Abstract
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.

Abstract
This paper discusses the effective contribution of a Learning Object (LO) to teach circuit theory based on research conducted with students of higher education, and their interaction with a teacher of Electronics. From the results of such research, it is pointed out which features one wants in the LO so that it successfully promotes learning. It is in this perspective that this work was conceived having as goal the development of LO, admitting that this may be a possible alternative to represent models of interactions, which occur within the area, thereby improving understanding of physical concepts, in particular those involved with the subject of electrical circuits. It has also as objective to characterize the learning process through a series of situations that are replicated leading to a set of behaviors from the students. It is assumed that the use of this tool can lead to acquiring a specific set of skills, a better practice and meaningful learning.

Abstract
With the development of synchronized phasor measurement technology in recent years, it gains great interest the use of PMU measurements to improve state estimation performances due to their synchronized characteristics and high data transmission speedThe ability of the Phasor Measurement Units (PMU) to directly measure the system state is a key over SCADA measurement system. PMU measurements are superior to the conventional SCADA measurements in terms of resolution and accuracy. Since the majority of measurements in existing estimators are from conventional SCADA measurement system, it is hard to be fully replaced by PMUs in the near future so state estimators including both phasor and conventional SCADA measurements are being consideredIn this paper, a mixed measurement (SCADA and PMU measurements) state estimator is proposedSeveral useful measures for evaluating various aspects of the performance of the mixed measurement state estimator are proposed and explainedState Estimator validity, performance and characteristics of the results on IEEE 14 bus test system and IEEE 30 bus test system are presented. © ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING.

Abstract
With the development of synchronized phasor measurement technology in recent years, it gains great interest the use of PMU measurements to improve state estimation performances due to their synchronized characteristics and high data transmission speedThe ability of the Phasor Measurement Units (PMU) to directly measure the system state is a key over SCADA measurement system. PMU measurements are superior to the conventional SCADA measurements in terms of resolution and accuracy. Since the majority of measurements in existing estimators are from conventional SCADA measurement system, it is hard to be fully replaced by PMUs in the near future so state estimators including both phasor and conventional SCADA measurements are being consideredIn this paper, a mixed measurement (SCADA and PMU measurements) state estimator is proposedSeveral useful measures for evaluating various aspects of the performance of the mixed measurement state estimator are proposed and explainedState Estimator validity, performance and characteristics of the results on IEEE 14 bus test system and IEEE 30 bus test system are presented. © ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING.

Abstract
Currently, it is an ordinary procedure to restrict the use of renewables, mainly wind power, to accommodate a more stable set of generating units (e.g.: thermal units) to supply the load. The purpose of this paper is to discuss particular aspects from the adequacy and security evaluation of generation and transmission (G&T) system that must be revised due to the massive integration of wind power in the present and future energy systems. By running a sequential Monte Carlo simulation (SMCS) algorithm it is possible to assess the system adequacy identifying possible security constrains. The demonstration cases are based on the modified IEEE-RTS 79 system and a small planned configuration for a real G&T system, typically radial. The results extracted from the case studies illustrate that the impact resulting from the massive integration of renewable sources should not be assessed from the adequacy evaluation perspective without considering system security issues.

Abstract
In the classical model of the photovoltaic (PV) cell/module, based on the single-exponential or double-exponential representation of PV cell/module behavior, parasitic parameters are ignored. Their presence, however, has multiple effects, such as the maximum power point tracking on the current-voltage curve, the switching ON/OFF of the inverters for grid connection, and the electrical safety of persons against indirect contact due to ground leakage currents and lightning phenomena. The effects of parasitic parameters can be visualized in the experimental results gathered through the transient charge of an external capacitor connected to the PV generator terminals. The impact of the parasitic components is different when considering a single PV module or a PV array composed of several PV modules. At the module scale, an oscillation occurs in the initial part of the current waveform, which indicates the presence of some inductive components. At the array scale, the inductive phenomena are overdamped, and parasitic capacitive effects become predominant. This paper shows how to determine the parameters of an extended model of PV modules embedding the parasitic parameter effects. It starts from the experimental results obtained from the fast-sampled voltage and current waveforms during the transient charge of an external capacitor. Numerical examples taken from real cases with different PV technologies are provided.