Academic literature on the topic 'Electromagnetic Transients Program (EMTP)'

The subject of this thesis is Current Transformer Transient response study using an electromagnetic Transient program (EMTP). Current transformers are considered eyes for power system protection. Behaviours of protection systems depend largely on information fed to them by instrument transformers. Ferromagnetic current transformers have for many years provided practical method of current measurement, however there are limitations associated with current transformer operation:- notably, difficult in maintaining accuracy over the full range of operating conditions, and most particularly current transformers tendency to suffer saturation of iron core during severe faults, with accompanying severe ratio or loss of output. These limitations might lead to mal operation of protective relays due to distorted inputs from current transformers particularly in transient periods. This thesis involved studying the behaviour of current transformers in both steady state and transient periods. An emphasis being put on transient periods which are very crucial in behaviour of current transformers because transformation errors are greatest in these periods. Errors in current transformer transformation might affect operation of entire protection schemes. Maloperation of current transformers in transient periods have very bad effect on relay co-ordination and worst condition might be failure of protection scheme operation altogether. Over the past decades engineers have been trying to develop a current transformer model that would represent a current transformer well in transient periods. It has proved to be rather difficult to come up with a single detailed model that would satisfy all possible conditions. This is due to non-linearity of magnetising curve and saturation effects of current transformer iron cores. The author has considered different current transformer models with their merits and demerits being highlighted. It has been shown that different current transformer models have to be used when considering different operating conditions of a current transformer in a power system. ATP-EMTP an Electromagnetic Transient Program was developed in the sixties for the study of electromagnetic transients in power systems. It has proved to be a very useful tool in this regard. The program development is still going on today to accommodate a wide application in power systems. Several components have been developed to represent different components in a power system. It is only recently that there has been a growing interest to include modelling of protective equipment. This has been accelerated by the inclusion of MODELS in the EMTP program. This thesis explores the effect of transients taking into account different conditions like transient fault currents, effects of high frequency waves and surges. Effects of different types of burdens on current transformers were explored as well. Due to limitations of EMTP, simulation results are only applicable to current transformers with ARMCO M4 oriented steel with ungapped cores. The author arrived at several conclusions. The most important conclusion is that mal operation of protective relays due to current transformer saturation can be avoided easily if proper current transformer selection is given priority in power protection design. EMTP package proved to be very useful and handy when studying transients though one has to be careful with numerical oscillations which might be present during simulations. Problems of numerical oscillations have been discussed under current transformer simulation tools.

The objective of this research project was to develop and implement a model for an A.C circuit breaker in the Electromagnetic Transients Program (EMTP). Various models for the arcing process were evaluated, and the modified Mayr equation was chosen for the model. Other equations were added to demonstrate the generality of the algorithm developed. Since the Electromagnetic Transients Program was not designed to accommodate directly elements whose resistance varies with time, such as an electric arc, several strategies for interfacing the model with the program were studied. The compensation method was selected, and was used for interfacing the circuit breaker model with the program. After implementation of the model, it was validated by comparing its performance with experimentally verified results reported previously. In order to render the model more practical, an auxiliary breaker parameter estimation routine was developed and tested.<br>M.S.

The following work presents a graphical pre-processor software as an alternative version of the Electromagnetic Transients Program (ATP-EMTP). It was developed to aid in the analysis of electromagnetic transients in power substations. The software has been developed using Java programming language and it was named Alternative Transients Program Substation Analysis (ATP-SA). Amongst its functionalities, it can be highlighted the representation of precursory events of electromagnetic transients in the ATP-EMTP standard, data predefinition for the modeling of these events, simulation configuration with compatible values in reference to the transient phenomena to be studied and management simulation through a databank. The transients to be considered are: occurrence and clearance of faults, transformer inrush, Transient Recovery Voltage (TRV) in circuit-breakers, circuit-breaker switching and lightning surges. The software aids in the simulation of transients occurred by these events in both deterministic and stochastic ways. In addition, to show its potentialities, examples of application are presented in a real power system simulations. Hence, with the use of the mentioned software, it is expected to support in subsidies and safety with respect of operations in substations, as well to aid in defect prevention, loss of equipment and potential shutdowns. This work is the main theme of a Research and Development (R&D) project developed by the Laboratory of Analysis and Protection of Power Systems, in the Power System and Energy Research Center, in a partnership along with the State Company of Generation and Transmission of Electric Energy of the Rio Grande do Sul State.<br>Este trabalho apresenta a implementação de um software pré-processador gráfico para a versão alternativa do ElectroMagnetic Transient Program (ATP-EMTP), desenvolvido para auxiliar a análise de transitórios eletromagnéticos em subestações de potência. Este software, concebido em linguagem de programação Java, recebeu a denominação de Alternative Transients Program Substation Analysis (ATP-SA). Dentre suas funcionalidades, está a representação de eventos precursores de transitórios eletromagnéticos no padrão ATP-EMTP, predefinição de dados para modelagem destes eventos, parametrização da simulação com valores compatíveis com o fenômeno analisado e gerenciamento de simulações através de um banco de dados. Os eventos contemplados pelo software compreendem: ocorrência e eliminação de curtos-circuitos, energização de transformador, Tensão de Restabelecimento Transitória (TRT) em disjuntores, manobras de abertura e fechamento de disjuntores e descargas atmosféricas. O software fornece suporte a simulação de transitórios provocados por estes eventos de forma determinística ou estocástica. Para demonstrar estas potencialidades, abordam-se exemplos aplicados sobre um sistema elétrico real. Com a utilização do software desenvolvido, espera-se fornecer subsídio e segurança para a realização de operações em subestações, bem como auxiliar a prevenção de falhas, perda de equipamentos e desligamentos. O presente trabalho é parte integrante de um projeto de Pesquisa e Desenvolvimento (P&D), desenvolvido pelo Laboratório de Análise e Proteção de Sistemas Elétricos do Centro de Estudos em Energia e Sistemas de Potência (LAPES-CEESP) da UFSM, em parceria com a Companhia Estadual de Geração e Transmissão de Energia Elétrica (CEEE-GT) do Rio Grande do Sul.

Les câbles sont utilisés de plus en plus pour le transport et la distribution de l'électricité en courant alternatif sur des distances de plus en plus longues. La prolifération de fermes éoliennes offshore qui nécessitent d'interconnexions avec le continent a aussi propulsé leur utilisation sous-marine. Modèles de câbles sont disponibles dans le bien connu logiciel Electro Magnetic Transient Program et sont destinés au domaine temporel. Ces modèles sont assemblés en utilisant différentes techniques, mais tous nécessitent une connaissance précise des paramètres des câbles dans le domaine fréquentiel. Dans ce but, pour le calcul des impédances des câbles tripolaires cette thèse propose une méthode qui améliore la prise en compte de la proximité entre tous les conducteurs : il s'agit d'une méthode semi-analytique qui utilise le concept duale de fils minces et sous-conducteurs pour décrire la densité de courant à l'intérieur des conducteurs et le calcul des impédances. L'effet du retour par la mer est aussi analysé et une méthode quasi Monte Carlo est proposé, afin de résoudre les intégrales qui décrivent la formulation des impédances pour le sol à deux couches (la mer et son fond) sur lequel ces câbles sont posés. L'effet du à la présence des couches de semi-conducteur dans les câbles est aussi traité. La méthode de collocation stochastique est aussi décrite et appliquée, afin de prendre en compte la variabilité des paramètres d'entrée.

A transmissão de energia em corrente contínua, a partir de conversores fonte de tensão, é oportuna ao progresso do sistema elétrico de potência e tem permitido vantajosas aplicações. Muito se dá, devido ao emprego na conexão de sistemas com frequências distintas, além da redução de perdas na transmissão, provida pelas características operacionais destes. VSCs também promovem o controle do fluxo de potência, possibilitando uma efetiva contextualização no âmbito das redes inteligentes. Diante deste cenário, este estudo pretende construir um perfil de corrente através do Cálculo de Curto-Circuito Probabilístico, que emprega a Simulação de Monte Carlo, para prover as informações ao desenvolvimento de projetos de equipamentos, ajustes da proteção e controle de sistemas de transmissão em corrente contínua. A Simulação de Monte Carlo requer muitas iterações, tendo um custo computacional elevado. Se forem executadas em programas comerciais, exige um tempo elevado para leitura dos sinais em arquivos. Devido a isso, um programa de código livre usando linguagem C++, foi desenvolvido para possibilitar acesso aos sinais de interesse ainda em memória, reduzindo desta forma o tempo computacional. Além disso, para melhorar a performance, foram usadas técnicas de processamento paralelo e de computação em nuvem. Desta forma, este estudo contribui com informações indispensáveis ao projeto de equipamentos de proteção dos sistemas de transmissão em corrente contínua de forma a cooperar com o desenvolvimento consistente desta tecnologia.<br>Transmitting electrical power in direct current using a VSC is suitable for the progress of these systems and has remarkable and advantageous applications. This happens in order to connect two systems with distinct frequencies. This type of line is also used in the reduction of losses in transmission over long distances, provided by their operating characteristics. These converters also promote the control of power flow between distinct generation units, making them effective in the context of Smart Grids. Based on this, the purpose of this research is to construct a profile of a current using a Probabilistic Short-Circuit Analysis by Monte Carlo Simulation to provide basic data to the optimum development of design equipment in protection and control. The Monte Carlo Simulation requires many iterations to find an optimal result. An open source program using C++ language was developed to describe all the system models variables in order to decrease the computation time, as it is time consuming to read signals stored on a disk using commercial software. Moreover, in order to lower computation costs, parallel process techniques and cloud computing were used. Therefore, this study contributes to the literature by providing essential information for designing equipment for Direct Current transmission protection systems.

The recent introduction of a new converter topology, the modular multilevel converter (MMC) is a major step forward in voltage sourced converter (VSC) technology for high voltage, high power applications. To obtain a multilevel ac output waveform, a large number of semiconductor switches has to be used in the converter. The number of switches in the MMC for HVDC transmission is typically two orders of magnitudes larger than that in a two or three level VSC used in earlier generation. This large device count creates a computational challenge for electromagnetic transients (EMT) simulation programs, as it significantly increases the simulation time. The purpose of this research is to investigate whether the simulation can be speeded up. This research develops an efficient, time-varying Thévenin's equivalent model for the MMC converter based on partitioning the system’s admittance matrix. EMT simulation results show that the proposed equivalent model can drastically reduce the computational time without loss of accuracy. The use of the proposed equivalent method is demonstrated by simulating a point to point MMC based HVDC transmission system successfully with more than 100 levels. This approach enables what was hitherto not practical; the modeling of large MMC based HVDC systems on personal computers. With the assumption of ideal switch operation and using an equivalent average capacitor value based approach, an average valued model of MMC is also proposed in this thesis. The average model can be accurately used in most of the system level studies. The control algorithms and other modeling aspects of MMC applications are also presented in this thesis. One of the advantages of multilevel converters is the low operating losses as the smaller switching frequency of each individual power electronics switch and the low voltage step change during each switching. Using a recently developed, time domain simulation approach, the operating losses of the MMC converter are estimated in this thesis. When comparing the MMC operating losses against the losses of two-level VSC, the power loss for the two-level VSC is found to be significantly higher than the power loss of the MMC.

碩士<br>國立臺南大學<br>電機工程學系碩博士班<br>106<br>One of critical concerns in the operation of lightning strikes is the surge characteristics. It is known that the lightning strikes may cause the power system faults and pose hazards to utility personnel even. Hence, in this thesis, a power system model, including of a 161 kV transmission line and transformer, based on the Alternative Transient Program- Electromagnetic Transient Program (ATP-EMTP) is developed to analysis the event of lightning strikes, different test cases have been carried out for the study considered. In the study, lightning arresters are installed at different equipment terminals to analyze the effect of lightning current on each terminal equipment and the suppression status of inrush current. Beside, according to the actual data of the system operation, the current installation location of the arrester is analyzed and compared with the simulation results to determine whether the arrester is a repetitive investment and the maximum efficiency installation point. The simulation results show that: (1) the lightning strikes may cause the switchgear to withstand abnormal overcurrent and be damaged. It is necessary to install arresters at the end of the transmission line in substation. (2) Installation of a series reactor can significantly suppress the lightning surge. (3) Within the substation overhead line and underground cable mixed system, installing underground lightning arrester on both ends can effectively reduce the lightning surge voltage. (4) Consider the protection of cables and transformers, the best place of lightning arrester installation should be near the transformer.