Nowadays, new challenges arise relating to the compensation of power quality problems, where the introduction of innovative solutions based on power electronics is of paramount importance. The evolution from conventional electrical power grids to smart grids requires the use of a large number of power electronics converters, indispensable for the integration of key technologies, such as renewable energies, electric mobility and energy storage systems, which adds importance to power quality issues. Addressing these topics, this paper presents an extensive review on power electronics technologies applied to power quality improvement, highlighting, and explaining the main phenomena associated with the occurrence of power quality problems in smart grids, their cause and effects for different activity sectors, and the main power electronics topologies for each technological solution. More specifically, the paper presents a review and classification of the main power quality problems and the respective context with the standards, a review of power quality problems related to the power production from renewables, the contextualization with solid-state transformers, electric mobility and electrical railway systems, a review of power electronics solutions to compensate the main power quality problems, as well as power electronics solutions to guarantee high levels of power quality. Relevant experimental results and exemplificative developed power electronics prototypes are also presented throughout the paper.

This paper presents a comparison between different possibilities for the vehicle-to-vehicle (V2V) power transfer between two electric vehicles (EVs). The traditional V2V operation mode is performed through a common energy aggregator, such as the electrical power grid, consisting of a combination of the vehicle-to-grid (V2G) and grid-to-vehicle (G2V) operation modes. The traditional V2V power transfer is based on four power conversions, since each on-board EV battery charger is comprised by two power converters (de-de and dc-ac). In this context, this paper proposes new perspectives for the V2V power transfer, both in ac and dc, focusing in the V2V power transfer using dc power (dcV2V). The proposed methods discard the need for an energy aggregator connection, being possible to directly connect two EV s, charging one EV from the other. Furthermore, the proposed dcV2V method allows the reduction of four power conversions to a single one, allowing to increase the overall efficiency of the power transfer between EVs, An efficiency-based evaluation of the different V2V methods is performed, supporting the benefits of dcV2V.

Concerns about greenhouse gas emissions are a key topic addressed by modern societies worldwide. As a contribution to mitigate such effects caused by the transportation sector, the full adoption of electric mobility is increasingly being seen as the main alternative to conventional internal combustion engine (ICE) vehicles, which is supported by positive industry indicators, despite some identified hurdles. For such objective, power electronics technologies play an essential role and can be contextualized in different purposes to support the full adoption of electric mobility, including on-board and off-board battery charging systems, inductive wireless charging systems, unified traction and charging systems, new topologies with innovative operation modes for supporting the electrical power grid, and innovative solutions for electrified railways. Embracing all of these aspects, this paper presents a review on power electronics technologies for electric mobility where some of the main technologies and power electronics topologies are presented and explained. In order to address a broad scope of technologies, this paper covers road vehicles, lightweight vehicles and railway vehicles, among other electric vehicles.

Nowadays, railway electrification is the most efficient way to power the trains. However, power quality (PQ) phenomena toward public power systems (PPSs) have always a main concern to the railway operators, especially when the single-phase traction power system is interconnected to the three-phase PPS. The last decades have witnessed an on-going evolution of PQ improvement and traction power supply systems, contributing to diminish the negative impacts of AC railway networks on PQ of the three-phase PPS. In this context, this paper presents a global overview of the PQ phenomena in AC railway electrification, as well as the impacts of the potential hazards on the safe operation of electrified railways. The paper also reviews PQ improvement methods from the early use of AC railway electrification until the emergence of the new power electronics devices in railways industry.

This paper presents the analysis and experimental validation of a single-phase off-board multi-functional electric vehicle (EV) charging station (MF-EVCS), which has a single ac interface and two dc interfaces. As innovative aspects, the proposed MF-EVCS handles the interface of the ac power grid, the dc interface of a renewable energy source (RES), as well as the dc interface of an EV to perform dc charging or discharging of the batteries (in off-board grid-to-vehicle (G2V) or vehicle-to-grid (V2G) modes). Considering the power grid, the individual operation modes of the RES and the EV interfaces can be considered. Moreover, a combination of these modes is also possible. Besides, the MF-EVCS has as key innovative aspect the possibility of operating as an active power filter (APF), supporting the operation with reactive power and/or selected current harmonics. This possibility can be associated with any of the previous mentioned modes. These new features are framed in two distinct scenarios: in a smart home, where the ac-side current can be determined as a function of the other electrical appliances; in a smart grid, where the ac-side current can be determined as a requisite of the power grid. The proposed power theory, as well as the current control strategies for both ac-side and dc-side of the MF-EVCS, are presented in the paper for all the possible operation scenarios. A laboratory prototype was developed to validate the proposed MF-EVCS and the experimental results confirm its suitability for smart homes.

This paper presents a single-phase Shunt Active Power Filter (SAPF) with a multilevel converter based on an asymmetric full-bridge topology capable of producing five distinct voltage levels. The calculation of the SAPF compensation current is based on the Generalized Theory of Instantaneous Reactive Power (p-q theory) modified to work in single-phase installations, complemented by a Phase-Locked Loop algorithm and by a dedicated algorithm to regulate the voltages in the DC-link capacitors. The control of the SAPF uses a closed loop predictive current control, followed by a multilevel Sinusoidal Pulse-Width Modulation technique with two vertical distributed carriers, which were specially conceived to deal with the asymmetric nature of the converter legs. Along the paper, some simulation results are used to show the main characteristics of the 5-level converter and control algorithms, and the hardware topology and control algorithms are described in detail. In order to demonstrate the feasibility and performance of the proposed SAPF based on a 5-level converter, a laboratory prototype was developed and experimental results obtained under diverse conditions of operation, with linear and non-linear loads, are presented and discussed in this paper.