HVDC Power Transmission Simulation for Offshore Wind System with Three-Level Converter

An integrated mathematical model for the simulation of an offshore wind system performance is presented in this paper. The mathematical model considers an offshore variable-speed turbine in deep water equipped with a permanent magnet synchronous generator using multiple point full-power clamped three-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a HVDC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the blades of the wind turbine, tower and generator due to the need to emulate the effects of the wind and the floating motion. Controller strategy considered is a proportional integral one. Also, pulse width modulation using space vector modulation supplemented with sliding mode is used for trigger the transistors of the converter. Finally, a case study is presented to access the system performance

Simulation by discrete mass modeling of offshore wind turbine system with DC link

This paper presents an integrated model for an offshore wind turbine taking into consideration a contribution for the marine wave and wind speed with perturbations influences on the power quality of current injected into the electric grid. The paper deals with the simulation of one floating offshore wind turbine equipped with a permanent magnet synchronous generator, and a two-level converter connected to an onshore electric grid. The use of discrete mass modeling is accessed in order to reveal by computing the total harmonic distortion on how the perturbations of the captured energy are attenuated at the electric grid injection point. Two torque actions are considered for the three-mass modeling, the aerodynamic on the flexible part and on the rigid part of the blades. Also, a torque due to the influence of marine waves in deep water is considered. Proportional integral fractional-order control supports the control strategy. A comparison between the drive train models is presented

Blade pitch control malfunction simulation in a wind energy conversion system with MPC five-level converter

This paper is on a wind energy conversion system simulation of a transient analysis due to a blade pitch control malfunction. The aim of the transient analysis is the study of the behavior of a back-to-back multiple point clamped five-level full-power converter implemented in a wind energy conversion system equipped with a permanent magnet synchronous generator. An alternate current link connects the system to the grid. The drive train is modeled by a three-mass model in order to simulate the dynamic effect of the wind on the tower. The control strategy is based on fractional-order control. Unbalance voltages in the DC-link capacitors are lessen due to the control strategy, balancing the capacitor banks voltages by a selection of the output voltage vectors. Simulation studies are carried out to evaluate not only the system behavior, but also the quality of the energy injected into the electric grid

Conversão eólica offshore ligada à rede elétrica: modelação e simulação

A tese incide sobre a modelação e simulação de um sistema de conversão de energia eólica offshore com ligação à rede elétrica por transmissão de energia elétrica estudada quer em corrente alternada quer em corrente contínua, no contexto atual de reestruturação do setor elétrico, e integrando a dinâmica relevante. Além da transmissão de energia elétrica, o sistema é constituído por uma plataforma flutuante semissubmersível; uma turbina eólica de velocidade variável; um sistema de transmissão de energia mecânica cuja dinâmica é descrita respetivamente por uma, duas, três ou cinco massas girantes; um gerador síncrono com excitação assegurada por meio de ímanes permanentes; um conversor eletrónico de energia, descrito respetivamente por um conversor de dois níveis ou por um conversor multinível na configuração de díodos de ligação múltipla de três, de quatro, de cinco ou de p níveis. O controlo do sistema utiliza o modo de deslizamento associado com a modulação PWM por vetores espaciais e controladores PI, ditos de clássicos, ou controladores PI de ordem fracionária. Os comportamentos que advêm do facto da energia eólica ser uma fonte de energia variável, com intermitência, assim como, os de eventuais falhas de funcionamento dos dispositivos que controlam o sistema são estudados na tese, recorrendo a simulações computacionais. As contribuições fundamentais envolvem a modelação do conversor de p níveis, as correntes nos bancos de condensadores associadas aos níveis de tensão e a estratégia de controlo do conversor multinível para a selecção do vetor de tensão. As simulações computacionais permitem concluir sobre o desempenho favorável do sistema e simultaneamente fornecem informação quantificada sobre o comportamento das grandezas mecânicas e elétricas, permitindo quer em fase de projeto, quer em fase de utilização o estudo de comportamentos que necessitam de serem corrigidos devido a serem potencialmente indesejáveis; Offshore Wind Energy Conversion System Connected to the Electric Grid: Modeling and Simulation Abstract: The thesis focuses on the modeling and simulation of offshore wind energy conversion systems connected to the electric grid either by an alternated current link or by a direct current link in a view of timeliness developments on electricity sector restructuring and integrating the relevant dynamics. Besides the electricity transmission, the system consists of a semi-submersible floating platform; a variable speed wind turbine; a mechanical transmission system described respectively by one, two, three, or five masses; a synchronous generator with excitation provided by means of permanent magnets; an electronic power converter, respectively described by a two-level converter or by a multi-level converter in a multiple point clamped topology of three, four, five, or p levels. The control of the system uses PWM by space vector modulation associated with sliding mode and classic PI or fractional order PIcontrollers. The behaviors due to fact that wind energy is a variable, intermittently, source of energy, as well as, due to eventual malfunctions of devices controlling the systems are studied in the thesis, using computer simulations. The fundamental contributions involve the modeling of the p levels converter, the capacitor banks current associated with the voltage level, the control strategy of the multilevel converter for the voltage vector selection. The computer simulations allow to conclude on the favourable performance of the system and simultaneously allow data on mechanical and electric quantities, allowing either in design phase or in usage phase the study of behaviors that need to be corrected because of the potentially undesirability

Simulation of OWES with five-Level converter linked to the grid: Harmonic assessment

This paper deals with a computing simulation for an offshore wind energy system taking into account the influence of the marine waves action throughout the floating platform. The wind energy system has a variable-speed turbine equipped with a permanent magnet synchronous generator and a full-power five level converter, injecting energy into the electric grid through a high voltage alternate current link. A reduction on the unbalance of the voltage in the DC-link capacitors of the five-level converter is proposed by a strategic selection of the output voltage vectors. The model for the drive train of the wind energy system is a two mass model, including the dynamics of the floating platform. A case study is presented and the assessment of the quality of the energy injected into the electric grid is discussed.Fundação para a Ciência e Tecnologia (FCT) under the: project LAETA 2015‐2020, reference UID/EMS/50022/2013; FCT Research Unit nº 151 C‐MAST Center for Mechanical and Aerospace Sciences and Technolog

Simulation of a rectifier malfunction on a offshore wind system with HVDC transmission

A new integrated mathematical model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase is presented in this paper. The mathematical model considers an offshore variable-speed wind turbine on a floating platform, equipped with a permanent magnet synchronous generator using full-power three-level converter to inject energy into the electric network, through a high voltage direct current transmission submarine cable. The model for the drive train is a discrete three mass, incorporating the dynamic of the moving surface. A case study is presented to access conclusion about the malfunction.Fundação Ciência e Tecnologia, through IDMEC/LAETA, Instituto Superior Técnico, Universidade de Lisbo

Participação em processos de consulta pública: Percepções dos cidadãos e recomendações para autoridades responsáveis

Este  relatório  inscreve-­‐se  no  projecto  COMPOLIS  –  Comunicação  e  Envolvimento  Político com Questões Ambientais, financiado pela Fundação para a Ciência e a Tecnologia  com  a  referência  EXPL/IVC-­COM/1717/2012.  O  projecto  foi  desenvolvido  entre 1 de Julho de 2013 e 31 de Dezembro de 2014, tendo sido Anabela Carvalho, membro do Centro de Estudos de Comunicação e Sociedade (CECS) da Universidade do  Minho,  a  investigadora  responsável.  O  relatório  dá  conta  de  conclusões  de  membros da equipa do projecto, que as apresentam a tal título, e não em nome da Universidade do Minho. Um dos objetivos do projecto COMPOLIS era analisar as experiências e percepções dos  cidadãos  sobre  processos  de  participação  pública  relacionados  com  questões  ambientais. Um dos casos estudados foi o do processo de consulta pública relativo ao projecto  de  instalação  de  uma  linha  de  transporte  de  energia  elétrica  de  muita  alta tensão entre Vila do Conde e a Rede Elétrica de Espanha, a 400Kv, cujo traçado previsto  atravessa  freguesias  dos  distritos  de  Viana  do  Castelo,  Braga  e  Porto.Financiado pelo COMPETE: POCI-01-0145-FEDER-007560 e FCT - Fundação para a Ciência e Tecnologia, no âmbito do projeto: UID/CCI/00736/2013. Projecto COMPOLIS

Hb Évora [α2-35 (B16), Ser→Pro], a novel hemoglobin variant associated with an α-thalassemia phenotype

We report a novel mutation in the α2-globin gene, codon 35 (T→C), detected in two unrelated Portuguese families. This mutation gives rise to a previously undescribed hemoglobin (Hb) variant, which we named Hb Évora. This variant seems to be responsible for the α-thalassemia phenotype present in its carriers. It cannot be detected by conventional laboratory techniques, probably because of its highly unstable nature

Facts related to the collection of biological samples in the National Health Examination Survey - Portuguese Component of the European Health Examination Survey

Abstrat disponível em: http://www.ichg2011.org/cgi-bin/showdetail.pl?absno=11013The objective of the National Health Examination Survey (NHES), which corresponds to the Portuguese component of the European Health Examination Survey (EHES), is to collect health data, related risk factors and biological samples of the Portuguese population, using the EHES recommended methodology. These surveys involve an interview, clinical and physical measurements and blood collection. In this context, we herein describe the pilot study performed in S. Brás de Alportel in the Algarve region. For this pilot study, we have recruited 221 individuals (95 males and 126 females), between 25 and 91 years old, who were enrolled in the Health Centre of S. Brás de Alportel (Algarve). For each participant, we have collected 16.5 ml of total blood, in five different Vacutainer® tubes, which was later processed into serum, plasma and DNA. We have performed several biochemical analyses(total cholesterol, LDL,HDL, glucose, tryglicerides, creatinine, ALT, AST, -GT, CRP and iron) and a complete blood count. From the 221 participants in this pilot study, we were able to collect blood to 219 (99.5%). To 185 of these (84.5%) we were able to collect the total amount of blood. The biochemical analyses were performed in all the samples. The total blood count was performed in 103 samples (47%) due to transport constraints. We have also collected DNA from 210 participants (95.9%). We have created a biobank comprising 1847 serum aliquots and 959 plasma aliquots, which have been stored at - 80°C and 210 DNA aliquots which have been stored at 4°C. In conclusion, during this study, we have optimized the logistics and procedures to perform the large scale study for the NHES and EHES. In addition, we have created a biobank comprising detailed questionnaire data, physical and clinical data and biological samples from a representative sample of S. Brás de Alportel in Algarve, Portugal. This biobank will allow us to perform future studies, including the determination of the prevalence of gene variants of public health interest, the characterization of gene-environment interactions in the development of chronic diseases and the genetic structure of the Portuguese population. The success rate, the quality of the data and of the biological samples was high and comparable to similar studies.Fundação para a Ciência e Tecnologia e European Commission/DG Sanc

Evaluation of claw lesions in beef cattle slaughtered in northern Portugal : a preliminary study

DATA AVAILABILITY STATEMENT : Data are contained within the article and Supplementary Materials.SUPPLEMENTARY MATERIAL : The supporting information provides details on cattle claw lesions by sex, age, hot carcass weight, carcass classification, and fat coverage.Claw diseases have a profound impact on cattle welfare, affecting behaviors such as grazing, rumination, rest, decubitus, and water consumption. This study aimed to assess the prevalence of claw lesions and classify them according to the ICAR Claw Health Atlas (International Committee of Animal Recording) in two slaughterhouses. The influence of claw lesions on carcass weight, classification, and fat deposition was also examined. Involving 343 crossbreed cattle from 103 different extensive or semi-intensive farms, this study found an animal prevalence of claw disorders at 65.8%, with a higher incidence in females (n = 207, 60.35%) compared to males (n = 136, 39.65%). Despite the observed prevalence, claw lesions were not influenced by age or sex (p > 0.05). The main claw lesions identified, including heel horn erosion, double sole, and asymmetric claw, were consistent with the cattle management practices in the study area. These cattle were raised in small, rustic premises with uneven floors, utilizing a mix of manure and plant material as bedding and lacking access to pasture. Also, no negative economic impact was detected concerning carcass weight, classification, or fat deposition. Consequently, it was concluded that the presence of claw lesions in beef cattle raised under the characteristic management of this geographical area does not adversely affect animal health or farm economics.The Portuguese Foundation for Science and Technology (FCT).https://www.mdpi.com/journal/animalsParaclinical SciencesSDG-02:Zero HungerSDG-03:Good heatlh and well-bein