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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 last 20 years have presented a favorable scenario for the incorporation of renewable energy sources into the energy matrix of developing countries. This situation promoted grid connected photovoltaic generation systems (GCPVS) to become one of the main protagonists in this new concept of energy matrix. In some developing countries the use of such systems is in its beginning. Promotion policies and technical as well as regulatory conditions for their installation have just started to be defined. In this context, there exists in Argentina a legal and regulatory framework for the implementation of large photovoltaic plants but there is a lack of such legal framework for distributed generation (DG) by means of grid connected photovoltaic into the medium and low voltage distribution networks. This situation led research centers, together with private and provincial Energy Agencies to install pilot systems in order to identify and characterize their impact on the low voltage distribution network, taking into account the local grid capacity and characteristics of each province. In this paper the implications of different degrees of penetration of solar photovoltaic power generation evaluated using technical parameters of the network is presented. A set of examples of residential users connected to a distribution substation in the city of Corrientes is analyzed by means of a simulation using real grid data with the incorporation of GCPVS generation. The simulation results show that both the level of penetration of GCPVS systems as well as location where these distributed energy sources should couple to the distribution grid must be carefully assessed to maximize the benefits of the inclusion of distributed generation in urban environments.

This paper presents a methodology associated to a set of explicit equations aimed to translate point-to-point the generated power to standard test conditions and its application to a real situation. Such equations are employed for monitoring and diagnostic of grid connected photovoltaic systems. The proposed method is based in the data analysis through statistical methods and it allows diagnosis or detection of instant decreases of generated power. The Experimental results are compared with other procedure of characterization of the nominal power of large photovoltaic generators under real operation conditions which are based on protocols similar to the one proposed in this paper. Results show differences less to 3% between both methods. In conclusion, the methodology presented is useful for real time diagnose of power decrease, when variation of maximum power with temperature is not known or in cases where catalog parameters are not available.

This article presents the development of a test bench for the characterization of batteries for solar uses as well as results of tests conducted using solar batteries. The test bench comprises three main blocks: the thermal module, the power supply and the measuring module. The thermal module consists of a thermally regulated bath with a heating and cooling system capable of maintaining a constant working temperature with an accuracy of ± 0.3 °C. The power supply is a bipolar Kepco, BOP 36-12D that allows charging and discharging of batteries with a control unit that allows its automatic operation. Finally, the measuring system comprises a set of sensors and circuits with the capability of logging battery voltage, charge / discharge current, density and temperature. All these variables are measured with an error lower than that specified by the standard IEC 61427 - 2005. Gathered data are transmitted to a PC where they are recorded and displayed in real time. The software supports various charge / discharge profiles with different values of the current, the bath temperature and test duration hence allowing the possibility of cyclic testing. The test bench developed is currently the first of its kind in the country with the capability to comply with standards as to the characterization of solar batteries is concerned.

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.

Se analiza el funcionamiento de un sistema fotovoltaico, compuesto por 12 paneles solares de 240 Wp conectados en serie y un inversor de 2,8 kW, sometido a la presencia de sombras parciales producidas por una baranda. Se presentan curvas corriente-tensión de un módulo fotovoltaico y de los 12 módulos conectados en serie, y se estima la pérdida de energía generada para días despejados dentro del período marzo-junio de 2014. El análisis se realizó a partir de mediciones de perfiles de generación obtenidos mediante un analizador/registrador de red. Las estimaciones arrojan valores de pérdidas diarias que superan el 10% para días despejados cercanos al solsticio de invierno, siendo significativamente menores en abril para finalmente ser despreciables (< 1%) en fechas próximas a los equinoccios., The operation of a photovoltaic system, consisting of 12 240 Wp photovoltaic modules connected in series and a 2.8 kW inverter, subject to the presence of partial shadows produced by a railing is analyzed. Current-voltage curves of a photovoltaic module and 12 modules connected in series are presented and the energy loss for clear days in the period from March to June 2014 is estimated. The analysis was performed using measurements obtained by a power monitoring instrument. The estimated daily energy losses exceed 10% for clear days near the winter solstice, being significantly lower in April and negligible (, Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES)

Summary form only given as follows. Electric utilities in Australia have been developing policies to stimulate interest and permit the purchase of electricity generated by renewable energy sources such as photovoltaic systems (PV). Studies show that under current conditions, it is technically feasible to introduce small-scale, grid connected, roof-top photovoltaic generation systems with or without battery storage. Economic analysis show that the electricity tariff structure for PV and other renewables requires a major change to allow a reasonable and an acceptable pay-back period if PV is to become an attractive economic investment to private owners. The technical policy developed by the utility should be reviewed to better match the operational characteristics of PV and inverter systems.

Αναπτύσσεται ένα πλήρες δυναμικό μοντέλο μετασχηματιστή που λαμβάνει υπόψη τη γεωμετρία του πυρήνα και τη συνδεσμολογία των τυλιγμάτων. Το μοντέλο μπορεί εύκολα να ενσωματωθεί στις καταστατικές εξισώσεις ενός συστήματος ισχύος με σκοπό τη μελέτη της δυναμικής του απόκρισης και τον υπολογισμό ανωτέρων αρμονικών. Ο βρόχος υστέρησης του υλικού του πυρήνα εισάγεται με το μοντέλο που: (α) προτείνει ο Tellinen και (β) προτείνουν οι Jiles και Atherton. Τα μοντέλα αυτά υπολογίζουν σωστά τις απώλειες υστέρησης του πυρήνα, επιτρέποντας στα διάφορα τμήματα του πυρήνα να διαγράφουν διαφορετικούς βρόχους. Η επίδραση των δινορευμάτων ενσωματώνεται στο μοντέλο με μη γραμμικές ωμικές αντιστάσεις για τον υπολογισμό των οποίων αξιοποιούνται οι σχετικές με τα δινορεύματα, ευρέως αποδεκτές, εργασίες του Bertotti. Ο πίνακας Ld των αυξητικών επαγωγών του μετασχηματιστή υπολογίζεται για οποιαδήποτε γεωμετρία πυρήνα και αριθμό τυλιγμάτων με την βοήθεια του Ισοδυνάμου Αυξητικού Κυκλώματος (ΙΑΚ) του πυρήνα. Ο αναλυτικός υπολογισμός των στοιχείων του πίνακα Ld αναδεικνύει τον τρόπο εξάρτησης των αυξητικών επαγωγών του μετασχηματιστή από τη γεωμετρία του πυρήνα και από τη χαρακτηριστική καμπύλη του υλικού. A dynamic and complete transformer model is developed which takes into account the magnetic core geometry and the windings connections. This model can easily be incorporated with the state equations of a power system, in order to calculate its dynamic response and the harmonic content. The magnetic hysteresis of the core material is introduced the model that is proposed by: (a) Tellinen and (b) Jiles and Atherton. These models can estimate the hysteresis power losses even when the hysteresis loops into several parts of the core differ. The eddy currents effects are incorporated into the model by non-linear ohmic resistances which are based on Bertotti’s work for the eddy currents. The matrix Ld of the incremental inductances of the windings is calculated, for any possible core geometry and number of windings, using the Equivalent Incremental Circuit (EIC) of the core. The analytical calculation of the elements of the matrix Ld shows the dependency of the incremental inductances on the core geometry and the characteristic curve of the core material.

No presente trabalho é feita uma descrição e análise dos componentes principais que constituem os sistemas fotovoltaicos autónomos e ligados à rede. Foram também sistematizados os passos que, no seu conjunto, constituem uma metodologia adequada para efectuar o dimensionamento de ambos os tipos de sistemas fotovoltaicos. Com base na metodologia identificada foi desenvolvida uma aplicação computacional em linguagem Hypertext Preprocessor (PHP) para a Internet, a qual foi utilizada em dois casos de estudo: Dimensionamento de um sistema fotovoltaico autónomo e de um sistema fotovoltaico ligado à rede. In this work, the main components of photovoltaic systems both stand alone and grid connected, are described and analysed. It was also presented the sequence of the main tasks, which constitutes a methodology suitable to carry out the sizing procedure of both stand-alone and grid connected photovoltaic systems. Based on this methodology, a computational application was developed under Hypertext Preprocessor (PHP) language for the Internet, which was used on two study cases: Sizing of a stand-alone photovoltaic system and grid connected photovoltaic system.