete elements that compose the DC/DC converter. Aiming to assess the performance of the proposed design methodology for a multivariable robust controller, to perform experiments of parametric variations on the DC/DC power converter, it is developed several experimental tests and simulations using the Matlab. The results show the improved performance of the proposed methodology.Item Acesso aberto (Open Access) Um método baseado em cruzamentos por zero para localização de faltas de alta impedância em redes aéreas de distribuição(Universidade Federal do Pará, 2024-06-05) HUAQUISACA PAYE, Juan Carlos; CARDOSO JUNIOR, Ghendy; http://lattes.cnpq.br/6284386218725402; https://orcid.org/0000-0002-1423-6968; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913The location of High-Impedance Faults (HIFs) is an increasingly relevant reliability issue in the electric power distribution industry. The development of practical and accurate single-terminal fault locating methods is vital for reducing the time and cost of restoring long-duration interruptions. However, the need to estimate both the parameters of the fault model and the fault current signal can compromise the accuracy and practicality of existing HIF location methods. This is due to the larger number of parameters that need to be estimated when a HIF model is included in the formulation, as well as the assumption that load currents at the network bars are constant during a pre- and post-HIF interval. In other words, the use of the fault model and waveform implies that the location method depends on the random characteristics and magnitudes of the fault current, which are determined by environmental, technical conditions, and the type of surface where the HIF occurs, including even the way the contact between the surface and the conductor occurs. This thesis proposes a fault-model-free iterative method based on zero-crossings of signals to locate HIFs in overhead distribution networks. Two insights on voltage signal relationships are provided to eliminate the need to estimate fault model parameters and the fault current signal in the HIF location process. The first insight is based on zero-crossings of the calculated voltage drop per unit length signal to estimate two parameters of the voltage signal at the fault point. The other insight is based on the zero-crossing of the voltage signal at the fault point, where the two parameters were previously estimated, to calculate the fault distance from the k-th node. Simulation results on a modified IEEE 34-node test feeder validate the high accuracy and robustness of the proposed method, considering the effect of various factors on the estimation of the HIF distance. Additionally, the convergence performance of the proposed method is evaluatedItem Acesso aberto (Open Access) Metodologia de Avaliação do desempenho energético da integração de carros elétricos à edificações(Universidade Federal do Pará, 2024-09-06) SOUZA, Ana Carolina Dias Barreto de; CARVALHO, Carminda Célia Moura de Moura; http://lattes.cnpq.br/1778332169942633; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148Energy diagnosis methodologies have been incorporating energy consumption and energy generation systems into their analysis, making it possible to classify energy-self-sufficient buildings as Near Zero Energy Buildings (NZEB) or Positive Energy Buildings (PEB). In electric mobility, the increased use of electric vehicles (EVs) brings challenges and opportunities in electricity consumption, management and efficiency. The impact of this robust and growing load when integrated into new and existing buildings is not yet considered in performance assessments. Consequently, the methodologies for obtaining certifications and labels do not consider the load of this system as an individual end-use. For buildings with energy efficiency (EE) and self-sufficiency labels, introducing EVs can result in the rating being downgraded due to increased energy consumption. Therefore, analyzing the impact of integrating EVs into buildings aims to support the formulation or revision of energy diagnosis methodologies that include EV charging systems integrated into buildings. This thesis evaluates the influence of EV charging in buildings with the NZEB/PEB label from the Brazilian Building Labeling Program (PBE Edifica). Using on-site surveys, computer modelling and thermo energetic analysis with software such as OpenStudio and EnergyPlus, an energy rating was carried out on a building in Belém, State of Pará, Brazil. Subsequently, energy flow simulations using probabilistic models with the Monte Carlo method were run in OpenDSS software to examine the impact of integrating EVs without (scenario 01) and with (scenario 02) the implementation of demand-side management techniques. Analysis using the labelling methodology showed that the building has an EE level C rating and NZEB self-sufficiency. Scenario 01 generated a 69.28% increase in energy consumption, reducing the EE level to D and resulting in the loss of the NZEB class. Scenario 02 increased consumption by 40.50%, a lower percentage than scenario 01 and guaranteed the return of the NZEB class lost in scenario 1, but did not return the EE level to class C. The results highlight the need for immediate and comprehensive energy management strategies. However, these strategies are not sufficient if other consumption restrictions or EE measures are not applied to other systems in the building. To this end, EE measures were proposed and evaluated in the air conditioning and lighting systems. Subsequently, an equation was drawn up to indicate the maximum level of energy X consumption that could be increased without compromising the building's energy performance and NZEB rating. Finally, OpenDSS software was used to simulate the increased availability of EV charging after the retrofit. With the proposed retrofit, the building improved its EE ratings by three levels, and the NZEB rating percentage increased by 33.28%. These measures also increased the EV charging load by 20% while maintaining the maximum EE level and NZEB rating.