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The grid penetration of distributed generation systems is rapidly increasing to meet the energy demands. In the grid connected operation of these systems, the islanding scenarios are considered as a critical threat for stable operation of the utility. This paper aims at developing an islanding classification technique to efficiently detect the grid abnormalities and classify the islanding scenario. The process involves generation of data sets corresponding to various grid abnormalities, and training them with a machine learning classifier. To realize this development, a 10 kW three-phase grid connected photovoltaic (PV) system is simulated and compiled in Typhoon hardware-in-loop (HIL) environment to get different data sets for grid abnormality conditions. Further, the data is trained with the k-nearest neighbor (kNN) classified to develop the islanding classification mechanism. The efficiency of trained classifier is 94.2 %, and has the capability for efficient classification at a speed of approximately 17000 observations per second.

The usage of the Photovoltaic (PV) power systems has been increased dramatically, due to the abundant of the solar irradiation, and the government incentives everywhere. In most of the developed countries, the standards for connecting the PV systems to the grid has been set and is already applied. The incentives and regulations that supports PV systems are increasing day by day in Turkey. Because of this regulations more and more PV systems are connecting to the grid. Such high penetration of the PV systems in the distribution network leads to voltage disturbances. This paper studies the causes and effects of the voltage problem and proposes the best solutions to; mitigate the voltage disturbances and increase the distribution network stability. © 2021 IEEE.

This paper presents the transient stability analysis of a photovoltaic (PV) system with account shading effects. Voltage and transient stability effect of PV system are assessed functions of an experimental study. The current advances in shading effect and temperature control of PV panels are studied. The study is performed on modeling and simulation of PV system with account shading effect. A shading effect system is introduced to reflect the transient response characteristics of PV generation model. An experimental setup is designed, constructed and assembled. The setup is provided with the necessary measuring instruments to carry out the required tests. A perspective on the other shading techniques for PV panels will be discussed in this paper.

Neste trabalho investigou-se a distorção harmônica total de corrente (DHTi) produzida por inversores fotovoltaicos em três sistemas distintos constituídos por: a) gerador fotovoltaico com potência nominal de 3,055 kWp e inversor fotovoltaico monofásico marca Eltek, modelo Theia, potência nominal de 2,9 kW; b) gerador fotovoltaico com potência nominal de 4,7 kWp e inversor fotovoltaico monofásico marca Eltek, modelo Theia, potência nominal de 4,4 kW; e c) gerador fotovoltaico com potência nominal de 41,3 kWp e inversor fotovoltaico trifásico marca Huawei, modelo SUN 2000-33KTL, potência nominal de 33 kW. Os três sistemas estão instalados na Escola de Engenharia Elétrica, Mecânica e de Computação (EMC) daUniversidade Federal de Goiás (UFG). Através de regressão linear polinomial, os dados de medições do conteúdo harmônico de corrente realizadas no ponto de acoplamento dos inversores nas instalações com medidor de qualidade de energia marca Fluke modelo 435-II, resultaram em polinômios que representam as relações da DHTi percentual e das correntes harmônicas de 3a e 5a ordens, em valores eficazes, com a irradiância solar global no plano horizontal e com as potências de carregamento dos inversores. Concluiu-se que a regressão polinomial de grau 3 é suficiente para representar o comportamento harmônico das correntes produzidas pelos inversores fotovoltaicos em função da irradiância e em função da carga. No mais, a classificação em quartis da DHTi percentual e das correntes harmônicas de 3a e 5a ordens, em valores eficazes, foi realizada por faixas de irradiação solar global no plano horizontal e também por faixas de potências de carregamento do inversor, com a determinação dos respectivos valores médios das correntes harmônicas eficazes e DTHi percentual para cada faixa. Verificou-se que os inversores Eltek com potência nominal de 4,4 kW e Huawei com potência nominal de 33 kW atendem aos limites estabelecidos nas Normas ABNT NBR 16149:2013 e IEEE 1547-2018. Com referência ao inversor Eltek com potência nominal de 2,9 kW, os resultados não são conclusivos, uma vez que as condições climáticas no momento das medições não permitiram que a potência de carregamento deste inversor ultrapassasse 62% do seu valor nominal. This investigation addresses the total harmonic distortion of current (THDi) produced by photovoltaic inverters installed in three different systems compounded by: a) photovoltaic generator rated at 3.055 kWp and photovoltaic single-phase inverter by Eltek, model Theia, rated at 2.9 kW; b) photovoltaic generator rated at 4.7 kWp and photovoltaic single-phase inverter by Eltek, model Theia, rated at 4.4 kW; c) photovoltaic generator rated at 41.3 kWp and photovoltaic three-phase inverter by Huawai, model SUN-2000-33KTL, with rated power at 33 kW. These three systems are installed on roof-tops at the Electrical, Mechanical and Computer Engineering School (EMC) of the Federal University of Goias (UFG). The percent THDi and 3rd and 5th order rms harmonic currents were measured with a power quality analyzer by Fluke, model 435-II, and a set of polynomial were achieved by means of linear polynomial regression in order to represent the behaviors of percent THDi and of 3rd and 5 th order rms harmonic currents as a function of global irradiance on horizontal plane and as function of inverter loads. The linear polynomial regression of grade three was sufficient to represent to represent the harmonic current behaviors produced by the solar inverters as a function of irradiance or load. In addition, the percent THDi and of 3rd and 5th order rms harmonic currents were classified into quartiles according to different ranges of solar irradiation on horizontal plane as well as different ranges of inverter loads, and the respective average values of rms harmonic currents and percent THDi to each one of the ranges were assessed. In conclusion, the Eltek inverter rated at 4.4 kW and the Huawei inverter rated at 33 kW meet the ABNT NBR 16149:2013 and IEEE 1547-2018 standard recommendations. The results regarding the Eltek inverter rated at 2.9 kW are not conclusive as the weather conditions at the moment measures were taken did not allow the inverter power to reach more than 62% of its rated power.

This paper presents the transient stability analysis of a photovoltaic (PV) system with account shading effects. Voltage and transient stability effect of PV system are assessed functions of an experimental study. The current advances in shading effect and temperature control of PV panels are studied. The study is performed on modeling and simulation of PV system with account shading effect. A shading effect system is introduced to reflect the transient response characteristics of PV generation model. An experimental setup is designed, constructed and assembled. The setup is provided with the necessary measuring instruments to carry out the required tests. A perspective on the other shading techniques for PV panels will be discussed in this paper.

This work presents the mapping of grid-connected photovoltaic systems supported by the Normative Resolution (NR) of the National Agency of Electric Energy (ANEEL) No 482/2012 in the city of Curitiba. Firstly, a brief introduction was made justifying the reasons that led to the development of this study, followed by the explanation about the methodology, procedures and criteria adopted in the study. A general mapping of all on-grid photovoltaic systems supported by NR No 482/2012 installed in the city of Curitiba, identified by class, is presented, indicating how the urban distribution of these photovoltaic systems occurs, and it is possible to observe in which regions the highest prevalence of installations occurs. From this, the general characterization of these photovoltaic systems is performed, classifying them by class, number of installed systems, power, number of modules, total occupied area, average power of modules and average efficiency of photovoltaic systems. Considerations are also raised regarding the reliability of the Database of Distributed Generation Consumer Units made available by ANEEL.

El presente trabajo propone una metodología para realizar un estudio técnico del impacto sobre la calidad de la potencia de la red eléctrica interna de la Universidad de Nariño (Red eléctrica de prueba) al momento de masificar sistemas fotovoltaicos conectados directamente a red. Dicha metodología es aplicada en cuatro escenarios de prueba, en los cuales se desarrollan procesos de cosimulación entre DigSilent/PowerFactory y Matlab/Simulink para evaluar parámetros importantes como: niveles de tensión, cargabilidad en conductores y transformadores, pérdidas totales, comportamiento del factor de potencia y contribuciones a la corriente de corto circuito a medida que el nivel de penetración de sistemas fotovoltaicos aumenta en la red propuesta. Dentro de las simulaciones desarrolladas, se utilizan datos reales de variables atmosféricas y eléctricas para modelar un sistema fotovoltaico conectado a red que permite replicar la operación dentro de la red eléctrica y determinar los impactos producidos al masificar este tipo sistemas. Los resultados en simulación darán indicadores importantes para determinar el máximo nivel de penetración fotovoltaica permitido en la red propuesta, además de plantear recomendaciones generales para mitigar las posibles consecuencias al momento de planear futuros proyectos fotovoltaicos al interior del campus universitario Abstract: The present work proposes a methodology to perform a technical study over power quality impacts into the University of Nariño’s internal electrical grid (Electrical test grid) when the grid connected photovoltaic systems are massified. This methodology is applied in four test scenarios to develop cosimulation process between DigSilent/PowerFactory and Matlab/Simulink. With this simulation, important parameters like voltage levels, loading in conductors and transformers, total losses, behavior of the power factor and contributions to the short-circuit current are evaluated at the moment of the penetration level of photovoltaic systems increases in the proposed grid. By developing these simulations, we used real data of atmospheric and electrical variables to model a connected photovoltaic system. That allow a replication of the operation within the electrical grid and determine the impacts when this type of photovoltaic systems are highly used. The simulation results is going to give the main indicators to determine the maximum level of photovoltaic penetration into the electrical grid proposal. In addition, it will present general recommendations to mitigate the possible consequences when future photovoltaic projects inside the university campus are development Maestría

The insertion of photovoltaic solar energy has increased considerably over the past few years, with remarkable growth since 2005. It is essential that the electrical energy delivered by the photovoltaic system to the grid has an acceptable quality level. This paper presents test results of power factor and harmonic distortion content in grid connected inverters for photovoltaic systems. Several tests of ten commercially available inverter models from three different manufacturers were performed at the Laboratory of Solar Energy (Labsol) at the Federal University of Rio Grande do Sul (UFRGS), using a test bench with a power analyzer. The power factor and total harmonic distortion in current curves were mathematically modeled as a function of relative power in order to be used in computer simulation of photovoltaic systems. For power loads close to the nominal values, the harmonic content was found to be low and in accordance with the standard requirements. Nevertheless, at low loading levels the inverters may inject high levels of harmonics into the grid.

The amount and quality of the energy converted by a photovoltaic system connected to the grid can be evaluated by experimental monitoring or computer simulation. The Solar Energy Laboratory at UFRGS developed a simulation software for analysis of grid connected photovoltaic systems (FVCONECT). In order to perform a reliable simulation, it is required for the implementation of suitable mathematical models that describe the behavior of each system component. The inverter is the equipment responsible for converting DC to AC. The manufacturers provide some technical parameters for the inverters. However, electrical and thermal characteristics require mathematical models which coefficients must be obtained from specific tests. This work presents a methodology for analysis of thermal behavior of inverters. Such analysis requires experimental determination of two thermal coefficients. Energy losses due to inverters overheating can be calculated through the proposed methodology, providing a more accurate simulation of a determined photovoltaic (PV) system. The proposed methodology has been tested in several inverters, providing good results.

The application of photovoltaic (PV) as a source of electrical energy in the distributed generation (DG) systems are gaining more attention with the advances in power electronics technology. The one of the key technologies in the PV based DG systems is grid connected inverter that is utilized to interface PV power systems into the utility grid. Multilevel multifunctional grid connected inverters (ML-MFGCIs) are new breed of power converter used in large scale PV applications and have superior advantages such as lower switching power dissipation, lower harmonic distortion and lower electromagnetic interference (EMI) outputs. ML-MFGCIs perform the high quality power from PV systems and provide flexible functionality with improved power quality (PQ), voltage and reactive power support and increased capability of the auxiliary service for the utility grid. This paper presents a detailed analysis of various ML-MFGCI configurations for 1-phase and 3-phase systems and control strategies to compensate the different PQ problems. Almost 100 papers including the practical applications and recent research studies on ML-MFGCIs are reviewed and analysed. © 2014 Elsevier Ltd.