The electrification of hybrid electric vehicle reduces the reliance of transportation on fossil fuels and reduces Green House Gas emissions. The economic and environmental benefits of the hybrid electric vehicles are greatly reshaping the modern transportation sector. The transportation electrification (TE) brings various challenges to the Smart Grid (SG), such as power quality, reliability, and control. Thus, there is a need to explore and reveal the key enabling technologies for TE. Moreover, the intermittent nature of Renewable Energy Resources (RER) based generation demands for efficient, reliable, flexible, dynamic, and distributed energy storage technologies. The Electrical Vehicles (EVs) storage battery is the promising solution in accommodating RER based generation within SG. The most efficient feature of transportation sector is Vehicle to Grid (V2G) concept that will help in storing the surplus energy and feeding back this energy to the main grid during period of high demands. The storage technology is an integral part of the SG that helps in attaining the proper utilization of RER. In this paper, our goal is to explore the TE sector and its impact on economy, reliability and eco-friendly system. We reviewed the V2G technology and their implementation challenges. We further reviewed various energy storage technologies deployed in EVs within SG, considering attention to their influence on the environment. Moreover, this paper presented a detailed overview of the on board and off board charging infrastructure and communication necessities for EV. The paper also investigated the current issues and challenges of energy storage technologies in EVs. The technical and economic benefits of storage technologies are also considered. Our analysis reviews the role of EVs in decarbonizing the atmosphere. Lastly, the survey explains the current regulation, Standard, and interfacing issues within SG.

A survey on electric vehicle transportation within smart grid system

In this paper, power electronic transformer (PET)-based railway traction systems are comprehensively reviewed according to the unique application features and requirements. By comparing PET and conventional line frequency transformer (LFT)-based systems, their pros and cons are summarized. By further reviewing all kinds of PET-based designs from the early concepts to the latest ones in the order of their publication dates, the developing trends are highlighted. By synthetically considering the requirements and the state of the art, the key challenges and opportunities are identified and discussed. It shows that although PET-based systems are still developing and far from mature, they are already superior to LFT-based systems in terms of system weight, efficiency, and functionalities especially for 15-kV/16.7-Hz applications. With the advancements on wide bandgap power devices, medium frequency transformers, and converters, PET systems will be even more promising and available for all types of railway tractions in the near future.

Power Electronic Transformer-Based Railway Traction Systems: Challenges and Opportunities

Energy management system for smart grid: An overview and key issues

Finite commutation times are associated with the concurrent occurrence of both voltageacross and current-through semiconductor switches, leading to switching power losses. To alleviate them, soft-switching techniques have been developed. Soft-switching converters can be classified into quasi-resonant and multiresonant, resonant-transition, and resonant power converters (RPCs). This article focuses on RPCs, due to their high power density and efficiency. Specifically, RPC topologies with multiple elements are described, and their input-output relationships and efficiency are illustrated. The merits and limitations of RPCs are discussed and compared. An RPC intended to charge the battery of an electric vehicle (EV) is presented, and experimental results are discussed.

Resonant Power Converters: An Overview with Multiple Elements in the Resonant Tank Network

The recent growing diffusion of dispersed generation in low voltage (LV) distribution networks is entailing new rules to make local generators participate in network stability. Consequently, national and international grid codes, which define the connection rules for stability and safety of electrical power systems, have been updated requiring distributed generators and electrical storage systems to supply stabilizing contributions. In this scenario, specific attention to the uncontrolled islanding issue has to be addressed since currently required anti-islanding protection systems, based on relays locally measuring voltage and frequency, could no longer be suitable. In this paper, the effects on the interface protection performance of different LV generators’ stabilizing functions are analysed. The study takes into account existing requirements, such as the generators’ active power regulation (according to the measured frequency) and reactive power regulation (depending on the local measured voltage). In addition, the paper focuses on other stabilizing features under discussion, derived from the medium voltage (MV) distribution network grid codes or proposed in the literature, such as fast voltage support (FVS) and inertia emulation. Stabilizing functions have been reproduced in the DIgSILENT PowerFactory 2016 software environment, making use of its native programming language. Later, they are tested both alone and together, aiming to obtain a comprehensive analysis on their impact on the anti-islanding protection effectiveness. Through dynamic simulations in several network scenarios the paper demonstrates the detrimental impact that such stabilizing regulations may have on loss-of-main protection effectiveness, leading to an increased risk of unintentional islanding.

/pdf/impact-of-distributed-generation-grid-code-requirements-on-3zfcd5yvcz.pdf

Impact of Distributed Generation Grid Code Requirements on Islanding Detection in LV Networks

Vehicle-to-grid (V2G) paradigm is a way of executing services in favor of the grid by electric vehicles (EVs) with bidirectional battery chargers (BBC). The V2G service that has attracted the major interest is the exchange of active power for load leveling purposes. Less attention has received the so-called ancillary V2G services, such as the reactive power compensation. This service is much attractive since it does not involve any exchange of active power and, therefore, leaves the EV batteries charged and does not expose them to additional discharging–charging cycles. The purpose of this paper is to investigate the capabilities of V2G-enabled EVs in executing the reactive power compensation, whether done alone or simultaneously with either battery charging or battery power delivery to the grid. Two topologies of BBC are examined, namely the topologies with the dc side of the charger either directly connected to the battery or through a bidirectional dc–dc converter of buck type. This paper closes by reporting experimental results that corroborate the theoretical findings.

Reactive Power Compensation Capabilities of V2G-Enabled Electric Vehicles

Nowadays the electrical main grid is managed in AC due to several reasons derived from the past. Recent years have experimented a rapid evolution of power electronic components able to dramatically enhance the effectiveness of the active and reactive power flow management. Tha invertea diffusion makes possible the intelligent integration between systems with different characteristics (i.e. in terms of voltage magnitude and frequency) and the exploitation of generation sources and storage systems typically operating in DC. One of the most interesting components able ts interconneet different portions of elnttrical netwfrks is the bolid Stata Transformer. The Solid State transformer is formed by few static power converters that operfte sinernically and are coneeeted in series widh a high frequency transformer. Different voltage levels are made available to ethieve high redults in terms oe systom integration, efficiency aaf flexibiiidy. Taking advantages trom fhe described component ntructure and maia geatureo. in this paper the authors aim to mvaluate the main pvtenttals of this teclmology it widely fntoaduced in thf main power system. Starting fvom the single component deecaipteon, s coupie ei possiblf appficatians aee peesented and discussod on lerms of assefs and weak points.

Applications of the solid state transformer concept in the electrical power system

The paper is concerned with the soft-switching capabilities of the Single Active Bridge (SAB) converter. At first, soft-switching of the double active bridge converter is reviewed. Then, operation of the SAB converter is investigated with the end of assessing its soft-switching capabilities in both the discontinuous and continuous conduction mode. It is found that the SAB converter experiences either full or incomplete soft-switching depending on the working conditions. Afterwards, the procedure to size the capacitors for implementing soft-switching is illustrated. At last, an under-development power supply equipment exploiting the theoretical findings of the paper is presented together with a preliminary design of its components.

Soft-switching capabilities of SAB vs. DAB converters

High-frequency isolated DC-DC converters are gaining momentum in applications where the demand of isolation matches with that one of compact and light equipment. A seminal topology, constituted by two bridges operating at high frequency and coupled by a transformer, has emerged as an attractive solution that fulfills the above-mentioned demands. The two most popular versions of such a topology are the Single Active Bridge (SAB) and Dual Active Bridge (DAB) converters. This paper deals with the characteristics of the two converters that are helpful in designing their input and output filters, transistors and diodes. Explicitly, the peak-to-peak ripple and the rms value of the alternate component of current at the converter input and output as well as the peak, average and rms values of current through transistors and diodes of the converter are calculated. All the quantities are expressed as a function of the load current and voltage along the operating range, by referring to an application requiring a unidirectional power flow of buck type. A comparative analysis of the design characteristics of the two converters closes the paper.

Design characteristics of SAB and DAB converters

Isolated multiport DC-DC converters offer an efficient solution to meet the increasing demand of integrating energy delivery elements (EDEs) of various type like renewable energy sources (RESs), energy storage devices (ESDs) and mains. This paper deals with an isolated three-port DC-DC converter (3PC): two ports are connected to EDEs, respectively to a RES and an ESD, and a port is connected to the load. The 3PC characteristics in terms of power capabilities and control laws are investigated for two discontinuous conduction mode (DCM) operations and two operational working situations. The DCM operations are i) full DCM (FDCM), with all the ports operating in DCM, and ii) mixed discontinuous conduction mode, with the ESD-connected port operating in DCM and the other ports in continuous conduction mode. The working situations are i) both EDEs deliver power to the load, and ii) RES delivers power to ESD and the load. The theoretical findings are explicated by waveforms and diagrams.

Christian Fontana

Papers

Reactive Power Compensation Capabilities of V2G-Enabled Electric Vehicles

Applications of the solid state transformer concept in the electrical power system

Soft-switching capabilities of SAB vs. DAB converters

Design characteristics of SAB and DAB converters

Power and control characteristics of an isolated three-port DC-DC converter under DCM operations