Voltage Stability Analysis of Power Systems with Doubly-fed Induction Generators Based Distributed Generation
Voltage Stability Analysis of Power Systems with Doubly-fed Induction Generators Based Distributed Generation

Author: Ayub Machiri Wanjala

Publisher:

Published: 2016

Total Pages: 226

ISBN-13:

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The increasing energy demand over the last few decades has led to more stresses on the power system. With the demand being equal to the available supply capacity and in some cases exceeding it, there is a need to increase the capacity of the electric system ensuring that the network security is maintained. Distributed Generation located in the Distribution Network provides the ability to meet the growing demand. With increasing concerns on the environmental impacts of conventional power stations, initiatives such as the Kyoto Protocol for Climate Change have encouraged the diversification and development of energy efficient systems. These systems rely on renewable energy sources such as wind, solar and tidal energy. However, the existing power system was not designed to include generating systems on the distribution network. As a result, the unplanned integrations of Distributed Generating Systems might cause some technical problems to the grid. Wind-based Distributed Generation Systems offer an economical and efficient solution. However, the incorporation of wind energy on the Distribution Network not only alters the power flow but in some cases results in imbalanced voltages at specific points in the network. Advances in technology has resulted in increased capacity of the Wind Energy Conversion System with some having the capability to generate more than 1MVA from a single turbine resulting in the possibility of higher Distributed Generation penetration levels on the Distribution Network. The main focus of this research is to analyse the impact of high Distributed Generating Systems penetration on the voltage stability of the network under various loading conditions. It will also analyse the control strategies to be employed to deal with any effects on the stability of the network.

Modeling, Stability Analysis, and Control of Distributed Generation in the Context of Microgrids
Modeling, Stability Analysis, and Control of Distributed Generation in the Context of Microgrids

Author: Ehsan Nasr-Azadani

Publisher:

Published: 2014

Total Pages: 121

ISBN-13:

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One of the consequences of competitive electricity markets and international commitments to green energy is the fast development and increase in the amount of distributed generation (DG) in distribution grids. These DGs are resulting in a change in the nature of distribution systems from being "passive", containing only loads, to "active", including loads and DGs. This will affect the dynamic behavior of both transmission and distribution systems. There are many technical aspects and challenges of DGs that have to be properly understood and addressed. One of them is the need for adequate static and dynamic models for DG units, particularly under unbalanced conditions, to perform proper studies of distribution systems with DGs (e.g., microgrids). The primary objective of this thesis is the development and implementation of dynamic and static models of various DG technologies for stability analysis. These models allow studying systems with DGs both in the long- and short-term; thus, differential and algebraic equations of various DGs are formulated and discussed in order to integrate these models into existing power system analysis software tools. The presented and discussed models are generally based on dynamic models of different DGs for stability studies considering the dynamics of the primary governor, generators, and their interfaces and controls. A new comprehensive investigation is also presented of the effects of system unbalance on the stability of distribution grids with DG units based on synchronous generator (SG) and doubly-fed induction generator (DFIG) at different loading levels. Detailed steady-state and dynamic analyses of the system are performed. Based on voltage and angle stability studies, it is demonstrated that load unbalance can significantly affect the distribution system dynamic performance. Novel, simple, and effective control strategies based on an Unbalanced Voltage Stabilizer (UVS) are also proposed to improve the system control and the stability of unbalanced distribution systems with SG- and DFIG-based DGs.

The Stability Analysis for Wind Turbines with Doubly Fed Induction Generators
The Stability Analysis for Wind Turbines with Doubly Fed Induction Generators

Author: Baohua Dong

Publisher:

Published: 2019

Total Pages: 0

ISBN-13: 9781392823828

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The quickly increasing, widespread use of wind generation around the world reduces carbon emissions, decreases the effects of global warming, and lowers dependence on fossil fuels. However, the growing penetration of wind power requires more effort to maintain power systems stability.This dissertation focuses on developing a novel algorithm which dynamically optimizes the proportional-integral (PI) controllers of a doubly fed induction generator (DFIG) driven by a wind turbine to increase the transient performance based on small signal stability analysis.Firstly, the impact of wind generation is introduced. The stability of power systems with wind generation is described, including the different wind generator technologies, and the challenges in high wind penetration conditions. Secondly, the small signal stability analysis model of wind turbines with DFIG is developed, including detailed rotor/grid side converter models, and the interface with the power grid. Thirdly, Particle swarm optimization (PSO) is selected to off-line calculate the optimal parameters of DFIG PI gains to maximize the damping ratios of system eigenvalues in different wind speeds. Based on the historical data, the artificial neural networks (ANNs) are designed, trained, and have the ability to quickly forecast the optimal parameters. The ANN controllers are designed to dynamically adjust PI gains online.Finally, system studies have been provided for a single machine connected to an infinite bus system (SMIB), a single machine connected to a weak grid (SMWG), and a multi machine system (MMS), respectively. A detailed analysis for MMS with different wind penetration levels has been shown according to grid code. Moreover, voltage stability improvement and grid loss reduction in IEEE 34-bus distribution system, including WT-DFIG under unbalanced heavy loading conditions, are investigated. The simulation results show the algorithm can greatly reduce low frequency oscillations and improve transient performance of DFIGs system. It realizes off-line optimization of MMS, online forecasts the optimal PI gains, and adaptively adjusts PI gains. The results also provide some useful conclusions and explorations for wind generation design, operations, and connection to the power grid.

Wind Power Integration
Wind Power Integration

Author: Brendan Fox

Publisher: IET

Published: 2007-06-20

Total Pages: 290

ISBN-13: 0863414494

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This essential book examines the main problems of wind power integration and guides the reader through a number of the most recent solutions based on current research and operational experience of wind power integration.

Fundamentals of Distributed Generation Systems
Fundamentals of Distributed Generation Systems

Author: Zivan Zabar

Publisher:

Published: 2022

Total Pages: 0

ISBN-13: 9780735425378

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This textbook addresses the fundamentals of employing distributed generation systems. The content is based on the development, changes, and needs of electric utility companies in restructuring the prevailing electrical grids. The material, the order of the chapters, and the practice problems are based on years of teaching experience, including students' reactions and their knowledge acquisition. It is divided into three main parts: -- Principles of operation of commonly used distributed generators: Fuel Cells, Solar Cells, Gas Turbines, Microturbines, Reciprocate Internal Combustion Engines, and Wind Turbines. -- Detailed analysis of three major components: the induction generator (including its doubly-fed configuration), the synchronous generator (including dynamic volt-ampere reactive control), and the power static converters (including DC/DC and self- and line-commutated units). -- Interaction with electric utility lines, including the effects of harmonic distortion, voltage stability, volt-ampere reactive control, and fault conditions. The book also includes many practice and drill problems and is an ideal text for graduate students and an invaluable handbook for engineers working in electrical power systems.

Voltage Stability Problem in a Distribution System with Distributed Generator
Voltage Stability Problem in a Distribution System with Distributed Generator

Author:

Publisher:

Published: 2008

Total Pages: 138

ISBN-13:

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With difficulties in building new transmission lines and power plants, due to environmental and political issues, while electricity demand is continuously increasing, it is expected that, in the near future, more distributed generations will penetrate into power systems, especially into the distribution system. As several competitive advantages of an induction generator compared to a synchronous generator such as durability, low investment cost and etc., it is possible that many of very small power producers may connect this type of generators into the distribution system. However, as we know, rather than generate reactive power, the induction generator consumes it. Thus, impact of the induction generator on voltage stability should be carefully investigated. We focus on this aspect in this thesis. Both static and dynamic analyses were performed in this thesis. In static analysis, the degree of voltage instability based on PQVSI index is used as the main tool to assess how close the present operating condition to the voltage instability point. In addition to the static analysis, the dynamic voltage stability was conducted as well. The dynamic voltage characteristics were observed, which is eventually used to verify the results obtained from the static analysis. It provides clearer and more accurate figure of the actual dynamics of voltage instability process following a disturbance in the system, which in this case is a load change. The studies indicating an unhealthy impact of induction generators on the system's voltage stability are shown in this thesis, especially when the system is intended to serve large inductive loads. These phenomena lead to both unstable of the induction generator itself, and unstable of the entire distribution system through voltage instability. As a consequence, special treatment should be implemented in the case of utilizing induction generators in the distribution system. An example treatment in this study, which is disclosing the advantage of installing capacitor at the induction generator terminal in enhancing the utilization of the induction generator, had been presented.

Wind Power in Power Systems
Wind Power in Power Systems

Author: Thomas Ackermann

Publisher: John Wiley & Sons

Published: 2012-04-23

Total Pages: 1132

ISBN-13: 111994208X

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The second edition of the highly acclaimed Wind Power in Power Systems has been thoroughly revised and expanded to reflect the latest challenges associated with increasing wind power penetration levels. Since its first release, practical experiences with high wind power penetration levels have significantly increased. This book presents an overview of the lessons learned in integrating wind power into power systems and provides an outlook of the relevant issues and solutions to allow even higher wind power penetration levels. This includes the development of standard wind turbine simulation models. This extensive update has 23 brand new chapters in cutting-edge areas including offshore wind farms and storage options, performance validation and certification for grid codes, and the provision of reactive power and voltage control from wind power plants. Key features: Offers an international perspective on integrating a high penetration of wind power into the power system, from basic network interconnection to industry deregulation; Outlines the methodology and results of European and North American large-scale grid integration studies; Extensive practical experience from wind power and power system experts and transmission systems operators in Germany, Denmark, Spain, UK, Ireland, USA, China and New Zealand; Presents various wind turbine designs from the electrical perspective and models for their simulation, and discusses industry standards and world-wide grid codes, along with power quality issues; Considers concepts to increase penetration of wind power in power systems, from wind turbine, power plant and power system redesign to smart grid and storage solutions. Carefully edited for a highly coherent structure, this work remains an essential reference for power system engineers, transmission and distribution network operator and planner, wind turbine designers, wind project developers and wind energy consultants dealing with the integration of wind power into the distribution or transmission network. Up-to-date and comprehensive, it is also useful for graduate students, researchers, regulation authorities, and policy makers who work in the area of wind power and need to understand the relevant power system integration issues.

Voltage Stability in Electrical Power Systems
Voltage Stability in Electrical Power Systems

Author: Farid Karbalaei

Publisher: John Wiley & Sons

Published: 2022-12-02

Total Pages: 292

ISBN-13: 1119830656

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Voltage Stability in Electrical Power Systems Explore critical topics and the latest research in voltage stability in electric power systems In Voltage Stability in Electrical Power Systems: Concepts, Assessment, and Methods for Improvement, three distinguished electrical engineers deliver a comprehensive discussion of voltage stability analysis in electrical power systems. The book discusses the concept of voltage stability, effective factors and devices, and suitable system modeling, offering readers an authoritative overview of the subject and strategies to prevent instability in power systems. The authors explore critical topics such as load and load tap changer (LTC) transformer modeling and the impact of distributed generation and transmission-distribution interactions on voltage stability. They also present practical methods to improve voltage stability. Readers will also find: Thorough introductions to voltage stability, effective factors and devices, and suitable systems modeling Comprehensive explorations of voltage stability assessment methods, including the continuation power flow methods and PV-curve fitting In-depth explorations of methods of improving voltage stability, including preventive and corrective methods Fulsome presentations of measurement-based indices and model-based indices of stability assessment Perfect for engineers and other professionals designing electric power systems, Voltage Stability in Electrical Power Systems: Concepts, Assessment, and Methods for Improvement will also earn a place in the libraries of graduate and senior undergraduate students with an interest in power systems.

Distributed Generation
Distributed Generation

Author: Loi Lei Lai

Publisher: John Wiley & Sons

Published: 2008-03-11

Total Pages: 262

ISBN-13: 9780470511817

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Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generator (IG) is the most commonly used and cheapest technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples to better demonstrate how the integration of energy sources can be accomplished. The book also provides the practical tools needed to model and implement new techniques for generating energy through isolated or grid-connected systems. Besides a chapter introducing the technical, economic and environmental impacts of distributed generation, this book includes: an examination of various phase-balancing schemes for a three-phase IG operating on a single-phase power system; a coupled circuit 2-D finite element analysis of a grid-connected IG, with Steinmetz connection; a study of self-excited induction generator (SEIG) schemes for autonomous power systems, and the voltage and frequency control of SEIG with a slip-ring machine (SESRIG); a report on a PM synchronous generator with inset rotor for achieving a reduced voltage regulation when supplying an autonomous power system, and an analysis of its performance using a two-axis model and finite element method; experimental work on various IG and SEIG schemes. This book is a must-read for engineers, consultants, regulators, and environmentalists involved in energy production and delivery, helping them to evaluate renewable energy sources and to integrate these into an efficient energy delivery system. It is also a superior reference for undergraduates and postgraduates. Designers, operators, and planners will appreciate its unique contribution to the literature in this field.

Integration of Distributed Generation in the Power System
Integration of Distributed Generation in the Power System

Author: Math H. J. Bollen

Publisher: John Wiley & Sons

Published: 2011-08-09

Total Pages: 526

ISBN-13: 0470643374

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The integration of new sources of energy like wind power, solar-power, small-scale generation, or combined heat and power in the power grid is something that impacts a lot of stakeholders: network companies (both distribution and transmission), the owners and operators of the DG units, other end-users of the power grid (including normal consumers like you and me) and not in the least policy makers and regulators. There is a lot of misunderstanding about the impact of DG on the power grid, with one side (including mainly some but certainly not all, network companies) claiming that the lights will go out soon, whereas the other side (including some DG operators and large parks of the general public) claiming that there is nothing to worry about and that it's all a conspiracy of the large production companies that want to protect their own interests and keep the electricity price high. The authors are of the strong opinion that this is NOT the way one should approach such an important subject as the integration of new, more environmentally friendly, sources of energy in the power grid. With this book the authors aim to bring some clarity to the debate allowing all stakeholders together to move to a solution. This book will introduce systematic and transparent methods for quantifying the impact of DG on the power grid.