Santiago Arnaltes

Bio: Santiago Arnaltes is an academic researcher from Charles III University of Madrid. The author has contributed to research in topics: AC power & Offshore wind power. The author has an hindex of 19, co-authored 37 publications receiving 2551 citations. Previous affiliations of Santiago Arnaltes include Carlos III Health Institute & Complutense University of Madrid.

Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid

Abstract: Wind energy is a prominent area of application of variable-speed generators operating on the constant grid frequency. This paper describes the operation and control of one of these variable-speed wind generators: the direct driven permanent magnet synchronous generator (PMSG). This generator is connected to the power network by means of a fully controlled frequency converter, which consists of a pulsewidth-modulation (PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator is controlled to obtain maximum power from the incident wind with maximum efficiency under different load conditions. Vector control of the grid-side inverter allows power factor regulation of the windmill. This paper shows the dynamic performance of the complete system. Different experimental tests in a 3-kW prototype have been carried out to verify the benefits of the proposed system.

Simplified Modeling of a DFIG for Transient Studies in Wind Power Applications

Abstract: Improving the fault ride-through (FRT) capability of doubly fed induction generators (DFIGs) in wind power applications is a very important challenge for the wind power industry. The mathematical models of such generators enable us to analyze their response under generic conditions. However, their mathematical complexity does not contribute to simplifying the analysis of the system under transient conditions and hence does not help in finding straightforward solutions for enhancing their FRT. This paper presents a simplified model of the DFIG, which has been extracted from the classical fifth-order model, which can accurately estimate the behavior of the system while significantly reducing its complexity. In this paper, the mathematical deduction of this model will be presented, and simulations and experimental results will be shown to demonstrate the accuracy and reliability of the proposed algorithm.

Direct power control of voltage source inverters with unbalanced grid voltages

Abstract: A new approach of direct power control (DPC) of a voltage source inverter for achieving symmetrical grid currents under unbalanced grid voltage conditions is presented. In these situations, negative sequence components appear on the grid voltage vector, leading to distorted currents if the power is maintained constant. Nevertheless, sinusoidal balanced grid currents can be achieved through control. Several current controllers have already been modified to overcome voltage imbalance with good results. Here, sinusoidal grid currents are obtained by directly controlling power, which becomes a novel approach and keeps DPC philosophy. A phase locked loop is necessary to obtain positive sequence voltage angle. A very simple positive and negative sequence calculator is also used so that power references can be modified in order to obtain balanced grid currents. Simulated and experimental results are presented to confirm the validity of the method.

Table-Based Direct Power Control: A Critical Review for Microgrid Applications

Abstract: Direct power control (DPC) has increasingly gained attention in the last years as a robust and simple control scheme. Yet, the implications of some of the assumptions made by the original table-based DPC are not well explained in the literature. Here, a new formulation of DPC is presented, that allows to analyze the shortcomings of this kind of algorithms, mainly regarding the power limits in which table-based algorithms are valid. This is a key aspect for microgrid applications, as they require a wide range of possible active and reactive power setpoints in order to be able to control the system's voltage and frequency. A new table is then presented that allows to overcome those limitations. The proposed table is valid at any point of the inverter's power limits.

Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays

Abstract: This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I-V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array data sheets, the method finds the best I-V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I-V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulations of PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.

Recent Advances and Industrial Applications of Multilevel Converters

Abstract: Multilevel converters have been under research and development for more than three decades and have found successful industrial application. However, this is still a technology under development, and many new contributions and new commercial topologies have been reported in the last few years. The aim of this paper is to group and review these recent contributions, in order to establish the current state of the art and trends of the technology, to provide readers with a comprehensive and insightful review of where multilevel converter technology stands and is heading. This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry. In addition, new promising topologies are discussed. Recent advances made in modulation and control of multilevel converters are also addressed. A great part of this paper is devoted to show nontraditional applications powered by multilevel converters and how multilevel converters are becoming an enabling technology in many industrial sectors. Finally, some future trends and challenges in the further development of this technology are discussed to motivate future contributions that address open problems and explore new possibilities.

Inductive Teaching and Learning Methods: Definitions, Comparisons, and Research Bases

Abstract: Traditional engineering instruction is deductive, beginning with theories and progressing to the applications of those theories Alternative teaching approaches are more inductive Topics are introduced by presenting specific observations, case studies or problems, and theories are taught or the students are helped to discover them only after the need to know them has been established This study reviews several of the most commonly used inductive teaching methods, including inquiry learning, problem-based learning, project-based learning, case-based teaching, discovery learning, and just-in-time teaching The paper defines each method, highlights commonalities and specific differences, and reviews research on the effectiveness of the methods While the strength of the evidence varies from one method to another, inductive methods are consistently found to be at least equal to, and in general more effective than, traditional deductive methods for achieving a broad range of learning outcomes

AC-microgrids versus DC-microgrids with distributed energy resources: A review

Abstract: This paper presents the latest comprehensive literature review of AC and DC microgrid (MG) systems in connection with distributed generation (DG) units using renewable energy sources (RESs), energy storage systems (ESS) and loads. A survey on the alternative DG units' configurations in the low voltage AC (LVAC) and DC (LVDC) distribution networks with several applications of microgrid systems in the viewpoint of the current and the future consumer equipments energy market is extensively discussed. Based on the economical, technical and environmental benefits of the renewable energy related DG units, a thorough comparison between the two types of microgrid systems is provided. The paper also investigates the feasibility, control and energy management strategies of the two microgrid systems relying on the most current research works. Finally, the generalized relay tripping currents are derived and the protection strategies in microgrid systems are addressed in detail. From this literature survey, it can be revealed that the AC and DC microgrid systems with multiconverter devices are intrinsically potential for the future energy systems to achieve reliability, efficiency and quality power supply.

Multiresonant Frequency-Locked Loop for Grid Synchronization of Power Converters Under Distorted Grid Conditions

Abstract: This paper presents a new multiresonant frequency-adaptive synchronization method for grid-connected power converters that allows estimating not only the positive- and negative-sequence components of the power signal at the fundamental frequency but also other sequence components at other harmonic frequencies. The proposed system is called MSOGI-FLL since it is based on both a harmonic decoupling network consisting of multiple second-order generalized integrators (MSOGIs) and a frequency-locked loop (FLL), which makes the system frequency adaptive. In this paper, the MSOGI-FLL is analyzed for single- and three-phase applications, deducing some key expressions regarding its stability and tuning. Moreover, the performance of the MSOGI-FLL is evaluated by both simulations and experiments to show its capability for detecting different harmonic components in a highly polluted grid scenario.