One of the major problems of voltage stability is the reactive power limit of the system. Improving the system's reactive power handling capacity via Flexible AC transmission System (FACTS) devices is a solution for prevention of voltage instability. In this paper it is studied the influence of Static Synchronous Compensators (STATCOM) and Static Var Compensators (SVC) in dynamic Voltage Stability during Low Voltage Ride Through (LVRT), in wind farms. The wind turbines are equipped with pitch control coupled with a Fixed Speed Induction Generator (FSIG). Due to the nature of asynchronous operation, system voltage instability of wind farms based on FSIG is largely caused by the excessive reactive power absorption by FSIG after a fault due to the large rotor slip gained during fault. Wind farm models based on FSIG and equipped with either STATCOM or SVC are developed in EUROSTAG. The Automatic Voltage Regulators (AVR) of the generating units and the turbine speed governors were modeled in detail. Different load models were used and the Under Load Tap Changers (ULTC) were also taken into account. Finally, some conclusions that provide a better understanding of the dynamic voltage stability of a system with FSIG model during LVRT, using various capacities of STATCOM and SVC are pointed out.

The energy sector is evolving rapidly, namely due to the increasing importance of renewable energy sources. The connection of large amounts of wind power generation poses new challenges for the dynamic voltage stability analysis of an electric power system, which has to be studied. In this paper, the traditional Doubly-Fed Induction Generator model is employed. Based on this model, a crowbar and chopper circuit is set up to protect the turbine during the short-circuit period. The EUROSTAG software package was used for the simulation studies of the system, and numerical results were obtained. Conclusions are drawn that provide a better understanding of the influence of crowbar and chopper protection on Doubly-Fed Induction Generators (DFIG), during low voltage ride through, in a system with wind power generation.

3D worlds provide excellent platforms to achieve performance results when designed for the needs of students, helping them to improve acquisition and allowing greater interaction with contents in a unique way. Virtual Labs are the future of education. Simulations, in which environmental measurements and data analysis can be simulated, are being created to combine real-world environments with information supplied by devices. Virtual Labs (VL) designed for educational purposes in Electrical Engineering provide tasks or problems within a virtual environment or context. Users can explore the environment and examine digital objects as they are designed to support inquiry-based learning and conceptual understanding. Online virtual labs simulate learning environments and are designed to be highly attractive. They can complement the traditional formal learning programs, providing the opportunity for an interaction across a range of learning experiences in 3D. Online learning such as virtual classrooms will become the major part of training education in the future. Virtual lab applications are an engaging and agreeable learning system. Educational virtual labs should not merely focus on the virtual environment; they are useful to help students learn to think creatively and understand the complexities of solving meaningful problems, but the support from the teacher is also important. This study presents a virtual scenario of an instrumentation and measurements laboratory. Students work with representations of electrical circuits focused on learning electrical concepts and circuit analysis, also studying and developing action procedures. The goal is to help them learn to think like engineers. While they are learning about circuit theory, they are also learning to apply the many skills of an engineer such as organizing information for writing technical reports. This work was developed to demonstrate how a desktop Virtual Reality (VR) prototype, "Virtual Electric Manual"VEMA, can be applied to an engineering unit and used to enhance security and resourcefulness in using electrical equipment. Several interactive scenes were developed to illustrate the idea using a measurements and instrumentation laboratory as virtual environment.

The key to succeed in engineering is to master information and the correct use of materials. The learning of the basic concepts of circuit theory, the type of concepts and the form of experimentation, traditionally acquired in educational laboratories, are fundamental and demand new and better tools. The teaching of electric circuit analysis requires students to compare theory and practice of “learning by doing”, using physical or virtual didactic benches. Virtual learning environments (VLE) allow the organization of more controlled courses, combining classroom and distance lessons, the use of only virtual classes, new possibilities of interaction over the internet, and a closer interaction between teachers and students. The goal of this project was to provide a virtual environment where students can learn and experiment electrical concepts in a user-friendly environment. The software used for this project was Autodesk® 3DS Max, VizUp, Wirefusion and Dreamweaver. An experimental model was designed, which provides the necessary simulations as well as a variety of configurations, to be used as part of the learning process. This prototype of a virtual lab, referred to as VEMA (Virtual Electric MAnual), was developed at the Instituto Superior de Engenharia de Coimbra (ISEC/DEE) to teach circuit theory. The aim of this prototype is the development of three-dimensional replicas of real electrical systems, so that the electrical components can be moved virtually, enabling an easy handling and control of lessons and educational activities in a virtual form. The main objective of the prototype is to be a tool for internet-based distance education (e-learning), complementary to the class contents of Circuit Theory I, also used by students and teachers in or outside the classroom.

The work reported in this paper has been conducted by a team from GE-Aircraft Engines, GE-CR&D, and Sundstrand under a contract sponsored by the USAF, Wright Laboratories, WPAFB, Contract No. F33615-90-C-2052. The objective of this contract is to prove the feasibility of an Integral Starter/Generator (IS/G) through the preliminary design stage and demonstrate the starter/ generator technology in the externally mounted version utilizing switched reluctance machine technology. This paper will report on the progress for the EIS/G-system through the initial testing stage. Comparison of the finished hardware with the design results presented earlier will lead of the paper. This is followed by the discussion of the early testing results for the system testing. Recommendation on additional testing will be presented at the end of the paper.

Higher education has evolved in the last decade with the use of information technology. This change was called distance education, a teaching method in which the student does not need to meet with the teacher on a certain day and time. The student may be either at home or at work and may have no interaction with the other parts, either the teacher or other students. It has allowed the institutions to resolve geographical gaps in order to reach the largest number of students. On the other hand, it paved the way for the “non-traditional” universities oriented for “adult work”, in a narrow range of graduation programs, compatible with the current demands from industry. It is also important to mention that distance education is becoming increasingly appropriate for non-academic studies, such as corporate training environments. This paper addresses Circuit Theory systems, more specifically laboratory practices geared towards teaching and learning. The choice was made from observing the needs in the specific context of a measures and instrumentation laboratory, mainly related with access to the means and equipment to carry out laboratory practice. The purpose of the work is the use of virtual experimentation to carry out laboratory practice and also as an alternative tool to meet the needs of access to the means and equipment of the laboratory. In the present case, the basis of the project was the construction of a 3D lab environment (Measures and Instrumentation) where the equipment and the components can be seen and manipulated. The project involves simple electrical schematics, which later can be changed in values, presenting new results, and displays a set of menus and submenus to support experiments. The virtual laboratory can accommodate new devices and scenarios, being adapted to new subjects, such as electric machines and power system analysis of the Electrical Engineering program. This work was developed to demonstrate how a desktop VR prototype, “Virtual Electric Manual” - VEMA, can be applied to an engineering unit and used to enhance security and resourcefulness in using electrical equipment. Several interactive scenes were developed to illustrate the idea using a measurements and instrumentation laboratory as virtual environment. The added value of these various features in the educational context is that they contribute to the construction of new virtual environments, able to benefit the communication between teachers and students and among themselves, thus creating new opportunities for each student to participate more actively in his/her own learning construction process. Rather than being seen as mere information files, these e-learning platforms should be perceived as a means to promote interaction and experimentation through technological resources.