WSEAS CONFERENCES. WSEAS, Unifying the Science

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 Volume 5, 2010
Print ISSN: 1790-5060
E-ISSN: 2224-350X








Issue 1, Volume 5, January 2010

Title of the Paper:  3D Finite Element Analysis for Arcing Chamber Optimization of the Current-limiting Circuit Breaker


Authors: Elena Otilia Virjoghe, Diana Enescu, Marcel Ionel, Florin Mihail Stan

Abstract: Direct current, which was one of the main means of distributing electric power, is still widespread today in the electrical plants supplying particular industrial applications. The advantages in terms of settings, offered by the applicants of d.c. motors and by supply through a single line, make direct current supply a good solution for railway and underground systems, trams, lifts and other transport means. The paper presents the calculation of the magnetic field in the arcing chamber of the current-limiting circuit breaker of the direct current 1250 A, 750 V. Current-limiting circuit breakers play an important role in electrical low-voltage circuits. Due to the high short-circuit currents it is necessary a very short time to switch off the defective branch. For this the current limiting circuit breakers are conceived as elaborated solutions especially for the arc quenching system, meaning the path of current and the arcing chamber. In this paper the authors present few optimization solutions of some quenching systems which will lead to more performing constructive choices. The finite element software package ANSYS is use for calculation of the magnetic field components.

Keywords: Arcing chamber, magnetic field, current-limiting circuit breaker, finite element method, software package ANSYS, optimization, numerical simulation

Title of the Paper:  Estonian Electricity Production Scenarios and their CO2 and SO2 Emissions until 2030


Authors: R. Kuhi-Thalfeldt, A. Kuhi-Thalfeldt, J. Valtin

Abstract: Closing of old oil-shale based power plants and fast development of wind power has raised several issues regarding possible future electricity production capacities in Estonia and their environmental performance. In February 2009 Estonian government adopted a new Development Plan of Energy Sector until 2020. This study was performed in conjunction to the strategic environmental assessment of the plan highlighting especially the CO2 and SO2 emissions of electricity production scenarios. The analysis is carried out using the Long range Energy Alternatives Planning System (LEAP) software, which is suitable for elaborating the scenarios and their impact on power balance and to the environment.

Keywords: Estonia, development plan, CO2 emissions, SO2 emissions, oil shale, wind power

Title of the Paper:  Sensitivity of Compact Fluorescent Lamps during Voltage Sags: An Experimental Investigation


Authors: Hussain Shareef, Azah Mohamed, Khodijah Mohamed

Abstract: The aim of this paper is to analyze the sensitivity of various compact fluorescent lamps (CFLs) which are used in residential and commercial applications during voltage sags. Laboratory tests were performed on different CFLs commonly available in the market. The tests are based on recent testing standards and utilizing a modern industrial power corruptor. For predefined malfunction criterion of zero illuminance condition, sag depth and duration are varied to construct individual voltage immunity curves. Experimental results show that all CFLs are sensitive to voltage sags and vary in a wide range. It also proves that some brands of CFLs having similar power rating are sensitive to both sag magnitudes and its duration. Finally a method to improve the sensitivity of CFLs to voltage sags is implemented. This technique increases the holdup time of the dc bus voltage by connecting additional dc capacitance at the rectifier output of the CFL’s ballast circuit.

Keywords: Voltage sag, ride through capability, ballast, CFL, voltage tolerance curves

Title of the Paper:  Electromagnetic Force Analyzed Results on Switchgear of Disconnector for Overevoltage Protector


Authors: Hitoshi Kijima, Tomooki Hasegawa

Abstract: A disconnector for overvoltage protector (OVP) is equipment which intercepts a circuit safely, when OVP breaks down in short circuit mode. As a disconnector, a Circuit Breaker (CB) is normally used. When a large current such as a lightning surge flows, switchgear of CB comes floating according to the electromagnetic force generated by large current which flows into a switchgear. The function of OVP is spoiled by this influence. If the problem which the switchgear comes floating can be solved, even when a large lightning surge flows through it, electrical aparatus can be protected by OVP.We have been analyzing this switchgear floating mechanisms using finit element method. This paper presents a way of preventing switchgear floating.

Keywords: Circuit breaker, lightning surge current, switch floating, current density, electromagnetic force

Issue 2, Volume 5, April 2010

Title of the Paper:  Preventing Over-offering Behavior in Capacity Markets


Authors: X. Wei, R. Li

Abstract: Capacity markets provides additional revenue stream for the power suppliers. In a capacity-energy combined market environment, suppliers have incentives to deliberately over-offering their capacities in the capacity market while bid very high price in the energy and ancillary markets to avoid operation. This paper analyzes the risks and profits of this capacity-over-offering behavior, and develops a method for computing non-operable penalty level which can prevent the capacity-over-offering behavior. It is found that the effective penalty level is highly correlated with the stochastic characteristics of supplier’s profit streams and supplier’s risk attitudes. Two types of suppliers are suggested as the potential cheaters in the analysis. The methodology and the results are potentially useful for the operation and mitigation in a capacity-energy market environment.

Keywords: Capacity Market, Over-offering, Risk Analysis, Non-operable Penalty, Prospect Theory, Monte-Carlo Simulation

Title of the Paper:  An Efficient Maximum Power Point Tracking Controller for Photovoltaic Systems Using New Boost Converter Design and Improved Control Algorithm


Authors: Tamer T. N. Khatib, A. Mohamed, N. Amin, K. Sopian

Abstract: This paper presents an efficient maximum power point tracking (MPPT) controller for a standalone photovoltaic (PV) generation system. To achieve an efficient MPPT controller, a new boost converter design and an improved MPPT algorithm are incorporated. In the proposed boost converter design, a passive regenerative snubber circuit is included to absorb the energy of stray inductance so as to reduce the IGBT switching losses. As for the improved MPPT algorithm, it is based on the curve fitting method which attempts to predict the power-voltage characteristic curve by a fourth order polynomial function. The predicted P-V curve strongly depends on the cell temperature and therefore the ambient temperature and solar radiation are used to track the maximum power point (MPP) of the PV module. Experimental results are given to verify the validity and performance of the MPPT algorithm which is embedded in a prototype MPPT controller. The experimental results showed that the proposed MPPT controller successfully tracked the MPP by giving an average tracking efficiency of 89.2%.

Keywords: MPPT, photovoltaic systems, PV controller, boost converter, curve fitting

Title of the Paper:  Numerical Simulation of Single Phase Faults in Medium Voltage Electrical Networks


Authors: Dumitru Toader, Stefan Haragus, Constantin Blaj, Iulia Cata

Abstract: In the paper is presented a virtual simulator for three-phased medium voltage electric circuits. The simulator allows analyzing transient regimes caused by the faults produced in electric distribution networks (simple grounding, double grounding, broken and grounded conductor). Also, in paper are presented the results of measurements made in the experimental area that was conceived for verification results obtained by numerical simulation in real condition. There are analyzed the dependence of the transient regimes on the initial phase of the voltage at the faulty place, the dependence on the grounding resistance at the faulty place and on the method used for grounding the neutral point of the electric network.

Keywords: Medium voltage electric networks, grounding faults, numerical simulation

Title of the Paper:  Experimental Characterization and Modeling of PEM Fuel Cells under Dynamic Load Variations


Authors: Giovanni Bucci, Edoardo Fiorucci, Fabrizio Ciancetta, Francesco Veglio

Abstract:The adoption of fuel cells (FCs) for industrial applications, transportations and home power generation is widely increased during recent years. Because FCs are still in the development stage, to evaluate and validate fuel cell technologies suitable test systems are needed. In a fuel cell both chemical and electric sections can be founded, so to control its behaviour the measurement of different parameters, as current, voltage, flow rate of the reactants and cell temperature is required. The performance evaluation of a fuel cell requires both static and dynamic characterizations, especially for the automotive applications, in which there is a dynamic variation of electric load. To better design this kind of applications, a FC mathematical model is required, to evaluate the performance at different working conditions. The synthesis of a dynamic model describing the FC behavior should be performed starting form the real system configuration, including pipes, flow and pressure regulators and valves. To this aim an automatic measurement system for the characterization of PEM (Polymer Electrolyte Membrane) fuel cells has been developed, and in this paper a dynamic model of a fuel cells stack is proposed, which has been validated through experimental measures.

Keywords: Fuel cells, Test system, Characterization, Data acquisition system, Dynamic testing, Supercapacitor

Title of the Paper:  Performance Analysis and Comparative Study of LMI-Based Iterative PID Load-Frequency Controllers of a Single-Area Power System


Authors: Ahmed Bensenouci, A. M. Abdel Ghany

Abstract: This paper provides a comparison of the performance and the design steps for four robust static output feedback Proportional-Integral-Derivative (PID) controllers. The first one presents an Iterative PID (IPID) that guarantees the stability of the closed-loop system. In the second and the third controllers, Iterative PID based on H2 (IPIDH2) and H? (IPIDHI) performances, respectively, are investigated. The role of H? is to minimize the disturbance effect whereas H2 is used to improve the transients of the system output. The last one is an Iterative PID that is characterized by the Maximum (IPIDM) regulated output of the closed loop system with its command input being bounded. The Iterative Linear Matrix Inequality (ILMI) technique is developed to find the feedback gains of the designed PID controllers. The proposed design technique is applied to the Load Frequency Control (LFC) problem of a single-area power system. The effects of ILMI tuning variables on the system dynamic response are given and discussed. To test and compare the effectiveness of the controllers, diverse simulation tests are carried out under diverse disturbances and parameters change with the presence of the Generation Rate Constraint (GRC), inherent system nonlinearity. The results prove that the proposed iterative PID controllers are very useful for LFC power system.

Keywords: Load frequency control, Iterative PID, Linear matrix inequalities, H-infinity norm, H-2 norm, maximum power output control

Title of the Paper:  Applicability of Trigeneration Systems in the Hotel Buildings: The North Cyprus Case


Authors: M. Ozdenefe, U. Atikol

Abstract: In North Cyprus (N. Cyprus), the installed power capacity fails to meet the demand in severe winter and summer conditions thus; new power capacities are needed to supply the required demand. One way of dealing with the deficiencies resulting from the inadequacy of installed power capacity is to make the distributed power widespread, especially the trigeneration systems which exploit energy in the fuel in the most efficient way by producing heat, electricity and cooling simultaneously. The objective of the present work is to propose a methodology through which the decision makers can assess the applicability of trigeneration systems for the hotel sector. The power demand of a representative hotel in N. Cyprus was monitored and segregated into base and cooling components for typical days of summer. On the other hand, five hotels were selected for conducting surveys on their electricity and heat demands. Correlations were obtained for the representative hotel for two different scenarios of capacity sizing; in scenario 1, it was aimed to meet the maximum value of the base electrical load of the hotels and in scenario 2 the aim was to meet the minimum base electrical load. The experimental correlations were used in determining the capacities of the trigeneration systems for the other five hotels. An economical feasibility analysis is carried out for both scenarios. The results showed that the application of trigeneration systems to the hotel sector in N. Cyprus can be feasible. It is found that application of scenario 2 is more feasible than application of scenario 1. For the representative hotel the simple payback period and savings to investment ratio of the trigeneration application based on scenario 2 is found to be 3.3 years and 1.8 respectively, which are acceptable. Other hotels investigated in this work also have similar results when the scenario 2 is applied. In addition to this, it is found that further benefit is achieved if the excess electricity is sold to the utility. By the application of scenario 2 to the hotels considered in this work; total annual electricity production by the systems would be 16.7 GWh. Considering the electricity production by the utility via gas turbines was 4 GWh in the year 2007, the application of the trigeneration systems would not only erase the running and maintenance costs of these old and inefficient units but also reduce the load coming to the power plants.

Keywords: Trigeneration, absorption chiller, economical analysis, energy, power demand, hotels

Title of the Paper:  Optimal Allocation of FACTS Devices in Deregulated Electricity Market Using Bees Algorithm


Authors: R. Mohamad Idris, A. Khairuddin, M. W. Mustafa

Abstract: In this paper, a novel method using Bees Algorithm is proposed to determine the optimal allocation of FACTS devices for maximizing the Available Transfer Capability (ATC) of power transactions between source and sink areas in the deregulated power system. The optimizations are made on three parameters: the location of the devices, their types and their sizes. The FACTS devices are located in order to enhance the available transfer capability (ATC) between source and sink area. Four types of emerging FACTS controllers are used and modeled for steady state studies, namely; TCSC, SVC, UPFC and TCPST. The IEEE9 bus test system and IEEE118 Bus test system are used to illustrate the applicability of the proposed algorithm to enhance ATC effectively. The installation costs of FACTS devices are also included. A Genetic Algorithm (GA) configured to the same purpose is used for validation. Results show the difference of efficiency of the devices used in this situation. They also show that simultaneous use of several kinds of controllers is the most efficient solution to increase the ATC. The obtained results indicate that both techniques can successfully find the optimal solution and parameter setting of FACTS devices, but BA is better in term of value of objective function and speed of convergence compared to GA.

Keywords: Bees Algorithm, GA, ATC, FACTS, SVC, UPFC, TCPST, TCSC

Title of the Paper:  Optimal Configuration of a Renewable-based Electricity Supply Sector


Authors: Tino Aboumahboub, Katrin Schaber, Peter Tzscheutschler, Thomas Hamacher

Abstract: Proposed emission reduction targets as well as the scarcity of fossil fuel resources make a transition of the energy system towards a carbon free electricity supply necessary. Promising energy resources are solar and wind energy. The high temporal and geographical variability of these resources is challenging for their integration. This study focuses on the question how a renewable-based energy system ideally should be designed. We investigate the optimal structure of a prospective renewable-based power supply system on two different scales: on the global and the European level. The paper describes the applied simulation technique, based on linear optimization, employed to combine an adequately precise geographical coverage with high temporal resolution. As results we obtain ideal energy mixes, generation sites, storage and interregional power transmission capacities required for different scenarios of highly renewable supply.

Keywords: Renewable Energy, Simulation, Linear Optimization, Power Supply, Geographic Information System (GIS), Supergrid, Energy System Model

Title of the Paper:  Study for the Integrated Automation of the Sao Paulo Subway System Rectifier Substations


Authors: Eduardo Mario Dias, Sergio Luiz Pereira, Carlos Alberto De Sousa

Abstract: This article shows a proposal for the integrated automation of the Sao Paulo subway system rectifier substations, supported on the gains of reliability which may be obtained in case it is implemented, and in the improvement of the efficiency of operation of the system open to question. To quantify these profits of reliability there is presented the development of the model of reliability of Markov devoted to the system of automation of rectifying substations. The used methodology proceeded to the lifting and analysis of the incidents when they were opened in the years of 2006, 2007 and 2008 in the rectifier substations of the subway of Sao Paulo, calculating HIS MTBF (Mean Time Between Failures). The study ends that the profit of reliability is significant in what it refers to the improvement of public transport with the application of the integration of the automation of the rectifying substations.

Keywords: Automation, Integrated automation system; rectifier substation; rectifier protection system

Title of the Paper:  The Slovenian Electricity Market and the Prices of Electricity


Authors: Viljem Pozeb, Tina Krope, Darko Goricanec, Jurij Krope

Abstract: The article is based on the analysis of the circumstances, occurred after the electricity market opening in the Republic of Slovenia, as a consequence of implementation of the EU legislation in the energy field. The market operation, the role of the national regulatory authority and the market conditions are described, all of which influences the supply and prices of electricity in 2010. Additionally, a model of price formation for industrial and household consumers is presented and an overview of the production and end use of electrical power in Slovenia.

Keywords: Energy, Electricity Market, Preferential Producers, Regulatory Authority, the Structure of the Electricity Price

Issue 3, Volume 5, July 2010

Title of the Paper:  The Development of Electricity Market in the European Union and the Legislative Framework


Authors: Tina Krope, Viljem Pozeb, Darko Goricanec

Abstract: The article gives an overview of the legislative framework at the EU level, describes the market operation, pointing out possible measures and activities, needed for the creation of a fully liberalised electricity market. Physical flow of electricity through the supply chain, from generation, transformation, distribution and supply to customers is described. Mechanisms to support preferential electricity production from some promising energy transformation technologies and possible solutions applicable for ensuring the use of renewable energy sources for production of electricity are discussed.

Keywords: EU - Energy market, Electricity market, Legislation, Renewable energy sources, Production of electricity

Title of the Paper:  Interpersonal Dependency on People with Major Depression Syndrome in Indonesia


Authors: Dery Abdurrachim Iskandar

Abstract: From cognitive model approach perspective, a person with major depressive disorder has commonly five depression symptoms i.e. affective, cognitive, motivational, physical and behavioral symptoms. Cognitive model expresses high possible dependency on a person with depression syndrome as one real form of behavioral symptom. High possibility on one person with depressive disorder tends to give him/her high possibility for interpersonal dependency, one dependency one experienced by a person making another person the dependent object. Used research method is qualitative with interview approach equipped with observation method. The population includes people who have been diagnosed for mayor depression by both psychologists and psychiatrist. Sampling has been made using theory based/operation construct in which the sample is selected by certain criteria, based on theory or operational depression construct included into DSM IV TR. here are various interpersonal dependencies on some people with depressive disorder classified into four dimensions, cognitive, motivational, affective and behavioral whereas cognitive and affective dimension have more dominant roles. In addition, there is one extrinsic factor on person with mayor depressive disorder which has role in the process of interpersonal dependency emergence. The factor is parenting style.

Keywords: Interpersonal Dependency, Major Depression, Symptom, Cognitive Models

Title of the Paper:  Restoration of Power System after Blackout and Synchro-Check Relays Setting in Transmission System


Authors: Zaneta Eleschova, Anton Belan, Marek Pipa, Attila Kment

Abstract: Connection of power lines in transmission system is activated after defined conditions are met in the setting of synchro-check relays; namely ΔV – difference in voltage amplitudes, Δf – frequency difference, and Δα – difference in phase angles. The aim of this contribution was experimental verification of the connection condition focused on transient phenomena course on connected line, the transient stability of generators, and the analysis of their influence on power system. As the past critical situations (state of an imminent blackout threat) in transmission system has shown, inability to connect line into the power system because the connection conditions are not met (blocking of a power switch) could have severe negative influence on the continual operation of the power network. Setting of synchro-check relays as connection conditions can influence also the process of electric power system restoration after collapse. Thus, this paper discusses also the actual state of synchro-check relays setting in transmission system.

Keywords: Transmission system, Connection of power line, Voltage phase shifts, Synchro-check relay

Title of the Paper:  Assessment and Classification of Line Overload Risk in Power Systems Considering Different Types of Severity Functions


Authors: Marayati Marsadek, Azah Mohamed, Zulkifi Mohd. Norpiah

Abstract: Power system security assessment based on the concept of risk is required in the current power environment. In risk based security assessment, the likelihood and severity of security violation are the two main factors that determine the security level of a power system. To evaluate likelihood of security violation, the probability technique based on Poisson probability distribution function is adopted. Severity function signifies the extent of security violation. Two types of severity functions, namely the continuous and percentage of violation severity functions are considered in this study. This paper presents the assessment of risk of line overload at various loading condition using a risk index. A risk classification technique is also proposed so as to provide a qualitative interpretation of the risk index value by classifying the risk as low, medium and high degree of risk. This paper presents the implementation of line overload security assessment on the IEEE 24 bus test system and practical interconnection power system so as to investigate the effect of severity functions on risk classification in risk assessment. Results are presented in terms of risk index curves.

Keywords: Line overload, Probability, Risk, Severity, Security, Uncertainty

Title of the Paper:  Description of Power System QV Curve by Fuzzy Modeling


Authors: Shu-Chen Wang, Chi-Jui Wu

Abstract: The purpose of this paper is to study the description of power system QV curves by using the method of fuzzy modeling for analysis of voltage stability. Voltage instability of power system comes from increasing load rapidly, and causes bus voltage to drop. When voltage is out of control and it can be voltage collapse. The QV curve can identify voltage stability limit, and it determine robustness of power system. The method of fuzzy modeling has been proven to be well-suited for modeling nonlinear industrial processes described by input-output data. The fuzzy system model is basically a collection of fuzzy IF-THEN rules that are combined via fuzzy reasoning for describing the features of a system under study. In view of the nonlinear characteristic of power system QV curve, the method of fuzzy modeling is employed for representing the curve. Based on the Sugeno-type fuzzy model, various models with different numbers of modeling rules are used to describing the QV curve. It is found that such fuzzy model offers both quantitative and qualitative descriptions for the QV curve.

Keywords: Fuzzy Modeling, Sugeno-type, ANFIS, QV Curve, Voltage Stability, Voltage Collapse

Title of the Paper:  New Features Regarding Pumps Command by Electrical Drives


Authors: Marius-Constantin Popescu, Nikos E. Mastorakis, Ilie Borcosi, Jean-Octavian Popescu

Abstract: As compared to hydraulic, pneumatic, or thermal motor devices, electrical drives have certain advantages owed to the ease of generating, transporting and distributing the electrical energy. This fact made them become the first choice in most of the cases emerging in actual activity. The present paper simulates the behavior of electrical drives powered by continuous current motors. The efficiency optimizing of the drive systems in industrial and modern appliances can be done through using vector control with DSP and intelligent power module for asynchronous motors. The authors contribution to this paper refer to the proposal and development of a control system of a rotation AC motor with field oriented control based on the signal processor TMS320F2812 DSP.

Keywords: Drive system, Vector control, DSP, Intelligent power module, Nonlinear command

Title of the Paper:  Techno-Economic Analysis of Illegal Electricity Usage in Turkey and Policy Proposals


Authors: Nevzat Onat

Abstract: Some part of the energy produced in electric power systems does not reach to consumers who make payment because of output loss and administrative applications. The energy loss can be considered in two categories as technical losses and nontechnical losses. Total of these losses is a significant parameter that affects capacity of the system. In this study, the transmission and distribution losses in Turkey power system were researched. The studies carried out for purpose of determining its illegal use and its socio-economical effects were analyzed. It is impossible to prevent the losses completely in the electric energy system. However, in developed countries, it generally remains below 6%. The lost illegal use rate in Turkey was determined as 14.4%. The cost resulting from only illegal use reaches to values that urge the economy of Turkey with a rate that is 1.7 times of the annual transmission and distribution system investment of the country. In terms of energy pricing Turkey is very competitive situation with European Union and OECD countries. However, the losses of Turkey are well above the world and OECD averages. To decrease the technical losses, very serious additional energy investment is needed in the country. Illegal use rate can be decreased to acceptable rates as a result of policy changes and some measures. In the study, some solution suggestions are made to decrease the loss rate that occurs as a result of illegal use. To achieve decrease in illegal use, some measures can be taken such as, speeding up privatization policies, regional price policies, raising of the awareness of the public about economical and social dimensions of the illegal electric use, encouraging of the public to use other energy sources means by being informed and supported economically, awarding of the government officials who determine the illegal use, giving of various incentives to citizens who denounce such use.

Keywords: Electricity theft, T&D loses, energy generation, electrical energy demand, cost

Title of the Paper:  Analysis of Turkey's Electric Power Demand Forecast and Generation Models Scenarios for the Next Ten Years


Authors: Haydar Bayar, Nevzat Onat

Abstract: The Turkish Government makes great efforts to increase the new and renewable energy resources, use new systems with low carbon emission instead of high carbon emission technologies, make energy saving and decrease the emission of Carbon-dioxide (CO2) and other sera gases by increasing the energy productivity by means of preventing losses in energy distribution systems. In production of electric energy, the high rate of the imported fossil fuel is a significant advantage. With this regard, the investments made to local and especially renewable energy resources must be increased. In this study, the technical and economical parameters such as primary energy resources, demand increases and price fluctuations are examined in detail. In the study legal regulations made for that purpose are also considered. By using the data published by Turkish Electricity Transmission Company (TEIAS), analysis of important parameters such as energy demand increase rates, investment plans, change in emission rates expected to occur until year of 2020 according to two scenarios, in terms of sustainability in energy production, is made. Consequently, within following ten years, a very small development in energy investment policies of Turkey is expected with effect of legal arrangements in favor of renewable energy resources. However, this increase is very low according to the potential usable in the country. This situation decreases the competition power of country with the OECD countries in terms of energy prices. For a sustainable development, the country must make significant changes in the foreign-dependent energy production policies. In the policies to be determined, supplying of continuously increasing demand from local resources must be encouraged. In some regions of the country, measures to decrease the air pollution that causes important social reactions and health problems must be taken and by rapidly completing the privatization studies, the weight of private sector also on installation of new plants must be increased.

Keywords: Turkey, sustainable consumption, legal arrangements, energy price, wind, solar, geothermal energy resources, investment plan, greenhouse gases

Title of the Paper:  The AHP and ANP Models for Transport Environmental Impacts Assessment


Authors: Helena Brozova, Miroslav Ruzicka

Abstract: This paper presents an assessment of environmental impact preferences of transport using the Analytical Hierarchical Process (AHP) and the Analytical Network Process (ANP). The authors suggest using these methods within the decision-making process and assessment of transport strategies or projects and their impacts on the environment. There are many various dependencies and links among factors influencing the decision-making process of transport implementation. It is not just environmental impacts that influences acceptance of decision-making, but also other major factors such as time (term), space (territory radius) and means of transport (mode). Finally many expectations of benefits obtained from transport implementation must be included in the decision-making process as well. The paper shows the complicated structure of these processes. The AHP model is used for preference evaluation of environmental impacts without any of the other factors or characteristics of transport projects, plans or strategies. The ANP model is more complex and is used for the evaluation including other characteristics of transports projects. The results of both models are compared.

Keywords: Transport policies, transport strategies and projects, decision making, environmental indicators, ANP method

Title of the Paper:  Failure Analysis in Power System by the Discrete Wavelet Transform


Authors: Ismail Yilmazlar, Gulden Kokturk

Abstract: Voltage variations are the most common power quality events that may result in corruption of different industrial processes. The electric power utility industry requires significant improvement in the quality of power provided to customers during faults or wide area system disturbance. Power system failure signals are monitored by using embedded systems. This paper presents an approach to provide the detection and location in time as well as the identification of power quality problems which are represented in both transient and fixed signals. The method was applied by using the discrete wavelet transform (DWT). The given signal is decomposed with wavelet transform and any change on the lower frequencies of the signal is detected at the finer wavelet transform resolution levels. The entropy contents of the signal are considered and a relationship between this entropy contents and the one of the corresponding component is accomplished. This paper shows wavelet transform can be used to reduce data set while covering original information. Because of the reduced data set embedded systems can work within a wider time range. Paper helps power system analysis and classifies power system failures.

Keywords: Discrete wavelet transform, wavelet entropy, power system failure

Title of the Paper:  Fuzzy Based SVC with Coordinated POD for Damping of Oscillations of Power System


Authors: S. V. Chandrakar, J. B. Helonde, R. M. Mohril, V. K. Chandrakar

Abstract: This paper is aim to present the SVC intelligent control strategy to achieve improvement in damping of oscillations of two machine system. The most of SVC controllers are proportional integral (PI) type, however its performance under varying system conditions is not satisfactory. This paper compared the performance of SVC with PI type and fuzzy based control schemes under various system conditions. The details of intelligent fuzzy control of SVC have been design to achieve smooth reactive power control. The input signal for fuzzy logic controller is deviation in measured voltage at SVC location. The minimum fuzzy rules are applied to achieve maximum performance of the controller. The additional power oscillation damping (POD) signal is applied with fuzzy controller to suppress the local mode as well as inter area mode of oscillations. The proposed fuzzy controller coordination with POD provides significant improvement in damping of the system. The effectiveness of the proposed control strategy is demonstrated in two machine systems. The results are validated in MATLAB.

Keywords: SVC, Fuzzy logic control, damping of oscillations, power system

Title of the Paper:  A Reliable Fuzzy Logic approach for Measurement Data Validation through Line Susceptance Estimation


Authors: K. N. Bhanuprakash, A. D. Kulkarni, B. R. Lakshmikantha, T. Ananthapadmanabha, K. Balaraman

Abstract: A novel approach is described to estimate the transmission line susceptances using the linear power flow model with linear relation between the measurement vector and the susceptance vector. The presently estimated susceptance is compared with the already stored correct value, to determine validity of the present measurement using the fuzzy inference.

Keywords: Data Validation, lower and upper bounds of state estimation, Interval arithmetic, Fuzzy logic, Reliabality

Issue 4, Volume 5, October 2010

Title of the Paper:  Five Level Parallel Inverter for DTC – SVM of Induction Motor


Authors: Jagan Mohana Rao Malla, Siva Ganesh Malla

Abstract: Direct Torque Control is a control technique used in AC drive systems to obtain high performance torque control. The conventional DTC drive contains a pair of hysteresis comparators, a flux and torque estimator and a voltage vector selection table. The torque and flux are controlled simultaneously by applying suitable voltage vectors, and by limiting these quantities within their hysteresis bands, de-coupled control of torque and flux can be achieved. However, as with other hysteresis-bases systems, DTC drives utilizing hysteresis comparators suffer from high torque ripple and variable switching frequency. The most common solution to this problem is to use the space vector with multilevel inverter depends on the reference torque and flux. The reference voltage vector is then realized using a voltage vector modulator. Several variations of DTC-SVM with low cost multilevel inverter or parallel inverter (five level) have been proposed and discussed in the literature. The work of this project is to study, evaluate and compare the various techniques of the DTC-SVM with parallel inverter applied to the induction machines through simulations. The simulations were carried out using MATLAB/SIMULINK simulation package. Evaluation was made based on the drive performance, which includes dynamic torque and flux responses, feasibility and the complexity of the systems. It is better technology in electric vehicles.

Keywords: Multilevel inverter, DTC-SVM, Converter, Electric Vehicles, Reliability, SVPWM, 5 Level parallel Inverter

Title of the Paper:  Dynamic Analysis of Grid Connected Wind Turbine with a Permanent Magnet Synchronous Generator during Fault Conditions


Authors: Lata Gidwani, Harpal Tiwari

Abstract: The use of wind turbines is increasing at very high rates in many countries around the world. Studies to evaluate the impact of connecting these new generation units to the existing power systems must be done. This paper proposes a wind energy conversion system for a grid connected permanent magnet synchronous generator (PMSG) and power electronic converter system. The model includes a PMSG model, a pitch-angled controlled wind turbine model, power electronic converters and a power system model. The control schemes in the paper include a pitch angle control for the wind turbine and voltage, var and current control for the power electronic converter. A phase to phase fault is simulated on 132 KV bus of power system model and the measured results obtained from grid connection of the permanent magnet synchronous generator are presented followed by some conclusions.

Keywords: Permanent Magnet, Synchronous Generator, Power Grid, Power Electronic Converter, Fault

Title of the Paper:  Innovative Technologies for Romanian Anti-Hail System


Authors: Laurentiu Alboteanu, Constantin Sulea, Gheorghe Manolea

Abstract: About 60% storms on the Romanian territory (during the march-September period of one year) are accompanied by hail falls and 40% of these hail falls lead to significant or even total losses of crops. So, this is a new and actual research domain that the present work is related to and its main goal consists in building up a study concerning the existing technical solutions and exploring some new ways in order to solve the identified problems. The paper outlines the concerns of the research team at the University of Craiova, Innovation and Technology Transfer Centre - CITT on combating hail. Mainly, the researches concern the equipments and the innovative technologies for Romanian anti-hail systems.

Keywords: Anti-hail, microcontroller, photovoltaic system, informatic system, monitoring information, environment

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