Design Considerations for a Voltage-Boosting DC-AC Modular Multilevel Converter

The Modular Multilevel Converter (M2C) is a relatively recent addition to the family of multilevel power converters. This paper describes the topology, dynamic phasor modeling, and operation of a voltage boosting DC-AC Modular Multilevel Converter. A “Semi-Full Bridge” submodule with only two controlled semiconductors and immune to shoot-through faults suitable for such applications is presented. An inherently scalable averaged model using dynamic phasors is also presented, with a control methodology to reduce losses and attenuate unwanted current harmonics in the arms and capacitors. Verification of the model is provided with simulations and an experimental prototype power converter

Adaptation of the Electric Machines Learning Process to the European Higher, Education Area

In this paper the basic lines of a complete teaching methodology that has been developed to adaptthe electric machines learning process to the European Higher Education Area (EHEA) arepresented. New teaching materials that are specific to Electric Machines have been created(textbooks, self-learning e-books, guidelines for achieving teamwork research, etc.). Working ingroups has been promoted, as well as problem solving and self-learning exercises, all of which areevaluated in a way that encourages students' participation. Finally, the students' learning process inthe lab has been improved by the development both of a new methodology to follow in the lab andnew workbenches with industrial machines that are easier to use and also enable the labexperiments to be automated. Finally, the first results obtained as a result of applying the proposedmethodology are presented

Design Parameter Analysis of Point Absorber WEC via an Evolutionary-Algorithm-Based Dimensioning Tool

Wave energy conversion has an essential difference from other renewable energies since the dependence between the devices design and the energy resource is stronger. Dimensioning is therefore considered a key stage when a design project of Wave Energy Converters (WEC) is undertaken. Location, WEC concept, Power Take-Off (PTO) type, control strategy and hydrodynamic resonance considerations are some of the critical aspects to take into account to achieve a good performance. The paper proposes an automatic dimensioning methodology to be accomplished at the initial design project stages and the following elements are described to carry out the study: an optimization design algorithm, its objective functions and restrictions, a PTO model, as well as a procedure to evaluate the WEC energy production. After that, a parametric analysis is included considering different combinations of the key parameters previously introduced. A variety of study cases are analysed from the point of view of energy production for different design-parameters and all of them are compared with a reference case. Finally, a discussion is presented based on the results obtained, and some recommendations to face the WEC design stage are given

Distributed generation system with PEM fuel cell for electrical power quality improvement

In this paper, a physical model for a distributed generation (DG) system with power quality improvement capability is presented. The generating system consists of a 5 kW PEM fuel cell, a natural gas reformer, hydrogen storage bottles and a bank of ultra-capacitors. Additional power quality functions are implemented with a vector-controlled electronic converter for regulating the injected power. The capabilities of the system were experimentally tested on a scaled electrical network. It is composed of different lines, built with linear inductances and resistances, and taking into account both linear and non-linear loads. The ability to improve power quality was tested by means of different voltage and frequency perturbations produced on the physical model electrical network

Characterization of the Rotor Magnetic Field in a Brushless Doubly Fed Induction Machine.

The large increase in wind generation could improve the final development of wind systems with brushless doubly-fed induction machines (BDFIM) as an alternative to the doubly-fed asynchronous machines. For this reason, a detailed study of several aspects of the BDFIM design, as well as of its rotor configuration, is absolutely essential. In this paper, the authors present an alternative formulation of the BDFIM operating principle in synchronous mode. Besides the basic equation of the machine operation, it presents as main advantage the precise characterization of all the magnetic field components in a BDFIM with idealized stator windings and an idealized rotor cage. Based on this formulation, the paper provides a standard that may be used to compare the fields created by different real BDFIMs. This standard has been validated by laboratory tests

Comparison of Current Control Strategies Applied to a Boost-Rectifier Connected to a Direct Drive Wave Energy Converter

Direct drive wave energy converters are characterized by a direct conversion of the wave energy into electricity with no intermediate mechanical conversion system. For this reason, optimization methods for maximizing the absorbed power have to be designed for acting on the electrical generator. Besides, this type of system requires power electronics to be connected to the grid. This paper evaluates three different current control strategies applied to a boost-rectifier in the ac-dc stage as part of an optimization method. The system is implemented and simulated in MATLAB/Simulink with real random waves. In direct drive wave energy conversion, unlike the original application of these controllers, the input electrical power is highly variable, both in amplitude and frequency. The controllers are assessed under these conditions and their advantages and disadvantages are presented

Emulation of an OWC Ocean Energy Plant With PMSG and Irregular Wave Model

Ocean energy is a promising resource for renewable electricity generation that presents many advantages, such as being more predictable than wind energy, but also some disadvantages such as large and slow amplitude variations in the generated power. This paper presents a hardware-in-the-loop prototype that allows the study of the electric power profile generated by a wave power plant based on the oscillating water column (OWC) principle. In particular, it facilitates the development of new solutions to improve the intermittent profile of the power fed into the grid or the test of the OWC behavior when facing a voltage dip. Also, to obtain a more realistic model behavior, statistical models of real waves have been implemented

Analysis of the impact of charging of PHEV and EV in Spain

This paper studies the effect of different penetration rates of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EV) in the Spanish electrical system. A stochastic model for the average trip evaluation and for the arriving and departure times is used to determine the availability of the vehicles for charging. A novel advanced charging algorithm is proposed, which avoids any communication among all agents. Its performance is determined through different charging scenarios

Computer-Based Simulation and Scaled Laboratory Bench System for the Teaching and Training of Engineers on the Control of Doubly Fed Induction Wind Generators

Among the existing renewable sources, wind energy is reaching production rates that are becoming important on the worldwide energy scene. Since the control of these wind generators is a very technical discipline, practical teaching methodologies are of special relevance. Paradoxically, in the past, the training of engineers specializing in this area has lacked the practical component represented by field tests, due to the difficulty of access to this kind of installation. This paper presents a system designed for use both in teaching and training procedures for control strategies for wind generators with doubly fed induction generator (DFIG) technology. The system includes two phases or levels of use: the first being a simulation phase based on computer models, and the second, an advanced level which allows for the conducting of tests on a laboratory scaled workbench composed of a wind turbine emulator coupled to an electric generator. With this equipment, the effectiveness of the wind generator regulation systems can be analyzed from the point of view of the maximum power point tracking control strategy, as well as from that of the contribution produced by the wind generator to the control of the operation of the electric grid to which it is connected

A Novel Education Proposal: Devising an Electric Power System

The study of electric power systems within the field of Electrical Engineering is usually approached by computer simulation because any actual test is quite complex to be implemented, especially with renewable energies. Having the aim to improve student learning about this topic, a new subject called “Devising an Electric Power System” was organized following a CDIO (Conceive-Design-Implement-Operate) approach. The subject is programmed for one academic year and based entirely on laboratory work. The students are divided into three teams. Every team would have to work on a power system that includes a solar PV generator and a pumping controlled drive, both connected to a three–phase grid. The third and last part of the subject is focused on “electric utility” business strategy. In the final day of the course a competition between the three teams takes place