...Stability of Power Systems Student’s Name The Name of the Class (Course) Professor (Tutor) The Name of the School (University) The City and State where it is located The Date Date of Submission Stability of Power Systems Power systems are studied under the branch of engineering known as power (systems) engineering. The subfield is concerned with the study of how electric power is generated, transmitted, distributed, and utilized. It also analyzes the electrical and electronics devices and gadgets that are connected to the power systems to assist in their functioning. Such devices include motors, transformers, and generators. Such devices offer optimal functionality when they are used under the right conditions and when they are stable. Stability is of critical importance to power systems. As such, this essay describes some of the fundamental concepts of the stability of power systems. It also highlights how balance is achieved in a synchronous generator. A system is said to be stable if it can regain its normal equilibrium state after an imposed disturbance is removed. Power system stability is referenced from a particular initial operating condition. As such, a system is said to be stable if the opposing forces within it are balanced and at a perfect equilibrium. Instability is caused by imbalance sustained when the opposing forces are not equal. The resulting disturbance causes instability within the power system (Grigsby 2012, p. 10). ...
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...Stability of Power Systems Student’s Name The Name of the Class (Course) Professor (Tutor) The Name of the School (University) The City and State where it is located The Date Date of Submission Stability of Power Systems Power systems are studied under the branch of engineering known as power (systems) engineering. The subfield is concerned with the study of how electric power is generated, transmitted, distributed, and utilized. It also analyzes the electrical and electronics devices and gadgets that are connected to the power systems to assist in their functioning. Such devices include motors, transformers, and generators. Such devices offer optimal functionality when they are used under the right conditions and when they are stable. Stability is of critical importance to power systems. As such, this essay describes some of the fundamental concepts of the stability of power systems. It also highlights how balance is achieved in a synchronous generator. A system is said to be stable if it can regain its normal equilibrium state after an imposed disturbance is removed. Power system stability is referenced from a particular initial operating condition. As such, a system is said to be stable if the opposing forces within it are balanced and at a perfect equilibrium. Instability is caused by imbalance sustained when the opposing forces are not equal. The resulting disturbance causes instability within the power system (Grigsby 2012, p...
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...the power system network to be studied is designed and simulated using the software, CYME 5.02 Power System Simulation Software. The system chosen for the study is that of a two machines system, involving two synchronous generators connected to a substation grid through circuit transmission lines. In order to gain much further comparison of the results, it is considered also the two different types of synchronous generators’ rotor types, salient-pole rotor and non-salient pole (round) type rotor. Transient stability studies are associated to the effects of faults on the synchronism of the generators. These disturbances may include faults on loss of load, loss of generation or loss of system components such as transformers or transmission lines. When fault is applied, the power generated from the nearby machine is reduced, producing speed differences during the time interval of the fault occurrence. Fig 1. Two machines system When the generator electrical load is suddenly increased, the electrical power exceeds the mechanical power input. This power deficiency is supplied by the kinetic energy stored in the rotating system. The reduction in kinetic energy resulted turbine speed to drop and as well as the frequency of the generator. This change of speed can be adjusted by a governor, which is an attachment to a machine for automatic control or limitation speed; it controls the energy through the prime mover to control its power. Governor changes the input valve to change...
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...ELECTRICAL MACHINES G.A.N BRIGHT REPORT PRESENTATION 1. Title 2. Aim 3. Apparatus/Equipments 4. Procedure/Method 5. Theory/Results 6. Safety Precaution 7. Conclusion N/B: Safety Precaution must be minimum of four PART 1 SYNCHRONOUS MACHINE 1.1 INTRODUCTION A synchronous machine is an a.c machine in which the rotor moves at a speed which bears a constant relationship to the frequency of currents, in the armature winding. A synchronous machine is one of the important type of electric machines. Large a.c networks operating at constant frequency of 50Hz rely almost exclusively on synchronous generators, also called the alternators, for the supply of electrical energy. Private, stand-by and peak load plants with diesel or gas-turbine prime movers also have synchronous generators. Synchronous motors provide constant speed industrial drives with the possibility of power factor correction. Synchronous machine are generally constructed in larger sizes. Small size alternators are not economical. The modern trend is to build alternators of very large size capable of generating 500MVA or even more. The synchronous motor is rarely built in small sizes owing to superior performance characteristics and economical construction of induction motors. 1.2 OPERATING PRINCIPLE The operating principle of a synchronous machine is fundamentally the same as that of a d.c machine, but, unlike the latter, in the synchronous machine...
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...INTRODUCTION: A synchronous machine rotates at a constant speed in the steady state. Unlike induction machine the rotating air gap field and the rotor in the synchronous machine rotate at the same speed called the synchronous speed. A synchronous machine can operate as both motor and generator. They are used primarily as electrical power generators. They are usually large machines generating electrical power at hydro, nuclear or thermal power stations. Synchronous generators with power rating of several hundred MVAs are quite common in generating stations. Synchronous generators are the primary energy conversion devices of the world’s electrical power systems today. Because the rotor speed is proportional to the frequency of excitation, synchronous motors can be used in situations where constant speed drive is required. In industry, synchronous motors are used mainly where constant speed is desired. In industrial drivers, therefore synchronous motors are not as widely used as induction or dc motors a linear version of the synchronous motor (LSM) is being considered for high speed transportation systems of the future. An important feature of the synchronous motor is that it can drop either lagging or leading reactive current from the ac supply systems. A synchronous machine is a doubly excited machine. Its rotor poles are excited by a dc current and its starter buildings are connected to the ac supply. The air gap flux is therefore the resultant of the fluxes due to both...
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...Chapter 1 INTRODUCTION 1.1 Background of the Study A synchronous electric motor is an AC motor distinguished by a rotor spinning with coils passing magnets at the same rate as the power supply frequency and resulting rotating magnetic field which drives it. Another way of saying this is that it does not rely on slip under usual operating conditions and as a result, produces torque at synchronous speed. Synchronous motors can be contrasted with an induction, which must slip in order to produce torque. They operate synchronously with line frequency. As with squirrel-cage induction motors, speed is determined by the number of pairs of poles and the line frequency. Synchronous motors are available in sub-fractional self-excited sizes to high-horsepower direct-current excited industrial sizes. In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. In high-horsepower industrial sizes, the synchronous motor provides two important functions. First, it is a highly efficient means of converting ac energy to work. Second, it can operate at leading or unity power factor and thereby provide power-factor correction. The operation of a synchronous motor is simple to imagine. The armature winding, when excited by a poly-phase (usually 3-phase) supply, creates a rotating magnetic field inside the motor. The field winding, which acts as a permanent magnet, simply locks in with the rotating magnetic field and rotates along with...
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...Torque Simulation Method for Permanent-Magnet Synchronous Machines Chun-Yu Hsiao *, Sheng-Nian Yeh and Jonq-Chin Hwang Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan; E-Mails: snyeh@mail.ntust.edu.tw (S.-N.Y.); jchwang@ee.ntust.edu.tw (J.-C.H.) * Author to whom correspondence should be addressed; E-Mail: D9607101@mail.ntust.edu.tw; Tel.: +886-921135781; Fax: +886-2-27376699. Received: 16 September 2011; in revised form: 22 November 2011 / Accepted: 30 November 2011 / Published: 6 December 2011 Abstract: Cogging torque exists between rotor mounted permanent magnets and stator teeth due to magnetic attraction and this is an undesired phenomenon which produces output ripple, vibration and noise in machines. The purpose of this paper is to study the existence and effects of cogging torque, and to present a novel, rapid, half magnet pole pair technique for forecasting and evaluating cogging torque. The technique uses the finite element method as well as Matlab research and development oriented software tools to reduce numerous computing jobs and simulation time. An example of a rotor-skewed structure used to reduce cogging torque of permanent magnet synchronous machines is evaluated and compared with a conventional analysis method for the same motor to verify the effectiveness of the proposed approach. The novel method is proved valuable and suitable for large-capacity machine design. Keywords: cogging torque; permanent...
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...Arab Academy for Science, Technology and Maritime Transport College of Engineering and Technology Department: Electrical and Computer Control Engineering B. Sc. Final Year Project WIND ENERGY Presented By: Ahmed Magdy Ahmed Mokhtar Latifa Ahmed Supervised By: Dr.Amr Magdy DECLARATION I hereby certify that this material, which I now submit for assessment on the programme of study leading to the award of Bachelor of Science in (insert title of degree for which registered) is entirely my own work, that I have exercised reasonable care to ensure that the work is original, and does not to the best of my knowledge breach any law of copyright, and has not been taken from the work of others save and to the extent that such work has been cited and acknowledged within the text of my work. Signed: _____________________________ Registration No.: ___________ Date: 6/7/2013 2 ACKNOWLEDGMENT To my honourable Dr.AMR MAGDY We were honoured and pleased at the same time to work under the supervision of you, you spent a lot of time with us, at the time you definitely had lots of other important occupations. This work would have never been done without your assistance.Very thanking prof.Dr. Yasser Galal on his effort with us the past five years.Thanking engineers Noha Magdy and Ashraf Brdwyli to help us in the project. 3 ABSTRACT Wind energy is fast becoming the most preferable alternative to conventional sources of electric power. wind turbines...
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...A Comprehensive Approach for Sub-Synchronous Resonance Screening Analysis Using Frequency scanning Technique Mahmoud Elfayoumy1, Member, IEEE, and Carlos Grande Moran2, Senior Member, IEEE Abstract: The paper presents a comprehensive approach for sub-synchronous resonance (SSR) screening analysis using a developed frequency scanning tool capable of handling power networks with hundreds of buses. PTI’s software packages like PSS/E and IPLAN programs were used for the development of the SSR tool. The frequency scanning technique scans for the sub-synchronous frequency range between 5 Hz to 59 Hz to determine the system driving point impedance (as a function of frequency) viewed from the neutral point of the generating unit under study. The proposed approach was applied to analyze the SSR phenomenon on several steam and gas driven turbine-generator plants in the northern part of the Western System Coordinating Council (WSCC) control area where several 500kV-transmission lines include series capacitor compensation. As a part of the study, credible contingencies that may lead to a network topology susceptible to SSR phenomenon are identified for proposed plants considered in the study. Key Words: Capacitor Compensated Transmission Lines, Sub-synchronous resonance. IEEE Sub-Synchronous Resonance Working Group report [4] presented the basic theory, problem definition, analytical tools, testing, and countermeasures for mitigating the SSR effects. The report also discussed some...
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...Abstract There is a growing importance for the studies of frequency stability and control of power system with increasing levels of wind power penetration, especially in United States with a goal of 20% or more by 2030. The increasing penetration of wind in to existing synchronous based generation capacity requires the modifications in the procedures of grid frequency control as wind turbine units fail to provide inertial support and primary control reserves during the initial and later stages of frequency events respectively. Therefore, it is necessary for the wind turbines to emulate the response of current synchronous based generation capacity so as to make the power system reliable. This type of response can be introduced by control schemes developed. This report provides a literature review of the frequency control basics and controller schemes used. And also it provides an overview of the basic concepts related to the effects of wind generation on frequency behavior of the power system network. Introduction Frequency stability and control very much dependent on active power balancing is a major research topic concerned with grid integration of large wind farms. The instability of frequency occurs when power system fails to maintain it within particular limits under normal conditions. Active power imbalance indicates the variations in frequency and consequently the constancy of frequency represents the quality of power supply. Such an imbalance can be due...
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...Basic Principles and Functions of Electrical Machines O.I. Okoro, Ph.D.1*, M.U. Agu, Ph.D.1, and E. Chinkuni, Ph.D.2 1 Department of Electrical Engineering, University of Nigeria, Nsukka, Enugu State, Nigeria * E-mail: oiokoro@hotmail.com 2 Polytechnic University of Namibia, Windhoek, Namibia E-mail: chikuni@yahoo.com ABSTRACT Recent advances in power electronics and highspeed microprocessors have led to considerable attention in electrical machines with regard to their applications in industrial drives. This paper brings to the fore, various types of electrical machines, their operations, and applications, as well as the method of determining their parameters. Various ways of protecting electric machines against overloads and mechanical faults are also highlighted. It is anticipated that the work presented in this paper will be of immense benefit to practicing engineers especially in areas of machine design, maintenance, and protection. (Keywords: electrical machines, operation design, maintenance, protection, stator) the stator and alternating currents are induced in the rotor by transformer action. In the synchronous machine, direct current is supplied to the rotor and Alternating Current (A.C.) flows in the stator. On the other hand, a D.C. machine is a machine that is excited from D.C. sources only or that itself acts as a source of D.C. [5]. It is a common practice in industry to employ A.C. motors whenever they are inherently suitable or can be given appropriate characteristics...
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...relationship between theory and research o theories and concepts emerge from the data Emphasis on words/text rather than numbers Systematic exploration of social phenomenon Description and analysis of social situations A “holistic” understanding Flexible and iterative research method Exploring a problem Identifying perceptions of a problem Identifying relevant interventions Investigating feasibility, acceptability & appropriateness of solutions Developing suitable information, education & communication Complementing quantitative data by helping to interpret it Designing more valid survey instruments 3 4 Qualitative techniques not based on numbers Accrual of large amounts of information about a few cases (people, organisations, facilities, programmes, locations) Data used: when the focus of the research is on meaning and feelings (although these can also be studied quantitatively) when working inductively when the researcher accepts that the concepts, terms and issues must be defined by the subjects and not by the researcher in advance when interaction between members of a group is of interest. Research problem Concept Concept Concept 5 Inductively developed theory 6 1 4/02/2015 “Qualitative researchers believe that since humans are conscious of their own behaviour, the thoughts, feelings and perceptions of their informants are vital” (Burns‟, 2000). The…. “methods used by qualitative researchers...
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...UNIVERSITY OF KERALA B. TECH DEGREE COURSE 2008 SCHEME ELECTRICAL AND ELECTRONICS ENGINEERING I to VIII SEMESTER SCHEME AND SYLLABUS BOARD OF STUDIES IN ENGINEERING AND FACULTY OF ENGINEERING AND TECHNOLOGY UNIVERSITY OF KERALA B.Tech Degree Course – 2008 Scheme REGULATIONS 1. Conditions for Admission Candidates for admission to the B.Tech degree course shall be required to have passed the Higher Secondary Examination, Kerala or 12th Standard V.H.S.E., C.B.S.E., I.S.C. or any examination accepted by the university as equivalent thereto obtaining not less than 50% in Mathematics and 50% in Mathematics, Physics and Chemistry/ Bio- technology/ Computer Science/ Biology put together, or a diploma in Engineering awarded by the Board of Technical Education, Kerala or an examination recognized as equivalent thereto after undergoing an institutional course of at least three years securing a minimum of 50 % marks in the final diploma examination subject to the usual concessions allowed for backward classes and other communities as specified from time to time. 2. Duration of the course i) The course for the B.Tech Degree shall extend over a period of four academic years comprising of eight semesters. The first and second semester shall be combined and each semester from third semester onwards shall cover the groups of subjects as given in the curriculum and scheme of examination ii) Each semester shall ordinarily comprise of not less than 400 working periods each of 60 minutes...
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...taken into account to achieve mutual understanding. They gradually come to realize the fact that we all are inhabitants of one planet – the Earth – and have to live together depending on each other, helping each other. But, the Internet is only one of the means to understand this and does not guarantee the comprehension of the people only by the technological and information opportunities that it provides. Everything depends on the people themselves, their mentality, their will and intellect. On the other hand, people in different countries, not only in the cultural and scientific centres, are able to get education in famous universities. Disabled children, invalids can learn at schools, colleges and universities by distance. Those who study at schools, universities, colleges can enhance their knowledge using the educational literature, encyclopaedia, references, dictionaries, databases, which are freely accessed, participating in distance educational courses, in collaborative projects with students from other schools,...
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...MINISTRY OF POWER AND MINERAL RESOURCES OF THE REPUBLIC OF KAZAKHSTAN APPROVED by Prikaz No 189 of the Minister of Power and Mineral Resources of the Republic of Kazakhstan, as of August 26, 2004.) REGULATIONS ON ELECTRICAL INSTALLATIONS OF THE REPUBLIC OF KAZAKHSTAN (PUE) Astana, 2003 TABLE OF CONTENTS SECTION 1: GENERAL REGULATIONS 10 CHAPTER 1.1: GENERAL 10 SCOPE, TERMS AND DEFINITIONS 10 GENERAL REGULATIONS FOR INSTALLATION OF ELECTRICAL EQUIPMENT 11 CONNECTION OF ELECTRICAL INSTALLATIONS TO THE POWER STATIONS 13 COMMISSIONING OF ELECTRICAL INSTALLATIONS 14 CHAPTER 1.2 POWER SUPPLY AND POWER SYSTEMS 14 SCOPE, DEFINITIONS 14 GENERAL REQUIREMENTS 14 CATEGORIES OF POWER CONSUMING DEVICES AND RELIABILITY OF POWER SUPPLY 15 VOLTAGE LEVELS AND CONTROLS, REACTIVE POWER COMPENSATION 16 CHAPTER 1.3 SELECTION OF CONDUCTORS: HEATING, CURRENT DENSITY AND CORONA DISCHARGE CONDITIONS 16 SCOPE 16 SELECTION OF CROSS-SECTION OF CONDUCTORS: HEATING 17 MAXUIMUM CONTINUOUS CURRENTS FOR WIRES, CORDS AND CABLES IN RUBBER OR PLASTIC INSULATION 18 MAXIMUM CONTINUOUS CURRENTS FOR CABLES IN IMPREGNATED PAPER INSULATION 22 MAXIMUM CONTINUOUS CURRENTS FOR BARE WIRES...
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