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Green Energy Research and Innovation - Volume:1 Issue: 2, Summer 2024

Journal of Green Energy Research and Innovation
Volume:1 Issue: 2, Summer 2024

  • تاریخ انتشار: 1403/03/12
  • تعداد عناوین: 6
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  • Saman Darvish Kermani, Mohammad Fayazi, Jamshid Barati, Mahmood Joorabian * Pages 1-14
    This paper presents the islanding and peninsulating of distributed generators (DGs), such as wind and solar ‎power plants, that feed microgrid systems. However, the paper does not focus on just an ordinary microgrid but ‎large microgrids that have several sub-microgrids with renewable energy resources and multiple connection ‎points (MCPs) to different grids. When islanding happens, the main microgrid disconnects some connection ‎points from grids whereas some connection points to other grids could be connected and divided into some sub-‎microgrids for better stability. Two new definitions are proposed for large microgrid islanding: percentage of ‎islanding and peninsulating. The former means how much it is possible that an islanding happens before it ‎happens, and the latter means that: “after separating from some connection points to grids in a large microgrid ‎with MCPs to different grids, remained large microgrid network is an island or a peninsula that is connected in ‎some connection points to other grids? So, peninsulating a large microgrid depends on the number of connection ‎points, at least two points, to different grids. This paper describes these two new definitions. The method involves ‎the measurement of utility currents, voltages, and other signals through a bidirectional communications system in ‎smart grids. These signals are used to calculate the percentage of islanding and decide on microgrid islanding or ‎peninsulating.
    Keywords: Islanding‎, Peninsulating, Microgrid‎, Smart grid‎, Distributed Generation
  • Seyed Ehsan Aminoroayaye Yamani, Mohammad Bahramian, Ali Asghar Ghadimi * Pages 15-30
    Doubly-fed induction generators (DFIGs) are crucial in wind turbines due to their advanced control features and efficient power conversion, but they're vulnerable to grid issues like voltage dips and short circuits. This study explores enhancing DFIGs' low voltage ride-through (LVRT) capabilities using a superconducting fault current limiter (SFCL) system. The SFCL's superconducting coil plays a key role by limiting fault current to stabilize power output, reducing excessive currents during faults, and mitigating voltage fluctuations, protecting the rotor-side converter and gearbox. The research focuses on optimizing the coil's inductance to improve SFCL performance, showing through MATLAB/Simulink simulations that adjusting inductance can lessen rotor current oscillations during short circuits. The results indicate significant enhancements in LVRT capabilities, reducing electrical and mechanical stress on generators and converters, preventing severe voltage drops, and maintaining torque levels. Incorporating an SFCL into DFIG systems greatly increases stability, reliability, and fault tolerance, supporting more wind energy integration.
    Keywords: Doubly-fed induction generator, Low voltage ride through, Superconducting fault current limiter, wind power plant
  • Mahdi Shiravand, Ali Nahavandi * Pages 31-45
    Nowadays, the use of renewable energy sources has gained more attention due to their lower pollution ‎and cost compared to traditional fossil fuel generators. Microgrid (MG) structures are used for better ‎management of these resources. This article focuses on power control in three-terminal AC/DC hybrid ‎MGs. For this purpose, a network backup converter is used to improve power sharing and reduce power ‎quality disturbances. The components of the MG include distributed generation units, AC loads, DC ‎loads, energy storage system (battery), and parallel connecting converters. In the studied topology of ‎AC/DC hybrid MG in this article, there are two main converters: a grid-forming converter that acts as ‎an intermediary converter and is used to control the MG voltage, and a VSC converter that is located ‎between the DC link (including the DC MG and battery) and the AC MG. In this article, a control ‎system is implemented for a hybrid MG and simulations are performed in MATLAB software for ‎four different scenarios related to active and reactive power of the MG and loads. Simulation results ‎show that the energy management system and power control in the AC/DC hybrid MG have reduced ‎harmonics and improved system reliability in the MG.
    Keywords: Renewable energy sources, Power control, Hybrid AC, DC Microgrid, Power Quality
  • Reza Eslami * Pages 46-63
    Controlling the frequency and voltage of the power network with renewable energy resources is one of the ‎most important things in the integrity of the network. Therefore, after occurring any accident or fault in the ‎network, the frequency and voltage and in general all the basic parameters of the network must return to ‎their acceptable range within a certain period of time. Despite all the technical, economic and environmental ‎advantages that renewable energy resources have, the presence of these kind of sources may have negative ‎effects on voltage profiles and protection coordination in distribution networks, it is also possible that a part ‎of the network acts as an unwanted island, which complicates the operation and control of the network and ‎creates a risk of electrocution for the network personnel. Therefore, islanding detection is very important ‎and necessary in network protection and load shedding methods are usually used to eliminate this event. In ‎this paper, a multi-objective load shedding method in microgrids is proposed for the frequency stability and ‎reduction of power outages. Among the advantages of the proposed method can be mentioned its flexibility, ‎speed of operation and high accuracy. The proposed method is applied and simulated on a microgrid in the ‎DIgSILENT software environment, and the results of the simulation confirm the advantages of the proposed ‎method.‎
    Keywords: Renewable Energy Resources, Power outages, Load shedding, Stability of the frequency, The islanded microgrid
  • Sasan Pirouzi *, Ali Naderi Pages 64-80
    The utilization of renewables is developing rapidly due to environmental issues and a lack of fuel fossils. In this regard, wind turbines, as a type of renewable energy source, have been widely adopted in the power system thanks to their higher power generation capacity. Numerous methods have been introduced so far to control wind turbines, which are essential in generating wind energy. The sliding mode control, because of its unique features like being resistant to external disturbances, dynamics unmodeled and uncertainty, the relative simplicity of the control law, a relatively small amount of calculations, and straightforward implementation, is amongst the most preferred control designs in this realm. In this study, the control strategy is based on a combination of sliding mode and particle swarm optimization and is applied to a wind turbine with a grid-connected squirrel cage induction generator. The proposed method maximizes the power output of the wind turbine by limiting small changes in the electromagnetic torque. The main goal of the suggested design is to reduce the squared error of the electromagnetic torque, rotor speed, and stator current. The sliding mode control for the wind turbine helps obtain optimal values for the parameters of the design.
    Keywords: Wind Turbine, sliding mode control, Particle Swarm Algorithm
  • Moaiad Mohseni *, Alireza Niknam Kumleh, Mehdi Alibakhshi, Mona Sheikhi Abou Masoudi Pages 81-102
    An established technique to maximize the output power of photovoltaic (PV) systems, thereby raising ‎the efficiency of renewable energy systems, is maximum power point tracking (MPPT). This paper ‎focuses on designing and controlling a boost converter for MPPT in a PV system to calculate the ‎appropriate range of output resistance, minimum inductance, input capacitor, and output capacitor for ‎the boost converter so that the maximum PV output is achieved and the decision speed of MOSFET ‎switching is obtained by adopting the combined resistance-predictive method. The simulation results ‎demonstrate the efficacy of the proposed method in attaining these objectives. The suggested technique ‎can effectively track the maximum power point (MPP) within a broad spectrum of solar radiation while ‎ensuring that the duty cycle remains within its permissible range.‎
    Keywords: Boost Converter, enhancement of MPPT, Predictive method, PV system, resistance method