Enrique Romero-Cadaval

• Institute of Electrical and Electronics Engineers

As the electricity landscape evolves towards greater penetration of renewable energy, voltage source inverters (VSIs) have established themselves as the key power electronics interface between distributed energy resources and the electrical power distribution in modern nanogrids (nGs), capable of working as grid‐following (GFL) converters during gr...

This paper presents a new high-voltage gain single-phase seven-level Boost inverter topology with reduced harmonic distortion. The proposed solution introduces a transformerless multilevel voltage source inverter with reduced number of passive and active power components using only a single input DC power source. The maximum voltage gain is three t...

Over the last few years, there has been a high demand for new or improved isolated DC-DC to fulfill requirements of applications related with RES. In this context, this paper introduces a new isolated DC-DC converter, for use in renewable energy applications. The topology proposed contains an Active quasi-switched Boost Three-Level T-type DC-DC con...

In power systems, nonlinear loads cause harmonic distortion, adversely affecting sensitive equipment such as induction motors, power electronics, and variable-speed drives. This paper presents a novel control strategy that integrates with existing hierarchical control systems to mitigate voltage imbalances and harmonic disturbances in AC-islanded m...

The novel forward-based converter for low-power solar applications is presented in this work. The proposed converter provides an efficient performance in a wide range of the input voltage with low component count. The proposed dc-dc topologies are advanced forward dc-dc converters with an additional clamped output capacitor. The idea of such a type...

The paper proposes a novel droop-control approach to fully cancel out unbalanced and harmonic voltages in AC-islanded microgrids, focusing on perfecting power distribution in distributed generators (DG). It designs a control system for DG units to immediately correct voltage imbalances and harmonics, ensuring even compensatory load distribution for...

The Quasi-Impedance-Source Inverter (Quasi-Z inverter) is an interesting DC-AC converter topology that can be used in applications such as fuel cells and photovoltaic generators. This topology allows for both boost capability and DC-side continuous input current. Another very interesting feature is its reliability, as it limits the current when two...

This article presents a new modulation technique called three-dimensional sigma–delta (3D-ΣΔ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D...

Restrictions on fossil fuels and related environmental pollution issues motivate many organizations and countries to set their focus on electric vehicles (EVs) rather than conventional internal combustion engine vehicles [1], [2]. EVs require an energy storage system to store converted electric power in another form of energy and then reconvert the...

In recent years, the number of electric vehicles has been at least doubling year after year. As a result, today electric vehicles already account for approximately 10% of the global automotive market, which positively affects environment in urbanized areas. However, to take full advantage of the EV integration it is necessary to use renewable sourc...

Virtual power plants are a useful tool for integrating distributed resources such as renewable generation, electric vehicles, manageable loads, and energy storage systems under a coordinated management system to obtain economic advantages and provide ancillary services to the grid. This study proposes a management system for a residential virtual p...

The use of renewable energy is on the rise and is expanding ever so greatly in this modern age of technology. However, it comes with a new set of challenges to properly integrate these renewable energy-based power plants thus forming a virtual power plant safely and reliably into the power grid in which a smart grid plays an effective role. The mai...

Hardware-in-the-loop (HIL) testing methods by means of HIL units or real-time simulators (RTS), are becoming broadly accepted for validating of control systems in many technical areas. This new approach brings advantages such as the acceleration of the industrial and the research development cycle and offers a risk-free and flexible environment for...

A new multilevel topology for an open-end winding motor drive is proposed in this paper, presenting a similar structure to the cascaded H-bridge multilevel inverter. The proposed topology combines three-phase and single-phase conventional H-bridge voltage source inverters ( VSI ). The topology is flexible, allowing to increase the number of voltag...

Smart transformers are considered a crucial part of future smart grids as they will operate as the energy router and be able to control the power flows from and to the microgrids since they are placed in the border. A multi-port transformer can integrate different energy resources, loads and energy storage systems, optimizing the power flows betwee...

Transactive Energy (TE) is an evolving concept that combines information and energy in order to enable highly coordinated energetic transactions. Different sources define transactive energy in different ways. The GridWise Architecture Council (GWAC) defines TE as “ A system of economic and control mechanisms that allows the dynamic balance of suppl...

Distributed energy resources (DER) such as solar photovoltaic (PV) interfaces with the utility grid by high-efficiency power electronic converters. This equipment is sometimes underutilized in terms of its power capacity; thus, the remaining capacity can be used to provide support to the distribution system. In this sense, this work assesses the pe...

This article presents an isolated single-stage ac–dc high-frequency link full-bridge cycloconverter (HFLC) with high conversion ratio. Despite certain advantages, such topologies generally suffer from transformer leakage inductance problems and lack of effective modulation methods, particularly in the ac–dc operation mode. In this study, for the in...

Microgrids/nanogrids of prosumers must be able to adapt to new business opportunities related to energy trading. Therefore, highly accepted hierarchical control strategies should be modified to allow deliberate energy interchange among prosumers, even when the microgrid they are integrated in, operates islanded. This is the main contribution of thi...

Regarding the control of micro- and nanogrids, LC- or LCL-filtered power inverters (acting as interfaces with distributed energy resources such as photovoltaic or wind) commonly perform as grid-forming or grid-supporting units to maintain both the frequency and voltage within pre-set standards. Nevertheless, these power inverters are assumed to be...

After approximately a decade of electric vehicles entering the mainstream car market, technological developments and coordinated efforts from private and public sectors are shaping a healthy ecosystem. A growing charging infrastructure offers a wide spectrum of charging options, allowing to accommodate various profiles of EV drivers. This paper pro...

In this paper, different Pulse Width Modulation (PWM) strategies for operating with a low-switching frequency, a topology that combines Conventional Matrix Converters (CMCs), and Coupled Reactors (CRs) are presented and discussed. The principles of the proposed strategies are first discussed by a conceptual analysis and later validated by simulatio...

This article presents three variants of the Pulse Width Modulation (PWM) for the Double Square Multiphase type Conventional Matrix Converters (DSM-CMC) supplying loads with the open-end winding. The first variant of PWM offers the ability to obtain zero value of the common-mode voltage at the load’s terminals and applies only six switches within th...

Although there is a growing interest in developing fast charging methods to enhance the Electric Vehicles’ appeal, the main energy supply is still the single-phase outlet. While single-phase charging may be simpler than three-phase, there are challenges in the integration of the propulsion and charging systems without adding inductive grid filters....

This paper describes an example of a solar inverter design based on the quasi-Z-source network taking into account multi-objective optimization. An overview of the solar inverter market is provided. Based on this overview, the specification of the most important parameters of commercial solutions is derived. The target efficiency profile and operat...

The article introduces methodology of lowering time and computational requirements for complex 3D finite element analysis. It is based on approximation of winding cross section with a proper polygonal shape which significantly reduces the number of mesh elements and eases the computational convergence. The attention is paid mainly to the case of si...

Since most power electronics used in photovoltaic (PV) inverters at commercial and industrial facilities exhibit behavior as non-linear loads from the grid side, these high-power demand installations are expected to have a major impact on the network’s power quality. In an attempt to facilitate their integration into the distribution grid, this pap...

A model for an equivalent electrical circuit designed for a ferrite (3C90) inductor usually used in power converters excited by a non-sinusoidal current appropriate for use in power electronics is proposed. This study, based on 3D finite element analysis, leads to significant precision advantages over 2D analysis for non-symmetric inductors. The fr...

Sensorless control of electrical drives is still a difficult task, especially in the lower speed region. Moreover, when the machine has a low saliency such as in the case of Surface Mounted Permanent Magnet Synchronous Motor (SMPMSM), high frequency injection techniques are even more challenging. In this paper, an enhanced demodulation algorithm fo...

OUTLINE OF THE SESSION Thanks to rapid advances in semiconductor and packaging technologies as well as to the development of new power converter topologies, the power electronics is being applied in brand new applications, such as Electronic Power Distribution Systems, also known as Active Distribution Networks or Smart Grids. Depending on the powe...

From the electrical energy point of view, the smart community (SC) concept is meant to be as a sustainable and environmentally friendly alternative to the classical configuration. The SC includes small‐scale renewable energy sources (RES) and small‐scale energy storage system (ESS). The SC energy management system acts as an aggregator, aiming to a...

Energy efficiency and consumers’ role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-sp...

Several main methodologies are used to estimate the core power loss (CPL) in magnetic components. One group is based in the Steinmetz equation (The modified one, the generalized one and the natural equations are the principals). Another one is the separation of losses between hysteresis, eddy current and excess losses. The third group is based math...

It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the co...

Purpose The purpose of this paper is the presentation of an electrical equivalent circuit for inductive components as well as the methodology for electrical parameter extraction by using a 3 D finite element analysis (FEA) tool. Design/methodology/approach A parameter extraction based on energies has been modified for three dimensions. Some simpli...

Based on the assumption that vehicles served by petrol stations will be replaced by Electric Vehicles (EV) in the future, EV public charging station facilities, with off-board fast chargers, will be progressively built. The power demand of these installations is expected to cause great impact on the grid, not only in terms of peak power demanded bu...

Nowadays, the research and industry societies showing their interest on permanent magnet assisted synchronous reluctance motors. One of the main disadvantages of using permanent magnets in electrical machines is a risk of demagnetization. This paper discusses a hybrid FEA-Simulink model with damaged permanent magnets in rotor flux barriers. Three s...

Debido a las limitaciones computacionales actuales, los análisis por elementos finitos en tres dimensiones no son posibles para todos los componentes magnéticos, por lo cual, algunas simplificaciones han sido analizadas en anteriores estudios [1]. Una de las soluciones más efectivas es la modificación de la sección del conductor de circular a polig...

The boost feature that characterizes Z-source and quasi-Z-source converters is usually achieved by means of a proper insertion of short-circuit states in the full DC-link. In this work, a novel pulse width modulation carrier-based strategy for a three-phase, three-level T-type, quasi-Z-source inverter is introduced, based on the addition of alterna...

This paper presents a comprehensive analytical comparison of the impedance-source-based dc-dc and dc-ac converters in terms of the passive component count and size, semiconductor stress, and range of input voltage variation. The conventional solution with a boost converter was considered as a reference value. The main criterion of the comprehensive...

The proliferation of residential photovoltaic (PV) prosumers leads to detrimental impacts on the low-voltage (LV) distribution network operation such as reverse power flow, voltage fluctuations and voltage imbalances. This is due to the fact that the strategies for the PV inverters are usually designed to obtain the maximum energy from the panels....

Microgrids of prosumers are a trendy approach within the smart grid concept, as a way to increase distributed renewable energy penetration within power systems in an efficient and sustainable way. Single prosumer individual management has been previously discussed in literature, usually based on economic profit optimization. In this paper, two nove...

In this paper, a comparative analysis is done for same frame induction and synchronous reluctance motors. Assessment is based on real tests that considers motor efficiency, frequency converter efficiency and a total efficiency of the motor drive system. The results show that used in the tests motors have a similar performance, that means for severa...

Integration of renewable energy sources, active role of consumers and energy management systems are currently among research priorities in energy systems. This paper proposes an innovative coordinated energy scheduling for a microgrid of neighbor prosumers with different consumption patterns. All prosumers have photovoltaic generation systems, Li-i...

In this paper grid-connected buck-boost inverter based on unfolding circuit is discussed. Proportional-Resonant controller along with repetitive controller are selected for output current control. Simulation results are presented for wide range of input voltage and power. It can be applied for renewable energy systems where high quality output curr...

This paper presents new Space Vector Pulse-Width Modulation (SVPWM) strategies for a single-phase three-level buck-boost Neutral Point Clamped (NPC) inverter coupled with Impedance-Source (IS) networks. These strategies can be implemented for systems with any IS networks with neutral point. The case study system is based on the quasi-Z-source inver...

Este manuscrito describe el circuito equivalente para un componente magnético con núcleo EE como también la metodología para la extracción de parámetros con la ayuda de análisis de elementos finitos en tres dimensiones. Este modelo tiene en cuenta tanto los efectos debidos a la frecuencia como los geométricos tales como el efecto skin, efecto de pr...

This paper presents a modified carrier level-shifted based control method for a pulse width modulation controlled three-phase three-level T-type quasi-impedance-source inverter. The benefits of proposed strategy are a uniform distribution of shoot-through states of constant width throughout the fundamental period, and the mitigation of the inner ca...

Smart grids aim to dramatically change residential area energy systems by creating active grid interaction. Specifically, renewable energies will play a key role when it comes to handle Energy Storage Systems (ESS) at houses within a Smart Community. This paper presents a novel global control strategy for distributed micro-storage energy system. Ea...

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and Energy Management Systems (EMS) are necessary. The trend directio...

This paper aims to provide control strategies for distributed micro-storage energy systems at the residential level to contribute to smart grid goals. A simulation model of an energy storage system (ESS) charger has been implemented to test these proposed control strategies. The smart community energy management system (SCEMS), acting as an aggrega...

The study of Noise, Vibration and Harshness (NVH) is becoming a key element when it comes to design and maintain a system that have rotatory elements. The understanding of the source of the vibrations can lead to a way of mitigating them, thus ensuring a better operation and expanding the life of the components. In this work, an analysis of the vib...

In recent years, the significant growth of the number of inverters connected to the grid as a consequence of the development of renewable energy sources, especially photovoltaic modules, has caused that focus is on innovative inverter circuitries. This paper presents a comparison between two different configurations of three-phase three-level inver...

Single-phase inverter suffers from double-frequency power ripples in the input side transferred there from the ac-side. To mitigate this ripple, two types of power decoupling approaches can be applied: passive power decoupling and active power decoupling. We present a technique of passive power decoupling realized by modifying the control strategy....

This paper proposes a comparative analysis of control strategies for active power flow between a smart community grid and an energy storage unit located in a house of the community, which is connected to the grid by a bidirectional charger. These strategies are applied to the bidirectional DC/DC converter of the charger and include an improved prec...

Impedance-source networks are an increasingly popular solution in power converter applications, especially in single-stage buck-boost power conversion to avoid additional front-end dc-dc power converters. In the survey papers published, no analytical comparisons of different topologies have been described, which makes it difficult to choose the bes...

This paper presents the design for the control scheme of a three-level three-phase neutral-point-clamped quasi-Z-Source inverter which employs an LCL filter for the connection to the grid. A state-feedback based control is developed so as to attain a fully decoupled control of the active and reactive power exchanged with the grid. In addition, a PI...

This paper presents a four wire dual-buck inverter integrated in a photovoltaic system with grid support capabilities. In the context of smart-grids this kind of systems can play an important role. In this particular case the system will supply the ancillary services for unbalanced loads and reactive power compensation. A dual-buck inverter is adop...

The main issues related to the integration of photovoltaic systems into the grid will be presented and discussed in this chapter. In the context of smart grids, photovoltaic installations, as distributed energy resources connected in many case to the distribution grid, can do much more than just injecting energy into the grid as an active part of t...

This paper proposes a new operation strategy for a three-phase three-level neutral-point-clamped quasi-impedance source inverter in a grid-connected mode. The strategy is intended for any inverter based on impedance source networks where the shoot-through states allow a wider input operation range. This feature is commonly requested in photovoltaic...

Electric vehicles (EV) can be used as distributed energy storage devices to provide to the smart grid different regulation services. However, to have enough impact in the grid, the trend is to jointly manage a set of EV by means of a new stakeholder called aggregator. Knowing the availability, mobility habits, and the state of charge (SOC) of each...