Datahallar behöver reservkraft av god kvalitet för att garantera upprätthållandet av dess funktion. Laster i en datahall kommer att generera ström och spänningsövertoner som kan skapa problematik med elkvaliteten. Coromatic är intresserade av att veta mer hur dessa laster påverkar reservkraftsgeneratorn. En mätning utfördes på en datahall under ett funktionsprov. Resultatet blev att halten av THD ökade, främst är det 3:e övertonen som är framträdande. Mätvärdena för THDV ligger under gränsvärdena för SS-EN 50160 och 61000-2-2, men gränsvärdena för 3:e ton ligger långt över. Ingen åtgärd föreslås i nuläget för att hantera problemet. Denna avhandling har gett värdefull information till Coromatic att ta i beaktande vid utförande av nya reservkraftsanläggningar. / A facility full with computers needs backup-power to guarantee the function. Loads in this facility will produce current and voltage harmonics that can pollute and cause trouble with the quality of electricity. Coromatic are interested in knowing more about how these loads can affect the generator. A measurement was performed on a facility when they ran a functional test. The results indicated that THD increased, the third harmonic turned out to be the single harmonic with the highest value. The value is within the boundaries for THDV according to SS-EN 50160 and 61000-2-2, except for the third harmonic. Its value was far too high. No action is propsed to deal with the problem at the moment. This thesis has provided Coromatic with valuable information too consider when they building new systems.

In recent decades there has been a rapidly growing demand for high quality, uninterrupted power. In light of this fact, this study has addressed some of the causes of poor power quality and control strategies to ensure a high performance level in inverter-fed power systems. In particular, specific loading conditions present interesting challenges to inverter-fed, high power systems. No-load, unbalanced loading, and non-linear loading each have unique characteristics that negatively influence the performance of the Voltage Source Inverter (VSI). Ideal, infinitely stiff power systems are uninfluenced by loading conditions; however, realistic systems, with finite output impedances, encounter stability issues, unbalanced phase voltage, and harmonic distortion. Each of the loading conditions is presented in detail with a proposed control strategy in order to ensure superior inverter performance. Simulation results are presented for a 90 kVA, 400 Hz VSI under challenging loading conditions to demonstrate the merits of the proposed control strategies. Unloaded or lightly loaded conditions can cause instabilities in inverter-fed power systems, because of the lightly damped characteristic of the output filter. An inner current loop is demonstrated to damp the filter poles at light load and therefore enable an increase in the control bandwidth by an order of magnitude. Unbalanced loading causes unequal phase currents, and consequently negative sequence and zero sequence (in four-wire systems) distortion. A proposed control strategy based on synchronous and stationary frame controllers is shown to reduce the phase voltage unbalance from 4.2% to 0.23% for a 100%-100%-85% load imbalance over fundamental positive sequence control alone. Non-linear loads draw harmonic currents, and likewise cause harmonic distortion in power systems. A proposed harmonic control scheme is demonstrated to achieve near steady state errors for the low order harmonics due to non-linear loads. In particular, the THD is reduced from 22.3% to 5.2% for full three-phase diode rectifier loading, and from 11.3% to 1.5% for full balanced single-phase diode rectifier loading, over fundamental control alone. / Master of Science

Nesta tese, apresenta-se a análise numérica e experimental do comportamento dinâmico não linear de um pórtico excitado por uma fonte não ideal - um motor elétrico de corrente contínua desbalanceado - como exemplo dessa classe de problemas. Elabora-se um modelo matemático com quatro graus de liberdade: dois relacionados com o deslocamento horizontal e vertical do ponto de apoio da máquina e dois com os parâmetros de funcionamento do motor elétrico. Adota-se a formulação Lagrangeana para gerar as equações de movimento contendo termos não lineares até ordem cúbica. A solução numérica é obtida através do método de Runge-Kutta com passo adaptativo. Ensaios dinâmicos e estáticos foram realizados com o motor e com o sistema completo, com vistas a validar o modelo matemático. Um sistema de medição digital armazenou todos os dados obtidos em arquivos de fácil leitura pelos programas atualmente disponíveis. Filmagens de alta velocidade e fotografia estroboscópica registraram movimentos típicos relacionados com comportamentos não lineares. Os resultados numéricos e experimentais mostram boa correlação entre si, além de apresentarem alguns dos fenômenos associados ao se forçar uma estrutura a passar por uma de suas ressonâncias excitando-a com um dispositivo com potência limitada, como o efeito Sommerfeld. Outros fenômenos, devido ao comportamento geometricamente não linear da estrutura, são também detectados, tais como saturação modal e transferência de energia. / Numerical and experimental analysis of the nonlinear dynamics of a portal frame excited by a non-ideal source - an unbalanced direct current motor - is presented in this thesis as an example of this class of problems. A four degree of freedom model is elaborated: two of them related to the horizontal and vertical structural displacements and two others to the functioning parameters of the motor. A Lagrangian approach for deducing the equations of motion, up to cubic non-linear terms is followed. The numerical solution is obtained through Runge-Kutta algorithm with adaptive step. Static and dynamic tests were performed with the motor and with the complete system, in order to validate the mathematical model. A digital acquisition system recorded all data in computer files, ready to be read by available commercial programs. High speed filming and stroboscopic photography were used to register typical movements related to nonlinear behavior. Numerical and mathematical results show good correlation, as well as present some phenomena related to passage through resonance with limited power excitation such as the Sommerfeld effect. Some other phenomena, related to the nonlinear behavior of the structure are also detected, as modal saturation and energy transference.

Nesta tese, apresenta-se a análise numérica e experimental do comportamento dinâmico não linear de um pórtico excitado por uma fonte não ideal - um motor elétrico de corrente contínua desbalanceado - como exemplo dessa classe de problemas. Elabora-se um modelo matemático com quatro graus de liberdade: dois relacionados com o deslocamento horizontal e vertical do ponto de apoio da máquina e dois com os parâmetros de funcionamento do motor elétrico. Adota-se a formulação Lagrangeana para gerar as equações de movimento contendo termos não lineares até ordem cúbica. A solução numérica é obtida através do método de Runge-Kutta com passo adaptativo. Ensaios dinâmicos e estáticos foram realizados com o motor e com o sistema completo, com vistas a validar o modelo matemático. Um sistema de medição digital armazenou todos os dados obtidos em arquivos de fácil leitura pelos programas atualmente disponíveis. Filmagens de alta velocidade e fotografia estroboscópica registraram movimentos típicos relacionados com comportamentos não lineares. Os resultados numéricos e experimentais mostram boa correlação entre si, além de apresentarem alguns dos fenômenos associados ao se forçar uma estrutura a passar por uma de suas ressonâncias excitando-a com um dispositivo com potência limitada, como o efeito Sommerfeld. Outros fenômenos, devido ao comportamento geometricamente não linear da estrutura, são também detectados, tais como saturação modal e transferência de energia. / Numerical and experimental analysis of the nonlinear dynamics of a portal frame excited by a non-ideal source - an unbalanced direct current motor - is presented in this thesis as an example of this class of problems. A four degree of freedom model is elaborated: two of them related to the horizontal and vertical structural displacements and two others to the functioning parameters of the motor. A Lagrangian approach for deducing the equations of motion, up to cubic non-linear terms is followed. The numerical solution is obtained through Runge-Kutta algorithm with adaptive step. Static and dynamic tests were performed with the motor and with the complete system, in order to validate the mathematical model. A digital acquisition system recorded all data in computer files, ready to be read by available commercial programs. High speed filming and stroboscopic photography were used to register typical movements related to nonlinear behavior. Numerical and mathematical results show good correlation, as well as present some phenomena related to passage through resonance with limited power excitation such as the Sommerfeld effect. Some other phenomena, related to the nonlinear behavior of the structure are also detected, as modal saturation and energy transference.

Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-09-14T11:19:37Z No. of bitstreams: 2 Tese - José Mário Menescal de Oliveira - 2018.pdf: 3555364 bytes, checksum: 7da381c5690449c518f20f2a3fd49fea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-09-17T10:48:33Z (GMT) No. of bitstreams: 2 Tese - José Mário Menescal de Oliveira - 2018.pdf: 3555364 bytes, checksum: 7da381c5690449c518f20f2a3fd49fea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-09-17T10:48:33Z (GMT). No. of bitstreams: 2 Tese - José Mário Menescal de Oliveira - 2018.pdf: 3555364 bytes, checksum: 7da381c5690449c518f20f2a3fd49fea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-07-13 / This thesis demonstrates the effects of harmonic pollution in a salient pole synchronous generator and an induction generator operating in parallel on an isolated system, supplying a non-linear load. The main contributions of this research-study consist of identifying and quantifying the oscillations that non-linear load cause on the electric variables of synchronous and induction generators, such as, the electromagnetic conjugate that presents oscillations of sixth harmonic due to the distorted currents. / Este trabalho mostra os efeitos da poluição harmônica em um gerador síncrono de polos salientes e um gerador de indução operando em paralelo em um sistema isolado suprindo carga não linear. As principais contribuições deste trabalho consistem em identificar e quantificar as oscilações que a carga não linear utilizada provoca nas variáveis elétricas dos geradores síncronos e dos geradores de indução, tal como, o conjugado eletromagnético que apresenta oscilações de sexto harmônico devido as correntes distorcidas.