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The Study of Load Characteristics in Taipower and Its Effect on Power System OperationKang, Meei-Song 06 July 2001 (has links)
Based on the load survey study, a stratified sampling method is proposed to select the proper size of customers so that the load patterns derived can represent the load behavior of whole customer population. In this study there are 1315 customers out of Taipower customers over various service classes are selected for the installation of intelligent meters in the field to measure the power consumption within every 15 minutes. The bad data detection is performed to identify the abnormal power consumption by executing the Chi-square test. The standardized daily load pattern of each customer class has been derived with the mean per-unit method of customer load. The billing data are retrieved from the customer information system and applied to derive the customer daily load pattern by considering the customer load patterns. According to the total power consumption by all customers within the same class and considering the corresponding daily load pattern, the daily load profile of the customer class is then determined. By aggregating the load profiles of all customer classes, the daily load composition and load model of each service district can therefore be solved. By the same manner, the daily load pattern of whole Taipower system can be derived and it can be used to support the proper design of tariff structure according to the respective contribution of system power demand by each customer class.
To investigate the overloading of distribution main transformers during the summer season, the correlations analysis of customer power consumption and temperature is performed. The effect of temperature change to the power consumption of each customer class is solved by multiple regression analysis with 95% confidential level. Based on the temperature sensitivity and the corresponding load composition, the load change due to temperature rise for various customer classes can be estimated. To demonstrate the impact of temperature change to distribution system operation, considering the temperature sensitivity of power consumption and load composition solves the power demand at each load bus. By updating the bus load demand due to temperature change, the feeder loading and power loss is therefore derived. To resolve the over loading problem of distribution feeders and main transformers during the summer season, a temperature adaptive switching operation has been proposed to perform the proper load transfer among the feeders/main transformers.
In this dissertation, the effect of temperature change to the time varying characteristics of load buses and power transmission in Taipower is investigated. The dc circuit model of Taipower system and the temperature effect of customer power consumption are considered in the stochastic load flow analysis. With the temperature rise, the power demand of northern buses is increased dramatically and more power has to be transmitted from the southern region. The large voltage angle difference is significantly various between system buses during the summer peak period. It is suggested that the safety margin assessment of system operation has to be executed by considering the temperature effect to the bus loading of power systems.
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Stochastic Harmonic Analysis and Harmonic Distortion Improvement for Mass Rapid Transit SystemsShiau, Hung-Ming 20 June 2002 (has links)
Abstract
The objective of this thesis is to perform the AC/DC load flow and harmonic analysis for the power supply system of mass rapid transit (MRT) system. According to the computer simulation of stochastic harmonic load flow analysis, the mean value and standard deviation of voltage harmonic distortion are derived. The mitigation of harmonic distortion has been proposed by the proper design of harmonic filter.
The mathematical model of 12 pulse uncontrolled rectifiers without interphase transformers is derived and applied in the AC/DC load flow analysis. The system voltage profiles and power consumption are obtained by computer simulation with the models derived. The Taipei MRT system is selected for simulation to solve the peak and off peak load of target year, bus voltage and power demand, and the harmonic current injection of traction substation. The voltage harmonic distortion is then calculated for each time snapshot according to the operation modes of all train sets on the main lines. According to the dynamic load behavior of train sets, the stochastic harmonic load flow analysis is executed to find the variation of harmonic distortion. To improve the power quality of MRT power systems, the proposed hybrid filter, which consists of both passive filter and active filter, is considered in the simulation. It is found that better distortion mitigation can be obtained with the hybrid filter by taking into account the stochastic harmonic current injection at the traction substations.
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Probabilistic modelling of plug-in hybrid electric vehicle impacts on distribution networks in British ColumbiaKelly, Liam 31 August 2009 (has links)
Plug-in hybrid electric vehicles (PHEVs) represent a promising future direction for the personal transportation sector in terms of decreasing the reliance on fossil fuels while simultaneously decreasing emissions. Energy used for driving is fully or partially shifted to electricity leading to lower emission rates, especially in a low carbon intensive generation mixture such as that of British Columbia’s. Despite the benefits of PHEVs for vehicle owners, care will need to be taken when integrating PHEVs into existing electrical grids. For example, there is a natural coincidence between peak electricity demand and the hours during which the majority of vehicles are parked at a residence after a daily commute. This research aims to investigate the incremental impacts to distribution networks in British Columbia imposed by the charging of PHEVs.
A probabilistic model based on Monte Carlo Simulations is used to investigate the impacts of uncontrolled PHEV charging on three phase networks in the BC electricity system. A model simulating daily electricity demand is used to estimate the residential and commercial demand on a network. A PHEV operator model simulates the actions of drivers throughout a typical day in order to estimate the demand for vehicle charging imposed on networks. A load flow algorithm is used to solve three phase networks for voltage, current and line losses. Representative three phase networks are investigated typical of suburban, urban and rural networks. Scenarios of increasing PHEV penetration on the network and technological advancement are considered in the absence of vehicle charging control.
The results are analyzed in terms of three main categories of impacts: network demands, network voltage levels and secondary transformer overloading. In all of the networks, the PHEV charging adds a large amount of demand to the daily peak period. The increase in peak demand due to PHEV charging increases at a higher rate than the increase in energy supplied to the network as a result of vehicles charging at 240V outlets. No significant voltage drop or voltage unbalance problems occur on any of the networks investigated. Secondary transformer overloading rates are highest on the suburban network. PHEVs can also contribute to loss of transformer life specifically for transformers that are overloaded in the absence of PHEV charging. For the majority of feeders, uncontrolled PHEV charging should not pose significant problems in the near term. Recommendations are made for future studies and possible methods for mitigating the impacts.
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Probabilistic Transmission Expansion Planning in a Competitive Electricity MarketMiao Lu Unknown Date (has links)
Changes in the electric power industry have brought great challenges and uncertainties in transmission planning area. More effective planning of transmission grids with the appropriate development of advanced planning technologies is badly-needed. The aim of this research is to develop an advanced probabilistic transmission expansion planning (TEP) methodology in a continually changing market environment. The methodology should be able to strengthen and increase the robustness of existing transmission network. By using the proposed probabilistic TEP methodology, it can reduce the risks of major outages and identify weak buses in the system. The significance of this research is shown by its comprehensiveness and powerful practicability. Results from this research are able to improve the planning efficiency and reliability with consideration of financial risks in an electricity market. In order to achieve the target, this research methodologies focused on two main important issues, (1) probability based technical assessment and (2) financial investment evaluation. During the first stage study, probabilistic congestion management, probabilistic reliability evaluation and probabilistic load flow for TEP under uncertainties have been investigated and improved. The developed methodologies and indices, which truly represent the composite impact from both critical state and probability, have linked with financial terms. At financial investment evaluation part, Monte Carlo market simulation is performed to assist economic analysis. The overall planning process has been treated as a constrained multi-objective optimisation task. Comprehensive investigations are conducted on several test systems and testified by real power systems using the available reliability data and economic information from the Australian National Electricity Market (NEM). Overall, this research developed probabilistic transmission planning methodologies that can reflect modern market structures more accurately and it enable a greater utilization of current generation and transmission resources to increase potential operation efficiencies.
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Desenvolvimento de um objeto de aprendizagem para análise de sistemas de energia elétricaPereira, Marcia Beatriz Carvalho [UNESP] 22 February 2008 (has links) (PDF)
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pereira_mbc_me_ilha.pdf: 1170771 bytes, checksum: f8ba8678a1d9af0316e036187c7f36d7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho tem por objetivo contribuir para o desenvolvimento de técnicas de Educação em Engenharia apresentando uma ferramenta de apoio ao Ensino/Aprendizagem de Sistemas Elétricos de Potência na forma de um software de interface amigável e baixo custo. O software desenvolvido em linguagem C++ segue os padrões de programação orientada a objetos e oferece ao usuário a resolução de fluxos de potência e simulações de casos de contingências transitórias com possibilidade de interatividade, apresentando resultados em ambiente gráfico. Desenvolvido para aplicação na área de Dinâmica e Estabilidade de Sistemas de Potência, suporta sistemas-exemplos clássicos do IEEE e também disponibiliza ao usuário ferramentas para personalização de arquivos de dados de entrada, tornando-se flexível e de fácil acesso aos casos já inseridos no sistema. O usuário também pode criar novos sistemas de acordo com suas necessidades. Os resultados são exibidos em forma numérica e também através de gráficos tridimensionais e animação, possibilitando fácil visualização de resultados, entendimento de fenômenos e análise de influências sobre o desempenho. / This work presents a contribution to the development of Engineering Education techniques by means of a Teaching/Learning support tool for Electrical Power System studies resulting in a friendly low cost interface software. It was developed in C++ language and follows the pattern of object oriented programming, offering to the user the resolution of load flow and digital simulations of transient stability with the possibility of interactivity, showing the results in a graphic environment. It was developed for use in applications of Static and Transient Power Systems Stability and it has enclosed classic sample-systems of IEEE and others and also allows the user to customize input data files. Then the tool is flexible and enables easy access to cases formerly inserted in the system. The user also can create new systems according to his needs. The machines rotors movement can be seen in a graphic animation, allowing easy visualization of events, phenomena comprehension and analysis of influences about the performance.
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Desenvolvimento de um objeto de aprendizagem para análise de sistemas de energia elétrica /Pereira, Marcia Beatriz Carvalho. January 2008 (has links)
Orientador: Laurence Duarte Colvara / Banca: Sergio Azevedo de Oliveira / Banca: Silvia Galvão de Souza Cervantes / Resumo: Este trabalho tem por objetivo contribuir para o desenvolvimento de técnicas de Educação em Engenharia apresentando uma ferramenta de apoio ao Ensino/Aprendizagem de Sistemas Elétricos de Potência na forma de um software de interface amigável e baixo custo. O software desenvolvido em linguagem C++ segue os padrões de programação orientada a objetos e oferece ao usuário a resolução de fluxos de potência e simulações de casos de contingências transitórias com possibilidade de interatividade, apresentando resultados em ambiente gráfico. Desenvolvido para aplicação na área de Dinâmica e Estabilidade de Sistemas de Potência, suporta sistemas-exemplos clássicos do IEEE e também disponibiliza ao usuário ferramentas para personalização de arquivos de dados de entrada, tornando-se flexível e de fácil acesso aos casos já inseridos no sistema. O usuário também pode criar novos sistemas de acordo com suas necessidades. Os resultados são exibidos em forma numérica e também através de gráficos tridimensionais e animação, possibilitando fácil visualização de resultados, entendimento de fenômenos e análise de influências sobre o desempenho. / Abstract: This work presents a contribution to the development of Engineering Education techniques by means of a Teaching/Learning support tool for Electrical Power System studies resulting in a friendly low cost interface software. It was developed in C++ language and follows the pattern of object oriented programming, offering to the user the resolution of load flow and digital simulations of transient stability with the possibility of interactivity, showing the results in a graphic environment. It was developed for use in applications of Static and Transient Power Systems Stability and it has enclosed classic sample-systems of IEEE and others and also allows the user to customize input data files. Then the tool is flexible and enables easy access to cases formerly inserted in the system. The user also can create new systems according to his needs. The machines rotors movement can be seen in a graphic animation, allowing easy visualization of events, phenomena comprehension and analysis of influences about the performance. / Mestre
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Accuracy of low voltage electricity distribution network modellingUrquhart, Andrew J. January 2016 (has links)
The connection of high penetrations of new low carbon technologies such as PV and electric vehicles onto the distribution network is expected to cause power quality problems and the thermal capacity of feeder cables may be exceeded. Replacement of existing infrastructure is costly and so feeder cables are likely to be operated close to their hosting capacity. Network operators therefore require accurate simulation models so that new connection requests are not unnecessarily constrained. This work has reviewed recent studies and found a wide range of assumptions and approximations that are used in network models. A number of these have been investigated further, focussing on methods to specify the impedances of the cable, the impacts of harmonics, the time resolution used to model demand and generation, and assumptions regarding the connectivity of the neutral and ground conductors. The calculation of cable impedances is key to the accuracy of network models but only limited data is available from design standards or manufacturers. Several techniques have been compared in this work to provide guidance on the level of detail that should be included in the impedance model. Network modelling results with accurate impedances are shown to differ from those using published data. The demand data time resolution has been shown to affect estimates of copper losses in network cables. Using analytical methods and simulations, the relationship between errors in the loss estimates and the time resolution has been demonstrated and a method proposed such that the accuracy of loss estimates can be improved. For networks with grounded neutral conductors, accurate modelling requires the resistance of grounding electrodes to be taken into account. Existing methods either make approximations to the equivalent circuit or suffer from convergence problems. A new method has been proposed which resolves these difficulties and allows realistic scenarios with both grounded and ungrounded nodes to be modelled. In addition to the development of models, the voltages and currents in a section of LV feeder cable have been measured. The results provide a validation of the impedance calculations and also highlight practical difficulties associated with comparing simulation models with real measurement results.
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Dynamic analysis of the impact of grid connection of "La Higuera" hydropower plant to the transmission gridFelix, Isbi January 2006 (has links)
Studies regarding the development of a new hydropower plant exploiting the water resources offered by the upper Tinguiririca river, located about 150 km south-east of the capital Santiago in Chile, has been done by Pacific Hydro Ltd from Australia and Lahmeyer International from Germany. These studies have resulted in proposals to construct two Hydropower Stations, �La Higuera� and �Confluencia�. Both hydropower stations will have a total installed capacity of 300 MW. When setting up a new hydropower plant, it is important to foresee how the hydropower plant would affect the existing transmission grid in different situations during operation as well as how events in the grid may affect the La Higuera and/or Confluencia hydropower stations. In this report three kind of analysis are highlighted, which are static analysis, large signal stability and rotor angle stability. To perform these analyses a simulation tool named DigSilent is used. DigSilent is used to perform these analyses in a simulated network of the studied transmission system. These two hydropower stations as shown in the results will improve the existing transmission system by enhancing the stability margins in the presence of a fault. When performing the simulation of the existing transmission system with the newly installed hydropower plant we could see that it had a poor damping after a disturbance; this might be due to the large distance between production plants and the existing loads. This phenomenon can be alleviated if a power system stabilizer (PSS) is integrated in the hydropower plant. The final conclusion is that the integration of the two hydropower plants will improve the existing transmission system in Chile.
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Voltage Regulation for an Electrical GridAlzubaidi, Jaafar, Antonsson, Rasmus January 2019 (has links)
The aim of this study is to analyse the voltage regulation of a power grid when wind power parks are connected to an existing power grid. Secondary the project have studied the placement of these wind power parks and costs related to connecting them to the grid. The goal was to achieve this grid with a smaller than 5% voltage margin and preferably a low phase deviation. The power grid is located in the area around Lule älven. Several issues with constructing and connecting windpower parks to an electrical grid have been studied by numerical analysis of a fictive grid but with real world variables. A balanced and stable grid is achieved with wind and hydro power and is able to successfully operate without non-renewable energy sources.The data was simulated in Matlab to analyse the power grid and the modification of it when connecting the wind power parks. The method used is power flow analysis through Matlab. All required unknown voltages and phase angles are determined and whether they are within given specifications. This entails that a stable electrical grid can be constructed
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Integrated high-resolution modelling of domestic electricity demand and low voltage electricity distribution networksRichardson, Ian January 2011 (has links)
Assessing the impact of domestic low-carbon technologies on the electricity distribution network requires a detailed insight into the operation of networks and the power demands of consumers. When used on a wide-scale, low-carbon technologies, including domestic scale micro-generation, heat pumps, electric vehicles and flexible demand, will change the nature of domestic electricity use. In providing a basis for the quantification of the impact upon distribution networks, this thesis details the construction and use of a high-resolution integrated model that simulates both existing domestic electricity use and low voltage distribution networks. Electricity demand is modelled at the level of individual household appliances and is based upon surveyed occupant time-use data. This approach results in a simulation that exhibits realistic time-variant demand characteristics, in both individual dwellings, as well as, groups of dwellings together. Validation is performed against real domestic electricity use data, measured for this purpose, from dwellings in Loughborough in the East Midlands, UK. The low voltage distribution network is modelled using real network data, and the output of its simulation is validated against measured network voltages and power demands. The integrated model provides a highly detailed insight into the operation of networks at a one-minute resolution. This integrated model is the main output of this research, alongside published articles and a freely downloadable software implementation of the demand model.
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