73 research outputs found

    Load Frequency Control in Isolated Micro-Grids with Electrical Vehicles Based on Multivariable Generalized Predictive Theory

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    In power systems, although the inertia energy in power sources can partly cover power unbalances caused by load disturbance or renewable energy fluctuation, it is still hard to maintain the frequency deviation within acceptable ranges. However, with the vehicle-to-grid (V2G) technique, electric vehicles (EVs) can act as mobile energy storage units, which could be a solution for load frequency control (LFC) in an isolated grid. In this paper, a LFC model of an isolated micro-grid with EVs, distributed generations and their constraints is developed. In addition, a controller based on multivariable generalized predictive control (MGPC) theory is proposed for LFC in the isolated micro-grid, where EVs and diesel generator (DG) are coordinated to achieve a satisfied performance on load frequency. A benchmark isolated micro-grid with EVs, DG, and wind farm is modeled in the Matlab/Simulink environment to demonstrate the effectiveness of the proposed method. Simulation results demonstrate that with MGPC, the energy stored in EVs can be managed intelligently according to LFC requirement. This improves the system frequency stability with complex operation situations including the random renewable energy resource and the continuous load disturbances

    Wind Farms and Flexible Loads Contribution in Automatic Generation Control: An Extensive Review and Simulation

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    With the increasing integration of wind energy sources into conventional power systems, the demand for reserve power has risen due to associated forecasting errors. Consequently, developing innovative operating strategies for automatic generation control (AGC) has become crucial. These strategies ensure a real-time balance between load and generation while minimizing the reliance on operating reserves from conventional power plant units. Wind farms exhibit a strong interest in participating in AGC operations, especially when AGC is organized into different regulation areas encompassing various generation units. Further, the integration of flexible loads, such as electric vehicles and thermostatically controlled loads, is considered indispensable in modern power systems, which can have the capability to offer ancillary services to the grid through the AGC systems. This study initially presents the fundamental concepts of wind power plants and flexible load units, highlighting their significant contribution to load frequency control (LFC) as an important aspect of AGC. Subsequently, a real-time dynamic dispatch strategy for the AGC model is proposed, integrating reserve power from wind farms and flexible load units. For simulations, a future Pakistan power system model is developed using Dig SILENT Power Factory software (2020 SP3), and the obtained results are presented. The results demonstrate that wind farms and flexible loads can effectively contribute to power-balancing operations. However, given its cost-effectiveness, wind power should be operated at maximum capacity and only be utilized when there is a need to reduce power generation. Additionally, integrating reserves from these sources ensures power system security, reduces dependence on conventional sources, and enhances economic efficiency

    Performance of Two-Area Interconnected Power System with High Wind Power Penetration in Presence of Plug-in Hybrid Electric Vehicles

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    Most of existing power grids are designed neither by latest technologies nor to comply with quickly climate changes, the new intelligent power grids are urgently needed and will soon be applied to the power markets. In the smart grid, the large-scale renewable energy contribution tends to expand vastly. This paper is focusing on the wind energy. Wind’s inherent intermittency and unpredictability make its increased penetration into the power system grids an area requiring significant analysis and research. Notwithstanding, because of the changeable nature of the wind energy, this may lead to a high oscillation on the power system frequency. From another aspect, A lot of scientific research is searching for smart solutions and tools to support and enhance the integration of the renewable energy resources into the electrical grids without additional costs for the power system, so the world scientific research is directed to exploit the plugin hybrid electric vehicles (PHEVs) which are considered as the sustainable and environmental friendly transportation system in the next period around the world. PHEVs are considered as the scattered batteries, which will enhance the integrating of the renewable energy resources into the electrical power system. In this paper, the performance of two-area interconnected power system with high wind energy penetration is analyzed in the presence of the plug-in hybrid electric vehicles when using Ziegler and Nicholas method (Nguyen & Mitra, 2018)

    Integration of Massive Plug-in Hybrid Electric Vehicles into Power Distribution Systems: Modeling, Optimization, and Impact Analysis

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    With the development of vehicle-to-grid (V2G) technology, it is highly promising to use plug-in hybrid electric vehicles (PHEVs) as a new form of distributed energy resources. However, the uncertainties in the power market and the conflicts among different stakeholders make the integration of PHEVs a highly challenging task. Moreover, the integration of PHEVs may lead to negative effects on the power grid performance if the PHEV fleets are not properly managed. This dissertation studies various aspects of the integration of PHEVs into power distribution systems, including the PHEV load demand modeling, smart charging algorithms, frequency regulation, reliability-differentiated service, charging navigation, and adequacy assessment of power distribution systems. This dissertation presents a comprehensive methodology for modeling the load demand of PHEVs. Based on this stochastic model of PHEV, a two-layer evolution strategy particle swarm optimization (ESPSO) algorithm is proposed to integrate PHEVs into a residential distribution grid. This dissertation also develops an innovative load frequency control system, and proposes a hierarchical game framework for PHEVs to optimize their charging process and participate in frequency regulation simultaneously. The potential of using PHEVs to enable reliability-differentiated service in residential distribution grids has been investigated in this dissertation. Further, an integrated electric vehicle (EV) charging navigation framework has been proposed in this dissertation which takes into consideration the impacts from both the power system and transportation system. Finally, this dissertation proposes a comprehensive framework for adequacy evaluation of power distribution networks with PHEVs penetration. This dissertation provides innovative, viable business models for enabling the integration of massive PHEVs into the power grid. It helps evolve the current power grid into a more reliable and efficient system

    The Impact of Large-Scale Renewable Energy on Grid Small-Signal and Frequency Stability: Modelling, Analysis, and Control

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    This thesis intends to discuss the influence of renewable energy sources (RES) on the stability of power system. Although integration of renewable brings incalculable optimistic aspects, the variability of RES concerning fluctuation of active power may exhibit adverse influence on stability issues regarding small-signal and frequency stability point of views. Thus, this thesis discusses those two stability aspects. From small-signal stability perspectives, the agenda is divided into three parts. First small signal research investigates the influence of time-varying RES on low frequency oscillation, which triggers weak frequency band of vulnerable modes on remote area. Second study of small signal is to observe the influence of high penetration change on interarea oscillation. Third research of small signal is to investigate the influence of solar irradiation and wind velocity with stochastic characteristics on small signal stability due to the change of the generation quantity of photovoltaics (PV) and wind turbine generators (WTG). From frequency stability perspectives, the future grid might be operated under reduced inertia and high penetration, resulting in deterioration of frequency stability. Against this backdrop, ESS emerges as a countermeasure for the implications of large fleet of RES. First chapter of frequency stability aspects introduces ESS methodology enabling ESS to coordinate ancillary service among existing equipment with proposed method: droop control and State-of-Charge feedback (DaSOF). The last chapter suggests a method for EV application, based on Smart Charging method and DaSOF method. The efficacy of large group of EV application with this method against variability of RES is investigated and proved on the Jeju island system in Korea

    Online Battery Protective Energy Management for Energy-Transportation Nexus

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    Impact of vehicle to grid in the power system dynamic behaviour

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    This work was supported in part by FCT-Fundação para a Ciência e a Tecnologia de Portugal, under the grant SFRH/BD/47973/2008 and within the framework of the Project "Green Island" with the Reference MIT-PT/SES-GI/0008/2008, by the European Commission within the framework of the European Project MERGE - Mobile Energy Resources in Grids of Electricity, contract nr. 241399 (FP7) and by INESC Porto - Instituto de Engenharia de Sistemas e Computadores do PortoTese de doutoramento. Sistemas Sustentáveis de Energia. Universidade do Porto. Faculdade de Engenharia. 201

    A bidirectional power charging control strategy for Plug-in Hybrid Electric Vehicles

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    © 2019 by the authors. Plug-in Hybrid Electric Vehicles (PHEVs) have the potential of providing frequency regulation due to the adjustment of power charging. Based on the stochastic nature of the daily mileage and the arrival and departure time of Electric Vehicles (EVs), a precise bidirectional charging control strategy of plug-in hybrid electric vehicles by considering the State of Charge (SoC) of the batteries and simultaneous voltage and frequency regulation is presented in this paper. The proposed strategy can control the batteries charge which are connected to the grid, and simultaneously regulate the voltage and frequency of the power grid during the charging time based on the available power when different events occur over a 24-h period. The simulation results prove the validity of the proposed control strategy in coordinating plug-in hybrid electric vehicles aggregations and its significant contribution to the peak reduction, as well as power quality improvement. The case study in this paper consists of detailed models of Distributed Energy Resources (DERs), diesel generator and wind farm, a generic aggregation of EVs with various charging profiles, and different loads. The test system is simulated and analyzed in MATLAB/SIMULINK software
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