Bandwidth enhancement of the LTE/WWAN handset antenna achieved by improving the excited surface current distribution in the system ground plane is presented. To achieve this goal, the system ground plane is shaped to be of a C-shape in this thesis. In this case, the longitudinal excited surface current in the system ground plane can have a smooth distribution. The proposed antenna is disposed at one edge of the C-shaped system ground plane, and the antenna comprises a driven monopole strip, a shorted monopole strip and a distributed parallel resonance (PR) circuit. By controlling the resonant frequency of the distributed PR circuit, it can result in dual-resonance excitation of the lowest resonant mode contributed by the shorted monopole strip to cover the LTE700/GSM850/900 operation. The antenna also occupies a small volume of 44 ¡Ñ 10 ¡Ñ 5 mm3 (about 2.2 cm3). Good radiation characteristics of the antenna are also obtained. For practical applications, effects of the electrical connection between the system ground plane and the surrounding metal elements such as the battery¡¦s metal casing and the handset metal midplate are studied. The simulated SAR (Specific Absorption Rate) and HAC (Hearing Aid Compatibility) results are also analyzed.

Submitted by RARISON ROBERTO ACACIO FORTES null (rarisonfortes@yahool.com) on 2016-05-05T14:43:06Z No. of bitstreams: 1 RFortes.pdf: 3576878 bytes, checksum: 1f31f85eeeb5bf64f3b8b9781d51941c (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-09T13:45:49Z (GMT) No. of bitstreams: 1 fortes_rra_me_ilha.pdf: 3576878 bytes, checksum: 1f31f85eeeb5bf64f3b8b9781d51941c (MD5) / Made available in DSpace on 2016-05-09T13:45:49Z (GMT). No. of bitstreams: 1 fortes_rra_me_ilha.pdf: 3576878 bytes, checksum: 1f31f85eeeb5bf64f3b8b9781d51941c (MD5) Previous issue date: 2016-03-12 / Fundação de Amparo à Pesquisa do Estado do Acre (FAPAC) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Como os sistemas de energia têm sido tradicionalmente projetados para produção centralizada, a penetração de sistemas de geração distribuída na rede tem causado mudança nesse perfil, criando novos desafios operacionais que se fazem importantes para a reestruturação dos sistemas tradicionais. No entanto, este novo cenário do sistema elétrico, introduzido pela resolução 482/2012 da Agência Nacional de Energia Elétrica – ANEEL, trouxe às distribuidoras de energia um novo panorama para as atividades de operação e manutenção de suas redes e ativos, principalmente devido à bidirecionalidade do fluxo de potência na rede, originado pela conexão de sistemas de geração distribuída. Os impactos técnicos devem ser previstos e analisados, sobretudo em redes de distribuição, para garantir os padrões mínimos de qualidade da energia no ponto de consumo e evitar o comprometimento das cargas alimentadas. Dentre os impactos, destaca-se o efeito sobre os bancos de capacitores devido à injeção de distorções harmônica produzida pelos inversores de sistemas fotovoltaicos, que sob certas condições, produzem conteúdo harmônico com nível acima do limite normatizado, podendo excitar uma condição prévia de ressonância no barramento. Neste contexto, esta dissertação tem como principal objetivo analisar o comportamento do sistema elétrico em condição de ressonância paralela e avaliar o grau de comprometimento dos bancos de capacitores instalados no sistema de distribuição com presença de frequências harmônicas e sugerir rotinas técnicas para evitar sua operação contingenciada. / As energy systems have been traditionally projected for centralized production, the penetration of distributed generation systems have caused a change in this profile, creating new operational challenges that are important for traditional systems restructuring. However, this new electrical system scenario, introduced by resolution 482/2012 of Brazilian Electricity Regulatory Agency – ANEEL, brought to energy distributors a new view to the operational and maintenance activities of their nets and actives, specially due to the net power flow bidirectionality, created by the distributed generation systems connection. Technical impacts must be estimated and analyzed, specially in distribution nets, to ensure minimum energy quality standards in the consumption point and avoid fed charges commitment. Among the impacts stands out the capacitor bench effects due to harmonic distortions injection produced by photovoltaic systems inverters, that under some conditions, produce harmonic content over the regulated limit, being able to excite a preview condition of resonance in the bus. In this context, this essay has the main objective to analyze the electrical system behavior in parallel resonance condition and evaluate the degree of commitment of the capacitor bench installed in the distribution system with harmonic frequencies and suggest technical routines to avoid the contingent operation. / FAPAC: 6068-14-0000093

Orientador: Luís Carlos Origa de Oliveira / Resumo: Como os sistemas de energia têm sido tradicionalmente projetados para produção centralizada, a penetração de sistemas de geração distribuída na rede tem causado mudança nesse perfil, criando novos desafios operacionais que se fazem importantes para a reestruturação dos sistemas tradicionais. No entanto, este novo cenário do sistema elétrico, introduzido pela resolução 482/2012 da Agência Nacional de Energia Elétrica – ANEEL, trouxe às distribuidoras de energia um novo panorama para as atividades de operação e manutenção de suas redes e ativos, principalmente devido à bidirecionalidade do fluxo de potência na rede, originado pela conexão de sistemas de geração distribuída. Os impactos técnicos devem ser previstos e analisados, sobretudo em redes de distribuição, para garantir os padrões mínimos de qualidade da energia no ponto de consumo e evitar o comprometimento das cargas alimentadas. Dentre os impactos, destaca-se o efeito sobre os bancos de capacitores devido à injeção de distorções harmônica produzida pelos inversores de sistemas fotovoltaicos, que sob certas condições, produzem conteúdo harmônico com nível acima do limite normatizado, podendo excitar uma condição prévia de ressonância no barramento. Neste contexto, esta dissertação tem como principal objetivo analisar o comportamento do sistema elétrico em condição de ressonância paralela e avaliar o grau de comprometimento dos bancos de capacitores instalados no sistema de distribuição com presença de frequências harmô... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: As energy systems have been traditionally projected for centralized production, the penetration of distributed generation systems have caused a change in this profile, creating new operational challenges that are important for traditional systems restructuring. However, this new electrical system scenario, introduced by resolution 482/2012 of Brazilian Electricity Regulatory Agency – ANEEL, brought to energy distributors a new view to the operational and maintenance activities of their nets and actives, specially due to the net power flow bidirectionality, created by the distributed generation systems connection. Technical impacts must be estimated and analyzed, specially in distribution nets, to ensure minimum energy quality standards in the consumption point and avoid fed charges commitment. Among the impacts stands out the capacitor bench effects due to harmonic distortions injection produced by photovoltaic systems inverters, that under some conditions, produce harmonic content over the regulated limit, being able to excite a preview condition of resonance in the bus. In this context, this essay has the main objective to analyze the electrical system behavior in parallel resonance condition and evaluate the degree of commitment of the capacitor bench installed in the distribution system with harmonic frequencies and suggest technical routines to avoid the contingent operation. / Mestre

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This thesis investigates the impact of resonant overvoltages and their origin. Series and parallel resonances are present in any electrical grid. The frequency of which this resonance occurs is called resonance frequency. For parallel resonance, which is mainly being studied in this thesis, a high impedance peak can be found at the resonance frequency. This impedance peak in conjunction with a harmonic rich current cause a kind of temporary overvoltages called resonant overvoltages. The harmonic content of the current is high following a fault clearing in the grid, due to transformer saturation. The resonance frequency is heavily dependent on the amount of reactance present in the grid, which entail that a change in reactance causes a change in the resonance frequency. The electromagnetic transient tool PSCAD has been used to investigate resonant overvoltages following transformer energization caused by faults and switching in Stockholm. Secondly, a model was created of a grid connecting off-shore wind power to the mainland via long AC submarine transmission cables. These cables, having a high capacitance, lower the resonance frequency. Faults in this model were simulated to investigate the phenomenon of resonant overvoltages in such a grid. This was especially interesting due to Swedens planned expansion of wind power in the Baltic sea. While resonant overvoltages were found in Stockholm they were not deemed significant due to their low magnitude and longevity. However, severe resonant overvoltages were found in the off-shore wind farm model. The worst resonant overvoltages had a maximum amplitude of the 2nd order harmonic voltage of 130 kV which, while eventually damped, were significant for up to 50 periods. Lastly, the phenomenon of an increased resonance frequency during the saturation of a transformer was studied. The most severe resonant overvoltages occured in a model where the frequency scans showed a resonance frequency of 98 Hz. Indicating, caution needs to be had during EMT-studies of resonant overvoltages while choosing what resonance frequency to study.