Search published articles


Showing 43 results for K.

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. K. Saini, R. K. Beniwal,
Volume 14, Issue 2 (June 2018)
Abstract

This paper presents a new framework based on modified EMD method for detection of single and multiple PQ issues. In modified EMD, DWT precedes traditional EMD process. This scheme makes EMD better by eliminating the mode mixing problem. This is a two step algorithm; in the first step, input PQ signal is decomposed in low and high frequency components using DWT. In the second stage, the low frequency component is further processed with EMD technique to get IMFs. Eight features are extracted from IMFs of low frequency component. Unlike low frequency component, features are directly extracted from the high frequency component. All these features form feature vector which is fed to PNN classifier for classification of PQ issues. For comparative analysis of performance of PNN, results are compared with SVM classifier. Moreover, performance of proposed methodology is also validated with noisy PQ signals. PNN has outperformed SVM for both noiseless and noisy PQ signals.

S. Hajiaghasi, K. Abbaszadeh, A. Salemnia,
Volume 15, Issue 1 (March 2019)
Abstract

Interturn fault detection is a challenging issue in power transformer protection. In this paper, interturn faults of distribution transformer are studied and a new online detection method based on vibration analysis is proposed. Transformer electromagnetic forces are analyzed by time stepping finite element (TSFE) modeling of interturn fault. Since the vibration associated with inter-turn faults is caused by electromagnetic forces, axial and radial electromagnetic forces for various interturn faults are studied. Transformer winding vibration under interturn faults is studied through an equivalent mathematical model combined with electromagnetic force analysis. The results show that it is feasible to predict the interturn winding faults of transformer windings with the transformer vibration analysis method. Simulation and experimentation studies are carried out on 20/0.4 kV, 50 kVA distribution transformer. The results confirm the effectiveness of the proposed method.

M. Srivastava, K. Bhardwaj,
Volume 15, Issue 3 (September 2019)
Abstract

In this paper two R‑L network simulator configurations employing a single VDDIBA, one resistance and one grounded capacitance are presented. The first configuration is a grounded series resistor-inductor (R‑L) network simulator and the second configuration is intended for grounded parallel resister-inductor (R‑L) circuit simulation. Both the proposed circuits enjoy several beneficial features such as: 1) compact structure employing only one VDDIBA and two passive elements, 2) electronic tuning of inductive part of realized series/parallel R‑L impedances, 3) independent control of inductive and resistive parts of realized parallel R‑L impedance, 4) no requirement of any component matching, and 5) un-deviated performance in non-ideal environment. By choosing appropriate values of active/passive elements, a series R‑L circuit for simulating resistance of 7.742 kΩ and inductance of value 7.742 mH has been developed. Similarly a parallel R‑L simulation circuit to simulate a resistance of value 1 kΩ and inductance of value 77.4 µH is implemented. To study the influence of parasitics on developed lossy inductances, the behavior of these configurations has been studied keeping terminal parasitics of VDDIBAs under consideration. To check the performance and usefulness of the proposed configurations some second-order filtering circuits have been designed. To confirm the theoretical analysis, PSPICE Simulation results have been included.

C. S. Vinitha, R. K. Sharma,
Volume 15, Issue 4 (December 2019)
Abstract

An efficient Lookup Table (LUT) design for memory-based multiplier is proposed.  This multiplier can be preferred in DSP computation where one of the inputs, which is filter coefficient to the multiplier, is fixed. In this design, all possible product terms of input multiplicand with the fixed coefficient are stored directly in memory. In contrast to an earlier proposition Odd Multiple Storage (OMS), we have proposed utilizing Even Multiple Storage (EMS) scheme for memory-based multiplication and by doing so we are able to achieve a less complex and high-speed design. Because of the very simpler control circuit used in our design, to extract the odd multiples of the product term, we are also able to achieve a significant reduction in path delay and area complexity. For validation, the proposed design of the multiplier is coded in VHDL, simulated and synthesized using Xilinx tool and then implemented in Virtex 7 XC7vx330tffg1157 FPGA. Various key performance metrics like number of slices, number of slice LUT’s and maximum combinational path delay is estimated for different input word length. Also, the performance metrics are compared with the existing OMS design. It is found that the proposed EMS design occupies nearly 62% less area in terms of number of slices as compared to the OMS design and the maximum path delay is decreased by 77% for a 64-bit input. Further, the proposed multipliers are used in Transposed FIR filter and its performance is compared with the OMS multiplier based filter for various filter orders and various input lengths.

M. El Alaoui, F. Farah, K. El Khadiri, H. Qjidaa, A. Aarab, A. Lakhssassi, A. Tahiri,
Volume 15, Issue 4 (December 2019)
Abstract

In this work, the design and analysis of new Level Shifter with Gate Driver for Li-Ion battery charger is proposed for high speed and low area in 180nm CMOS technology. The new proposed level shifter is used to raise the voltage level and significantly reduces transfer delay 1.3ns (transfer delay of conventional level shifter) to 0.15ns with the same input signal. Also, the level shifter with gate driver achieves a propagation delay of less than 0.25ns and the total area is only 0.05mm2. The proposed level shifter with gate driver was designed, simulated and layouted in Cadence using TSMC 180nm CMOS technology.

D. Jamunaa, G. K. Mahanti, F. N. Hasoon,
Volume 16, Issue 2 (June 2020)
Abstract

This paper describes the synthesis of digitally excited pencil/flat top dual beams simultaneously in a linear antenna array constructed of isotropic elements. The objective is to generate a pencil/flat top beam pair using the excitations generated by the evolutionary algorithms. Both the beams share common variable discrete amplitude excitations and differ in variable discrete phase excitations. This synthesis is treated as a multi-objective optimization problem and is handled by Quantum Particle Swarm Optimization algorithm duly controlling the fitness functions. These functions include many of the radiation pattern parameters like side lobe level, half power beam width and beam width at the side lobe level in both the beams along with the ripple in the flat top band of flat top beam. In addition to it, the dynamic range ratio of the amplitudes excitations is set below a certain level to diminish the mutual coupling effects in the array. Two sets of experiments are conducted and the effectiveness of this algorithm is proved by comparing it with various versions of swarm optimization algorithms.

P. Gupta, S. K. Jana,
Volume 17, Issue 2 (June 2021)
Abstract

The advancement in the integrated circuit design has developed the demand for low voltage portable analog devices in the market. This demand has increased the requirement of the low-power RF transceiver. A low-power phase lock loop (PLL) is always desirable to fulfill the need for a low power RF transceiver. This paper deals with the designing of the low power transconductance- capacitance (Gm-C) based loop filter with the help of the gate-driven quasi bloating Bulk (GD-QFB) MOS technique. The GD-QFB MOS-based operational transconductance amplifier (OTA) has been proposed with a high dc gain of 82.41 dB and less power consumption of 188.72 µW. Further, Gm-C based active filter has been designed with the help of the proposed GD-QFB OTA. The simulation results of Gm-C filter attain a -3 dB cut-off frequency of 59.08 MHz and power consumption of 188.31µW at the supply voltage of 1V. The proposed Gm-C filter is suitable for the designing of 1-3 GHz low power PLL.

S. K. Gudey, S. Andavarapu,
Volume 17, Issue 3 (September 2021)
Abstract

A three-phase dual-port T-type asymmetrical multilevel inverter (ASMLI) using two sources, solar forming the high voltage level and the battery forming the low voltage level, is considered for grid interconnection. A vertical shifted SPWM is used for the ASMLI circuit. A transformerless system for grid interconnection is achieved for a 100-kW power range. A well-designed boost converter and a Buck/Boost converter is used on the front side of the inverter. Design of battery charge controller and its controlling logic are done and its SOC is found to be efficient during charging and discharging conditions. A closed-loop control using PQ theory is implemented for obtaining power balance at 0.7 modulation index. The THD of the current harmonics in the system is observed to be 0.01% and voltage harmonics is 0.029% which are well within the permissible limits of IEEE-519 standard. The power balance is found to be good between the inverter, load, and the grid during load disconnection for a period of 0.15s. A comparison of THD’s, voltage, current stresses on the switches, and conduction losses is also presented for a single-phase system with respect to a two-level inverter which shows improved efficiency and low THD. Hence this system can be proposed for use in grid interconnection with renewable energy sources.

S. V. Akram, R. Singh, A. Gehlot, A. K. Thakur,
Volume 17, Issue 4 (December 2021)
Abstract

Waste management is crucial for maintaining the hygienic environment in urban cities. The establishment of a reliable and efficient IoT system for waste management is based on integrating low power and long-range transmission protocol. Low Power Wide Area Network (LPWAN) is specially designed for the aforementioned requirement of IoT. LoRa (Long Range) is an LPWAN transmission protocol that consumes low power for long-range transmission. In this study, we are implementing long-range (LoRa) communication and cloud applications for real-time monitoring of the bins. The customized sensor node and gateway node are specifically designed for sensing the level of bins using ultrasonic sensor and communicating it to the cloud via long-range and internet protocol connectivity. Blynk and cayenne are the two cloud-based applications for storing and monitoring the sensory data receiving from the gateway node over internet protocol (IP). The customization of nodes6 and utilization of two cloud-based apps are the unique features in this study. In the future, we will implement blockchain technology in the study for enabling a waste-to-model platform.

A. Zakipour, K. Aminzare, M. Salimi,
Volume 18, Issue 3 (September 2022)
Abstract

Considering the presence of different model parameters and controlling variables, as well as the nonlinear nature of DC to AC inverters; stabilizing the closed-loop system for grid current balancing is a challenging task. To cope with these issues, a novel sliding mode controller is proposed for the current balancing of local loads using grid-connected inverters in this paper. The closed-loop system includes two different controlling loops: a current controller which regulates the output current of grid-connected inverter and a voltage controller which is responsible for DC link voltage regulation. The main features of the proposed nonlinear controller are reactive power compensation, harmonic filtering and three-phase balancing of local nonlinear loads.  The developed controller is designed based on the state-space averaged modelling its stability and robustness are proved analytically using the Lyapunov stability theorem. The accuracy and effectiveness of proposed controlled approach are investigated through the PC-based simulations in MATLAB/Simulink.

R. Gandotra, K. Pal,
Volume 18, Issue 3 (September 2022)
Abstract

The growing demand increases the maximum utilization of transmission and distribution lines which causes overloading, high losses, instability, contingency, and congestion. To enhance the performance of AC transmission and distribution systems FACTS devices are used. These devices assist in solving different issues of transmission lines such as instability, congestion, power flow, and power losses. Advancement in developed technology leads to the development of special application-based FACTS controllers. The main issues are concerned while placing the FACTS controller in the transmission and distribution lines to maximize the flow of power. Various methods like analytic method, arithmetic programming approaches, meta-heuristic optimization approaches, and hybrid approaches are being employed for the optimal location of FACTS controllers. This paper presents a review of various types of FACTS controllers available with both analytical and meta-heuristic optimization methods for the optimal placement of FACTS controllers. This paper also presents a review of various applications of FACTS devices such as stability improvement, power quality, and congestion management which are the main issues in smart power systems. Today’s smart power systems comprise the smart grids with smart meters and ensure continuous high quality of power to the consumers.

K. Fertas, F. Fertas, S. Tebache, A. Mansoul, R. Aksas,
Volume 18, Issue 3 (September 2022)
Abstract

In this paper, a frequency switchable antenna design using genetic algorithms (GAs) for dual band WiMAX (3.5GHz) and WLAN (5.2GHz) applications is proposed. The area of the radiating patch element is divided into 2 mm square cells, with each cell assigned a conducting or non-conducting characteristic. To realize frequency reconfiguration, switches are incorporated into appropriate locations to activate/deactivate corresponding cells. The on/off states of the switches are represented by the presence or absence of conductor, respectively. Hence, the proposed approach allows the antenna to operate as mono-band or dual-band radiator according to the desired application. Further, measurements and simulations are carried out and a reasonable agreement is achieved.

A. Hesami Naghshbandy, K. Naderi, U. D. Annakkage,
Volume 18, Issue 3 (September 2022)
Abstract

The most challenging circumstance of forced oscillations (FOs) is when the power system is forced to oscillate at its natural frequencies. This paper uses a novel PMU data-driven mechanism to pinpoint the source of such phenomena under resonance. Following the detection of FOs, the instantaneous changes in the output power and angular velocity of the rotors are calculated. Accordingly, an energy-driven multilateral interaction pattern is obtained for all synchronous generators. Next, an appropriate positive weighted undirected graph is constructed through these functional patterns based on the spectral graph theory. These quantitative indicators are then analyzed through the eigenvalue spectrum of the normalized Laplacian matrix of the system graph reduced to the internal generator buses. Finally, the smallest value in eigenvectors corresponding to the two largest eigenvalues reveals the location of the source. The proposed methodology’s validation and verification studies have been performed on the WECC 3-machine 9-bus and New England 10-machine 39-bus benchmark power systems modeled in the Real-Time Digital Simulator (RTDS) and then analyzed in the MATLAB environment. The proposed methodology revealed to be fast and accurate in locating the source of FOs under challenging resonance situations with promising results while addressing the generator side origins.

S. M. Ahmed, K. S. Ahmed, Y. M. Shuaib,
Volume 19, Issue 1 (March 2023)
Abstract

This article discusses the operating principle and simulation of closed loop control of a three phase induction motor (IM) powered by five level diode clamped multilevel inverter (DCMLI) using direct torque control (DTC) technique. The main purpose of this article is to regulate the torque and speed of an IM and to decrease total harmonic distortion (THD). In this article, a five-level inverter's direct modulation approach with the dc link voltage self-balancing is presented. To reduce capacitor voltage variation, the redundancies of various switch topologies for the creation of intermediate voltages are also used. The use of LC filter results in lower output voltage and current distortion. A multicarrier PWM control technique is used for DCMLI to provide high quality sinusoidal output voltage with decreased harmonics. This can be obtained by employing Sinusoidal Pulse Width Modulation (SPWM) method for speed and torque control. This demonstrates that the recommended method of controlling the motor's speed and torque is effective. The simulation result reveals that DTC for the five-level inverter fed IM drive gives a rapid dynamic response, lower voltage and current THDs, and much less flux and torque distortion. The simulation is carried out in MATLAB Simulink (R2014).

A. Rahali, K. El Khadiri, A. Tahiri,
Volume 19, Issue 1 (March 2023)
Abstract

In this paper, a Li-Ion Battery Charger Interface (BCI) circuit with fast and safe charging for portable electronic devices is proposed. During the charging of Li-Ion battery, current spikes due to asynchronous control signals, and temperature are factors that greatly affect battery performances and life. This circuit has the following features: prevents current spikes and also incorporates a permanent battery temperature monitoring block. The BCI uses a dual current source and generates a constant current in a large current mode of 1.5 A, further reducing charging time. The proposed BCI was designed and simulated in Cadence Virtuoso using TSMC 180 nm technology. The simulation results of the control signals show that the proposed architecture was able to eliminate the current drifts and keep the battery temperature within the normal operating range.

K. Zarrinnegar, S. Tohidi, M. R. Mosavi, A. Sadr, D. M. de Andrés,
Volume 19, Issue 1 (March 2023)
Abstract

The Global Positioning System (GPS) is vulnerable to various deliberate and unintentional interferences. Therefore, identifying and coping with various interferences in this system is essential. This paper analyzes a method of reducing the dimensions of Cross Ambiguity Function (CAF) images in improving the identification of spoofing interference at the GPS using Multi-Layer Perceptron Neural Network (MLP NN) and Convolutional Neural Network (CNN). Using the proposed method reduces data complexity, which can reduce the number of learning data requirements. The simulation results indicate that, by applying the proposed image processing algorithm for different dimensions of CAF images, the CNN performs better than MLP NN in terms of training accuracy; the MLP NN is superior to CNN in terms of convergence speed of training. In addition, the results demonstrate that the operation of the proposed method is appropriate in the case of small-delay spoofed signals. Therefore, for the intervals above 0.25 code chip, the proposed method detects spoofing attacks with a correct detection probability close to one.

A. O. Akande, F. A. Semire, Z. K. Adeyemo, C. K. Agubor,
Volume 19, Issue 2 (June 2023)
Abstract

The quality of signal at a particular location is essential to determine the performance of mobile system. The problem of poor network in Lagos, Nigeria needs to be addressed especially now that the attention is toward online learning and meetings. Existing empirical Path Loss (PL) models designed elsewhere are not appropriate for predicting the 4G Long-Term Evolution (LTE) signal in Nigeria. This research developed a modified Okumura-Hata model in 4G network. The Okumura-Hata model being the closest to the measured values was modified using the PL exponent. The modified model was enhanced by Gravitational Search Algorithm (GSA). The measured data, modified and existing models were simulated using MATLAB R2018a software. Root Mean Square (RMSE) was used to evaluate the performance modified and existing and models. The result showed that Enhanced GSA model outperformed the existing models. The study successfully developed a modified PL model for LTE in Lagos, Nigeria. Therefore, modified model will be a good model in network planning for voice and fast online data connection in 4G LTE network.

I. K. Okakwu, O. E. Olabode, D. O. Akinyele, T. O. Ajewole,
Volume 19, Issue 2 (June 2023)
Abstract

This paper evaluates the wind potential of some specified locations in Nigeria, and then examines the response of wind energy conversion systems (WECSs) to this potential. The study employs eight probability distribution (PD) functions such as Weibull (Wbl), Rayleigh (Ryh), Lognormal (Lgl), Gamma (Gma), Inverse Gaussian (IG), Normal (Nl), Maxwell (Mwl) and Gumbel (Gbl) distributions to fit the wind data for nine locations in Nigeria viz. Kano, Maiduguri, Jos, Abuja, Akure, Abeokuta, Uyo, Warri and Ikeja. The paper then uses the maximum likelihood (ML) method to obtain the parameters of the distributions and then evaluates the goodness of fit for the PD models to characterize the locations’ wind speeds using the minimum Root Mean Square Error (RMSE). The paper analyses the techno-economic aspect of the WECSs based on the daily average wind speed; it evaluates the performance of ten 25 kW pitch-controlled wind turbines (WT1 – WT10) with dissimilar characteristics for each location, including the cost/kWh of energy (COE) and the sensitivity analyses of the WECSs. Results reveal that Ryh distribution shows the best fit for Kano, Jos, Abeokuta, Uyo, Warri and Ikeja, while the Lgl distribution shows the best fit for Maiduguri, Abuja and Akure due to their minimum RMSE. WT7 achieves the least COE ranging from $0.0328 in Jos to $4.4922 in Uyo and WT5 has the highest COE ranging from $0.1380 in Ikeja to $53.371 in Uyo. The paper also details the sensitivity analysis for the technical and economic aspects.

Das P. Chennamsetty, Sravana K. Bali,
Volume 19, Issue 2 (June 2023)
Abstract

Symmetrical nature of mean of electrical signals during normal operating conditions is used in the fault detection task for dependable, robust, and simple fault detector implementation is presented in this work. Every fourth cycle of the instantaneous current signal, the mean is computed and carried into the next cycle to discover nonlinearities in the signal. A fault detection task is completed using a comparison of two sub cycle means, and the same concept is extended to faulty phase classification. Under various fault and system operating situations, the suggested technique is assessed for regular faults, remote end faults, high resistive faults, and high impedance arcing faults. This paper's extensive case studies illustrate the suggested scheme's simplicity, computational flexibility, speed, and reliability. The suggested approach yields 100% consistent results in 4-8 msec detection time. 


Page 2 from 3     

Creative Commons License
© 2022 by the authors. Licensee IUST, Tehran, Iran. This is an open access journal distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.