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Effects of fractional-order PI controller on delay margin in single-area delayed load frequency control systems

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 380-389页

作者： Vedat CELIK Mahmut Temel OZDEMIR Kwang Y.LEE department of electrical and Electronics engineering Faculty of EngineeringFirat UniversityElazigTurkey department of electrical and Computer engineering Baylor UniversityWacoUSA

This study aims to determine the improvement effect on the delay margin if fractional-order proportional integral(PI) controller is used in the control of a singlearea delayed load frequency control(LFC) system. The delay margin of the system with fractional-order PI control has been obtained for various fractional integral orders and the effect of them has been shown on the delay margin as a third controller parameter. Furthermore,the stability of the system that is either under or over the delay margin is examined by generalized modified Mikhailov *** stability results obtained have been confirmed numerically in time domain. It is demonstrated that the proposed controller for delayed LFC system provides more flexibility on delay margin according to integer-order PI controller.

关键词： Delay dependent stability Delay margin Fractional-order proportional integral(PI) Generalized modified Mikhailov criterion Load frequency control with delay

Evaluating transient behaviour of large-scale photovoltaic systems during lightning events using enhanced finite difference time domain method with variable cell size approach

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High Voltage 2024年第3期9卷 636-647页

作者： Ibrahim Hetita Diaa-Eldin A.Mansour Yang Han Ping Yang Congling Wang Mohamed M.F.Darwish Matti Lehtonen Amr S.Zalhaf School of Mechanical and electrical engineering University of Electronic Science and Technology of China(UESTC)ChengduChina electrical Power and Machines engineering department Faculty of EngineeringHelwan UniversityCairoEgypt electrical Power and Machines engineering department Faculty of EngineeringTanta UniversityTantaEgypt department of electrical Power engineering Faculty of EngineeringEgypt-Japan University of Science and TechnologyAlexandriaEgypt department of electrical engineering Faculty of Engineering at ShoubraBenha UniversityCairoEgypt department of electrical engineering and Automation School of Electrical EngineeringAalto UniversityEspooFinland

Photovoltaic(PV)arrays are usually installed in open areas;hence,they are vulnerable to lightning strikes that can result in cell degradation,complete damage,service disruption,and increased maintenance *** a result,it is imperative to develop an effective and efficient lightning protection system by evaluating the transient behaviour of PV arrays during lightning *** aim is to evaluate the transient analysis of large-scale PV systems when subjected to lightning strikes using the finite difference time domain(FDTD)*** overvoltages are calculated at various points within the mounting *** optimise the FDTD method's execution time and make it more suitable for less powerful hardware,a variable cell size approach is ***,larger cell dimensions are used in the earthing system and smaller cell dimensions are used in the mounting *** FDTD method is utilised to calculate the temporal variation of transient overvoltages for large-scale PV systems under different scenarios,including variations in the striking point,soil resistivity,and the presence of a metal *** results indicate that the highest transient overvoltages occur at the striking point,and these values increase with the presence of a PV metal frame as well as with higher soil ***,a comparison is performed between the overvoltage results obtained from the FDTD approach and the partial element equivalent circuit(PEEC)method at the four corner points of the mounting systems to demonstrate the superior accuracy of the FDTD ***,a laboratory experiment is conducted on a small-scale PV system to validate the simulation *** calculated overvoltages obtained from the FDTD and PEEC methods are compared with the measured values,yielding a mean absolute error of 5%and 11%for the FDTD and PEEC methods,respectively,thereby confirming the accuracy of the FDTD simulation model.

关键词： transient behaviour finite

A tri-level programming model for attack-resilient control of power grids

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Journal of Modern Power Systems and Clean Energy 2018年第5期6卷 918-929页

作者： Hamzeh DAVARIKIA Masoud BARATI department of electrical engineering Louisiana State University department of electrical and Computer engineering University of Pittsburgh

The significance of modern power grids is acknowledged every time there is a major threat. This paper proposes the novel approaches to aid power system planner to improve power grid resilience by making appropriate hardening strategies against man-made attack or natural hazards. The vulnerability indices are introduced, which return the most vulnerable component in the system based on a tri-level defender-attacker-operator(DAO) interdiction problem which solves iteratively. The output of DAO is the set of hardening strategies that optimally allocated along the network to mitigate the impact of the worst-case damages. By repeating DAO problem based on the proposed algorithm, the various crafted attack is imposed on the system, and the defender's behavior demonstrates how an element is vulnerable to threats. The WSCC 9-bus, IEEE 24-bus, and IEEE 118-bus systems are employed to evaluate the model *** counter-intuitive results are proven by the proposed robust hardening strategy, which shows how the hardening strategy should be allocated to improve power network resilience against threats.

关键词： Cyber attack Defender Hardening Protection Resilience Vulnerability

Security in edge-assisted Internet of Things:challenges and solutions

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Science China(Information Sciences) 2020年第12期63卷 27-40页

作者： Shuaiqi SHEN Kuan ZHANG Yi ZHOU Song CI department of electrical and Computer engineering University of Nebraska-Lincoln School of Computer and Information engineering Henan University department of electrical engineering Tsinghua University

The flourish of 5th generation wireless systems(5G) network has brought numerous benefits to the Internet of Things(IoT) with universal connectivity, improved data rate, and decreased latency. The development of IoT extends the computation-intensive applications from centralized servers to the edge of the network, promoting the paradigm of edge computing. Edge computing brings great assistance to IoT architecture by efficiently accomplishing tasks with lower latency, less energy consumption and reduced network bandwidth. Edge-assisted IoT emerges to provide location-aware services and offload computational tasks to edge nodes near the IoT devices. However, a series of security challenges still exist in edge-assisted IoT owing to the inherent vulnerabilities of edge nodes and sensitive nature of the collected data. Among the emerging and existing security schemes in IoT applications, security and energy consumption are two overriding yet conflicting requirements. The tradeoff between security and energy is critical to the sustainability of the IoT ecosystem but still lacks sufficient discussion. In this article, we investigate the security challenges in edge-assisted IoT and how the constraints in energy consumption can affect the design of security ***, we firstly present the architecture of edge-assisted IoT and its unique characteristics. Secondly,we identify the security threats in the edge-assisted IoT applications and the security-energy tradeoff during implementation. Thirdly, in a case study of distributed denial of service(DDoS) and malware injection attack, we propose a preliminary solution to address the conflict between security and energy ***, we discuss some open issues and identify future research directions for security and energy efficiency in edge-assisted IoT.

关键词： Internet of Things edge computing network security machine learning data analytics

Characterization of a-Si:H/SiN multilayer waveguide polarization using an optical pumping application—LED

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2009年第10期10卷 1421-1427页

作者： Mohd Saiful Dzulkefly ZAN Isamu KATO Mohammad Syuhaimi AB-RAHMAN Seri Mastura MUSTAZA department of electrical Electronic and System EngineeringFaculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia department of electrical engineering and Bioscience Waseda University

This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its *** using double tubed coaxial line(DTCL) microwave plasma chemical vapor deposition(MPCVD) equipment,an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer *** main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon *** the sample was ready,another major objective of the experiment was to analyze the polarization characteristics of the fabricated *** idea of the experiment was to analyze how the waveguide reacts when three types of LED(blue,yellow,and red) are radiated onto its *** results showed that the fabrication of the a-Si:H/SiN sample is *** effective transmission results,which accord with the polarization characteristics analysis,were obtained.

关键词： Waveguide Multilayer Optical pumping Light-emitting diode (LED) Double tubed coaxial line microwave plasma chemical vapor deposition (DTCL-MPCVD)

Efficient Wind Turbine Generation Planning for Decreasing Distribution System Company Payments in Real Applications

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Journal of Modern Power Systems and Clean Energy 2022年第1期10卷 81-90页

作者： Mohammad Hasan Hemmatpour Mohammad Hossein Rezaeian Koochi electrical engineering department Faculty of EngineeringJahrom UniversityJahromIran department of electrical engineering Shahid Bahonar University of KermanKermanIran

Wind energy has posed new challenges in both transmission and distribution systems owing to its uncertain nature. The effect of wind turbines (WTs) on the actual payments charged by upstream networks to distribution system companies (DISCOs) is one challenge. Moreover, when the grid-connected inverters of WT operate in the lead or lag modes, WTs absorb or inject reactive power from the system. This paper proposes an approach to assess the importance of operation modes of WTs to minimize the costs by DISCOs in the presence of system uncertainties. Accordingly, an optimization problem is formulated to minimize the costs to DISCO by determining the optimal locations and sizes of WTs in optimally reconfigured distribution systems. In addition, an improved vector-based swarm optimization (IVBSO) algorithm is proposed because it is highly suitable for vector-based problems. Two distribution systems are used in the simulations to evaluate the proposed algorithm. Firstly, the capabilities of the IVBSO algorithm to determine better solutions over other heuristic algorithms are confirmed using the IEEE 33-bus test system. Secondly, the BijanAbad distribution system (BDS) is used to demonstrate the effectiveness of the proposed optimization problem. Accordingly, the distribution system model, cumulative distribution function of wind speed, and load profile are all extracted from the actual data of the BijanAbad region. Finally, the optimization problem is applied to BDS in both the lead and lag modes of WTs. Results indicate that the total costs of DISCO are lower when WTs operate in the lag mode than in the lead mode.

关键词： Distribution system companies(DISCOs) improved vector-based swarm optimization(IVBSO) reconfiguration wind turbine operation mode

A new technique for fault diagnosis in transformer insulating oil based on infrared spectroscopy measurements

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High Voltage 2024年第2期9卷 319-335页

作者： Mohamed M.F.Darwish Mohamed H.A.Hassan Nagat M.K.Abdel-Gawad Matti Lehtonen Diaa-Eldin A.Mansour department of electrical engineering Faculty of Engineering at ShoubraBenha UniversityCairoEgypt department of electrical engineering and Automation School of Electrical EngineeringAalto UniversityEspooFinland department of electrical Power engineering Egypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityEgypt department of electrical Power and Machines engineering Faculty of EngineeringTanta UniversityTantaEgypt

Condition monitoring of the insulating system within power transformers has a massive importance according to the electrical *** gas analysis(DGA)is frequently used for this ***,DGA lacks the necessary level of accuracy to identify all equipment faults,particularly in their initial stages of ***,it does not have the capability for real-time monitoring and relies on manual sampling and laboratory testing,causing potential delays in fault ***,the interpretation of DGA data necessitates specialised expertise,which may pose difficulties for smaller entities that have limited access to ***,the contribution of this research is to use infrared spectroscopy measurements as a new effective technique substituting the DGA method for fault diagnosis in insulating *** inception faults that were considered in this study were the electrical fault(discharges of high energy)and the thermal fault(300°C

关键词： fault diagnosis spectroscopy

Decoherence of genuine multipartite entanglement for local non-Markovian–Lorentzian reservoirs

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Chinese Physics B 2015年第12期24卷 215-221页

作者： Mazhar Ali department of electrical engineering Faculty of Engineering Islamic University in Madinah

We study decoherence effects on genuine multipartite entanglement for three and four qubits, spatially separated and subjected to local Lorentzian reservoirs. Employing recent techniques to compute genuine negativity for multipartite systems and an exact solvable model, we analyze the dynamics of genuine entanglement for different coupling bandwidths and detunings. We find that collapses and revivals can occur by varying these parameters for various multipartite quantum states.

关键词： genuine negativity decoherence random states

Analysis of highly efficient perovskite solar cells with inorganic hole transport material

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Chinese Physics B 2019年第12期28卷 393-399页

作者： I Kabir S A Mahmood department of electrical and Electronics engineering Bangladesh University of Engineering and Technology

Organo-halide perovskites in planar heterojunction architecture have shown considerable promise as efficient light harvesters in solar cells. We carry out a numerical modeling of a planar lead based perovskite solar cell(PSC) with Cu2ZnSnS4(CZTS) as the hole transporting material(HTM) using the one-dimensional solar cell capacitance simulator(SCAPS-1 D). The effects of numerous parameters such as defect density, thickness, and doping density of the absorber layer on the device performance are investigated. The doping densities and electron affinities of the electron transporting material(ETM) and the HTM are also varied to optimize the PSC performance. It has been observed that a thinner absorber layer of220 nm with a defect density of 1014 cm-3 compared to the reference structure improves the device performance. When doping density of the absorber layer increases beyond 2×1016 cm-3, the power conversion efficiency(PCE) reduces due to enhanced recombination rate. The defect density at the absorber/ETM interface reduces the PCE as well. Considering a series resistance of 5 ?·cm2 and all the optimum parameters of absorber, ETM and HTM layers simultaneously, the overall PCE of the device increases significantly. In comparison with the reference structure, the PCE of the optimized device has been increased from 12.76% to 22.7%, and hence the optimized CZTS based PSC is highly efficient.

关键词： CH3NH3PbI3 Cu2ZnSnS4(CZTS) SCAPS-1D absorption coefficient