Ferramenta computacional para análise do potencial de bombeamento de água utilizando aerogeradores de pequeno porte acoplados a motobombas por meio de inversores de frequência

O objetivo desta dissertação é desenvolver uma ferramenta computacional para a análise do potencial de bombeamento de água com base nos valores de velocidades de vento de uma localidade, utilizando um aerogerador de pequeno porte acoplado a um conjunto motobomba convencional, por intermédio de um inversor de frequência. No trabalho são apresentados dois métodos para o cálculo da vazão. O método 1 utiliza um modelo teórico, enquanto que no método 2 o modelamento é feito a partir de dados de bombeamento obtidos em laboratório. Os dois métodos descrevem o funcionamento de um sistema de bombeamento de água envolvendo os equipamentos citados. Utilizando os modelos matemáticos descritos, foi criado um programa em linguagem Delphi®, para a obtenção dos valores de vazão e volume de água bombeada, além do número de pessoas que podem ser atendidas, com base nos dados de velocidade de vento do local, para com isso, ser possível analisar a viabilidade ou não de instalação do sistema. O funcionamento do programa é descrito através de um exemplo, que contém valores reais de velocidade de vento, e cujos resultados são analisados de forma a possibilitar seu entendimento.

Acionamento vetorial por controlador fuzzy modo deslizante de motor de indução

Este trabalho estuda a técnica de acionamento vetorial aplicado ao motor de indução trifásico (MIT), utilizando como estratégia de controle a combinação de controle fuzzy com controladores chaveados do tipo modo deslizante, em uma configuração aqui denominada de Controlador Fuzzy Modo Deslizante (FSMC – Do inglês: Fuzzy Sliding Mode Control). Um modelo dinâmico do MIT é desenvolvido em variáveis ‘d-q’ o que conduziu a um modelo eletromecânico em espaço de estados que exibe fortes não linearidades. A este modelo são aplicadas as condições de controle vetorial que permitem desacoplar o torque e o fluxo no MIT, de maneira que o seu comportamento dinâmico se assemelha àquele verificado em uma máquina de corrente contínua. Nesta condição, são implementados controladores do tipo proporcional e integral (PI) às malhas de controle de corrente e velocidade do motor, e são realizadas simulações computacionais para o rastreamento de velocidade e perturbação de carga, o que levam a resultados satisfatórios do ponto de vista dinâmico. Visando investigar o desempenho das estratégias não lineares nesta abordagem é apresentado o estudo da técnica de controle a estrutura chaveada do tipo modo deslizante. Um controlador modo deslizante convencional é implementado, onde se verifica que, a despeito do excelente desempenho dinâmico a ocorrência do fenômeno do “chettering” inviabiliza a aplicação desta estratégia em testes reais. Assim, é proposta a estratégia de controle FSMC, buscando associar o bom resultado dinâmico obtido com o controlador modo deslizante e a supressão do fenômeno do chettering, o que se atinge pela definição de uma camada de chaveamento do tipo Fuzzy. O controlador FSMC proposto é submetido aos mesmos testes computacionais que o controlador PI, conduzindo a resultados superiores a este último no transitório da resposta dinâmica, porém com a presença de erro em regime permanente. Para atacar este problema é implementada uma combinação Fuzzy das estratégias FSMC com a ação de controle PI, onde o primeiro busca atuar em regiões afastadas da superfície de chaveamento e o segundo busca introduzir o efeito da ação integral próximo à superfície. Os resultados obtidos mostram a viabilidade da estratégia em acionamento de velocidade variável que exigem elevado desempenho dinâmico.

Wind turbines equipped with fractional-order controllers: Stress on the mechanical drive train due to a converter control malfunction

This paper is on variable-speed wind turbines with permanent magnet synchronous generator (PMSG). Three different drive train mass models and three different topologies for the power-electronic converters are considered. The three different topologies considered are respectively a matrix, a two-level and a multilevel converter. A novel control strategy, based on fractional-order controllers, is proposed for the wind turbines. Simulation results are presented to illustrate the behaviour of the wind turbines during a converter control malfunction, considering the fractional-order controllers. Finally, conclusions are duly drawn. Copyright (C) 2010 John Wiley & Sons, Ltd.

Servo drive in hoist application

The objective of this master thesis is to test according to hoisting requirements, a servo drive system and compare its performance with the performance of a drive equipped with a vector controlled frequency converter. Both systems utilize closed-loop vector control based on PCL program control. In order to compare the results of tests both systems were connected to the same motor driving a variable speed electrical chain hoist. Tests were based on requirements to both systems. As requirements of tests zero speed operation, operation in field weakening, positioning accuracy and smoothness of motion are taken into consideration. Both systems demonstrate quite similar performance and meet the requirements. Servo drive system demonstrates a high positioning accuracy and dynamic performance. Frequency converter is not able to provide the same positioning accuracy and dynamic performance as servo drive.

A new control strategy with saturation effect compensation for an autonomous induction generator drivenby wide speed range turbines

This paper presents a variable speed autonomous squirrel cage generator excited by a current-controlled voltage source inverter to be used in stand-alone micro-hydro power plants. The paper proposes a system control strategy aiming to properly excite the machine as well as to achieve the load voltage control. A feed-forward control sets the appropriate generator flux by taking into account the actual speed and the desired load voltage. A load voltage control loop is used to adjust the generated active power in order to sustain the load voltage at a reference value. The control system is based on a rotor flux oriented vector control technique which takes into account the machine saturation effect. The proposed control strategy and the adopted system models were validated both by numerical simulation and by experimental results obtained from a laboratory prototype. Results covering the prototype start-up, as well as its steady-state and dynamical behavior are presented. (C) 2011 Elsevier Ltd. All rights reserved.

Comando de ondulador de tensão trifásico por PWM e técnica U/F com implementação por microcontrolador

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Automação e Electrónica Industrial

Simulation of offshore wind system with two-level converters: HVDC power transmission

A new integrated mathematical model for the simulation of offshore wind energy conversion 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 full-power two-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a high voltage DC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the structure and tower due to the need to emulate the effects of the moving surface. 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 transistor of the converter. Finally, a case study is presented to access the system performance. © 2014 IEEE.

Simulation of offshore wind system with two levels converters: HVDC power transmission

A new integrated mathematical model for the simulation of offshore wind energy conversion 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 full-power two-level converter, converting the energy of a variable frequency source in injected energy into the electric network with constant frequency, through a high voltage DC transmission submarine cable. The mathematical model for the drive train is a concentrate two mass model which incorporates the dynamic for the structure and tower due to the need to emulate the effects of the moving surface. 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 transistor of the converter. Finally, a case study is presented to access the system performance. © 2014 IEEE.

Simulation of rectifier voltage malfunction on OWECS, four-level converter, HVDC light link: Smart grid context tool

This paper presents a model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase. The offshore wind system model comprises a variable-speed wind turbine supported on a floating platform, equipped with a permanent magnet synchronous generator using full-power four-level neutral point clamped converter. The link from the offshore floating platform to the onshore electrical grid is done through a light high voltage direct current submarine cable. The drive train is modeled by a three-mass model. Considerations about the smart grid context are offered for the use of the model in such a context. The rectifier voltage malfunction domino effect is presented as a case study to show capabilities of the model. (C) 2015 Elsevier Ltd. All rights reserved.

Retificador trifásico controlado com fator de potência quase unitário

Dissertação de Mestrado para obtenção do grau de Mestre em Engenharia Eletrotécnica Ramo Automação e Eletrónica Industrial

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.

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.

Pla de màrqueting per al llançament d'un nou producte en el mercat dels motors elèctrics per a bancs de proves

Ningú no dubte ja del canvi de mentalitat que s’ha produït en els darrers anys en els compradors pel què fa al mercat de l’automòbil. La seguretat i el respecte per el medi ambient, són actualment dos dels factors claus que el consumidor té en compte a l’hora de comprar un vehicle. D’altra banda en els darrers anys la Unió Europea, ha fixat tota una sèrie normatives per tal de reduir les emissions nocives a l’atmosfera. Així doncs, més seguretat i menys emissions, signifiquen vehicles que incorporin components i sistemas cada cop més sofisticats, els quals, a la vegada, necessiten de bancs d’assaig i equips de test per tal de ser validats. Aquest fet ha provocat una revolució dins dels sistemes de test per a vehicles, per als quals han augmentat enormement les exigències en quan a precisions i repetibilitat per tal d’intentar reproduir, amb la màxima fiabilitat possible, les condicions de treball que hauran de suportar els components durant el seu ús real. Les característiques dels motors elèctrics, resulten ideals per a accionar aquest tipus d’aplicacions, ja que permeten un control del parell molt acurat i una repetibilitat quasi perfecte enfront d’altres sistemas utilitzats fins no fa massa temps. Aquesta demanda creixent d’aquest tipus de màquines elèctriques, obra una nova oportunitat de negoci per a les empreses fabricants de motors elèctrics. L’objectiu principal d’aquest treball és identificar i satisfer les necessitats dels clients, dins d’un mercat industrial concret: el mercat dels motors elèctrics per a bancs de proves de components per a la indústria de l’automoció. La fita és doncs la de proporcionar les eines necessàries per tal de que una empresa, fabricant de motors elèctrics de velocitat variable, pugui realitzar el disseny, desenvolupament i llançament comercial d’un nou tipus de motor, específicament pensat per aquest mercat, amb les màximes garanties d’èxit. Com a principal conclusió, el treball argumenta que el nou producte representa una oportunitat de negoci força atractiva i rendible per a l’empresa, i permetrà diversificar la oferta de la companyia cap a un nou sector fins ara no explotat.

Performance Characteristics of an Axial-Flux Solid-Rotor-Core Induction Motor

The integration of electric motors and industrial appliances such as pumps, fans, and compressors is rapidly increasing. For instance, the integration of an electric motor and a centrifugal pump provides cost savings and improved performance characteristics. Material cost savings are achieved when an electric motor is integrated into the shaft of a centrifugal pump, and the motor utilizes the bearings of the pump. This arrangement leads to a smaller configuration that occupies less floor space. The performance characteristics of a pump drive can be improved by using the variable-speed technology. This enables the full speed control of the drive and the absence of a mechanical gearbox and couplers. When using rotational speeds higher than those that can be directly achieved by the network frequency the structure of the rotor has to be mechanically durable. In this thesis the performance characteristics of an axial-flux solid-rotor-core induction motor are determined. The motor studied is a one-rotor-one-stator axial-flux induction motor, and thus, there is only one air-gap between the rotor and the stator. The motor was designed for higher rotational speeds, and therefore a good mechanical strength of the solid-rotor-core rotor is required to withstand the mechanical stresses. The construction of the rotor and the high rotational speeds together produce a feature, which is not typical of traditional induction motors: the dominating loss component of the motor is the rotor eddy current loss. In the case of a typical industrial induction motor instead the dominating loss component is the stator copper loss. In this thesis, several methods to decrease the rotor eddy current losses in the case of axial-flux induction motors are presented. A prototype motor with 45 kW output power at 6000 min-1 was designed and constructed for ascertaining the results obtained from the numerical FEM calculations. In general, this thesis concentrates on the methods for improving the electromagnetic properties of an axial-flux solid-rotor-core induction motor and examines the methods for decreasing the harmonic eddy currents of the rotor. The target is to improve the efficiency of the motor and to reach the efficiency standard of the present-day industrial induction motors equipped with laminated rotors.

Cooling system optimization in medium-speed engines

Tässä työssä optimoidaan keskinopean Wärtsilä 32 -dieselmoottorin jäähdytysjärjestelmää ja tutkitaan taajuusmuuttajien käyttömahdollisuutta kiertopumppujen yhteydessä niin, että järjestelmässä saataisiin kiertämään vain kulloinkin tarvittava määrä vettä. Tutkimuksen mallinnus on toteutettu laatimalla aiemmin käytössä olleista yksinkertaisista simulointimalleista yksi malli, johon on sisällytetty sekä virtauksen että lämmönsiirron laskenta, jotka on aiemmin mallinnettu erillisillä ohjelmilla. Diplomityö on osa projektia, joka on tehty Sähkötekniikan osaston tutkijan Mikko Pääkkösen kanssa yhteistyössä. Tämän diplomityö keskittyy lähinnä virtausteknisiin ja lämmönsiirtoon liittyviin asioihin, kun taas sähkötekniikan osuus on esitetty Mikko Pääkkösen raportissa. Tulosten perustella voidaan sanoa, että taajuusmuuttajakäyttö kannattaa kiertopumppujen yhteydessä. Käyttämällä pumppujen virtaussäätöä voidaan jäähdytysjärjestelmästä jättää monia komponentteja, kuten termostaattiventtiilejä pois. Mallinnetut yksinkertaiset piiriratkaisut näyttävät toimivan ainakin yleisellä tasolla. Tutkimusta pumppujen säädöstä ja tässä projektissa luoduista jäähdytysjärjestelmäkonfiguraatioista kannattaa jatkaa.