Design of a power electronic assisted series compensator for grid voltage regulation

In recent years, high penetration of distributed generation (DG) driven by PV panels and heavy load insertion in the distribution network has led to frequent voltage fluctuations in the form of undervoltage and overvoltage. Voltage control using traditional voltage regulators are unable to cope with this situation as frequent tap changes reduce the lifetime of the mechanical taps due to arcing. Further, the nature of European distribution network in general, makes voltage control through shunt compensation methods typically ineffective and expensive. Series compensation through centralized on-load tap changing (OLTC) distribution transformers or feeder-specific compensators is hence a suitable strategy for voltage regulation in Europe. The thesis work describes the design of a novel, power electronic assisted OLTC transformer that provides voltage regulation in the European distribution network through series compensation. The aim is to ensure that the tap changes occur in an arc free manner, thus providing for long lifetime of the OLTC. Different topologies for OLTC are examined in detail and shortlisted based on the steady state operation and power ratings of transformer and switches required. A novel design of a partially rated autotransformer is proposed which has taps developed through a combination of no-load switches and a single hybrid switch. The hybrid switch is composed of a mechanical switch and two semiconductor switches which are used for steady state and tap change operation respectively. The mechanical switch ensures low steady state losses and the semiconductor switches are used for arc-free tap changing. Back-back series connected IGBT with anti-parallel diodes are used for the two semiconductor switches and voltage polarity based 4-step commutation is used for commutation between the taps. The novel design of the OLTC autotransformer is cost effective, efficient and has long lifetime. The complete system is simulated in the PLECS and the steady state and transient operation of the system have been investigated. The OLTC has customized for application in both MV and LV three phase distribution network. Detailed study of the failure mechanisms owing to internal and external faults is performed and possible protection mechanisms are suggested. A low level control mechanism is also developed, thus providing a holistic design for building a prototype.Electrical Power ProcessingElectrical Sustainable EnergyElectrical Engineering, Mathematics and Computer Scienc

The electrical vehicle photovoltaic grid

DC systems, Energy conversion & Storag

Optimal System Design for a Solar Powered EV Charging Station

Charging electric vehicles (EV) from photovoltaic (PV) panels provides a sustainable mode of transportation. In order to reduce the net costs of charging EV from PV and the grid, the PV generation and/or the EV charging can be controlled based on the energy prices in the grid. The traditional approach to designing the solar system for EV charging is to maximize the energy yield. In this paper, an alternate approach to PV system design is proposed by which the PV panels are orientated so as to maximize the PV revenue. This technique is compared with that of reducing the net costs by smart charging of the EV based on energy prices. Two case studies for Netherlands and Texas are done to compare the PV energy generated and the net cost of EV charging from PV based on the two techniques.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.DC systems, Energy conversion & Storag

A Comprehensive Review on Off-Grid and Hybrid Charging Systems for Electric Vehicles

In recent years, the research interest in off-grid (standalone mode) and hybrid (capable of both standalone and grid-connected modes) charging systems for electric vehicles (EVs) has increased. The main reason is to provide a seamless charging infrastructure in urban and rural areas where the electrical grid is unreliable or unavailable so that EV adoption can be increased worldwide. In this regard, this article reviews the state-of-the-art architectures of the off-grid and hybrid charging systems and investigates their various subsystems, such as single or multiple energy sources, power electronics converters, energy storage systems, and energy management strategies. These subsystems should be optimally integrated and operated to achieve low-cost and efficient EV charging. Moreover, each subsystem is explored in detail to find the current status and technology trends. Furthermore, EV charging connectors, their power level, and standards for all kinds of EVs (ranging from one-wheeler to four-wheelers) are reviewed, and suggestions are discussed related to the non-standardization of charging plugs. Finally, conclusions show the continuous efforts of the researchers in improving the systems in various aspects, such as cost reduction, performance improvement, longevity, negative environmental effect, system size minimization, and efficient operation, and highlight challenges for both charging systems.DC systems, Energy conversion & Storag

Comparison of system architecture and converter topology for a solar powered electric vehicle charging station

Accepted Author ManuscriptOld - EWI-ESE-DC&S DC systems & StoragePhotovoltaic Materials and Device

Optimal Sizing and Control of a PV-EV-BES Charging System Including Primary Frequency Control and Component Degradation

This paper proposes a method for optimally dimensioning the components of a prosumer energy management system that integrates photovoltaic (PV) panels, multiple bidirectional electric vehicle chargers, an inverter, and a battery energy storage charger. Besides optimally dimensioning the components, it also optimizes power management while integrating the frequency containment reserve market and Li-ion battery degradation. The results show that the integration of the frequency containment reserve (FCR) market can increase lifetime cost savings by 36%, compared to optimal power management alone and up to 460% compared to non-optimal power management. Furthermore, the effects of PV and battery energy storage (BES) degradation on reservable capacity are analyzed including the importance of battery second-life value on lifetime net present cost is investigated.DC systems, Energy conversion & Storag

Increasing the Braking Energy Recuperation in Electric Transportation Grids Without Storage

When the braking energy in electric transportation grids is not met by another vehicle's demand, it is either harvested by storage systems or wasted in braking resistors. This paper looks at three methods for increasing the amount of harvested braking energy without the use of expensive storage systems: decreasing the substation voltage, decreasing the catenary/rail resistance, and adding smart grid loads such as EV chargers. Compared to the baseline scenario of a presented case study, the first method allowed the recuperation of all the braking energy yet increased the line transmission losses. The second method presented a better performance in both types of losses (23 %), while the third method offered a 66 % reduction in losses in addition to offering more utilities from the same infrastructure. The final paper will go into further detail with a full-day simulation.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.DC systems, Energy conversion & Storag

A Comprehensive Review on the Characteristics and Modeling of Lithium-Ion Battery Aging

Battery aging is one of the critical problems to be tackled in battery research, as it limits the power and energy capacity during the battery's life. Therefore, optimizing the design of battery systems requires a good understanding of aging behavior. Due to their simplicity, empirical and semiempirical models (EMs) are frequently used in smart charging studies, feasibility studies, and cost analyses studies, among other uses. Unfortunately, these models are prone to significant estimation errors without appropriate knowledge of their inherent limitations and the interdependence between stress factors. This article presents a review of empirical and semiempirical modeling techniques and aging studies, focusing on the trends observed between different studies and highlighting the limitations and challenges of the various models. First, we summarize the main aging mechanisms in lithium-ion batteries. Next, empirical modeling techniques are reviewed, followed by the current challenges and future trends, and a conclusion. Our results indicate that the effect of stress factors is easily oversimplified, and their correlations are often not taken into account. The provided knowledge in this article can be used to evaluate the limitations of aging models and improve their accuracy for various applications.DC systems, Energy conversion & Storag

Future of Electric Vehicle Charging

Charging infrastructure for electric vehicles (EV) will be the key factor for ensuring a smooth transition to e-mobility. This paper focuses on five technologies that will play a fundamental role in this regard: smart charging, vehicle-to-grid (V2G), charging of EVs from photovoltaic panels (PV), contactless charging and on-road charging of EVs. Smart charging of EVs is expected to enable larger penetration of EVs and renewable energy, lower the charging cost and offer better utilization of the grid infrastructure. Bidirectional EV chargers will pave the way for V2G technology where the EV can be used for energy arbitrage and demand-side management. Solar charging of EV will result in sustainable transportation and use of the EV battery as PV storage. On the other hand, stationary contactless charging and on-road inductive charging of EV will remove the necessity for any cables, eliminate range anxiety issues and pave the way for automated driving. The electromagnetic and power converter design for contactless power transfer systems for future highways is reviewed in this paper.Accepted Author ManuscriptDC systems, Energy conversion & Storag

A Multi-Objective Design Approach for PV-Battery Assisted Fast Charging Stations Based on Real Data

This paper presents a multi-objective approach to designing an optimal PV-BES assisted EV fast charging station. The trade-offs between lifetime net present value (NPV), energy independence, and grid power reduction are analyzed using particle swarm optimization and real 50kW fast charging data. Our results show a maximum lifetime profit of close to 4M euro. Furthermore, for only a 8% decrease in profit the we can achieve up to 62% of the maximum energy independence and 46% peak power demand reduction. This show that EV fast charging stations can become more significantly more sustainable and have a less fluctuating demand, for very little reduction in profits.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.DC systems, Energy conversion & Storag