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Articles 1021 - 1050 of 3106
Full-Text Articles in Engineering
Improving Word Embeddings Projection For Turkish Hypernym Extraction, Savaş Yildirim
Improving Word Embeddings Projection For Turkish Hypernym Extraction, Savaş Yildirim
Turkish Journal of Electrical Engineering and Computer Sciences
Corpus-driven approaches can automatically explore is-a relations between the word pairs from corpus. This problem is also called hypernym extraction. Formerly, lexico-syntactic patterns have been used to solve hypernym relations. The language-specific syntactic rules have been manually crafted to build the patterns. On the other hand, recent studies have applied distributional approaches to word semantics. They extracted the semantic relations relying on the idea that similar words share similar contexts. Former distributional approaches have applied one-hot bag-of-word (BOW) encoding. The dimensionality problem of BOW has been solved by various neural network approaches, which represent words in very short and dense …
Nvrh-Lut: A Nonvolatile Radiation-Hardened Hybrid Mtj/Cmos-Based Look-Up Table For Ultralow Power And Highly Reliable Fpga Designs, Vahid Jamshidi
Nvrh-Lut: A Nonvolatile Radiation-Hardened Hybrid Mtj/Cmos-Based Look-Up Table For Ultralow Power And Highly Reliable Fpga Designs, Vahid Jamshidi
Turkish Journal of Electrical Engineering and Computer Sciences
Complementary metal oxide semiconductor (CMOS) downscaling leads to various challenges, such as high leakage current and increase in radiation sensitivity. To solve such challenges, hybrid MTJ/CMOS technology-based design has been considered as a very promising approach thanks to the high speed, low power, good scalability, and full compatibility of magnetic tunnel junction (MTJ) devices with CMOS technology. One important application of MTJs is the efficient utilization in building nonvolatile look-up tables (NV-LUTs) used in reconfigurable logic. However, NV-LUTs face severe reliability issues in nanotechnology due to the increasing process variations, reduced supply voltage, and high energetic particle strike at sensitive …
Hypothesis-Based Vertex Shift Method For Embedding Secret Logos In The Geometric Features Of 3d Objects, Arthy R, Mala K, Suresh Babu R
Hypothesis-Based Vertex Shift Method For Embedding Secret Logos In The Geometric Features Of 3d Objects, Arthy R, Mala K, Suresh Babu R
Turkish Journal of Electrical Engineering and Computer Sciences
A recent challenge in information technology is to protect secret data and preserve the ownership of a product. There are many duplicate products being released on a daily basis. Owners have a high risk in proving their products. Watermarking is a technique used to preserve ownership by hiding the owner's information in their products. The proposed hypothesis-based vertex shifting algorithm embeds 2D secret logos in 3D cover objects. The 3D objects are represented using vertices and facets. 3D watermarking faces various challenges and one among them is capacity. In this work, capacity is addressed by using a hypothesis-based vertex shift …
A Hybrid Multiband Printed Loop Antenna For Wlan/Wimax Bands For Applications In Mimo Systems, Ali Shahshahani, Mohammad Amin Honarvar
A Hybrid Multiband Printed Loop Antenna For Wlan/Wimax Bands For Applications In Mimo Systems, Ali Shahshahani, Mohammad Amin Honarvar
Turkish Journal of Electrical Engineering and Computer Sciences
In this article a thin hybrid multiband printed loop antenna is presented for application in multiple-input multiple-output (MIMO) systems. The proposed antenna has several advantages; for example, the pseudofilter feature of the proposed antenna is one of this antenna's advantages. Because of the antenna's width ($9.5$~mm), it can be used on the edges of the board. The first resonant frequency is generated by the original loop of the antenna. Incorporation of different embedded components, i.e. a subsidiary loop, extended ground-traces, parasitic patch, and the slits, results in the proposed antenna resonating as a multiband antenna. This antenna is adjusted in …
Line Independency-Based Network Modelling For Backward/Forward Load Flow Analysis Of Electrical Power Distribution Systems, Reyhaneh Taheri, Alimorad Khajezadeh, Mohammad Hossein Rezaeian Koochi, Abbas Sharifi Nasab Anari
Line Independency-Based Network Modelling For Backward/Forward Load Flow Analysis Of Electrical Power Distribution Systems, Reyhaneh Taheri, Alimorad Khajezadeh, Mohammad Hossein Rezaeian Koochi, Abbas Sharifi Nasab Anari
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper a straightforward method for line independency-based modelling of electrical power distribution systems is proposed. The proposed method can determine the backward and forward sweeping routes of distribution systems for calculating line currents and bus voltages. To do that, the method identifies the independent lines in consecutive steps. An independent line is a line in the distribution system whose current does not depend on the current of other lines in the system. The proposed line independency-based network modelling is required to be performed only once and prior to the load flow analysis. The output of the proposed method, …
Optimal Siting, Sizing, And Parameter Tuning Of Statcom And Sssc Using Mpso And Remote Coordination Of The Facts For Oscillation Damping Of Power Systems, James Garba Ambafi, Sunusi Sani Adamu
Optimal Siting, Sizing, And Parameter Tuning Of Statcom And Sssc Using Mpso And Remote Coordination Of The Facts For Oscillation Damping Of Power Systems, James Garba Ambafi, Sunusi Sani Adamu
Turkish Journal of Electrical Engineering and Computer Sciences
In electromechanical oscillation damping within power system, power system stabilizers (PSSs) are often deployed. However, a PSS is less effective in damping interarea oscillation and is limited by changes in network configuration due to weak tie-lines and load variations. Consequently, this paper presents a wide-area coordination approach that damps interarea oscillations using FACTS devices and phasor measurement units. We selected a static synchronous compensator (STATCOM) and static series synchronous compensator (SSSC) for realistic power system interarea oscillation damping. The performance of the coordinated FACTS installed in a power system depends on their suitable locations, sizes, tuned parameters, and remote input …
Computation Of Stability Regions For Load Frequency Control Systems Including Incommensurate Time Delays, Şahi̇n Sönmez
Computation Of Stability Regions For Load Frequency Control Systems Including Incommensurate Time Delays, Şahi̇n Sönmez
Turkish Journal of Electrical Engineering and Computer Sciences
This article studies the impact of incommensurate communication time delays on stability regions defined in proportional-integral (PI) controller parameter space for a two-area load frequency control (LFC) system. Distributed power generations and large power plants increase the complexity and control issues of interconnected power systems. In interconnected power systems, LFC systems need to have complex communication networks to exchange data between control center and geographically dispersed generations. The receiving/transmitting of remote measuring data through communication infrastructures causes inevitable time delays, which adversely affect controller performance and stability of the LFC system. Time delays introducing feedback control loops of a multiarea …
The Impact Of Demand Response Programs On Upfc Placement, Abbas Sharifi Nasab Anari, Mehdi Ehsan, Mahmud Fotuhi Firuzabad
The Impact Of Demand Response Programs On Upfc Placement, Abbas Sharifi Nasab Anari, Mehdi Ehsan, Mahmud Fotuhi Firuzabad
Turkish Journal of Electrical Engineering and Computer Sciences
Demand response (DR) and flexible AC transmission system (FACTS) devices can be effectively used for congestion management in power transmission systems. However, demand response program (DRP) implementation can itself affect the optimum location of FACTS devices, which is one of the main issues in power system planning. This paper investigates the impact of DRPs on unified power flow controller (UPFC) placement. The harmony search algorithm is employed to determine the optimum locations and parameter setting of UPFC in a long-term framework. The optimization problem is solved with different objectives including generation and congestion cost reduction, as well as loss reduction. …
Global Maximum Operating Point Tracking For Pv System Using Fast Convergence Firefly Algorithm, Madhusmita Mohanty, Sankar Selvakumar, Chandrasekaran Koodalsamy, Sishaj Pulikottil Simon
Global Maximum Operating Point Tracking For Pv System Using Fast Convergence Firefly Algorithm, Madhusmita Mohanty, Sankar Selvakumar, Chandrasekaran Koodalsamy, Sishaj Pulikottil Simon
Turkish Journal of Electrical Engineering and Computer Sciences
Global maximum operating point (GMOP) tracking is an important requirement of solar photovoltaic (PV) systems under partial shading conditions (PSCs). Though the perturb and observe algorithm is simple and effective, it fails to recognize the GMOP. This paper explores the application of the firefly algorithm (FA) to the maximum power point tracking (MPPT) problem of PV systems. In order to determine the shortest path to reach the GMOP under various PSCs, a new fast convergence firefly algorithm (FA) is proposed. Additionally, the change in firefly position is limited to a maximum value identified based on the characteristics of the PSC. …
A New Approach For Wind Turbine Placement Problem Using Modified Differential Evolution Algorithm, Hüseyi̇n Hakli
A New Approach For Wind Turbine Placement Problem Using Modified Differential Evolution Algorithm, Hüseyi̇n Hakli
Turkish Journal of Electrical Engineering and Computer Sciences
Energy use is increasing worldwide with industrialization and advancing technology. Following this increase, renewable energy resources are increasingly preferred to reduce the costs of energy production. Wind energy is preferred as a renewable energy resource because it is clean and safe. Wind turbines are used to meet the demand for wind energy. They are placed close to each other to generate higher amounts of energy. However, the wake effect problem arises in these types of layouts, and this hinders the turbines from producing the desired yield. A modified differential evolution (MDE) algorithm was proposed in this study to solve the …
Design And Control Of An Lcl-Type Single-Phase Grid-Connected Inverter With Inverter Current Feedback Using The Phase-Delay Method, Fati̇h Evran
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a novel single-phase grid-connected microinverter system and its control applications are introduced for solar energy systems. The proposed system consists of two stages to transfer solar power to the grid. In the first stage, an isolated high-gain DC/DC converter is used to increase low solar panel output voltage. In the second stage, an inverter is used to supply a sinusoidal current to the grid. Moreover, a proportional resonant controller is adopted to reduce grid current total harmonic distortions (THDs) and an LCL filter is used to provide better harmonic attenuation. However, the ratio between the sampling frequency …
A Novel Initial Rotor Position Alignment Method For Permanent Magnet Synchronous Motor Using Incremental Encoder, Si̇nan Yilmaz, Mehmet Ti̇mur Aydemi̇r
A Novel Initial Rotor Position Alignment Method For Permanent Magnet Synchronous Motor Using Incremental Encoder, Si̇nan Yilmaz, Mehmet Ti̇mur Aydemi̇r
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a new method for the alignment of the rotor of permanent magnet synchronous motors with the phase axis of the stator during start-up. Once the rotor alignment is achieved, the real rotor position angle can be measured by using an incremental encoder and this value can be used in the field oriented control of the motor. Typically, a current is forced into the q-axis. In the proposed method a current is formed in the d-axis instead. Rotor alignment with the phase axis is achieved without any sudden motion by using a PI controller in the current loop. …
A Two-Stage Power Converter Architecture With Maximum Power Extraction For Low-Power Energy Sources, Ridvan Umaz
A Two-Stage Power Converter Architecture With Maximum Power Extraction For Low-Power Energy Sources, Ridvan Umaz
Turkish Journal of Electrical Engineering and Computer Sciences
A two-stage power converter with maximum power extraction for energy harvesting is presented. The power converter consists of two stages; a maximum power extraction stage (i.e. first stage) and a regulation stage (i.e. second stage). The first stage consists of a number of charge pumps connected in parallel to extract power from the energy source while the second stage steps up low input voltage level to a usable level for a load. Proposed converter operates as low as 0.3 V and the output up-converts to 3.3 V. The proposed converter is aimed to extract maximum power from either low-power energy …
Comparative Evaluation Of A-B-C And Stationary Frame Of Reference For Permanent Magnet Brushless Dc Motor Drive Applied For Generation Of Switching Pattern, Manish Trivedi, Ritesh Keshri
Comparative Evaluation Of A-B-C And Stationary Frame Of Reference For Permanent Magnet Brushless Dc Motor Drive Applied For Generation Of Switching Pattern, Manish Trivedi, Ritesh Keshri
Turkish Journal of Electrical Engineering and Computer Sciences
This paper focuses on the evaluation of the operation of permanent magnet brushless DC (PM BLDC) motor through the control implemented in the natural reference frame (a-b-c frame) and the stationary reference frame ($\alpha-\beta$ frame). To a large extent, ripple-free torque and attainment of higher torque-speed characteristic depend on the gating pulses/switching patterns of the inverter employed. PM BLDC motor requires injection of the square wave current for the maximum torque per ampere, so the reference is required to be generated and tracked accordingly. The effectiveness of the strategies of pulse-width-modulation-based current control in the a-b-c plane and, the case …
Quantification Of Resistive Wall Instability For Particle Accelerator Machines, Fati̇h Yaman
Quantification Of Resistive Wall Instability For Particle Accelerator Machines, Fati̇h Yaman
Turkish Journal of Electrical Engineering and Computer Sciences
The aim of this study is to quantify longitudinal resistive wall impedances, corresponding wake functions, and wake potentials for different accelerator machines of interest. Accurate calculations of wake potentials by particle-in-cell codes are extremely difficult for the investigated parameters; therefore, we use an analytical approach and consider large domains with fine discretization for the required numerical integrations. The semianalytical wake potential computations are benchmarked against numerical general purpose 2D/3D Maxwell solver software codes and a different analytical approach for a certain set of parameters. We report examples to illustrate limitations of wake potential estimations from coupling impedances, and computations for …
Predicting Co And Nox Emissions From Gas Turbines: Novel Data And A Benchmark Pems, Heysem Kaya, Pinar Tüfekci̇, Erdi̇nç Uzun
Predicting Co And Nox Emissions From Gas Turbines: Novel Data And A Benchmark Pems, Heysem Kaya, Pinar Tüfekci̇, Erdi̇nç Uzun
Turkish Journal of Electrical Engineering and Computer Sciences
Predictive emission monitoring systems (PEMS) are important tools for validation and backing up of costly continuous emission monitoring systems used in gas-turbine-based power plants. Their implementation relies on the availability of appropriate and ecologically valid data. In this paper, we introduce a novel PEMS dataset collected over five years from a gas turbine for the predictive modeling of the CO and NOx emissions. We analyze the data using a recent machine learning paradigm, and present useful insights about emission predictions. Furthermore, we present a benchmark experimental procedure for comparability of future works on the data
Adaptive Iir Filter Design Using Self-Adaptive Search Equation Based Artificial Bee Colony Algorithm, Burhanetti̇n Durmuş, Gürcan Yavuz, Doğan Aydin
Adaptive Iir Filter Design Using Self-Adaptive Search Equation Based Artificial Bee Colony Algorithm, Burhanetti̇n Durmuş, Gürcan Yavuz, Doğan Aydin
Turkish Journal of Electrical Engineering and Computer Sciences
Infinite impulse response (IIR) system identification problem is defined as an IIR filter modeling to represent an unknown system. During a modeling task, unknown system parameters are estimated by metaheuristic algorithms through the IIR filter. This work deals with the self-adaptive search-equation-based artificial bee colony (SSEABC) algorithm that is adapted to optimal IIR filter design. SSEABC algorithm is a recent and improved variant of artificial bee colony (ABC) algorithm in which appropriate search equation is determined with a self-adaptive strategy. Moreover, the success of the SSEABC algorithm enhanced with a competitive local search selection strategy was proved on benchmark functions …
Ingaas Nbn Swir Detector Design With Lattice-Matched Inalgaas Barrier, Fati̇h Uzgur, Serdar Kocaman
Ingaas Nbn Swir Detector Design With Lattice-Matched Inalgaas Barrier, Fati̇h Uzgur, Serdar Kocaman
Turkish Journal of Electrical Engineering and Computer Sciences
Dark current optimization with band gap engineering has been numerically studied for InGaAs nBn type infrared photodetectors. Undoped InAlGaAs grading layers are utilized in constructing the barrier and dipole delta-doped layers are placed in both sides of the graded layers for eliminating valence band offset. As a result, the high band gap barrier layer blocks the majority carriers and allows minority carrier flow while minimizing various dark current components, as expected from an nBn detector. Substantial improvement has been shown in the dark current level without compromising any photoresponse compared to the conventional pn junction and recently proposed all InGaAs …
Sensorless Second-Order Switching Surface For A Three-Level Boost Converter, Tarek Messikh, Nasrudin Abd Rahim, Saad Mekhilef
Sensorless Second-Order Switching Surface For A Three-Level Boost Converter, Tarek Messikh, Nasrudin Abd Rahim, Saad Mekhilef
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes a sensorless second-order switching surface to control a three-level boost converter (TLBC). A predictive current method is proposed to reduce the number of sensors in the normal second-order switching surface method. Based on a developed model of the TLBC, the current is estimated and a switching surface is formulated in the state-energy plane. Simulation and hardware tests are carried out to verify the viability and the effectiveness of the proposed control technique. Results obtained show a good performance of the converter in term of DC-bus balancing and fast dynamic response under sudden load change.
Investigating The Occurrence Mechanism Of Cytokine-Like Formations By The Electromagnetic Approach, Cahi̇t Canbay, Özgün Palak, Aydoğa Kallem
Investigating The Occurrence Mechanism Of Cytokine-Like Formations By The Electromagnetic Approach, Cahi̇t Canbay, Özgün Palak, Aydoğa Kallem
Turkish Journal of Electrical Engineering and Computer Sciences
This study aims to elucidate the production mechanism of cytokine-like formations secreted from T cells and similar cells by electromagnetic modeling techniques. Three Hertz dipole antennas polarized in arbitrary directions were placed without touching each other at the center of spherical T-cell models to test the Canbay hypothesis about the formation mechanism of cytokines (CHAFMOC) on T-cell surfaces. A dielectrophoretic force field was created within the gelatin layer of the T-cell model. The prepared control and electromagnetically stimulated T-cell model samples were incubated in water in a glass container in a Faraday cage for the specified period and then photographed. …
Electron Energy Loss Spectroscopy Simulation By A Frequency Domain Surface Integral Equation Solver, İsmai̇l Enes Uysal
Electron Energy Loss Spectroscopy Simulation By A Frequency Domain Surface Integral Equation Solver, İsmai̇l Enes Uysal
Turkish Journal of Electrical Engineering and Computer Sciences
Plasmonic nanoparticles have been mostly studied using conventional light sources. Recently, electron energy loss spectroscopy (EELS) has started to be used to analyze plasmonic nanoparticles where incident electromagnetic fields are created by swift electrons. To accurately simulate EELS experiments, several numerical methods have been adapted. In this paper, a frequency domain surface integral equation (FDSIE) solver is modified to simulate EELS for plasmonic nanoparticles of gold and silver. Accuracy and versatility of the proposed FDSIE solver are shown by several numerical examples and compared to existing numerical, analytical, and experimental results.
Outage Probability Analysis And Adaptive Combiner For Multiuser Multipolarized Antenna Systems, Abdul Hai Muzammil Mohammed, Muhammad Moinuddin, Ubaid Muhsen Al-Saggaf, Ahmad Kamal Hassan
Outage Probability Analysis And Adaptive Combiner For Multiuser Multipolarized Antenna Systems, Abdul Hai Muzammil Mohammed, Muhammad Moinuddin, Ubaid Muhsen Al-Saggaf, Ahmad Kamal Hassan
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, we characterize the performance metrics of a multiuser multipolarized antenna system in a Rayleigh fading channel. We start by formulating a downlink system model that features a multiuser scenario in the presence of additive noise and a multipolarized antenna system; this is followed by evaluation of the outage probability in closed form. This is done by deriving the cumulative distribution function (CDF) of the signal-to-interference-plusnoise ratio using the approach of the ratio of indefinite quadratic forms. We thereby characterize the gradient of this CDF with respect to the combining vectors. Eventually, we obtain the optimum combining vectors …
Bow-Tie-Shaped Wideband Conformal Antenna With Wide-Slot For Gps Application, Ratikanta Sahoo, Damera Vakula
Bow-Tie-Shaped Wideband Conformal Antenna With Wide-Slot For Gps Application, Ratikanta Sahoo, Damera Vakula
Turkish Journal of Electrical Engineering and Computer Sciences
In this article, a novel wideband cylindrical conformal antenna using a wide slot in the ground plane is proposed. A bow-tie-shaped patch antenna is designed for Global Positioning System applications. The bandwidth of the antenna is improved by using a similar bow-tie-shaped slot in the ground plane with a larger dimension. The bandwidth is further enhanced by introducing a dumbbell-shaped slit in the patch. The antenna is fed by a 50-$ \Omega $ microstrip line. The proposed planar antenna is printed on a ground plane of size 0.5$ \lambda $ mm$ \times $ 0.5$ \lambda $ mm, where $ \lambda …
Three-Channel Control Architecture For Multilateral Teleoperation Under Time Delay, Uğur Tümerdem
Three-Channel Control Architecture For Multilateral Teleoperation Under Time Delay, Uğur Tümerdem
Turkish Journal of Electrical Engineering and Computer Sciences
Multilateral teleoperation is an extension of bilateral/haptic teleoperation framework to multiple operators/robots and finds applications in haptic training. As in bilateral teleoperation, time delay is an important problem, and stability and transparency, which quantifies the performance of the teleoperation system, are critical in the design of multilateral control systems. This paper proposes a novel three-channel-based multilateral control architecture with damping injection to guarantee delay-independent L2 stability and high transparency in multilateral teleoperation systems. The theoretical and computational analyses are verified with experiment results.
Optimal Contract Pricing Of Load Aggregators For Direct Load Control In Smartdistribution Systems, Ali Shayegan-Rad, Ali Zangeneh
Optimal Contract Pricing Of Load Aggregators For Direct Load Control In Smartdistribution Systems, Ali Shayegan-Rad, Ali Zangeneh
Turkish Journal of Electrical Engineering and Computer Sciences
Distribution system operators (DSOs) are interested in demand side participation programs as an efficient and secure resource to manage electricity supply and demand. However, it is usually difficult for DSOs to aggregate demand response of large/small consumers. Thus, in some electricity markets, an entity called an aggregator is defined to aggregate the load response of consumers. In this paper a bilevel scheduling model is proposed to determine the long-term optimal contract price between the DSO and aggregator for executing direct load control in smart distribution systems. The DSO and aggregator are considered as two different agents with individual objectives in …
Optimal Placement Of Switching And Protection Devices In Radial Distribution Networks To Enhance System Reliability Using The Ahp-Pso Method, Masoud Amohadi, Mahmud Fotuhi Firuzabad
Optimal Placement Of Switching And Protection Devices In Radial Distribution Networks To Enhance System Reliability Using The Ahp-Pso Method, Masoud Amohadi, Mahmud Fotuhi Firuzabad
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a new method to determine the optimal number and locations of autorecloser and sectionalizer switches (AR/S) in distribution networks. The costs of AR/S investment, switch maintenance, and undistributed energy as well as reliability coefficients are considered in the objective function. Reliability parameters such as SAIFI, SADI, MAIFI, and ENS are evaluated in the case study system. As a new method, the weights of the reliability parameters are obtained by decision-makers using the analytical hierarchy process (AHP). The optimal size, type, and location of automatic switches are determined by minimizing the objective function using the particle swarm optimization …
A Developed Flywheel Energy Storage With Built-In Rotating Supercapacitors, Hamidreza Toodeji
A Developed Flywheel Energy Storage With Built-In Rotating Supercapacitors, Hamidreza Toodeji
Turkish Journal of Electrical Engineering and Computer Sciences
Flywheel energy storage can store large amounts of kinetic energy in its rotating parts, but its inertia restricts the rate of power exchange. On the other hand, there is supercapacitor with the ability of exchanging large amounts of instantaneous power. Therefore, the combination of these two systems can significantly improve the dynamic response of conventional flywheel energy storage. This paper proposes a novel design for this combined system in which supercapacitors are located inside the rotating disk. Therefore, supercapacitors can significantly improve the dynamic performance of the flywheel energy storage with trivial effects on its size and weight. Moreover, the …
Thyristor-Based "Phase Hopping" Frequency Conversion Technique, Zhenwang Xu, Jiarui Zhang, Yuchun Yi, Cheng Chen, Jiaqi Yu, Wei Mei, Daiwei Feng
Thyristor-Based "Phase Hopping" Frequency Conversion Technique, Zhenwang Xu, Jiarui Zhang, Yuchun Yi, Cheng Chen, Jiaqi Yu, Wei Mei, Daiwei Feng
Turkish Journal of Electrical Engineering and Computer Sciences
This study proposes a new AC/AC "phase hopping" frequency conversion method based on the analyses of the disadvantages of the conventional cosine wave-crossing method. The advantages of this new method include no circulating current, no dead time, and an output frequency close to the power frequency. This study also introduces the basic principles of the "phase hopping" method and analyzes these principles combined with the voltage phase-changing comparison to that of the cosine wave-crossing method. The "phase hopping" principles are used to analyze the generation of thyristor trigger pulses, including the generation time and duration. A simulation is conducted in …
Evaluation Of Power System Robustness In Order To Prevent Cascading Outages, Farnaaz Hajbani, Heresh Seyedi, Kazem Zare
Evaluation Of Power System Robustness In Order To Prevent Cascading Outages, Farnaaz Hajbani, Heresh Seyedi, Kazem Zare
Turkish Journal of Electrical Engineering and Computer Sciences
Power system robustness against overload condition is a challenging issue in the fields of power system planning and operation. In this paper, two indices are proposed to evaluate power system robustness. The proposed indices are used to identify critical lines whose failure is due to overload, leading the power system to cascading outages and blackout. The first proposed index is a linear index. The second index is based on graph theory metrics. To prevent cascading outages, system robustness is calculated for all N-1 and N-2 contingencies. The lines whose outages lead to the smallest robustness values are considered as critical …
Improved Vsm Control Of Pmsg-Based Wind Farms For Transient Stability Enhancement, Mohamed Abbes, Ines Mehouachi, Souad Chebbi
Improved Vsm Control Of Pmsg-Based Wind Farms For Transient Stability Enhancement, Mohamed Abbes, Ines Mehouachi, Souad Chebbi
Turkish Journal of Electrical Engineering and Computer Sciences
This paper analyzes the optimal control strategy of PMSG-based wind farms during faults in order to improve the transient stability of a power system with a high penetration rate of wind power. The investigated control strategies are the unity power factor (UPF), reactive power control (RPC), and particularly the concept of virtual synchronous machine (VSM). The transient stability level is assessed using the critical clearing time index, which was calculated based on trajectory sensitivity analysis. In light of the obtained results, it was found that RPC gives the best transient stability level, followed by the classical VSM control. Hence, an …