Tutorials

Title: Basic Concepts of Modular Multilevel Converters and Applications in Medium and High Voltage Fields

Abstract: Due to the limitations in the voltage ratings of power semiconductors, the use of multilevel convertersis a topological solution for medium and high voltage applications. Electric drives, Static Synchronous Compensators, HVDC systems and Energy Storage systems are examples of possible applications. In view of the disadvantages related to other multilevel solutions, the modular multilevel converter (MMC) has become in the last years the most attractive converter topology for medium and high voltage applications. The MMC topology is featured by many advantages as low switching frequency, high efficiency, higher number of levels, design flexibility, high reliability, redundant structure and fault-tolerant operation. This tutorial aims to introduce to the researches the main characteristics, operation principles, control tasks and modeling of modular multilevel converters. Aspects related to converter design, control architectures and simulation of modular multilevel converters are approached in a didactic way. Analytical, experimental results and simulation models are employed to show the important characteristics of this interesting converter topology.

Authors: Heverton A. Pereira (UFV), Allan F. Cupertino (CEFET-MG), Seleme I. Seleme Junior (UFMG)

Title: Microgeração Solar Fotovoltaica

Abstract: A geração solar fotovoltaica é uma tecnologia em franca ascensão para atender a crescente demanda de energia elétrica. Ainda hoje, a carência nacional de qualificação técnica em energias renováveis, por parte de agentes e de consumidores, dificulta um crescimento mais acelerado de sistemas instalados. A título de exemplo, são escassas as linhas de crédito para financiar a instalação de sistemas solares fotovoltaicos. Este fato, associado ao elevado custo inicial, limita o perfil de clientes a classe social A1, a despeito do interesse de outras classes. A preocupação mundial com relação à preservação do meio ambiente tem impulsionado o uso de fontes de geração mais limpas de energia. O Brasil apresenta uma grande diversidade de recursos naturais propícios para geração renovável como, por exemplo, solar, eólica e biomassa. A despeito da predominância da produção de eletricidade renovável, em usinas hidroelétricas, os períodos prolongados de estiagem revelaram a necessidade de diversificar a matriz energética. A necessidade da redução da dependência dos combustíveis fósseis e da minimização dos impactos ambientais, associado aos avanços tecnológicos e incentivos na alteração da legislação tributária, tem sido determinísticos para a rápida ampliação das fontes renováveis.

Authors: Salatiel C. Lobato, Jonathan H. D. G. Pinto, Fernando H. Oliveira, Paula V. Pengo, Guilherme F. Avelar, Lucas M. P. Deotti, José Américo Valentim, Flavio Vanderson Gomes, André Augusto Ferreira (UFJF)

Title: Modeling of Long Feeders in Power Electronics Based Systems

Abstract: This tutorial presents some modeling guidelines regarding more accurate representation of long feeders in power electronics simulations considering renewables, variable speed drives and HVDC systems. The focus is in the cases where feeders are based on insulated cables that can be used underground, underwater or laid out in aerial configurations. Given the distributed nature and skin effect in the conductors, the cable introduces new resonances that demands more complex models when compared with those associated with overhead lines. This tutorial details how to derive such models in the frequency domain and presents some guidelines regarding the minimally accurate models when electromagnetic transients programs are used to assess the voltage/current profile.

Authors: Antonio C. S. Lima (UFRJ), Robson F. S. Dias (UFRJ), João P. L. Salvador (CEFET-RJ), Antônio P. C. Magalhães (UFRJ), Maria Teresa Correia de Barros (IST-ULisboa, Portugal)

Title: Modular Multilevel Converters: Topologies, Operation and Control

Abstract: Current high voltage and high power applications that employ Power Electronics converters see a clear trend towards modularity. The main drivers being: lower solution costs, configuration flexibility, reliability concerns with the series connection of power semiconductor devices, improved loss distribution among converter components, reduced harmonic and EMC filter requirements. The first modular multi-level converter solutions have seen the use of isolated dc sources to feed each converter unit (module or submodule depending on the specific type of converter). These dc sources were typically implemented by phase-shifting transformers with multi-pulse rectifiers. However, the invention of the converter named “Modular Multilevel Converter” by the group of Prof. Marquardt, in 2003, eliminated the need for isolated voltage sources and created a very interesting concept for several applications. The most prominent been HVDC rectifiers. Afterwards, MMC converters were proposed as a solution for various applications, including renewable generation, energy storage systems, static compensation, active filters, FACTS devices, solid state transformers, high voltage dc-dc converters and medium voltage adjustable speed drives. This tutorial will review important stages of the history of the MMC converters, focusing in relevant progress milestones in the areas covered in the tutorial. Topologies, control and operation of ac-dc, dc-ac and dc-dc converters will be reviewed.

Authors: Marcelo Lobo Heldwein, Gean Jacques Maia de Sousa, Marcelo Dias Pedroso (UFSC)

Title: Metodologia de Avaliação de Controladores (Drivers) de LEDs para Iluminação Viária à Luz de Normativas Brasileiras

Abstract: Esse tutorial está focado na metodologia de avaliação de luminárias LED (SSL: solid-state lighting) para iluminação pública, com estudo de caso relacionado à implantação de um sistema SSL no campus principal da Universidade Federal de Juiz de Fora (UFJF). Luminárias comerciais fornecidas por diversos fabricantes são avaliadas e comparadas com base nas normativas e requisitos estabelecidos por um edital típico aplicado a órgãos públicos.
As principais normas aplicáveis em sistemas de iluminação pública empregando LEDs são abordadas. Normas nacionais e internacionais, destinadas tanto para o sistema de iluminação, quanto para equipamentos empregando LEDs, com ênfase para as normas que tratam dos circuitos eletrônicos de acionamento das luminárias LEDs (drivers) são detalhadas. Os tipos básicos de drivers também foram apresentados, com ênfase para os drivers passivos de baixa frequência, drivers ativos de alta frequência e os drivers ativos de baixa frequência.
Esse tutorial também aborda um pré-regulador boost comutado no dobro da frequência da rede elétrica (nesse caso, 120 Hz) empregado como driver de LED. É mostrado que esse driver pode acionar uma luminária LED de 160 W obtendo elevado fator de potência, elevada eficiência elétrica, reduzida distorção harmônica total da corrente de entrada, conformidade com norma IEC 61.000-3-2 Classe C e possibilidade de elevada vida útil devido à ausência de capacitores eletrolíticos.

Authors: Fernando J. Nogueira, Cristiano G. Casagrande, Lucas H. G. Resende, Ruan M. Ferraz, Felipe B. Marinho, e Henrique A. C. Braga (UFJF)

Title: Hardware-in-the-Loop techniques for smart inverter control design, testing, and certification

Abstract: In this practically oriented, hands-on tutorial, attendees will learn how to design, test, and pre-certify a 3-phase battery inverter digital controller. They will learn both underlying theoretical concepts as well as hands on; apply acquired knowledge to design, implement, and test an inverter controller during the course.  They will first learn the theoretical foundation for digital control of 3-phase solar inverters in DQ reference frame including space-vector modulation basics, PLL design, and filter design. Then, they will implement their inverter controller on a real-time ultra-high fidelity HIL platform and run the complete inverter and controller model in real-time.  After the inverter is up and running they will learn how to tune the current loop PI controllers, in runtime, using real-time simulation and virtual impedance analyzer in HIL.  Finally, we will introduce a HIL based methodology how to test and validate the performance and robustness of the inverter controller in realistic grid tie settings (i.e. weak and strong grid conditions) and we will introduce all the key grid support requirements for the UL1741 SA and Rule 21, the emerging smart inverter grid code, and explain all the grid support functionality. Attendees will also learn how to pre-certify their smart inverter controller and prepare their designs for full inverter certification.

Author: Murilo Machado de Almeida (Typhoon HIL, Inc.)