Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-09-28Bitstream added on 2014-06-13T19:08:14Z : No. of bitstreams: 1 daltin_rs_me_ilha.pdf: 841004 bytes, checksum: da77f2e8d8ccd4d0094ea607844c7530 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esta dissertação descreve um processo alternativo para decompor uma linha de transmissão trifásica, simétrica e não transposta nos seus modos exatos por meio da utilização de duas matrizes de transformação. A primeira é a matriz de Clarke que desacopla a linha em suas componentes a, ß e zero. A componente ß é um modo exato enquanto que as componentes a e zero são acopladas. Em seguida, as componentes a e zero são representadas por uma linha bifásica que pode ser decomposta em seus modos exatos por meio de uma matriz de transformação adequada, cujos elementos podem ser sintetizados, no domínio do tempo, por técnicas de aproximações por curvas. O método pretende unir as vantagens da matriz de transformação exata (que produz modos exatos) com as vantagens da matriz de Clarke, que é real, independente da freqüência e facilmente representável em programas que realizam simulações de transitórios, como é o caso do EMTP. Assim, o método pode ser utilizado em situações em que o acoplamento entre as componentes a e zero não possa ser desconsiderado. O processo foi utilizado para simular a energização de uma linha trifásica, sem transposição, com um plano de simetria vertical, 440 kV e comprimento de 500 km que foi representada no domínio modal por meio do método proposto e também por meio do uso da matriz de autovetores (como sendo a matriz de decomposição modal). O método é coerente, pois foram obtidos resultados semelhantes com os dois métodos de decomposição modal, enquanto que com o uso somente da matriz de Clarke, verificou- se certa diferença em relação aos valores esperados. / This dissertation describes an alternative procedure to decompose a non-transposed threephase transmission line into exact modes, by using two transformation matrices. The first one is Clarke's matrix, which separates the line into quasi-modes a, ß e zero. The ß component is an exact mode while a and zero are coupled. After that, the coupled components are represented by using a two-phase transmission line without a vertical symmetry plane that can be decomposed with a modal transformation matrix whose elements can be achieved, in timedomain, through standard curve-fitting techniques. The method intends to join the Clarke's matrix advantages which crucial aspect is being real, frequency-independent and easily represented in computational transient programs (EMTP) with eigenvector's matrix used in situations where the coupling between a and zero components cannot be disconsidered. The process was used to energize a three-phase transmission line with a vertical symmetry plane, which nominal voltage is 440kV and its length, 500km. It was represented in the modal domain by considered method and, on the other hand, by using eigenvector's matrix (as being the decomposition matrix). In fact, the obtained results had shown that the method is coherent, because it is obtained similar results with the application of the two mentioned modal decomposition methods, whereas with the use of Clarke's matrix, a perceptible difference in relation to the expected values was verified.

No / Under local multi-machine condition, voltage and current changes of generator d and q axis are important parameters that mirror the coupling characteristics between local generator and others. Fifth order generator Hamiltonian model included electromagnetic transient of the d and q axis is established in this paper, which provides a foundation that reveals inner dynamics mechanism of multi-machine coupling and interaction. Based on electromechanical analysis dynamics theory, each of subsystem Lagrange function, dissipative function and generalized forces can be derived from fundamental energy relationship of the generator, then the Lagrange-Maxwell equations of the generator can be derived. The equations are transformed into the generalized Hamiltonian model by defining the generalized momentum, in which its structure is clear, its energy flow is consistent with actual physical system ones. The Hamiltonian model of generator is improved by the transition to that with practical parameters resulting from local simplified method. The conception of the local multi-machine system of power station is proposed, implicit multi-machine system Hamiltonian model described by measurable parameters on the generator port is derived. Analysis show that proposed model is well in structure.

The purpose of this research is to develop a method of making system equivalents for the Real Time Digital Simulator (RTDS), which should enhance its capability of simulating large power systems. The proposed equivalent combines a Frequency Dependent Network Equivalent (FDNE) for the high frequency electromagnetic transients and a Transient Stability Analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the Vector Fitting method. An approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data is also introduced. A new scheme of incorporating TSA solution in RTDS is proposed. This report shows how the TSA algorithm can be adapted to a real time platform. The validity of this method is confirmed with examples, including the study of a multi in-feed HVDC system based network.

The purpose of this research is to develop a method of making system equivalents for the Real Time Digital Simulator (RTDS), which should enhance its capability of simulating large power systems. The proposed equivalent combines a Frequency Dependent Network Equivalent (FDNE) for the high frequency electromagnetic transients and a Transient Stability Analysis (TSA) type simulation block for the electromechanical transients. The frequency dependent characteristic for FDNE is obtained by curve-fitting frequency domain admittance characteristics using the Vector Fitting method. An approach for approximating the frequency dependent characteristic of large power networks from readily available typical power-flow data is also introduced. A new scheme of incorporating TSA solution in RTDS is proposed. This report shows how the TSA algorithm can be adapted to a real time platform. The validity of this method is confirmed with examples, including the study of a multi in-feed HVDC system based network.

Orientador: Maria Cristina Dias Tavares / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e Computação / Made available in DSpace on 2018-08-08T12:51:45Z (GMT). No. of bitstreams: 1 Pinheiro_MichelGonA§alves_M.pdf: 1094075 bytes, checksum: 1c9863b695ee82d8312c89c87f94085b (MD5) Previous issue date: 2005 / Resumo: Este trabalho apresenta uma extensa análise de sensibilidade dos parâmetros elétricos longitudinais e transversais de uma linha de transmissão trifásica em função da freqüência. Uma linha real de 440 kV foi utilizada como base para as análises. Considerando determinadas hipóteses simplificadoras, foram calculados os parâmetros elétricos da linha: resistência, indutância e capacitância no domínio da freqüência. Esses parâmetros foram apresentados em termos das parcelas das matrizes primitivas, das matrizes reduzidas e componentes modais. Na análise de sensibilidade variaram-se as seguintes características da linha: diâmetros dos cabos pára-raios, diâmetros dos condutores fase, altura dos condutores, distância horizontal entre as fases, espaçamento vertical dos sub-condutores dos feixes das fases externas. Para cada variação observou-se o comportamento dos parâmetros elétricos em função da freqüência, em termos das parcelas das matrizes primitivas e em termos dos modos. Também foi observado o fator de aterramento e foram estimados os aumentos de potência natural em função das variações realizadas. As linhas com elevada potência natural (LPNE) foram avaliadas no âmbito da análise efetivada / Abstract: In this work a large sensitivity analysis of longitudinal and transversal electrical parameters of a three-phase transmission line in frequency domain was performed. An actual 440 kV transmission line was used as reference in the analysis. Considering some simplified hypothesis, electrical parameters, as resistance, inductance and capacitance, were evaluated in frequency domain. Those parameters were presented in terms of parcels of primitive matrices and reduced matrices in phase modal domain. An extensive sensitivity analysis was performed and the following line caracteristics were varied: ground wires diameter, phase conductors diameter, height of conductors, horizontal distance among phases and vertical spacing within external phases bending. For each line caracteristic, the performance of electrical parameters in frequency domain, in terms of primitive and modal matrices was observed. Also, it was observed the ground factor and it was estimated the increases on natural power. Using of High Natural Power Lines was studied and related to variations of line geometry / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

<p>Electromagnetic transients impinging on electromagnetic power devices - such as electric machines, transformers and reactors - can stress the design severely. Thus the magnitudes of the transients are often decisive for the design of the devices. Further, the operation of a device can be transient in itself. This is the case for the explosive magnetic flux compression generator (EMG) and a ferromagnetic actuator. </p><p>Models are presented that are mainly intended for transients in the millisecond range and faster. Hence, eddy currents and the related skin and proximity effect become significant in windings, magnetic cores and in the armatures of the devices. These effects are important for, e.g., the damping of the transients. Further, the displacement current in the insulation of the winding is significant. It changes the response of the windings dramatically, as it manifests the finite velocity of propagation of the electromagnetic fields. Under such circumstances, reflections and excited resonances can make the transient voltage and current distribution highly irregular. </p><p>Induced voltages are modelled with self and mutual inductances or reluctances combined with winding templates. The displacement currents are modelled with capacitances or coefficients of potential. Cauer circuits and their dual form are used to model eddy currents in laminated cores and in conductors. The Cauer circuit enables one to consider hysteresis and the non-linear response of a magnetic core. It is also used to model the eddy currents in the moving armature of an EMG. </p><p>A set-up is presented that can be used to study the transient voltage and the current distribution along a coil. </p><p>The transient response of coaxially insulated windings is analysed and modelled in detail. A lumped circuit model is developed for a coil, Dryformer^TM - the new high-voltage transformer - and Powerformer^TM, the new high-voltage generator. An alternative model, a combined lumped circuit and FEM model, is presented for a coaxially insulated winding in two slot cores.</p>

Electromagnetic transients impinging on electromagnetic power devices - such as electric machines, transformers and reactors - can stress the design severely. Thus the magnitudes of the transients are often decisive for the design of the devices. Further, the operation of a device can be transient in itself. This is the case for the explosive magnetic flux compression generator (EMG) and a ferromagnetic actuator. Models are presented that are mainly intended for transients in the millisecond range and faster. Hence, eddy currents and the related skin and proximity effect become significant in windings, magnetic cores and in the armatures of the devices. These effects are important for, e.g., the damping of the transients. Further, the displacement current in the insulation of the winding is significant. It changes the response of the windings dramatically, as it manifests the finite velocity of propagation of the electromagnetic fields. Under such circumstances, reflections and excited resonances can make the transient voltage and current distribution highly irregular. Induced voltages are modelled with self and mutual inductances or reluctances combined with winding templates. The displacement currents are modelled with capacitances or coefficients of potential. Cauer circuits and their dual form are used to model eddy currents in laminated cores and in conductors. The Cauer circuit enables one to consider hysteresis and the non-linear response of a magnetic core. It is also used to model the eddy currents in the moving armature of an EMG. A set-up is presented that can be used to study the transient voltage and the current distribution along a coil. The transient response of coaxially insulated windings is analysed and modelled in detail. A lumped circuit model is developed for a coil, DryformerTM - the new high-voltage transformer - and PowerformerTM, the new high-voltage generator. An alternative model, a combined lumped circuit and FEM model, is presented for a coaxially insulated winding in two slot cores.

This thesis introduces a new modeling approach that allows very large power systems to be modeled on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs. The key step in achieving this is the development of an improved wide-band multi-port equivalent, which reduces a large power network into a small manageable equivalent model that preserves wideband behaviors. This approach has a foundation method that use a two part equivalent in which the high frequency behavior of the equivalenced network is represented by a terminating frequency dependent network equivalent (FDNE), with the low frequency behavior being modeled using a detailed Transient Stability Analysis (TSA) model that only models the electromechanical behavior. This approach allowed the modelling of medium size electric regions up to hundreds of buses in real time. This thesis extends the equivalent by implementing a reduced order of the detailed electromechanical TSA equivalent mentioned above. Coherency based reduction is used for the electromechanical model of the power network to be equivalenced, and is implemented as a Transient Stability Analysis (TSA) type electromechanical equivalent. A challenge in implementing the FDNE is to ensure that it is a passive network, as otherwise its inclusion could lead to unstable simulation. This thesis also introduces a practical procedure to enforce passivity in the FDNE. The validity of the proposed technique is demonstrated by comparing the approach with detailed electromagnetic simulations of the well-known 39 bus New England system and a modified 39 bus system with an HVDC infeed with coupling between the dc line and an adjacent ac line, in addition to a 108 bus ac system. The power of the method is demonstrated by the real-time simulation of a large system with 2300 busses and 139 generators. It has been shown that this approach has the potential to increase by at least one order of magnitude the size of the network that can be modeled and thus on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs.

This thesis introduces a new modeling approach that allows very large power systems to be modeled on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs. The key step in achieving this is the development of an improved wide-band multi-port equivalent, which reduces a large power network into a small manageable equivalent model that preserves wideband behaviors. This approach has a foundation method that use a two part equivalent in which the high frequency behavior of the equivalenced network is represented by a terminating frequency dependent network equivalent (FDNE), with the low frequency behavior being modeled using a detailed Transient Stability Analysis (TSA) model that only models the electromechanical behavior. This approach allowed the modelling of medium size electric regions up to hundreds of buses in real time. This thesis extends the equivalent by implementing a reduced order of the detailed electromechanical TSA equivalent mentioned above. Coherency based reduction is used for the electromechanical model of the power network to be equivalenced, and is implemented as a Transient Stability Analysis (TSA) type electromechanical equivalent. A challenge in implementing the FDNE is to ensure that it is a passive network, as otherwise its inclusion could lead to unstable simulation. This thesis also introduces a practical procedure to enforce passivity in the FDNE. The validity of the proposed technique is demonstrated by comparing the approach with detailed electromagnetic simulations of the well-known 39 bus New England system and a modified 39 bus system with an HVDC infeed with coupling between the dc line and an adjacent ac line, in addition to a 108 bus ac system. The power of the method is demonstrated by the real-time simulation of a large system with 2300 busses and 139 generators. It has been shown that this approach has the potential to increase by at least one order of magnitude the size of the network that can be modeled and thus on a real time electro-magnetic transients (EMT) digital simulator with reduced hardware costs.

Made available in DSpace on 2014-12-17T14:54:58Z (GMT). No. of bitstreams: 1 ArrheniusVCO_TESE.pdf: 1241211 bytes, checksum: 636a162e62ee1658f0ee78ed1516228d (MD5) Previous issue date: 2011-03-03 / Eventually, violations of voltage limits at buses or admissible loadings of transmission lines and/or power transformers may occur by the power system operation. If violations are detected in the supervision process, corrective measures may be carried out in order to eliminate them or to reduce their intensity. Loading restriction is an extreme solution and should only be adopted as the last control action. Previous researches have shown that it is possible to control constraints in electrical systems by changing the network topology, using the technique named Corrective Switching, which requires no additional costs. In previous works, the proposed calculations for verifying the ability of a switching variant in eliminating an overload in a specific branch were based on network reduction or heuristic analysis. The purpose of this work is to develop analytical derivation of linear equations to estimate current changes in a specific branch (due to switching measures) by means of few calculations. For bus-bar coupling, derivations will be based on short-circuit theory and Relief Function methodology. For bus-bar splitting, a Relief Function will be derived based on a technique of equivalent circuit. Although systems of linear equations are used to substantiate deductions, its formal solution for each variant, in real time does not become necessary. A priority list of promising variants is then assigned for final check by an exact load flow calculation and a transient analysis using ATP Alternative Transient Program. At last, results obtained by simulation in networks with different features will be presented / Na opera??o de sistemas el?tricos verificam-se, eventualmente, viola??es de restri??es operativas, como sobrecargas em linhas de transmiss?o e transformadores de pot?ncia de subesta??es ou viola??es de limites de tens?es em barramentos. Caso o monitoramento dessas grandezas indique poss?veis problemas, ? necess?rio adotar medidas corretivas para elimin?los ou atenuar sua intensidade, devendo a restri??o de carga ser utilizada como ?ltimo recurso. Uma medida de controle bastante eficaz ? a t?cnica intitulada Chaveamentos Corretivos, capaz de influenciar o fluxo de pot?ncia de redes malhadas a partir de altera??es em suas topologias, sem, entretanto, produzir qualquer custo operacional adicional. Em trabalhos anteriores, o c?lculo desenvolvido para verificar a capacidade de uma determinada variante de chaveamento em eliminar a sobrecarga em um ramo espec?fico era realizado atrav?s de redu??o de redes ou atrav?s de an?lises heur?sticas. O presente trabalho objetiva a dedu??o anal?tica de equa??es para estimar a altera??o de corrente em um ramo espec?fico, ap?s a realiza??o de chaveamentos em subesta??es, mediante o emprego de poucos c?lculos, decorrentes de aproxima??es lineares. Para o acoplamento de barras de subesta??es, as dedu??es ser?o baseadas na teoria de curto-circuito e na metodologia da Fun??o de Al?vio. J? para a abertura de barras de subesta??es, ser? deduzida uma nova Fun??o de Al?vio, fundamentada na t?cnica de circuito equivalente. Embora sistemas de equa??es lineares sejam utilizados para fundamentar as dedu??es, sua solu??o formal para cada variante, em tempo real n?o ? necess?ria. A partir das estimativas realizadas, elabora-se uma lista de variantes priorit?rias, para teste final atrav?s de um c?lculo exato de fluxo de carga e de uma an?lise de transit?rios atrav?s do software ATP Alternative Transient Program. Por fim, apresentamse resultados obtidos atrav?s de simula??es em redes el?tricas de caracter?sticas distintas