A nonlinear and non-ideal wind generator supporting structure

We present a simple mathematical model of a wind turbine supporting tower. Here, the wind excitation is considered to be a non-ideal power source. In such a consideration, there is interaction between the energy supply and the motion of the supporting structure. If power is not enough, the rotation of the generator may get stuck at a resonance frequency of the structure. This is a manifestation of the so-called Sommerfeld Effect. In this model, at first, only two degrees of freedom are considered, the horizontal motion of the upper tip of the tower, in the transverse direction to the wind, and the generator rotation. Next, we add another degree of freedom, the motion of a free rolling mass inside a chamber. Its impact with the walls of the chamber provides control of both the amplitude of the tower vibration and the width of the band of frequencies in which the Sommerfeld effect occur. Some numerical simulations are performed using the equations of motion of the models obtained via a Lagrangian approach.

Development of a grid connected micro wind generator. A practical activity for the course on electric generation with wind energy

This paper describes a practical activity, part of the renewable energy course where the students have to build their own complete wind generation system, including blades, PM-generator, power electronics and control. After connecting the system to the electric grid the system has been tested during real wind scenarios. The paper will describe the electric part of the work surface-mounted permanent magnet machine design criteria as well as the power electronics part for the power control and the grid connection. A Kalman filter is used for the voltage phase estimation and current commands obtained in order to control active and reactive power. The connection to the grid has been done and active and reactive power has been measured in the system.

Low Voltage Ride-through in DFIG Wind Generators by Controlling the Rotor Current without Crowbars

Among all the different types of electric wind generators, those that are based on doubly fed induction generators, or DFIG technology, are the most vulnerable to grid faults such as voltage sags. This paper proposes a new control strategy for this type of wind generator, that allows these devices to withstand the effects of a voltage sag while following the new requirements imposed by grid operators. This new control strategy makes the use of complementary devices such as crowbars unnecessary, as it greatly reduces the value of currents originated by the fault. This ensures less costly designs for the rotor systems as well as a more economic sizing of the necessary power electronics. The strategy described here uses an electric generator model based on space-phasor theory that provides a direct control over the position of the rotor magnetic flux. Controlling the rotor magnetic flux has a direct influence on the rest of the electrical variables enabling the machine to evolve to a desired work point during the transient imposed by the grid disturbance. Simulation studies have been carried out, as well as test bench trials, in order to prove the viability and functionality of the proposed control strategy.

Tuulivoimalan staattoripakan puristusrakenteen kehittäminen

Diplomityössä tutkittiin voidaanko tuulivoimalan generaattorin staattoripakan puristamisessa hyödyntää komposiittista rakenneratkaisua. Tyypillisesti generaattorissa staattorin teräslevyt puristetaan erilaisilla teräsrakenteilla toisiaan vasten. Tavoitteena oli selvittää, voidaanko puristavan komposiittirakenteen osana hyödyntää liimaliitosta tai laminoitua liitosta. Tarkoitus oli etsiä rakenteeseen soveltuva liima ja liimaliitoksen arvot tai laminoitu rakenne ja sille soveltuvat materiaalit ja suoritustapa. Työssä on perehdytty erilaisiin tuulivoimalatyyppeihin, sekä niissä käytettäviin kesto- ja vierasmagnetoituihin generaattorityyppeihin. Tämän lisäksi on tarkasteltu niissä käytettävien staattorien valmistusvaihtoehtoja ja syitä miksi niissä olevat teräslevyt on puristettava toisiaan vasten. Samalla on luotu katsaus nykyisin käytössä oleviin rakenteisiin, joilla puristus voidaan toteuttaa. Liimauksesta on käsitelty perusteoriaa, sekä seikkoja jotka vaikuttavat liimaliitoksen kestoon. Työssä tutkittavaan liitokseen soveltuvien liimojen ominaisuuksia on käsitelty. Myös laminoituun liitokseen jo aiemmin kovettuneeseen komposiittiin on perehdytty. Tutkittavaan rakenteeseen soveltuvia hartsi- ja lasikuitutyyppejä on esitelty. Komposiittien mekaaniseen liittämiseen on lyhyesti perehdytty. Työssä suoritettiin useita vetokokeita, joilla selvitettiin puristusrakenteen tutkimista varten valmistettujen koekappaleiden suurin vetokuormankesto. Vetokokeiden perusteella voitiin valita soveltuvin rakenne staattorin puristamiseksi.

Tuulivoimalan lapojen huolto ja tarkastukset

Uusiutuva energia elää voimakasta kasvukautta ja hallituksen tekemien tukipäätösten vuoksi tuulivoimaa tullaan rakentamaan huomattavasti lisää tulevien vuosien aikana. Tuuligeneraattorin siipien huolto- ja tarkastustoiminta on uusi ja kehittyvä toimiala. Tämä diplomityö onkin tehty oppaaksi helpottamaan tuulivoimaa omistavien, rakentavien, tai tuulivoimapuiston perustamista harkitsevien tahojen huoltosuunnitelmien tekemistä varten. Diplomityössä käydään läpi yleisimmät tuulivoimaloiden lapojen vikaantu-miset, sekä työskentelytavat ja käytettävät laitteistot voimaloiden lapojen huoltoja ja tarkastuksia tehtäessä.

Sähköverkosta irti olevan pienhybridijärjestelmän toteutus

Lappeen siniset –partiolippukunnalla on käytössään leiripaikka Humaljärvellä, Lappeenrannassa. Leiripaikalla ei ole liityntää sähköverkkoon, joten leiripaikalle on asennettu kaksi erillistä aurinkovoimalla toimivaa sähköjärjestelmää. Leiripaikan sähköistetyt rakennukset ovat pääkämppä ja saunan sekä vanhan kämpän muodostama kokonaisuus. Aurinkopaneeleilla tuotettu sähköenergia varastoidaan akustoihin. Lippukunta on havainnot käytössä, ettei talvella tuotettu aurinkoenergia riitä kattamaan pääkämpän sähkönkulutusta, joten leiripaikalle on päätetty hankkia tuulivoimala lisäämään tuotantoa. Tässä kandidaatin työssä esitellään hybridijärjestelmään kuuluvien aurinko- ja tuulivoiman toimintaperiaatteita sekä näiden komponentteja. Aurinko- ja tuulivoimalla tuotetulle sähköenergialle lasketaan arviot, joita verrataan leiripaikan sähköjärjestelmän arvioituun kulutukseen. Leiripaikalle tulevaa tuuliturbiinia ja sen lataussäädintä testataan laboratoriossa, jotta varmistutaan niiden soveltuvuudesta sekä toimivuudesta kohteeseen. Testausten ja laitteiden datalehtien avulla suunnitellaan leiripaikalle toimiva hybridijärjestelmä, joka kattaa leiripaikan ympärivuotisen sähkönkulutuksen.

Desenvolvimento de Modelos no Programa DigSILENT PowerFactoryTM para o Estudo de Estabilidade Transitória em Sistemas Elétricos de Potência com Aerogerador

This work presents a description of models development at DigSILENT PowerFactoryT M program for the transient stability study in power systems with wind turbine. The main goal is to make available means to use a dynamic simulation program in power systems, widely published, and utilize it as a tool that helps in programs results evaluations used for this intent. The process of simulations and analyses results starts after the models setting description phase. The results obtained by the DigSILENT PowerFactoryT M and ATP, program chosen to the validation also international recognized, are compared during this phase. The main tools and guide lines of PowerFactoryT M program use are presented here, directing these elements to the solution of the approached problem. For the simulation it is used a real system which it will be connected a wind farm. Two different technologies of wind turbines were implemented: doublyfed induction generator with frequency converter, connecting the rotor to the stator and to the grid, and synchronous wind generator with frequency converter, interconnecting the generator to the grid. Besides presenting the basic conceptions of dynamic simulation, it is described the implemented control strategies and models of turbine and converters. The stability of the wind turbine interconnected to grid is analyzed in many operational conditions, resultant of diverse kinds of disturbances

Desenvolvimento de modelos no programa digSILENT powerfactoryTM para o estudo de estabilidade transitória em sistemas elétricos de potência com aerogerador

This work presents a description of models development at DigSILENT PowerFactoryTM program for the transient stability study in power systems with wind turbine. The main goal is to make available means to use a dynamic simulation program in power systems, widely published, and utilize it as a tool that helps in programs results evaluations used for this intent. The process of simulations and analyses results starts after the models setting description phase. The results obtained by the DigSILENT PowerFactoryTM and ATP, program chosen to the validation also international recognized, are compared during this phase. The main tools and guide lines of PowerFactoryTM program use are presented here, directing these elements to the solution of the approached problem. For the simulation it is used a real system which it will be connected a wind farm. Two different technologies of wind turbines were implemented: doubly-fed induction generator with frequency converter, connecting the rotor to the stator and to the grid, and synchronous wind generator with frequency converter, interconnecting the generator to the grid. Besides presenting the basic conceptions of dynamic simulation, it is described the implemented control strategies and models of turbine and converters. The stability of the wind turbine interconnected to grid is analyzed in many operational conditions, resultant of diverse kinds of disturbances

Controlador adaptativo por posicionamento de pólos e estrutura variável aplicado ao controle de geradores eólicos baseados em máquina de indução duplamente alimentada

In the last decade, the renewable energy sources have present a major propulsion in the world due to several factors: political, environmental, financial and others. Within this context, we have in particular the energy obtained through wind, wind energy - that has highlighted with rapid growth in recent years, including in Brazil, mostly in the Northeast, due to it s benefit-cost between the clean energies. In this context, we propose to compare the variable structure adaptive pole placement control (VS-APPC) with a traditional control technique proportional integral controller (PI), applied to set the control of machine side in a conversion system using a wind generator based on Double-Fed Induction Generator (DFIG). Robustness and performance tests were carried out to the uncertainties of the internal parameters of the machine and variations of speed reference.

Otimização de sistema de bombeamento com energia eólica: sistema de bombeamento de São Gabriel/BA

After the Protocol of Kyoto and of the ECHO 92 - Rio de Janeiro, the attentions of the world focus to the preservation of the environment and of the maintainable use of the natural resources. People were looking for preserving environment for the future generations. Ever since, solutions are looked for the supply of energy in its more acquaintances forms and the substitution of the use of fossil fuels for the such alternative forms as: Photovoltaics, solar heat systems for water, wind , bio-diesel, etc. and in this context the Company of Engineering of the State of Bahia - Cerb changed a diesel pumping system by an wind one, It´s the first community system of this nature in Bahia. Facing problems with the model, a Cerb involved the academic segment of the Federal Center of Technological Education of Bahia Cefetba looking for a solution. This work intends to demonstrate the possibilities of optimization of the pumping communit system that supply water to approximately 50 people in the place of Romão, municipal district of São Gabriel-Ba. Technical reports were published in AGRENERGD2004-Unicamp SP and Scientific Magazine ETC,Cefetba, 2005. A simulation of the increase of energy is presented for heights of 15 and 20m, considering the eletromecanical balance from the pumping energy to the wind turbine. From the accomplished bibliographical revision, we emphasized the mechanical aspects of the engineering once in UFRN, those studies concentrate on the Department of Mechanical Engineering while, in others eletroelectronic are more emphasized. Finally, documents that we judged important were enclosed for the perfect understanding of this work

Desempenho de um sistema híbrido eólico-fotovoltaico de pequeno porte para energização rural

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Avaliação de estratégias de controle de potência reativa de aerogeradores síncronos em redes elétricas

No presente trabalho é avaliada uma metodologia de injeção de potência reativa em redes elétricas durante afundamentos de tensão provocados por curto-circuito, em parques eólicos interligados, adotada em alguns países com maturidade tecnológica na produção de energia eólica. Nos estudos desenvolvidos, foi utilizado o aerogerador síncrono a imã permanente com conversor pleno em função da grande controlabilidade do conversor interligado à rede e por possuir elevada capacidade de fornecimento de potência reativa, comparada a outras tecnologias de aerogeradores. No Brasil, os requisitos de interligação de parques eólicos as redes elétricas, definido pelo Operador Nacional do Sistema, ainda não estipula a necessidade de adoção de tal metodologia durante defeitos na rede elétrica, apenas especifica a curva de capacidade de afundamentos de tensão que os aerogeradores devem seguir para evitar o desligamento frente a afundamentos de tensão. Os critérios de proteção do aerogerador síncrono são avaliados a partir de simulações de curto-circuito em uma rede de teste adotando-se os requisitos do Brasil, sem injeção de potência reativa, sendo comparados com o de outros países que adotam curvas de injeção de potência reativa.

A bidding strategy for minimizing the imbalances costs for renewable generators in Spanish power markets

The aim of this paper is to suggest a simple methodology to be used by renewable power generators to bid in Spanish markets in order to minimize the cost of their imbalances. As it is known, the optimal bid depends on the probability distribution function of the energy to produce, of the probability distribution function of the future system imbalance and of its expected cost. We assume simple methods for estimating any of these parameters and, using actual data of 2014, we test the potential economic benefit for a wind generator from using our optimal bid instead of just the expected power generation. We find evidence that Spanish wind generators savings would be from 7% to 26%.

Digital control and integration of a 192 MW wind farm with doubly fed induction generator into the Brazilian power system

This paper reports on design of digital control for wind turbines and its relation to the quality of power fed into the Brazilian grid on connecting to it a 192 MW wind farm equipped with doubly fed induction generators. PWM converters are deployed as vector controlled regulated current voltage sources for their rotors, for independent control of both active and reactive power of those generators. Both speed control and active power control strategies are analyzed, in the search for maximum efficiency of conversion of wind kinetic energy into electric power and enhanced quality of delivered power. (C) 2009 Elsevier B.V. All rights reserved.

Modeling, control and simulation of full-power converter wind turbines equipped with permanent magnet synchronous generator

In this paper, two wind turbines equipped with a permanent magnet synchronous generator (PMSG) and respectively with a two-level or a multilevel converter are simulated in order to access the malfunction transient performance. Three different drive train mass models, respectively, one, two and three mass models, are considered in order to model the bending flexibility of the blades. Moreover, a fractional-order control strategy is studied comparatively to a classical integer-order control strategy. Computer simulations are carried out, and conclusions about the total harmonic distortion (THD) of the electric current injected into the electric grid are in favor of the fractional-order control strategy.