1,720,957 research outputs found
Integration of Energy Storage in Solar-powered EV Smart Charging Systems
No full textThis thesis investigates the integration of electric vehicle (EV) charging, photovoltaic (PV) power, and battery energy storage (BES), using a direct current (DC) integrated multi-port power converter. The goal is to aid the energy transition using the intelligent operation of the aforementioned components to provide a more cost-effective system that helps increase the penetration of small-scale local PV system and increase the sustainability of local loads, such as EV charging. To achieve this, this work focuses ontwo parts: the power electronic converter and the smart charging control, including battery degradation.A. Power Electronics In this thesis a modular DC-integrated multi-port converter is developed. The DC integration allows to reduce the amount of power converters hereby reducing its costs, while increasing efficiency and power density. All converters ports are developed for bidirectional operation to maximize its flexibility. a two level DC-AC converter is used for the bidirectional AC grid connection. Next, a 4-phase interleaved flyback converter is used for isolated EV charging. Finally, two interleaved four-switch buck-boost (FSBB) converters are used for both the PV and BES ports. All DC-DC converters utilize quasi-resonant boundary conduction mode (QR-BCM), combined with silicon carbide semiconductors to achieve efficiencies up to above 99%. A novel control method for the interleaved FSBB converter is proposed to enable multi-mode QR-BCM operation. Based on an experimental comparison with three other soft-switching modulation schemes it is shown that the proposed modulation and control achieve the highest efficiency (up to 99.5%) with little to no compromise in power density and control complexity.B. Smart Charging Next, a two-level smart charging structure is proposed to utilize the flexibility obtained from the multi-directional power electronic hardware. The first level is a non-linear programming (NLP) model that optimizes the charging powers of the EV and BES in a moving horizon context, to minimize the operational costs, including primary frequency control market participation and battery degradation. To minimize the battery degradation, a literature survey study has been done on lithium-ion ageing mechanisms and how to model it. Based on this survey the best suited degradation model is chosen and integrated in the NLP model. The second level of the proposed smart charging structure recalculates the setpoints based on grid frequency deviation, and PV forecasting errors. Both the theoretical and experimental results show that the proposed control method is effective in reducing the lifetime system costs. In combination with optimal sizing of the components the total lifetime system costs can be reduced up to 460% compared to conventional non-optimal charging methods.DC systems, Energy conversion & Storag
Techno-economic evaluation of energy markets for demand response and congestion management in future decentralized energy systems
No full textIn the context of the energy transition, the energy sector is experiencing a paradigm shift towards electrification in a decentralized model, where renewable energy sources are becoming the protagonists. However, such shift comes with several challenges. In particular for this thesis, the intermittency of renewable energy sources coupled with increased load demand and generation from small scale prosumers is expected to increase grid congestion at a distribution level.The main purpose of this thesis is to investigate and evaluate the techno-economic feasibility of novel market mechanisms that incentivize demand response from prosumers for congestion management. The focus of this work is on market-based mechanisms that use economic signals to stir prosumers' demand response. The mechanisms investigated are: 1) hard constraint that physically limits prosumers, 2) capacity subscription, 3) peak tariff, and 4) dynamic tariff; these are capacity mechanisms that limit the peak drawing and feeding power from prosumers. Moreover, the day ahead, intraday and frequency containment reserve (FCR) markets are incorporated to the capacity mechanisms to evaluate their compatibility in the context of the Dutch power markets.The advent of smart energy systems enables prosumers to become active participants in the market and aid in the grid's management. Thus, the approach of this thesis is to simulate prosumers' response to economic signals and evaluate the effects in a low voltage test feeder. To achieve this, the work develops on an existing smart charging algorithm that optimizes the components of the smart energy system. The system is composed of a multi port converter that incorporates a PV maximum power point tracking device (MPPT), a bidirectional EV charger, and a bidirectional battery energy storage (BES) charger; additionally, the grid is connected to a heat pump and load from appliances, which are non-flexible. The distribution network is IEEE's European low voltage test feeder, which is comprised of 55 households.The techno-economic feasibility evaluation is done by benchamarking the capacity mechanisms against an energy tariff in two scenarios: winter, and summer. The benchmark results indicate that aligning prosumers with only an energy tariff leads to congestion in the feeder. In response, all capacity mechanisms evaluated were effective at managing congestion if properly designed, although, some restrict prosumers more than others. The hard constraint made prosumers lose the most load, and the total cost incurred by the prosumers in the feeder was greatest with the capacity subscription. The peak tariff had the lowest cost of lost load, and the least overall costs, consequently, the peak tariff was chosen to incorporate the day ahead, intraday and FCR markets to it. The incorporation of day ahead and intraday markets decreased the exposure to imbalance costs under the assumption that new forecasts with better accuracy were available one time step (15 min) before delivery. The incorporation of FCR increased the exposure to imbalance costs due to deviations from the day ahead schedule. Furthermore, FCR with the peak tariff showed conflicting incentives, i.e., the peak tariff reduces the amount of reserved power for balancing regulation, else if full available power is reserved congestion increases. The results of this thesis point towards the potential that prosumers' demand response will have in shaping future decentralized energy systems, however, the market mechanisms in place need to be properly designed to ensure economic feasibility and resolve conflicting incentives between markets such as balancing and local congestion management.Electrical Engineering | Sustainable Energy Technolog
A Multi-Objective Design Approach for PV-Battery Assisted Fast Charging Stations Based on Real Data
No full textThis 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
Design of Misalignment Tolerant Control for an Inductive Charger with V2G Possibilities
No full textSince the power transfer efficiency in inductive power transfer (IPT) systems is directly related to the coupling of the transformer, coil misalignment can drastically decrease the efficiency. In this paper a misalignment tolerant control scheme is proposed which tracks the maximum power transfer efficiency point under misalignment. It does this by matching the impedance of the load with respect to the transformer based on an online coupling factor estimation, as well as tracking the resonance of the system. The control scheme is implemented on a series-series compensated system and designed such that it can be operated bidirectionally in the future, however this is not in the scope of this paper. The proposed control results in an overall efficiency improvement of 5% and 23% under 0 and 8 cm misalignment, respectively, compared to a constant rectifier output voltage of 48V.DC systems, Energy conversion & Storag
Optimal Sizing and Control of a PV-EV-BES Charging System Including Primary Frequency Control and Component Degradation
No full textThis 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
A Comprehensive Review on the Characteristics and Modeling of Lithium-Ion Battery Aging
No full textBattery 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
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Determining the effects of different market mechanisms on the power flow of a prosumer building: An analysis of feed-in tariff, capacity mechanism and frequency regulation on the power flow of a building with its own generation and storage
No full textWith distributed energy sources becoming prominent, it is expected that new market mechanisms would become necessary to overcome the issues caused by the intermittency of those sources. This research determines the effect of certain market mechanisms, which have been proposed to either incentivize the distributed generation or to reduce their undesirable effects, on power flow of a prosumer household. The prosumer household was assumed to consist of PV generation system, an Electric Vehicle which was capable of V2G and a household battery. The market mechanisms used were Feed-in tariffs, Capacity Mechanism and Frequency Containment Reserve. An Energy Management System which determines both, the optimal system size and the optimal power flow by minimizing the operational costs was used to achieve this. It was observed that different level of feed in tariff affected the optimal system size and the power flow. At high feed-in tariff, the system size was the largest and high grid peak power was observed. Furthermore, the introduction of the capacity mechanism in the form of capacity tariffs per kW led to reduction in grid power consumption and feeding in. Finally, it was observed that the energy management system was able to reserve power for the frequency regulation market. Compared to an uncontrolled case, a reduction of 70.26% in total costs was achieved when the EMS control was introduced. A cost reduction of 52.02% compared to the uncontrolled case was achieved when an additional capacity tariff was also introduced to the control. Finally, introduction of the frequency regulation mechanism in the EMS control led to even further reduction in costs with a drop of 1205.07% compared to the uncontrolled case
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