1,721,012 research outputs found
A fuzzy logic-based control algorithm for the recharge/v2g of a nine-phase integrated on-board battery charger
No full textEnergy demand associated with the ever-increasing penetration of electric vehicles on worldwide roads is set to rise exponentially in the coming years. The fact that more and more vehicles will be connected to the electricity network will offer greater advantages to the network operators, as the presence of an on-board battery of discrete capacity will be able to support a whole series of ancillary services or smart energy management. To allow this, the vehicle must be equipped with a bidirectional full power charger, which will allow not only recharging but also the supply of energy to the network, playing an active role as a distributed energy resource. To manage recharge and vehicle-to-grid (V2G) operations, the charger has to be more complex and has to require a fast and effective control structure. In this work, we present a control strategy for an integrated on-board battery charger with a nine-phase electric machine. The control scheme integrates a fuzzy logic controller within a voltage-oriented control strategy. The control has been implemented and simulated in Simulink. The results show how the voltage on the DC-bus is controlled to the reference value by the fuzzy controller and how the CC/CV charging mode of the battery is possible, using different charging/discharging current levels. This allows both three-phase fast charge and V2G operations with fast control response time, without causing relevant distortion grid-side (Total Harmonic Distortion is maintained around 3%), even in the presence of imbalances of the machine, and with very low ripple stress on the battery current/voltage
Microgrids-Based Approach for Voltage Control in Distribution Systems by an Efficient Sensitivity Analysis Method
No full textHigh levels of renewable energy sources (RESs) in distribution networks have led to complex operational needs. The management of the network in microgrids (MGs) allows the implementation of effective and innovative management strategies. We propose a hybrid control strategy to maintain voltage levels within the operational limits using the RESs reactive and active power outputs. The proposed regulation strategy considers different MGs that are managed by different owners, who contribute to regulating the voltage on the distribution systems. In order to obtain an effective regulation, each MG can collaborate with the others. In the first instance, voltage is regulated inside MG using available distributed generation resources in correspondence of the bus of over/undervoltage is detected (stage 1). Next, more MGs can contribute to alleviating the problem involving other distributed generation resources (stage 2). The control method is based on sensitivity analysis, which allows selecting the appropriate distributed resources: we propose also a new method of calculating the sensitivity coefficients for radial and meshed networks. We demonstrate the effectiveness and the robustness of the proposed voltage control scheme using comparisons and representative studies by extensive simulations on two test networks performed by the proposed methodology. The results demonstrate the effectiveness of the control actions and the used algorithm
Pilot Nodes Searching for Voltage Regulation in Distribution Systems by OLTC
No full textDistribution System Operators (DSOs) have to face new challenges due to the constant growing of Distributed Generation (DG) on networks. Due to the growing diffusion of electric vehicles, also power demand is raising. For this reasons, the classical control strategies currently implemented for the On-Load Tap Changers in primary substations could result ineffective for voltage regulation. In this paper, a strengthened control strategy for the OLTC installed in a primary station of an MV distribution network is proposed. It is based on the voltage measurements coming from a few pilot nodes of the network. Besides, the method to individuate the pilot nodes is formalized. Performances of the proposed control method, compared with the ones of a classical regulation strategy, are analyzed through simulations on a realistic MV distribution network
Achieving Consensus in Self-Organizing Electric Vehicles for Implementing V2G-based Ancillary Services
No full textThe integration of Electric Vehicles (EVs) equipped with Vehicle-to-Grid (V2G) technology has been recognized as a promising solution to enhance the flexibility of modern power distribution systems. However, to make this a reality, there is a need for flexible, reliable, and highly scalable computing architectures that can coordinate the charging and discharging process of EV fleets while identifying the best trade-offs between the vehicle charging expectations and the grid requirements. This challenging problem has been formalized in this paper as a welfare maximization problem, by defining proper utility functions to quantify the marginal cost/benefits of the charging and discharging process. Then, a self-organizing solution scheme is proposed in the task of enabling the EVs fleet to solve the welfare maximization problem by only exchanging local non-sensitive information. The insight is to define a formal connection between the charging/discharging scheduling problem and the economic dispatch of thermal generators, hence exploiting all the vast literature on the theory of the marginal cost for the decentralized solution of the scheduling problem, which is one of the main contributions of this paper. Simulation results obtained on two case studies are presented and discussed in order to assess the effectiveness of the proposed technique in solving complex scheduling problems in realistic operation scenarios
A novel fuzzy system for wind turbines reactive power control
No full textThe paper proposes a new fuzzy controller for variable speed wind turbines (WTs) in order to compensate the variations at the point of common coupling (PCC) by controlling the reactive power generated by WTs. A protection system is used to disconnect the WTs from the grid when the controller is unable to compensate the voltage variations. Simulations carried out on a real 37-bus Italian weak distribution network demonstrated that the controller allows compensating voltage variations during voltage sags
A Fuzzy Control for a Nine-Phase Integrated On-Board Battery Charger
No full textRecharging faster and faster while making the vehicle less heavy and expensive is an increasingly stimulating challenge for the automotive industry. With regard to AC charging systems, which require appropriate energy conversion structures to be installed on board, the charging speed is directly proportional to the size of the mounted charger. A possible solution that allows eliminating the installed charger and using the same powertrains components both in charging and propulsion mode is the integrated on-board battery charger. In this paper we propose a recharging control algorithm for an electric vehicle's (EV) powertrain based on a nine-phase machine with a nine-phase inverter/rectifier and used as an integrated charger. The proposed algorithm combines the voltage oriented control with both fuzzy logic and adaptive hysteresis band control. Both charging mode (single-phase or three-phase) an vehicle-to-grid (V2G) are achievable at unity power factor grid side and without torque production by the machine
Impact Assessment of Energy Storage Systems Supporting DC Railways on AC Power Grids
No full textEnergy storage systems (ESSs) represent an established solution for energy saving and voltage regulation in DC urban railway systems. In particular, ESSs can store the braking energy of light rail vehicles (LRVs) and support the DC feeder system during traction operations. Moreover, ESSs can significantly improve the operating conditions of the AC supply system by reducing voltage drops and current spikes. This paper investigates the impact on the bus voltages and branch currents of the AC grid of wayside and on-board ESSs supporting the DC railway infrastructure. An iterative algorithm solves the decoupled AC/DC power flow considering the 3-phase bridge rectifier model of traction substations. The work presents a novel mathematical formulation of the optimization problem to solve the positioning and sizing of supercapacitor-based wayside ESSs, considering both DC and AC network constraints. The effectiveness of the proposed method is proved through numerical simulations on a real Italian DC railway system. Obtained results are presented and discussed comparing the proposed methodology to several existing literature solutions
Modeling of Lithium-Ion Batteries for Electric Transportation: A Comprehensive Review of Electrical Models and Parameter Dependencies
No full textThe power and transportation sectors contribute to more than 66% of global carbon emissions. Decarbonizing these sectors is critical for achieving a zero-carbon economy by mid-century and mitigating the most severe impacts of climate change. Battery packs, which enable energy storage in electric vehicles, are a key component of electrified transport systems. The production of these batteries has significantly increased in recent years to meet rising demand, and this trend is expected to continue. However, current traction batteries exhibit lower energy density compared to fossil fuels. As a result, accurate battery models that balance computational complexity and precision are essential for designing high-performance energy storage systems. This paper provides a comprehensive review of the most used electrical models for lithium-ion batteries in traction applications, as reported in the technical literature. By exploring the strengths and limitations of different modeling approaches, this paper aims to offer valuable insights into their practical applicability for the electrification of transportation systems. Additionally, this paper discusses the primary methods employed to derive the values of the electrical components within these models. Finally, it examines the key parameters—such as temperature, state of charge, and aging—that significantly influence the component values. Ultimately, it guides researchers and practitioners in selecting the most suitable modeling approach for their specific needs
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