Showing 33 results for Su
Sujan Rajbhandari, Zabih Ghassemlooy, Maia Angelova,
Volume 5, Issue 2 (June 2009)
Abstract
Artificial neural network (ANN) has application in communication engineering in diverse areas such as channel equalization, channel modeling, error control code because of its capability of nonlinear processing, adaptability, and parallel processing. On the other hand, wavelet transform (WT) with both the time and the frequency resolution provides the exact representation of signal in both domains. Applying these signal processing tools for channel compensation and noise reduction can provide an enhanced performance compared to the traditional tools. In this paper, the slot error rate (SER) performance of digital pulse interval modulation (DPIM) in diffuse indoor optical wireless (OW) links subjected to the artificial light interference (ALI) is reported with new receiver structure based on the discrete WT (DWT) and ANN. Simulation results show that the DWT-ANN based receiver is very effective in reducing the effect of multipath induced inter-symbol interference (ISI) and ALI.
R Subramanian, K Thanushkodi, A Prakash,
Volume 9, Issue 4 (December 2013)
Abstract
The Economic Load Dispatch (ELD) problems in power generation systems are to reduce the fuel cost by reducing the total cost for the generation of electric power. This paper presents an efficient Modified Firefly Algorithm (MFA), for solving ELD Problem. The main objective of the problems is to minimize the total fuel cost of the generating units having quadratic cost functions subjected to limits on generator true power output and transmission losses. The MFA is a stochastic, Meta heuristic approach based on the idealized behaviour of the flashing characteristics of fireflies. This paper presents an application of MFA to ELD for six generator test case system. MFA is applied to ELD problem and compared its solution quality and computation efficiency to Genetic algorithm (GA), Differential Evolution (DE), Particle swarm optimization (PSO), Artificial Bee Colony optimization (ABC), Biogeography-Based Optimization (BBO), Bacterial Foraging optimization (BFO), Firefly Algorithm (FA) techniques. The simulation result shows that the proposed algorithm outperforms previous optimization methods.
M. Khodsuz, M. Mirzaie,
Volume 10, Issue 2 (June 2014)
Abstract
Metal oxide surge arresters (ZNO) are used widely in power system to protect equipments from over voltages. Non uniform potential distribution leads to the depressed service life and low safe reliability, so grading ring is applied on HV surge arrester order to uniform the electric field distribution. One of the problems of arresters is leakage current in power frequency that different parameters such as internal structure of varistors, heat sinks, grading ring can be influence on leakage current.
In this paper Maxwell and EMTP/ATP software has been applied to calculate the electric field, voltage distribution and leakage current in a high voltage surge arrester. First Maxwell is used to calculate the electric field and voltage distribution of a 230kV surge arrester with and without grading ring. Then equivalent circuit of surge arrester has been achieved by applying Maxwell software for 230kV surge arrester and extracting stray capacitances. The derived equivalent circuit has been simulated in EMTP/ATP software for evaluation of leakage current. Also in this work, the effect of grading ring dimensions and number of heat sinks on leakage current variation has been investigated. Results show grading ring dimension and heat sinks number impact on arrester leakage current.
F. Hunaini, I. Robandi, I. N. Sutantra,
Volume 11, Issue 1 (March 2015)
Abstract
Steer-by-wire is the electrical steering systems on vehicles that are expected with the development of an optimal control system can improve the dynamic performance of the vehicle. This paper aims to optimize the control systems, namely Fuzzy Logic Control (FLC) and the Proportional, Integral and Derivative (PID) control on the vehicle steering system using Imperialist Competitive Algorithm (ICA). The control systems are built in a cascade, FLC to suppress errors in the lateral motion and the PID control to minimize the error in the yaw motion of the vehicle. FLC is built has two inputs (error and delta error) and single output. Each input and output consists of three Membership Function (MF) in the form of a triangular for language term "zero" and two trapezoidal for language term "negative" and "positive". In order to work optimally, each MF optimized using ICA to get the position and width of the most appropriate. Likewise, in the PID control, the constant at each Proportional, Integral and Derivative control also optimized using ICA, so there are six parameters of the control system are simultaneously optimized by ICA. Simulations performed on vehicle models with 10 Degree Of Freedom (DOF), the plant input using the variables of steering that expressed in the desired trajectory, and the plant outputs are lateral and yaw motion. The simulation results showed that the FLC-PID control system optimized by using ICA can maintain the movement of vehicle according to the desired trajectory with lower error and higher speed limits than optimized with Particle Swarm Optimization (PSO).
M Khodsuz, M Mirzaie,
Volume 11, Issue 4 (December 2015)
Abstract
This paper introduces the indicators for surge arrester condition assessment based on the leakage current analysis. Maximum amplitude of fundamental harmonic of the resistive leakage current, maximum amplitude of third harmonic of the resistive leakage current and maximum amplitude of fundamental harmonic of the capacitive leakage current were used as indicators for surge arrester condition monitoring. Also, the effects of operating voltage fluctuation, third harmonic of voltage, overvoltage and surge arrester aging on these indicators were studied. Then, obtained data are applied to the multi-layer support vector machine for recognizing of surge arrester conditions. Obtained results show that introduced indicators have the high ability for evaluation of surge arrester conditions.
S. Sivasakthi, R. K. Santhi, N. Murali Krishnan, S. Ganesan, S. Subramanian,
Volume 13, Issue 2 (June 2017)
Abstract
The increasing concern of global climate changes, the promotion of renewable energy sources, primarily wind generation, is a welcome move to reduce the pollutant emissions from conventional power plants. Integration of wind power generation with the existing power network is an emerging research field. This paper presents a meta-heuristic algorithm based approach to determine the feasible dispatch solution for wind integrated thermal power system. The Unit Commitment (UC) process aims to identify the best feasible generation scheme of the committed units such that the overall generation cost is reduced, when subjected to a variety of constraints at each time interval. As the UC formulation involves many variables and system and operational constraints, identifying the best solution is still a research task. Nowadays, it is inevitable to include power system reliability issues in operation strategy. The generator failure and malfunction are the prime influencing factor for reliability issues hence they have considered in UC formulation of wind integrated thermal power system. The modern evolutionary algorithm known as Grey Wolf Optimization (GWO) algorithm is applied to solve the intended UC problem. The potential of the GWO algorithm is validated by the standard test systems. Besides, the ramp rate limits are also incorporated in the UC formulation. The simulation results reveal that the GWO algorithm has the capability of obtaining economical resolutions with good solution quality.
M. Khodsuz, S. Seyyedbarzegar,
Volume 15, Issue 1 (March 2019)
Abstract
The essential role of surge arresters is equipment protection against over-voltages to increase system reliability. Different monitoring techniques have been used to diagnose surge arrester condition. Leakage current analysis methods by the extraction resistive and capacitive components of leakage current are a conventional method for surge arrester monitoring. Insufficient appropriate thresholds are most important restriction of these kinds of methods. In this paper, the impact of pollution, ultraviolet aging and varistors fault on harmonic spectrum of leakage current have been evaluated experimentally. Real tests and examinations have been done on different metal oxide surge arresters to investigate effects of mentioned factors on leakage current harmonics. To show results performance, bees-adaptive network based fuzzy inference system has been applied.
R. Shariatinasab, M. Rasuli, J. Gholinezhad,
Volume 15, Issue 1 (March 2019)
Abstract
In this paper a novel method based on evolutionary algorithms is presented to estimate the harmonic components. In general, the optimization of the harmonic estimation process is a multi-component problem, in which evaluation of the phase and harmonic frequency is the nonlinear part of the problem and is solved based on the mathematical and evolutionary methods; while estimation of amplitude of the harmonic component is a linear issue that is performed by combining the least squares method with the aforementioned approaches. In this paper, firstly, the optimal estimation of integer harmonic components has been introduced based on the improved shuffled frog leaping algorithm (ISFLA) in the presence of two types of noise. The obtained results present the lower error of the proposed method than to IGHS, FBF PSO, GA and FFT methods. Thereafter, the effectiveness of the presented algorithm in optimal estimation of frequency, phase, and amplitude of the integer and non-integer harmonics are investigated. The optimization of the estimation of various harmonic components under different conditions using ISFLA leads to an improvement in the assessment of power quality in power systems especially in the distribution networks, considering a lot of the nonlinear loads and harmonic resources connected to the network.
A. P. Hutomo, I. P. Buditomo, A. P. Putra, S. Suhariningsih, S. D. Astuti,
Volume 15, Issue 4 (December 2019)
Abstract
The Functional Electrical Stimulator design using monophasic spike-exponential waveform was proposed and described in this study. The monophasic square waveform has benefit in generating an action potential, but it could cause side effects such as toxic caused by the electrode polarization. The square waveform signal which the frequency and pulse width could be modulated was manipulated to be the monophasic spike-exponential waveform. Transformer OT240 was applied at the end of the FES system part and functioned as a voltage amplifier and DC signal isolator. On every frequency range between 5–100 Hz, the 16 peak voltage stages with the lower limit of 45 Volt and an upper limit of 400 Volt was arranged to obtain VRMS value in each stage. Characterization result shows that the produced waveform was monophasic spike-exponential with the narrow pulse width (t1/2 = 7 µs) and VRMS in the maximum frequency and peak voltage was 8.99 Volt. This study showed that the designed FES had high VP and low VRMS, thus, it could be concluded that this FES system design could be a candidate for its application.
A. N. Patel, B. N. Suthar,
Volume 16, Issue 1 (March 2020)
Abstract
Cogging torque is the major limitation of axial flux permanent magnet motors. The reduction of cogging torque during the design process is highly desirable to enhance the overall performance of axial flux permanent magnet motors. This paper presents a double-layer magnet design technique for cogging torque reduction of axial flux permanent magnet motor. Initially, 250 W, 150 rpm axial flux brushless dc (BLDC) motor is designed for electric vehicle application. Initially designed reference axial flux BLDC motor is designed considering 48 stator slots and 16 rotor poles of NdFeb type single layer permanent magnet. Three-dimensional finite element modeling and analysis have been performed to obtain cogging torque profile of reference motor. Additional layer of the permanent magnet is created keeping usage of permanent magnet same with an objective of cogging torque reduction. Three-dimensional finite element modeling and analysis have been performed to obtain cogging torque profile of improved axial flux BLDC motor with double layer permanent magnet design. It is analyzed that double-layer magnet design is an effective technique to reduce the cogging torque of axial flux BLDC motor.
A. N. Patel, B. N. Suthar,
Volume 16, Issue 3 (September 2020)
Abstract
Optimization of specific power of axial flux permanent magnet brushless DC (PMBLDC) motor based on genetic algorithm optimization technique for an electric vehicle application is presented. Double rotor sandwiched stator topology of axial flux permanent magnet brushless DC motor is selected considering its best suitability in electric vehicle applications. Rating of electric motor is determined based on vehicular dynamics and application needs. Double rotor sandwiched stator axial flux PMBLDC motor is designed considering various assumed design variables. Initially designed axial flux PMBLDC motor is considered as a reference motor for further analysis. Optimization of the specific power of electric motor for electric vehicle applications is a very important design issue. The Genetic Algorithm (GA) based optimization technique is proposed for optimization of specific power of axial flux permanent magnet brushless DC motor. Optimization with an objective of maximum specific power with the same torque rating is performed. Three-dimensional finite element analysis is performed to validate the proposed GA based specific power optimization. Close agreement between results obtained from finite element analysis and analytical design establishes the correctness of the proposed optimization technique. The performance of the improved motor is compared with the initially designed reference motor. It is analyzed that the specific power of axial flux PMBLDC motor is enhanced effectively with the application of GA based design optimization technique.
S. A. Rahman, S. Birhan, E. D. Mitiku, G. T. Aduye, P. Somasundaram,
Volume 17, Issue 4 (December 2021)
Abstract
Aim of this paper is to attain the highest voltage sag and swell compensation using a direct converter-based DVR topology. The projected DVR topology consists of a direct converter with bidirectional switches, a multi winding transformer with three primary windings and secondary winding and a series transformer. When voltage swell occurs in a phase, the same phase voltage can be utilized to mitigate the swell as huge voltage exists in the phase where swell has occurred. So it is possible to mitigate an infinite amount of swell. In all the DVR topologies, the converter is only used to synthesize the compensating voltage. The range of voltage sag mitigation depends upon the magnitude of input voltage available for the converter. If this input voltage of the direct converter is increased, then the range of voltage compensation could also be increased. Input voltage of the direct converter is increased using the multi winding transformer. The direct converter is synthesizing the compensating voltage. This compensating voltage is injected in series with the supply voltage through the series transformer and the sag is mitigated. In this proposed topology, the input voltage for the direct converter is increased by adding the three phase voltages using a multi winding transformer. Thus the voltage sag compensating range of this topology is increased to 68% and the swell compensating range is 500%. Ordinary PWM technique has been used to synthesize the PWM pulses for the direct converter and the THD of the compensated load voltage is less than 5%. This topology is simulated using MATLAB Simulink and the results are shown for authentication.
M. Khodsuz,
Volume 18, Issue 2 (June 2022)
Abstract
Lightning is the main factor of outage and insulation breakdown of power system. The lightning event can produce dangerous overvoltage, equipment failures, and power supply interruption. In this paper, externally gapped Line arresters (EGLAs) performances have been investigated to evaluate the lightning performances of a typical 63 kV transmission line. A probabilistic analysis has been done to study the EGLA performance in transmission line by Monte-Carlo method. The results show the EGLA performance dependency to soil resistivity and lightning strike parameters.
G. Vasudeva, B. V. Uma,
Volume 18, Issue 3 (September 2022)
Abstract
Successive approximation register (SAR) analog to digital converter (ADC) architecture comprises submodules such as comparator, digital to analog converters (DAC), and SAR logic. Each of these modules imposes challenges as the signal makes transition from analog to digital and vice-versa. Design strategies for optimum design of circuits considering 22nm FinFET technology meeting area, timing, power requirements, and ADC metrics are presented in this work. Operational Transconductance Amplifier (OTA) based comparator, 12-bit two-stage segmented resistive string DAC architecture, and low power SAR logic are designed and integrated to form the ADC architecture with a maximum sampling rate of 1 GS/s. Circuit schematic is captured in cadence environment with optimum geometrical parameters and performance metrics of the proposed ADC are evaluated in MATLAB environment. Differential nonlinearity and integral nonlinearity metrics for the 12-bit ADC are limited to +1.15/-1 LSB and +1.22/-0.69 LSB respectively. ENOB of 10.1663 with SNR of 62.9613 dB is achieved for the designed ADC measured for conversion of input signal of 100 MHz with 20dB noise. ADC with sampling frequency up to 1 GSps is designed in this work with low power dissipation of less than 10 mW.
Pravat Biswal, Veera Venkata Subrahmanya Kumar Bhajana, Pavel Drabek,
Volume 18, Issue 4 (December 2022)
Abstract
This paper proposes two new soft-switching transformerless converters with high voltage conversion ratio. These proposed converters achieve soft-switching each with a single auxiliary resonant cell. The merit of these converters is reduced switching losses with lesser number of devices. The main switching devices are turned off with zero current switching (ZCS). Apart from the soft-switching feature, the voltage conversion ratio is increased in comparison with the existing topologies. The operating principles and the simulation results on 12V/200V/500W converter system are presented in this paper.
P. Lakshman Naik, H. Jafari, T. Sudhakar Babu, A. Anil, S. Venkata Padmavathi, D. Nazarpour,
Volume 19, Issue 2 (June 2023)
Abstract
This paper demonstrates an enhancement of power quality in grid integrated systems with the help of the proposed control strategy for voltage source converter based active power filters. The Shunt Active Power filters (SAPF) are extensively utilized in modern grid integrated systems to diminish the power quality concerns associated with it. The SAPF is one of the various power filters, which has better dynamic performance. The SAPF requires an accurate control strategy that provides robust performance under source and loads unbalance conditions. The proposed control scheme is responsible for generating the gate signals to activate the operation of Voltage Source Converter (VSC) based Active Power Filter. Thus, the performance of mitigation of harmonics of source current principally depends on the adopted algorithm. The present paper represents a performance study of a control scheme to mitigate power quality issues in the grid integrated system. The proposed system is modelled and simulated in MATLAB-Simulink in Simpower system block set.
A. O. Issa, A. I. Abdullateef, A. Sulaiman, A. Y. Issa, M. J. E. Salami, M. A. Onasanya ,
Volume 19, Issue 3 (September 2023)
Abstract
Grid-connected photovoltaic (PV) system is often needed whenever utilities fail to provide consumers with a reliable, sufficient and quality power supply. It provides more effective utilization of power, however, there are technical requirements to ensure the safety of the PV installation and utility grid reliability. In solar systems there is often excessive use of components, resulting in high installation costs. Consequently, appropriate measures must be taken to develop a cost-effective grid-connected PV system. An optimally sized PV system incorporated into an existing unreliable grid-connected commercial load for Mount Olive food processing is presented in this paper. The study focused on providing a reliable electricity supply which is cost-effective and environment-friendly. The techno-economic analysis of grid-connected PV/Diesel/Battery Storage systems was carried out using HOMER Pro software. Results showed that Grid/PV/BSS are technically, economically and environmentally feasible with the cost of energy at 0.136$/kWh and net present cost at $254,469. Also, the excess electricity produced by this combination is 13,264kWh/year, which generates income for the company by selling excess generated energy back to the grid if net metering were to be implemented. Furthermore, the CO2 emissions for these combinations decreased to 10,081.6 kg/year as compared to the existing systems (Grid/Diesel Generator) with emissions of 124,480 kg/year. This is an additional advantage in that it improves the greenhouse effect. A sensitivity analysis was carried out on the variation of load change, grid power price and schedule outages for the optimal system.
Oorappan G Murugan, Jeevanandham Arumugam, Suresh Velliangiri,
Volume 19, Issue 4 (December 2023)
Abstract
Single Source Cross Connected Reduced Activated Switched-Capacitor Multilevel Inverter (S2C2RASCMLI) accompanied by fewer active switching components is appealing to nine-level of voltage with its simplicity and a solid network. In AC power distribution systems, multi-level inverters are used as DC-to-AC converter operations to achieve the desired output magnitude and frequency. It is employed for the smooth operation of electrical machines. The proposed S2C2RASCMIL cell yields a nine-level voltage with ten switches, nine driver signals, and two flying capacitors for dynamic load operation with reduced active switches. It has the capability of boosting the input voltage double the times. The proposed multilevel inverter operated on nine switching modes and in each mode, three switches have been conducted. It can be extended horizontal and/or vertical structure to produce more levels of output voltages. The hardware prototype was made and the results have been presented. To demonstrate the advantages of the new proposed multilevel inverter topology, a comprehensive comparison with a few other similar multilevel inverter configurations is done. Analysis and simulation output waveforms for a variety of load conditions were tested to check the feasibility of the proposed new multi-level inverter. The proposed MLI offers better performance than existing multilevel inverters.
Jhanvi Gupta, Sanskar Jain, Suprava Chakraborty,
Volume 19, Issue 4 (December 2023)
Abstract
A powerhouse under development, India is slowly breaking free from its traditional methods of operations. It has been chosen for analysis as it offers a plethora of diverse cultures and a variety of indigenous groups of people. The energy sector of the country is transitioning to adopt policies that are in line with its sustainable goals. Focusing on peer-to-peer energy trading and the development of blockchain technologies, unconventional methods are slowly being incorporated with the help of various experimental projects. This is backed up by peer-to-peer trading of energy providing a prosumer with an autonomous environment. The paper looks into the ongoing trends in this sector and major reforms that are required to bring about the necessary shift. Challenges and their recommendations are also been discussed along with the need to implement them. Suitable conclusions have been drawn that aim towards favoring the P2P style of open-source electricity trading as the need for such an analysis is vital to achieve a decentralized energy system.
Ayotunde Abimbola Ayorinde, Sulaiman Adeniyi Adekola, Ike Mowete,
Volume 19, Issue 4 (December 2023)
Abstract
This paper, using the circuit-geometric features of the Method of Moments (MoM), presents a comprehensive analytical treatment of an exponentially non-uniform helical antenna (ENH), mounted on a ground plane of finite extent. Earlier investigations reported in the literature established that the introduction of an exponential non-uniformity in the turns spacing of an otherwise uniformly wound helical antenna significantly improves its axial ratio and power gain profiles, but failed to address two important questions; one concerning the influence of the degree of non-uniformity on the antenna performance: and the other, the associated return loss profile, which is of particular importance in practical applications. It is shown in this paper, that when a properly designed impedance matching circuitry is introduced, a return loss of the ENH of close to 60 dB is achievable; without compromising axial ratio and gain performances. Indeed, axial ratio bandwidth remained unchanged at 54.55% for both the impedance-matched and unmatched ENHs, whilst maximum gain changed marginally from 14.19dB, for the unmatched ENH to 14.18dB for the impedance-matched antenna.
