Showing papers in "International Journal on Electrical Engineering and Informatics in 2011"

Optimization of pv/wind/ micro-hydro/diesel hybrid power system in homer for the study area

Abstract: A large proportion of the world's population lives in remote rural areas that are geographically isolated and sparsely populated. This paper proposed a hybrid power generation system suitable for remote area application. The concept of hybridizing renewable energy sources is that the base load is to be covered by largest and firmly available renewable source(s) and other intermittent source(s) should augment the base load to cover the peak load of an isolated mini electric grid system. The study is based on modeling, simulation and optimization of renewable energy system in rural area in Sundargarh district of Orissa state, India. The model has designed to provide an optimal system conFigureuration based on hour-by-hour data for energy availability and demands. Various renewable/alternative energy sources, energy storage and their applicability in terms of cost and performance are discussed. The homer software is used to study and design the proposed hybrid alternative energy power system model. The Sensitivity analysis was carried out using Homer program. Based on simulation results, it has been found that renewable/alternative energy sources will replace the conventional energy sources and would be a feasible solution for distribution of electric power for stand alone applications at remote and distant locations.

Dynamic Voltage Restorer (DVR) for Voltage Sag Mitigation

Abstract: The Dynamic Voltage Restorer (DVR) is fast, flexible and efficient solution to voltage sag problem. The DVR is a power electronic based device that provides three-phase controllable voltage source, whose voltage vector (magnitude and angle) adds to the source voltage during sag event, to restore the load voltage to pre-sag conditions. The DVR is designed for protecting the whole plant with loads in the range of some MVA. The DVR can restore the load voltage within few milliseconds. Several configurations and control methods are proposed for the DVR. In this paper, an overview of the DVR, its functions, configurations, components, compensating strategies and control methods are reviewed along with the device capabilities and limitations.

Simulation of Partial Discharge in High Voltage Power Equipment

Abstract: In high voltage (HV) electrical power system, variety of solid, liquid and gaseous materials are used for insulation purpose to protect the incipient failure inside the HV power equipment. Among these the solid insulation is widely used for high voltage power equipment HV electrical power system. Most of insulating materials are not perfect in all respect and contains always some impurities. The presence of air bubble is one of such impurities in insulating materials and highly undesirable for such type of insulation which causes a local weak zone inside the insulator. Insulation of the HV power equipment gradually degrades inside the insulator due to cumulative effect of electrical, chemical and thermal stress. Due to the high voltage stress the weak zone inside the insulator causes the partial discharge (PD) which is known as local electrical breakdown. As a result the insulation properties of such materials are enormously degrades its quality due to the PD. In this work, the simulation of PD activity due to presence of a small cylindrical void inside the solid insulation material of high voltage power equipment is studied with the MATLAB Simulink platform.

Solution of Economic Load Dispatch Problems by a Novel Seeker Optimization Algorithm

Abstract: This article presents an efficient approach for solving economic load dispatch (ELD) problems in different test power systems using a novel seeker optimization algorithm (SOA) In the SOA, the act of human searching capability and understanding are exploited for the purpose of optimization. In this algorithm, the search direction is based on empirical gradient by evaluating the response to the position changes and the step length is based on uncertainty reasoning by using a simple fuzzy rule. In this paper, four test systems of the ELD problems are solved by adopting the SOA. A comparison of obtained simulation results by adopting the SOA is carried out with those published in the recent literatures. It is revealed from comparison that the optimization efficacy of the SOA over the prevailing optimization techniques for the solution of the multimodal, non-differentiable, highly non-linear, and constrained ELD problems is promising.

Intelligent Controllers for Shunt Active Filter to Compensate Current Harmonics Based on SRF and SCR Control Strategies

Abstract: This paper presents a three-phase three-wire shunt active filter based on intelligent controllers to compensate current harmonics. Shunt active filter is the best solution to eliminate harmonics drawn from nonlinear load especially for low power system, the most inverter used is the two-level voltage source. The control strategies adopted to determine the compensation currents are the synchronous reference frame (SRF) detection method and the synchronous current reference (SCR) detection method. To improve the performance of the conventional control scheme based on hysteresis controller and take advantages of intelligent techniques, fuzzy and ANN current controllers are proposed in this paper. To maintain the dc voltage capacitor constant and compensate the inverter losses a proportional integral voltage controller is used. The numerical simulation is developed and performed using MATLAB-Simulink and SimPowerSystemd Toolbox from complete structure including control and power circuits. The obtained results show the simplicity and the effectiveness of the two proposed intelligent current controllers.

Farsi Handwritten Recognition Using Combining Neural Networks Based on Stacked Generalization

Abstract: Stack Generalization is a general method for combining low-level classifiers to achieve high-level classifier for impetrate to higher recognition rate. This paper proposed method based on Stack Generalization that named Modified Stack Generalization. In rour proposed model, unlike the conventional stacked generalization, the combiner receives the output of base classifiers and original input directly. The experiments have been done on 780 samples of 30 city names of Iran that for different experiments different number of training and testing samples was chosen. In the feature extraction Stage Gradient, Zoning methods are used, and also other method base on Gradient is suggested. Results show that Modified Stack generalization method with the recommended feature extraction method has been achieved to 92.21% recognition rate. Furthermore, Comparison test with other combination methods indicates that the proposed method yields improved recognition rate in the Farsi handwritten word recognition.

Modeling and Analysis of Cascaded H-Bridge Inverter for Wind Driven Isolated Self – Excited Induction Generators

Abstract: This paper describes the simulation model and the harmonics analysis of multi level inverters fed RL load and induction motor load. The SEIG fed Hbridge multi level inverter (MLI) for variable speed wind energy conversion systems are considered for various stand alone applications. In this paper, the SEIG fed cascaded five levels inverter for induction motor load systems are clearly explained with the help of MATLAB / SIMULINK models. The generated voltage of the wind driven self – excited induction generator (SEIG) is mainly depending on the wind velocity fluctuations, appropriate capacitance values and load conditions. The five levels cascaded inverter has interface with the wind driven self – excited induction generator (SEIG). The variable magnitude, variable frequency voltage of the generator can be controlled by choosing the proper modulation index. The simulation and harmonic analysis of the proposed inverter will be discussed and the total harmonic distortion will be evaluated.

Application of GPS for Sag Measurement of Overhead Power Transmission Line

Abstract: Overhead conductor sag may be measured by different methods. In the paper measurement of sag of 66KV power transmission line under shut down conditions at no wind load using standard handheld GPS receiver BT 359 has done. The real time direct measurement of overhead conductor sag is needed for the operation of power transmission system. The measurement of conductor tension, temperature and ambient weather conditions are not required to monitor in this method. The digital signal processing (DSP) techniques is used to get better accuracy of GPS measurements. The Least Square Parameter Estimation (LSPE) method for the error estimation of GPS measurements is also incorporated.

Torque Ripple Minimization of 4 Phase 8/6 Switched Reluctance Motor Drive with Direct Instantaneous Torque Control

Abstract: The switched reluctance motor drives has evolved as an alternative to conventional motors in variable speed drives because of advantages like simple and rugged structure, absence of rotor winding, adaptability to harsh environments like coal mining, high speed operation etc. Because of nonlinearity, torque ripple is high in the motor. This paper presents a high dynamic control technique called Direct Instantaneous Torque Control (DITC) where in the torque is maintained within a hysteresis band by changing the switching states of the phases. Thus torque ripple minimization and fast torque response is an inherent property of DITC. This paper analyses performance of the drive mainly in terms of the torque ripple during acceleration and steady state conditions with DITC in MATLAB/SIMULINK environment and results are discussed elaborately.

Design of a Quasi- elliptic Lowpass Filter using A New Defected Ground Structure and Capacitively Loaded Microstrip Line

Abstract: The modern microwave and millimeter wave communication system demands good filtering characteristics with compact sizes. In this paper the attention has been given towards the design of a good elliptical lowpass filter with sharp transition between passband and stopband, negligible passband insertion loss and wide stop band. A new defected ground structure (DGS) consisting of two square slots connects with a rectangular slot by two thin transverse slots underneath a microstrip line is proposed. In the frequency characteristics of proposed unit pattern provides an attenuation zero close to an attenuation pole. As a result, better transition sharpness, lower passband insertion loss and broader stopband are observed compares to dumbbell DGS. An equivalent lumped L-C network is proposed to model the introduced DGS unit and corresponding L-C parameters are extracted. A 3rd order quasi-elliptic lowpass filter with 1.4 GHz cut- off frequency, 1.7 GHz attenuation pole frequency, negligible passband insertion loss, almost 100 dB/GHz sharpness factor and 1.56GHz passband bandwidth (at -15 dB) is designed by cascading three investigated DGS units of different dimensions under capacitively loaded microstrip line.

A DSP-Based Approach for Gene Prediction in Eukaryotic Genes

Abstract: A simple algorithm to improve the identification accuracy of protein coding regions (exons) in Deoxyribonucleic Acid (DNA) sequences exploiting period-3 property is proposed. Three base periodicity is quite pronounced in exons and is commonly used in Digital Signal Processing (DSP) based methods to locate the exonic regions. Improvement in the accuracy of the protein coding regions has been achieved by extracting the background noise that comes from long range correlation present in DNA sequences and then eliminating this noise from the period-3 power spectrum. Proposed algorithm is data independent as it does not requires the empirical determination of any parameter for increasing the discrimination between coding and non-coding regions of a DNA sequence. Performance of the algorithm has been evaluated on F56F11 C.elegans chromosome-III nucleotide sequences. Performance of this algorithm has been compared with the spectral content method and an improvement in the correlation coefficient (CC), the performance metric used in this work, is observed.

MareText Independent Speaker Identification based on K-mean Algorithm

Abstract: This paper proposes a text-independent speaker identification system based on Mel Frequency Cepstral Coefficients as a feature extraction and Vector Quantization technique that would minimize the data required for processing. The correlation between the identification success rate and the various parameters of the system including the feature extraction tools and the data minimization technique will be examined. Extracted features of a speaker are quantized by a number of centroids and the K-mean algorithm has been integrated into the proposed speaker identification system. Such centroids constitute the codebook of that speaker. MFCC are calculated in both training and testing phases. To calculate these MFCC speakers uttered different words, once in a training session and once in a testing one. The speakers were identified according to the minimum quantization distance which was calculated between the centroids of each speaker in the training phase and the MFCC of individual speakers in the testing phase. Analysis was carried out to identify parameter values that could be used to improve the performance of the system. The experimental results illustrate the efficiency of the proposed method under several conditions Speaker recognition aims at recognizing speakers from their voices as each person has his own speech characteristics and his way of speaking. Speaker recognition is basically divided into speaker identification and speaker verification. Speaker identification is the process of determining which registered speaker provides the speech input, while verification is the task of automatically determining if a person really is the person he or she claims to be. Speaker recognition has many particular applications as a speaker's voice can be used to verify their identity and control access to services such as banking by telephone, database access services, voice dialing telephone shopping, information services and voice mail. Another important application of speaker recognition technology is for forensic purposes (1). Speaker recognition can be classified as based on text-dependent or text-independent methods. In the text dependent method, the speaker has to say key words or sentences having the same text for both training and recognition trials. Whereas in the text independent case the system can identify the speaker regardless of what is being said (2), (3), (4). The goal of this study is a real time text-independent speaker identification system, which consists of comparing a speech signal from an unknown speaker to a database of known speakers. The system will operate in two modes: a training mode and a recognition mode. During the training mode users will record their voices and make a feature model it. The recognition mode will use the information that the user has provided in the training mode and attempt to isolate and identify the speaker. The Mel Frequency Cepstral Coefficients (MFCC) and the Vector Quantization (VQ) algorithms are used to implement this process. The simple K-means clustering algorithm is used in this study whereas the LBG is used in other similar work (4).

A Comparison of Three-Phase Uncoupled and Directly Coupled Interleaved Boost Converter for Fuel Cell Applications

Abstract: Interleaved boost converter is well suited for high power and high performance applications. This paper investigates the performance of three-phase uncoupled and directly coupled Interleaved Boost Converter (IBC) for fuel cell applications. By employing directly coupled inductors for IBC, the overall current ripple can be effectively reduced which increases the lifetime of fuel cells. In this paper, a three phase interleaved boost converter using CoolMOS and Silicon Carbide (SiC) diode has been proposed for fuel cells compared to the classical IBC reported in the literature. Mathematical analysis of overall current ripple and the design equations for IBC has been presented. Analysis based on the relationship between current ripples and operating conditions such as duty cycle and coupling coefficient has been investigated for uncoupled and directly coupled IBC. The performance parameter of IBC such as switching losses and efficiency has been studied. Simulation of IBC interfaced with Proton Exchange Membrane (PEM) fuel cells has been studied using MATLAB/SIMULINK. Experimental prototype has been built to validate the results.

Rectangular to Circular Waveguide Converter for Microwave Devices Characterization

Abstract: In this paper, a rectangular to circular waveguide converter is investigated numerically and characterized experimentally for microwave devices characterization. The converter is designed as an excitation method of circular waveguide to produce its dominant mode as the problem of circular waveguide in the excitation process. A WR248 type rectangular waveguide transducer with working frequency of 2.60–3.95GHz for TE10 mode is used as the wave exciter to be converted to a WC248 type circular waveguide. Prior to the fabrication, physical parameters of converter including length of rectangular segment, length of transition segment and length of circular segment are analyzed to obtain the optimum design. It shows that the length of transition segment affects to the return loss of converter and its length to produce TE11 mode of circular waveguide smoothly has to be more than twice of waveguide wavelength. From the result, the length of transition segment is chosen to be 275mm as it demonstrates better return loss compared to other lengths almost in the designated working frequency. To verify the design result, the prototype of converter is then realized and characterized experimentally. Furthermore, some discussion related to the results of experimental characterization is also presented.

An Integrative Method on the Remote Monitoring of Walking Activity Using Ubiquitous Healthcare System

Abstract: The present concept of u-Healthcare is based on treatment and recuperation and in the future it will become specialized as wellness based on prevention. It is predicted that wellness care among others will develop to become the key field of u-Healthcare. For this reason in this research, ubiquitous technology was grafted to the passometer (P-meter) which is frequently used for monitoring during existing walking exercises. Emerging from the existing method of the P-meter which simply calculates the amount of exercise by counting the number of steps taken, using the GPS incoming data, the distance and speed of the location changes is calculated and the acceleration sensor will reflect the steps and intensity of movement to measure the walking activity amount to realize a smart walker system which will help the maintenance and promotion of modernists health.In this paper, we propose an integrative remote monitoring system for measuring walking activities under ubiquitous healthcare environment considering walking effects in healthcare of human life through the calculation of the distance of location changes and speed using GPS reception data and reflecting the steps and intensity of movement using the acceleration sensor.

Enriched Efficiency with Cost effective Manufacturing Technique in 3.7 kW Submersible pump sets using DCR Technology

Abstract: This paper describes the overall efficiency improvement in Submersible pump sets with reduced cost by increasing the efficiency of the submersible motor using die cast rotor (DCR) technology. The important parameters responsible for the submersible motor characteristics like Efficiency, Locked rotor Torque, Slip etc., are compared with the existing Copper Fabricated Rotor (CFR) and proposed DCR in a 5HP 3phase wet type water cooled induction motors in accordance with IS 9283. The overall performance, possible efficiency improvements in Submersible pump sets and cost comparisons between the existing CFR and DCR's are also practically verified and reported in accordance with IS 8034. It is estimated that about 30 % to 40 % of electrical energy produced in India is consumed by motorized pump sets employed in agricultural sector (1). Pumps and pumping systems use 60% of the new motors in the OEM supply chain. Any improvement in efficiency of motor would therefore result in increased efficiency of the system at end use. Low-voltage motors of up to 37.5 kW consume most of the energy size, which offer maximum potential for energy savings. Most of the energy is consumed by low-voltage motors of up to 37.5 kW size which offer maximum potential for energy savings. One of the ways to address the problem of energy shortage is to reduce demand mainly by increasing end use efficiency. As motors are the largest users of the electrical energy, even small efficiency improvements can produce very large savings across the country, Energy conservation measures taken by individual consumers in this direction will increase the comprehenses of the national economy and benefit the environment on a global scale. The total number of irrigation pump sets in India during the year 2001 was 12.5 million. In the year 2002-03 the Annual power consumption was 118,059 GWh by Agri-pump sets, based on this information, the number of pump- sets works out to 15.7412 Million. The demand is seen to be increasing year after year and also the resulting shortage of electrical energy. In the states of Andhra Pradesh and Gujarat, the agricultural sector alone accounts for 37.45 % and 40 % of total power consumption respectively (2,3). Based on the statistics, the total electricity consumption during the year 2002-03 was 562,572 GWh and the consumption by Agri-pump sets was 118,029 GWh, which works out to only 20.98%. By considering the average connected load of the pump as 6.5 kW per pump set and 1800 pumping hours annually, the total power consumption by agri-sector will be 184,172 GWh, and the percentage works out to 32.7%, which reasonably matches with the other studies. Numerous field studies have revealed that 90% of the agri-pump sets used in India are far inefficient and are wasting power worth of Crores of Rupees. Because there is no energy classification for pumps due to large variety of pumping systems.

Design and Development of Lowpass Filter and Harmonics Reduction

Abstract: The shape of a popular split-ring defected ground structure (DGS) is modified by etching two concentric split-ring defective pattern which have different size and inverse split direction in the ground plane underneath a microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. As a result, better transition sharpness is observed. An equivalent lumped L-C network is proposed to model the introduced DGS unit and corresponding L-C parameters are extracted. A 3 rd order quasi-elliptic lowpass filter is designed by cascading the three investing DGS units under High-Low impedance microstrip line and the generated first harmonic has been removed with the help of defected microstrip structure (DMS) underneath the cascading DGS unit.

Partial Discharge Characteristics with Morphological Analysis and Tensile Properties of Linear Low-density Polyethylene-Natural Rubber Blends

Abstract: A series of linear low-density polyethylene (LLDPE)-natural rubber (NR) blends of composition 80/10, 70/20, 60/30, 50/40 and 40/50 containing nano-sized fillers montmorillonite (MMT) and Titanium(IV) Oxide (TiOâ‚‚) were produced by a twin-screw extruder with maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MAH) of 10 wt% as a compatibilizer. An electrical performance test through partial discharge (PD) characteristics using CIGRE Method II test was conducted to study the electrical performance of the samples. Applied voltage was set on 7kVrms for 1 hour. The discharge characteristics were observed using picoscopeâ„¢ and LabViewâ„¢ programming. Morphological analysis using scanning electron microscope (SEM) was also conducted after the sample of composite was subjected to high voltage stress. The degradation of composite surface was analyzed. Then tensile test carried out to investigate the mechanical performance of the composites. The combine results of PD characteristics and tensile properties described the insulating performance of the composites. The results revealed that total PD numbers decrease with increasing of weight percentages of natural rubber in the composition of the composite without any filler. In addition, it is found that total PD numbers significantly decreased on sample with MMT filler compared to TiOâ‚‚ one.

Modeling of a Second Order Sigma-Delta Modulator with Imperfections

Abstract: Abdelghani Dendouga, Nour-Eddine Bouguechal, Souhil Kouda and Samir Barra Advanced Electronic Laboratory, Batna University, Algeria 05 Avenue Chahid Boukhlouf, 05000 BATNA, ALGERIE E-mail: dendouga_gh@hotmail.com Abstract—Sigma delta modulators (ΣΔMs) form part of the core of today’s mixed-signal designs. The ongoing research on these devices shows the potential of ΣΔ data converters as a promising candidate for high-speed, high-resolution, and low-power mixed-signal interfaces. This work presents a new accurate behavioral model of a second order law-pass Switched Capacitor (SC) Sigma-Delta modulator. Our main contribution consists to predict the effect of almost sources of noise on the operation of sigma delta modulator such as non idealities of op-amp and switches. The purpose of this work is the presentation of a behavioral model of a second order switched capacitor ΣΔ modulator considering (Error due to Clock Jitter, Thermal noise Amplifier Noise, Amplifier Slew-Rate, Non linearity of amplifiers, Gain error, Charge Injection, Clock Feed-through, and Nonlinear onresistance). A comparison between the use of MOS switches and the use transmission gate switches use is analyzed.

DCF Throughput Analysis of IEEE 802.11a/g/n-based Mobile LAN over Correlated Fading Channel

Abstract: This paper explores a MAC (Medium Access Control) layer throughput with DCF (Distributed Coordination Function) protocol in the IEEE 802.11a/g/n-based mobile LAN. It is evaluated in Rayleigh fading wireless channel, using theoretical analysis method. The DCF throughput performance is analyzed by using the number of stations with both variable payload size and mobile speed on the condition that fading margin and transmission probability are fixed. In the IEEE 802.11n, A-MSDU (MAC Service Data Unit Aggregation) scheme is considered and number of subframe is used as the variable parameter. It is identified that MAC efficiency of IEEE 802.11n is the best out of four schemes.

Bee Hive Algorithm to Optimize Multi Constrained Piecewise Non-Linear Economic Power Dispatch Problem in Thermal Units

Abstract: This paper presents application of a Bee Hive Algorithm to Economic Load Dispatch which considers practical constraints and non linear characteristics. The proposed ED formulation includes ramp rate limits, valve loading effects, multiple fuels, equality and inequality constraints, which usually are found simultaneously in realistic power systems. Conventional methods such as Lambda iteration and Base point participation are not able to obtain optimal solution for units having discontinuous fuel cost functions. Bee Hive Algorithm can overcome the difficulties and provides an almost global optimal solution, since they don’t get stuck up at local optimum.

A Novel Resampling Method for Particle Filter for Mobile Robot Localization

Abstract: This paper present a particle filter for mobile robot localization also known as Monte Carlo Localization (MCL) to solve the localization problem of autonomous mobile robot. A new resampling mechanism is proposed. This new resampling mechanism enables the particle filter to converge quicker and more robust to kidnaping problem. This particle filter is simulated in MATLAB and also experimented physically using a simple autonomous mobile robot built with Lego Mindstorms NXT with 3 ultrasonic sonar and RWTH Mindstorms NXT Toolbox for MATLAB to connect the robot to MATLAB. The particle filter with the new resampling algorithm can perform very well in thesimulation as well as in physical experiments.

Improved Fuzzy Load Models by Clustering Techniques in Distribution Network Control

Abstract: In operation and planning of the power systems, the analysis of the consumption trends depends on the evolution of economic activities and competition among several sources of energy, which affect forecasts. The loads estimation represents the basis of the system state estimation and influences various aspects of power system planning such as: transformer and conductor sizing, capacitor bank placement and so on. The main difficulties in modeling of the nodal loads result from the random nature of loads, the deficiency of measured data and the fragmentary and uncertain character of information on loads and customers. Thus, a modern method for expressing the uncertainty in load models is fuzzy technique. A fuzzy set is a set containing elements that have varying degrees of membership in the set. There are different ways to derive membership functions. Subjective judgment, intuition and expert knowledge are commonly used in constructing membership function. Because in many situations the choices of the membership functions are subjective, in the paper the clustering techniques are proposed for the improved of the defining of membership functions corresponding to the load profiles and customers consumption categories. Results obtained demonstrate the ability of the fuzzy load models to overcome difficult aspects encountered in process control and operation problems.

Fuzzy Sliding-Mode Control for a five drive web-winding System

Abstract: In this contribution, a control scheme based on multi input multi output Fuzzy Sliding Mode control (MIMO-FSMC) for linear speed regulation of winding system is proposed. Once the decoupled model of the winding system is obtained, a smooth control function with a threshold was chosen to indicate how far the state from to the sliding surface is. However, the magnitude of this control function depends closely on the upper bound of uncertainties, and this generates chattering. So, this magnitude has to be chosen with great care to obtain high performances. Usually the upper bound of uncertainties is difficult to known before motor operation, so, a Fuzzy Sliding Mode controller is investigated to solve this difficulty, a simple Fuzzy inference mechanism is used to reduce the chattering phenomenon by simple adjustments. A simulation study is carried out and shows that the proposed fuzzy sliding mode controllers have great potential for use as an alternative to the conventional sliding mode control.

Optimized Combined System of Shunt Active Power Filters and Capacitor Banks

Abstract: In larges electrical system used in industries, office builidings, or hotels, capacitor banks are usually utilized to compensate the required VAR absorbed by the loads. As the nonliniear loads are increasing rapidly, the risk of resonance phenomenon occured is becoming higher as its terminal voltages are not anymore sinusoidal. On the other hand, many customers have become aware to the problems caused by the harmonics due to the nonlinear loads. In this case, the active power filters (APFs) offer many interesting properties i.e. the elimination of harmonics, phase balancing feature and the power factor correction. The power factor correction feature suggests that the APFs are also able to compensate the VAR which means that the APFs are able to replace completely the capacitor banks. However, the higher reactive power occured in APFs is responsible to the higher current flowing in the switches, thus the higher rating of switches are required which leads to more expensive system. In this paper, an optimized combined system between APF and capacitor bank is proposed. It is not necessary to dump the installed capacitor bank. In contrary, the capacitor bank will help the APF to compensate the VAR as the APF will concentrate mostly to eliminate the harmonics.

Design Consideration of LLC Resonant Converter for Electrolyser

Abstract: Electrolytic hydrogen offers a promising alternative for long-term energy storage of renewable energies (RE). The long-term excess energy with respect to load demand has been sent to the Electrolyser for hydrogen production and then the fuel cell has utilized this stored hydrogen to produce electricity when there were insufficient wind and solar energies with respect to load requirements. The RE system components have substantially different voltage-current characteristics and they are integrated on the DC bus through a power conditioning devices for optimal operation. The DC power required by the Electrolyser system is supplied by the DC-DC LLC resonant converter. The simulation and experimental results show that the power gain obtained by this method clearly increases the hydrogen production and storage rate from wind-PV systems.

Differential Evolution based Multi-objective Optimization of a Deregulated Power Network under Contingent State

Abstract: This paper proposes a methodology to limit the variations in generation cost in a power system under normal and contingent state using Differential Evolution (DE) optimization technique keeping consumer welfare in view. The aim of this proposed methodology is to minimize the deviations of generation cost, during contingency, from a preferred value by rescheduling of the generation with a controlled load curtailment technique and hence relieving the lines from overloading for congestion management. A comparative study between rescheduling with and without load curtailment has also been presented in this paper. Numerical results on test system, namely IEEE 30 Bus System, are presented for illustration purpose and the same has been verified by a well esteemed optimization technique, Particle Swarm Optimization (PSO). The comprehensive simulation results establish that the developed method not only reduces the economic variations of the market but also ensures the voltage stability of the system during contingency.

Model Transformation Method of Embedded System Hardware for Improving Design Process Performance

Abstract: Gap between designer productivity and IC technology is a challenge for improving embedded system design methodology. Register Transfer Level (RTL) is a current design abstraction that no longer adequate as the starting abstraction level. It needs a new methodology for facing the lack of RTL. Transaction Level Modeling (TLM) is a candidate design methodology to improve designer productivity. It offers many advantages especially on process time reduction. In this paper, a new model transformation method is proposed for transforming TLM model to RTL model design incrementally. TMC (TLM-RTL Model Communicator) is used as a key component in this method. TMC communicates between TLM and RTL model. GCD (Greatest Common Divisor) processor is designed to show transformation process from TLM to RTL model. The experiment results show that model transformation method using TMC is effective for transforming TLM model to RTL model incrementally. These results show the design process improvement using this method.

Fuzzy Logic Based Window Operation of DSTATCOM for an Autonomous Asynchronous Generator

Abstract: Large inductive loads require larger rating of DSTATCOM to generate the required reactive power of the load. Larger the rating of the DSTATCOM higher is the cost. Most distribution system has a base reactive power requirement. The reactive power demand at any instant varies around the base value. A window operation of the DSTATCOM is proposed in this paper. The base reactive power is provided by the TSCs and the DSTATCOM operates within a window (comprising of both inductive and capacitive reactive power) beyond the base reactive power provided by the TSCs. Thus the range of the reactive power compensation of the system is enhanced without the system being limited by the steps in which the TSCs operate. Within the window range, the DSTATCOM provides a continuous and smooth variation in the reactive power generation and can track the change in the VAr requirement very fast. To obtain optimal performance of the combined system, the TSCs are switched through a Fuzzy Logic controller. In this paper, window operation of the DSTATCOM along with Fuzzy Logic Controller operated TSCs is demonstrated for an autonomous asynchronous generator. The entire system has been simulated on MATLAB platform.