This dissertation aims to present a detailed analysis of the grid voltage disturbance in frequency domain for the current control design in the grid-tie inverter applications and to propose current control techniques in order to minimize its impact and maximize feasibility of the power conditioning system in distributed generations. Because the grid voltage is constantly changing, the inverter must be able to response to it. If the inverter is unable to respond properly, then the grid voltage power comes back to the system and damages the fuel cell power conditioning systems. A closed-loop dynamic model for the current control loop of the grid-tie inverter has been developed. The model explains the structure of the inverter admittance terms. The disturbance of the grid voltages has been analyzed in frequency domain. The admittance compensator has been proposed to prevent the grid voltage effect. The proposed lead-lag current control with admittance compensator transfers current properly without system failure. In order to get rid of the steady-state error of the feedback current, a proportional-resonant controller (PR) has been adopted. A PR control with admittance compensation provides great performance from zero power to full power operation. In addition, active and reactive power flow controller has been proposed based on the PR controller with admittance compensation. The proposed active and reactive power flow control scheme shows a wide range power flow control from pure leading power to pure lagging power. Finally, the proposed controller scheme has been verified its feasibility in three phase grid-tie inverter applications. First of all, a half-bridge grid-tie inverter has been designed with PR controller and admittance compensation. Then three individual grid-tie inverters has been combined and produced three phase current to the three phase grid in either balanced condition or unbalanced condition. The proposed control scheme can be applied not only single phase grid-tie inverter application, but also three phase grid-tie inverter application. This research can be applicable to the photovoltaic PCS as well. This technology makes renewable energy source more plausible for distributed generations. / Ph. D.

Neste trabalho são descritos e avaliados diferentes modelos de linhas aéreas de transmissão, considerando a variação dos parâmetros da linha com a frequência. Em geral os modelos apresentados são baseados no uso da matriz de admitâncias nodais, com algumas análises complementares empregando o método das características. São testados casos de circuito-aberto, curto-circuito, linha em carga e manobras com chaves. Os resultados de cálculo são comparados com as respostas simuladas nos programas ATP e PSCAD. Também são apresentadas as formulações para o cálculo de parâmetros da linha de transmissão, considerando o efeito pelicular e a resistividade do solo São avaliadas as respostas no domínio do tempo para diferentes modelos equivalentes de linha de transmissão, obtidos do modelo polo-resíduo com passividade da matriz de admitâncias nodais, sendo empregados: i) transformação do modelo racional para uma representação em espaço de estados, ii) construção de uma rede elétrica equivalente com resistências, indutores e capacitores e iii) representação por meio de um equivalente de Norton. Também é analisado o equivalente de Norton obtido dos modelos polo-resíduo com passividade de uma linha equivalente dobrada nas condições em curto-circuito e circuito-aberto. Foi analisada a solução de redes elétricas no domínio da frequência usando uma formulação nodal e sem a necessidade de ajustes intermediários da matriz de admitâncias nodais. As respostas de tensão e corrente são antitransformadas para o domínio do tempo por meio de diferentes formulações baseadas na transformada inversa de Fourier, levando em conta os métodos que mitigam erros de truncamento e discretização. As seguintes formulações foram avaliadas: i) transformada modificada de Fourier, ii) transformada inversa rápida de Fourier e iii) transformada inversa de Fourier com integração semianalítica. É também apresentado um modelo para linhas de transmissão em paralelo, baseado no domínio modal usando uma matriz de transformação constante, juntamente com a aplicação do método de ajuste Vector Fitting com o objetivo de modelar com precisão o efeito de acoplamento mútuo entre linhas. / In this work different overhead transmission lines models are described and evaluated, considering the frequency dependence of parameters. In general, the models are based on the nodal admittance matrix, with some complementary analysis using the method of characteristics. Cases of open-circuit, short-circuit, line connected to a load and switching maneuvers are tested. The calculation results are compared with the simulated responses obtained with the ATP and PSCAD. The formulations for the transmission line parameters are also presented, taking into account the skin effect and the ground return. The time-domain responses for different transmission line models are evaluated. These models are obtained from the passive pole-residue model of the nodal admittance matrix. The equivalent models are: i) state-space representation, ii) electrical network composed of resistors, inductors and capacitors, iii) the Norton\'s equivalent. In addition, an evaluation is performed for the Norton\'s equivalent obtained from the pole-residue models for the open-circuit and short-circuit conditions of a folded line equivalent. On the other hand, the network is solved completely in frequency-domain using a nodal formulation, without the fitting of the nodal admittance matrix. The voltage and current responses are transformed back to the time-domain by different formulations based on the inverse Fourier transform, taking into account methods to minimize errors by truncation and discretization. The formulations investigated are: i) modified Fourier transform, ii) fast Fourier transform, iii) inverse Fourier transform with semianalytic integration. The model for parallel transmission lines is also evaluated, based on modal domain using a constant transformation matrix and the application of the vector fitting method, with emphasis on accurate representation of mutual coupling effects.

No description available.

Recently, the environmental impact of aircraft and rising fuel prices have become an increasing concern in the aviation industry. To address these problems, organizations such as NASA have set demanding goals for reducing aircraft emissions, fuel burn, and noise. In an effort to reach the goals, a movement toward more-electric aircraft and electric propulsion has emerged. With this movement, the number of critical electrical loads on an aircraft is increasing causing power system reliability to be a point of concern. Currently, power system reliability is maintained through the use of back-up power supplies such as batteries and ram-air-turbines (RATs). However, the increasing power requirements for critical loads will quickly outgrow the capacity of the emergency devices. Therefore, reliability needs to be addressed when designing the primary power distribution system. Power system reliability is a function of component reliability and redundancy. Component reliability is often not determined until detailed component design has occurred; however, the amount of redundancy in the system is often set during the system architecting phase. In order to meet the capacity and reliability requirements of future power distribution systems, a method for redundancy allocation during the system architecting phase is needed. This thesis presents an aircraft power system design methodology that is based upon the engineering decision process. The methodology provides a redundancy allocation strategy and quantitative trade-off environment to compare architecture and technology combinations based upon system capacity, weight, and reliability criteria. The methodology is demonstrated by architecting the power distribution system of an aircraft using turboelectric propulsion. The first step in the process is determining the design criteria which includes a 40 MW capacity requirement, a 20 MW capacity requirement for the an engine-out scenario, and a maximum catastrophic failure rate of one failure per billion flight hours. The next step is determining gaps between the performance of current power distribution systems and the requirements of the turboelectric system. A baseline architecture is analyzed by sizing the system using the turboelectric system power requirements and by calculating reliability using a stochastic flow network. To overcome the deficiencies discovered, new technologies and architectures are considered. Global optimization methods are used to find technology and architecture combinations that meet the system objectives and requirements. Lastly, a dynamic modeling environment is constructed to study the performance and stability of the candidate architectures. The combination of the optimization process and dynamic modeling facilitates the selection of a power system architecture that meets the system requirements and objectives.

The pixel element which is an integrated combination of a p-i-n diode with a thin film transistor (TFT) is used to produce image sensor arrays in scanning and displays technologies, necessitating the deposition of hydrogenated silicon based semiconducting and insulating thin films such as a-Si:H, a-SiNx:H over large area. The widely used techniques to achieve this goal is the plasma enhanced chemical vapor deposition (PECVD) due to its large area and low temperature (&amp / #61603 / 300 &amp / #61616 / C) abilities. In particular, PECVD has proved to be able to deposit both high quality insulator (a-SiNx:H) and active layer of p-i-n diode (intrinsic hydrogenated amorphous silicon carbide, a-SiCx:H) and by sequential deposition, it is possible to minimize the interface related problems, which play an important role in metal insulator semiconductor (MIS) and TFT structures. PECVD deposited a-SiCx:H films over p-type crystal Si and metal substrates (MIS and MIM) were investigated by both admittance spectroscopy (Capacitance or conductance vs. voltage, temperature or frequency measurements) and Deep Level Transient spectroscopy (DLTS) to investigate the interface related problems. In this respect, instability phenomena (due to the creation of metastable states and charge injection into the gate electrode) were studied via the c-Si/a-SiCx:H (and/or a-SiNx:H) heterojunction. Specially, capacitance voltage kinetics were worked out and then the enrolled trap energies were identified with temperature mode DLTS. The expertise gathered as a result of these studies were used in the fabrication and characterization of TFT&amp / #65533 / s. In this respect, inverted gate staggered type Thin Film Transistor produced and characterized for the first time after Combo-251 Pattern Generator was implemented.

Abstract Attention deficit hyperactivity disorder (ADHD) and disruptive behavior disorder (DBD) are two very common and co-occurring psychiatric disorders among children and adolescents. They are among the leading reasons for clinical referrals to child and adolescent mental health facilities worldwide and have many unfavorable consequences with a high cost to society. In this thesis, the potential early risk factors associated with ADHD and/or DBD were examined, the current well-being of the adolescent with ADHD and/or DBD was evaluated and the later education and the psychiatric morbidity of the adolescent were researched. The study population in this thesis is based on a subsample of the Northern Finland Birth Cohort 1986 (NFBC 1986) containing 457 study subjects, of which 91 (19.9%) were diagnosed with ADHD, 44 (9.6%) with DBD, 72 (15.6%) with comorbid ADHD and DBD and 250 (54.7%) with neither of these disorders. Confirmatory factor analysis, Kaplan-Meier survival analysis, Kruskal-Wallis one-way analysis of variance and several regression analyses were carried out in the study. This thesis contains four original publications. The results in the first publication indicated that there are different risk factors in childhood associating with different behavioral problems in adolescence. The differences between behavioral problems were also visible in the results of the second publication, where those adolescents who were diagnosed with both ADHD and DBD had more severe conduct disorder symptoms and had increased risks for many psychiatric disorders. The results from the third publication suggested that those adolescents who were diagnosed with both ADHD and DBD fared worse in school at the end of ninth grade and were later less likely to achieve higher than basic education. Finally, the fourth publication showed that the adolescents diagnosed with DBD (both with and without ADHD) seemed to have an increased risk for admittance to the psychiatric inpatient hospital. This thesis underlines the differences between children and adolescents diagnosed with ADHD and/or DBD and emphasizes the role of comorbidity between these disorders as an indicator of poorer outcomes later in life. / Tiivistelmä Tarkkaavaisuus- ja ylivilkkaushäiriö (attention deficit hyperactivity disorder, ADHD) sekä käytös- ja uhmakkuushäiriöt (disruptive behavior disorder, DBD) ovat hyvin yleisiä – ja usein yhtä aikaa ilmeneviä – lasten ja nuorten psyykkisiä häiriöitä. Nämä häiriöt ovat hyvin usein syynä lasten ja nuorten psykiatristen terveyspalveluiden käyttöön. Niillä on myös todettu olevan useita epätoivottuja seurauksia, joiden hoitaminen puolestaan nostaa yhteiskunnan kuluja. Tämä väitöskirjatyö tutkii mahdollisia varhaisia riskitekijöitä, jotka assosioituivat ADHD- ja/tai DBD-häiriöiden kanssa, arvioi näillä häiriöillä diagnosoitujen nuorten sen hetkistä hyvinvointia ja tutkii näiden nuorten kouluttautumista sekä muuta psykiatrista sairastavuutta. Tutkimusaineisto koostuu Pohjois-Suomen syntymäkohortti 1986 (Northern Finland Birth Cohort 1986, NFBC 1986) -aineiston osaotoksesta, johon kuuluu 457 henkilöä. Osaotoksesta 91:llä (19,9 %) oli diagnosoitu ADHD, 44:llä (9,6 %) DBD ja 72:lla (15,6 %) komorbidi ADHD ja DBD. 250 henkilöllä (54,7 %) osaotoksesta ei ollut diagnosoitu kumpaakaan diagnoosia. Aineiston analysoinnissa käytettiin konfirmatorista faktorianalyysiä, Kaplan-Meierin elossaolomenetelmää, Kruskal-Wallisin yksisuuntaista varianssianalyysiä ja useita regressioanalyysejä. Tämä väitöskirja koostuu neljästä osajulkaisusta. Ensimmäisen osajulkaisun tulokset osoittivat, että eri riskitekijät lapsuudessa assosioituivat eri käytösongelmiin nuoruudessa. Eri käytösongelmien eroavaisuudet olivat myös nähtävillä toisessa osajulkaisussa: niillä nuorilla, joilla oli diagnosoitu komorbidi ADHD ja DBD, todettiin olevan vakavampia käytöshäiriöiden oireita sekä kohonnut riski useisiin muihin psykiatrisiin sairauksiin. Kolmannen osajulkaisun tulokset viittasivat näiden nuorien, jotka oli diagnosoitu komorbidillä ADHD:lla ja DBD:llä, pärjäävän huonommin koulussa ja valmistuvan muita todennäköisemmin vain peruskoulusta. Lopuksi neljännessä osajulkaisussa todettiin, että DBD diagnoosin nuorena saaneilla (riippumatta ADHD diagnoosista) näytti olevan kohonnut riski psykiatriseen osastohoitoon joutumiselle. Tämä väitöskirjatyö alleviivaa tarkkaavaisuus- ja ylivilkkaushäiriöllä sekä käytös- ja uhmakkuushäiriöillä diagnosoitujen lasten ja nuorten eroavaisuuksia ja korostaa kyseisten häiriöiden komorbidin ilmenemisen roolia huonon lopputuloksen ennustetekijänä myöhemmin nuoren elämässä.

This master thesis discusses the design of Synthetic immittance dipoles using active current elements. The introduction presents aktive current elemetns MO-CF and DACA as buildings blocks for analog filters that are able to process signals with frequencies up to ten megahertz. Methods of synthetic elements using active current elements design is described in this thesis.Is resulted from full addmitances net which contains one active current element Subsequently there are designed various types of frequency filters working in current mode. The functionality of designed filters was verified by computer simulation. Selected designed filter were practically verified with commercially available elelments and active element MO-CF. Measurements in the frequency domain were carried on. On all of types of filters are made sensitivity analysis.

No description available.

Shunt compensation devices have been a powerful candidate for expanding the limits of transmission facilities, allowing more active power transport and supporting voltage and overall stability of the network. An example of such devices is the Static Synchronous Compensator (STATCOM) which is based on Voltage Source Converter (VSC) which synthesizes output voltage and current for mainly reactive power compensation. STATCOMs might be accompanied with a Thyristor Switched Capacitor (TSC) or Reactor (TSR) which are controllable shunt devices for extra VARs required, along with passive filters for absorbing the switching harmonics generated by the VSC. Such STATCOM topology is referred as the Hybrid STATCOM.However, such configuration typically results in parallel resonances with the maingrid’s passive elements at different harmonic frequencies. This leads to amplification of background harmonics, if any exist, at the Point of Common Coupling (PCC) where the Hybrid STATCOM is connected. This thesis deals with the VSC control in the STATCOM to mitigate the harmonic amplification behavior by active filtering,which is based on emulating an impedance by the control. Also, the overall system passivity is essentially studied, which ensures a passive system with respect to harmonics. / Shunt-kompensationsanordningar har varit en kraftfull kandidat för att öka gränserna för överföringsanläggningar, vilket möjliggör högre aktiv effekt och understöderspännings-stabilitet och övergripande stabilitet i kraftnätet. Ett exempel på sådana enheter är Static Synchronous Compensator (STATCOM) som är baserat på Voltage Source Converter (VSC) som syntetiserar utspänning och ström för huvudsakligen reaktiv effektkompensation. STATCOMs kan åtföljas av en Thyristor Switched kapacitor (TSC) eller Reaktor (TSR) som är kontrollerbara shunt-apparater som ökar kapaciteten för reaktiv effekt (VARs), tillsammans med passiva filter för att absorbera övertoner som genereras av VSC. Sådan STATCOM-topologi kallas HybridSTATCOM. Emellertid, en sådan konfiguration resulterar i parallella resonanser med huvudnätets passiva element vid olika övertoner. Detta leder till förstärkning av bakgrundsövertoner, om någon existerar, vid Point of Common Coupling (PCC) där Hybrid STATCOM är ansluten. Denna avhandling behandlar hur VSC kontrolleras i STATCOM för att mildra förstärkningen av nivåer för övertoner genom aktivfiltrering, vilket är baserat på att VSC kontrollen emulerar en impedans. Dessutom studeras övergripande systempassivitet, vilket säkerställer ett passivt system med avseende på övertoner.

No / A novel multi-standard dual-wide band filter with a compact size of only 8.8 mm by 16.8mm is designed and developed for transceiver devices. The proposed filter has a fundamental bandwidth of 1.6GHz with fractional bandwidth (FBW) of 29.7% centered at the 5.4GHz band, and second bandwidth of 300.0MHz with FBW of 3.6% centered at the 8.15GHz band. The basic dual-wide bandwidth is attributed to the interaction of the novel modified polygon pair and upper stub loaded stepped impedance resonator. Moreover, the added down stub loaded stepped impedance resonator (SLSIR) further enhances the pass band performance by widening the bandwidth and optimizing reflection coefficient performance considerably. To validate the proposed ideas, the multi-standard filter is designed and simulated by Ansoft HFSS software. The simulated results agree well with the theory predictions. The featured broad bandwidths over two frequency bands and the miniaturized size of the proposed filter make it very promising for applications in future multi-standard wireless communication.