A PRE THESIS SYNOPSIS ON Comparative Analysis of Faults for a Grid Connected WTG For a project Report to be submitted in partial fulfillment For the requirement of the Award of Degree of M. Tech (ENERGY MANAGEMENT SYSTEM) BY RASHTRASANT TUKDOJI MAHARAJ NAGPUR UNIVERSITY, NAGPUR (M.S.) SUBMITTED BY Anand.V.Satpute Third Sem, M.Tech. (E.M.S.) SUPERVISOR Subroto Dutt Department Of Electrical Engineering DEPARTMENT OF ELECTRICAL ENGINEERING RAJIV GANDHI COLLEGE OF ENGINEERING RESEARCH AND TECHNOLOGY, CHANDRAPUR 2012-13 CERTIFICATE This is to certify that Mr. Anand.V.Satpute is carrying out project entitled Comparitive Analysis of Faults for a Grid Connected WTG. towards partial fulfillment for the requirement of thr award of M-tech (Energy Management System) by RTM Nagpur University. This is the pre-thesis synopsis & accordingly the project work shall be carried out exclusively on the line proposed here. The work shall be original & exclusive to be carried out by the candidate under my supervision & shall not be allowed to be used for award of any other degree. Certified on this_______________day of ______2012, at Chandrapur. DEPARTMENT OF ELECTRICAL ENGINEERING RAJIV GANDHI COLLEGE OF ENGINEERING RESEARCH AND TECHNOLOGY, CHANDRAPUR 2012-13 ABSTRACT Many power system operators issue grid connection requirements that specifically address wind turbines and demand them to ride through transient faults. Understandings of such faults provide a blue print for the wind farm operators to extend stable performance in power delivery systems. A wind farm must be designed and modeled in the way so that whenever that to be integrated with the existing power system network, should must synchronized with reference to all the parameters dictates the reliable behavior of the same . For such integration a pre requisite is needed that to study and analyse the fault patterns may occur probably to whole the system. WTG is meant for generating electrical power, hence a wind farm is the representation of numbers of WTGs connected in proper manner. In this proposed work possible line faults that occurs in the power system is aimed to simulate and the pre and post response will be analyzed. INDEX 1 Introduction 2 Literature Survey 3 Proposed Work 4 Methodology 5 Chapter Scheme 6 Conclusions 7 References 1. Introduction Electricity can be generated in many ways. In each case, a fuel is used to turn a turbine, which drives a generator, which feeds the grid. The turbines are designed to suit the particular fuel characteristics. The same applies to wind-generated electricity: the wind is the fuel, which drives the turbine, which generates electricity. But unlike fossil fuels, it is free and clean. As per the World Energy Outlook 2010, the prospect renewable energy based electricity generation hinge critically on government policies to encourage their development. Worldwide the share of renewable in electricity increases from 19% in 2008 to 35% in 2035 in the new policies scenario. The rising cost of fossil fuels and declining make renewable more competitive with conventional technology. Hydro power has been the dominant renewable source of electricity for over a century .the recent string growth in new technologies for wind power and solar power has created expectation among policy makers and the industry alike that these technologies will make a major contribution to meet growing electricity needs in the near future. It has also been forecasted that the increase in electricity generation from renewable sources between 208 to 2035 will be primarily derived from wind and hydro power which will contribute 36% and 31% additional demand respectively.[8] . The installation of a wind power plant has significantly increased since several years due to the recent necessity of creating renewable, sustainable and clean energy sources. Before the accomplishment of a wind power project many pre--studies are required in order to verify the possibility of integrating a wind power plant in the electrical network. The creation of models in different software and their simulation can bring the insurance of a secure operation that meets the numerous requirements imposed by the electrical system. In many countries all over the world wind power is expanding and covers a steadily increasing part of these countries’ power demand. However, if wind turbines are to substitute for conventional power plants they have to take over many of the control tasks as well as protection schemes those keep the power system stable [9]. One of these control tasks is to ride through transient faults in power systems [29]. This means that generation must not be lost due to voltage excursions caused by transient faults. As wind power penetration increases, the respective power system operators are concerned about the stability and reliability of their networks [30]. This is why many power system operators issue grid connection requirements that specifically address wind turbines and demand them to ride through transient faults. Understandings of such faults provide a blue print for the wind farm operators to extend stable performance in power delivery systems. A wind farm must be designed and modeled in the way so that whenever that to be integrated with the existing power system network, should must synchronized with reference to all the parameters dictates the reliable behavior of the same [29]. For such integration a pre requisite is needed that to study and analyse the fault patterns may occur probably to whole the system. 2. Literature survey Comparitive Analysis of Faults for a Grid Connected WTG. i. H.M. Abdel Mageed Sayed, S.M. Sharaf , S.E. Elmasry, M. Elharony,“Simulation of the Different Transmission Line Faults for a Grid Connected Wind Farm with Different Types of Generators” IJPEDS Vol.1, No.2, December 2011. This paper aims to simulate a wind farm model that includes wind turbine and DFIG and describes the simulation of the different faults that occur along the transmission line of the power system analyzed and discussed to compare the transient response of DFIG. ii. Kumar.P.V,”Transient Fault Response of Grid Connected Wind Electric Generators” PEDES 2006 available on http://www.lw20.com/201106041344703.Html Author’s dealt with simulation studies on grid connected wind electric generators (WEG). Their dynamic responses to wind speed variations and transient faults on transmission line are studied in this paper. iii. Xingjia Yao, “Uninterrupted operation of doubly-fed induction generator based wind turbine during network” ISEMS 8 OCT 2007.. available on http://pubget.com/paper/pgtmp_4711b12a0112e6888c7c7d5f44c4eef6/ This paper mainly discusses the method to improve the uninterrupted operation ability of doubly-fed induction generator (DFIG) based wind turbine under voltage sags. iv. Arulampalam.A,” Fault Ride Through operation of a DFIG wind farm connected through VSC HVDC” ICIIS 2010. This paper discuss the electromechanical transients during a de-loading of a DFIG turbine and the Fault Ride Through (FRT) capability of a DFIG wind farm. .The electromechanical oscillations during a deloading operation of a DFIG are simulated. v. Mohseni.M,”Impacts of symmetrical and asymmetrical voltage sags of DFIG based Wind Turbine” Power Electronics IEEE Transactions on May 2011. This paper presents a new analysis into the impacts of various symmetrical and asymmetrical voltage sags on doubly fed induction generator (DFIG)-based wind turbines. vi. V. Gevorgian, M. Singh, and E. Muljadi,“Symmetrical and Unsymmetrical Fault Currents of a Wind Power Plant “ IEEE Power and Energy Society General Meeting San Diego, California July 26, 2012. This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. Both symmetrical faults and unsymmetrical faults are investigated. vii. Gabriele Michalke, Anca D. Hansen, Thomas Hartkopf,” Dynamic behaviour of a DFIG wind turbine subjected to power system faults” Available on www.risoe.dk/rispubl/art/2007_154_paper.pdf Authors in this paper presents a study of the dynamic interaction between variable speed DFIG wind turbines and the power system subjected to disturbances, such as short circuit faults. 2.1 Objective of the Proposed Work WTG is meant for generating electrical power, hence a wind farm is the representation of numbers of WTGs connected in proper manner. A wind farm must be designed and modeled in the way so that whenever that to be integrated with the existing power system network, should must synchronized with reference to all the parameters dictates the reliable behavior of the same. For such an integration a pre requisite is needed that to study and analyse the fault patterns may occur probably to whole the system. In this proposed work possible line faults that may be occur in the power system is aimed to simulate and the pre and post response will be analyzed. 3. Wind Farm and Fault Analysis Fig. 1. Grid-connected DFIG WT with a back-to-back converter Wind Power generation has significantly increased during the last years. The European wind power industry has formulated generation targets of 180 GW in 2020 and 300 GW by the end of 2030 [10]–[14]. Experiences in countries with high penetration of wind power, such as Denmark, Spain, and Germany, together with national power system studies [8], have demonstrated that this scenario is technically and economically feasible. The transmission system operators (TSOs) currently demand more reliability to wind power technologies; therefore, standards with regard to the connection, operation, and maintenance of such power plants become more restrictive [16]–[20]. 50% of the installed wind turbines (WTs) worldwide in on-shore applications [21]. The layout of a WT that is based on this technology is shown in Fig. 1.As explained in [22], the success of this kind of WTs lies in the fact that it offers a good solution for controlling the active and reactive power generation, in a reasonable ±30% range around the generator’s nominal power [23], [24] Although the operation of DFIG WTs is satisfactory under grid balanced conditions, its performance is not so good when affected by voltage sags or network unbalances [26], [25]. Under such conditions, the electromagnetic transient of the DFIG gives rise to high overcurrents in the converter, which may produce its disconnection to avoid damages in the semiconductors. 3.1 Different Faults In an electric power system, a fault is any abnormal flow of electric current. For example, a short circuit is a fault in which current flow bypasses the normal load. An open-circuit fault occurs if a circuit is interrupted by some failure. In three-phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a "ground fault" or "earth fault", current flows into the earth. The prospective short circuit current of a fault can be calculated for power systems. In power systems, protective devices detect fault conditions and operate circuit breakers and other devices to limit the loss of service due to a failure. An asymmetric or unbalanced fault does not affect each of the three phases equally. Common types of asymmetric faults, and their causes: Line-to-line - a short circuit between lines, caused by ionization of air, or when lines come into physical contact, for example due to a broken insulator. Line-to-ground - a short circuit between one line and ground, very often caused by physical contact, for example due to lightning or other storm damage Double line-to-ground - two lines come into contact with the ground (and each other), also commonly due to storm damage. In this proposed work possible line faults that may be occur in the power system is aimed to simulate and the pre and post response will be analyzed. In addition to the objective results obtained will be compared with SCIG wind electricity generation system. 4. Methodology Introductory literature survey will be extended to the detailed survey. Wind energy generation scenario of India will be then studied. In the next phase WTG technology and types will be studied for modeling of DFIG. Along with the same different types of fault and their causes in occurance will be studied to formulate them for mathematical modeling. Thus, a simulation model of the DFIG wind turbine will be developed in the power system simulations software MATLAB and different case studies will be carried out for the understanding of the grid fault impact on both DFIG wind turbines and on the power system itself[31],[32] 5. Chapter scheme Introduction Literature Survey Wind Energy Generation Scenario in India WTG technology Modeling of DFIG. Simulation of Wind Farm Faults Result and Discussion Conclusion and Future Scope References 6. Conclusion A wind farm must be designed and modeled in the way so that whenever that to be integrated with the existing power system network, should must synchronized with reference to all the parameters dictates the reliable behavior of the same. For such integration a pre requisite is needed that to study and analyse the fault patterns may occur probably to whole the system. 7. References [1] H.M. Abdel Mageed Sayed, S.M. Sharaf , S.E. Elmasry, M. Elharony,“Simulation of the Different Transmission Line Faults for a Grid Connected Wind Farm with Different Types of Generators” IJPEDS Vol.1, No.2, December 2011. [2] Kumar.P.V,”Transient Fault Response of Grid Connected Wind Electric Generators” PEDES 2006 http://www.lw20.com/201106041344703.Html [3] Xingjia Yao, “Uninterrupted operation of doubly-fed induction generator based wind turbine during network” ISEMS 8 OCT 2007. http://pubget.com/paper/pgtmp_4711b12a0112e6888c7c7d5f44c4eef6/ [4] Arulampalam.A,” Fault Ride Through operation of a DFIG wind farm connected through VSC HVDC” ICIIS 2010. [5] Mohseni.M,”Impacts of symmetrical and asymmetrical voltage sags of DFIG based Wind Turbine” Power Electronics IEEE Transactions on May 2011. [6]. V. Gevorgian, M. Singh, and E. Muljadi,“Symmetrical and Unsymmetrical Fault Currents of a Wind Power Plant “ IEEE Power and Energy Society General Meeting San Diego, California July 26, 2012. [7] Gabriele Michalke, Anca D. 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