ABSTRACTS
Disturbances correlated to compensation of reactive power in a system with wind generation – estimation of transient components’ parameters
Przemyslaw Janik, Zbigniew Leonowicz, Jacek Rezmer, Piotr Ruczewski, Zbigniew Waclawek, Hortensia Amaris, and Carlos Alvarez
Precise computation of current components is a key prerequisite for reliable assessment of power quality. Especially in networks with wind generation we may observe increased number of possible disturbing phenomena. This paper presents an approach to accurate computation of currents components with two similar parametric methods based on singular value decomposition (SVD) and Prony model. Those methods seem to be applicable for the detection of non integer multiples of the main frequency in decaying signals. Results of both methods have been compared and evaluated with respect to traditional Fourier approach.
Electrical Energy Measurements for Rome LV Customers by Distributed Web-Server Instruments
Fabio Leccese
Power Quality (PQ) measurements for low voltage (LV) customers, domestic and business, have been carried out in order to detect the behaviour of the electric net over time and the quality of the electric energy being bought. In order to measure PQ parameters, we realized an instrument based on web server personal computers, which are common in office or in domestic environment. This allows us to conjugate the high PC calculus capability with the possibility to send data via internet to a central server; moreover, the use of the existing hardware infrastructure makes the instruments extremely cheap.
Optimal Capacitor Placement on Interconnected Distribution Systems in Presence of Nonlinear Loads Using Genetic Algorithms
Ahmad Galal Sayed
Due to simplicity of analysis of radial distribution systems, all previous work studied the effect of nonlinear loads on only radial distribution systems. The study of the optimal capacitor placement on distorted interconnected distribution systems in presence of nonlinear loads using Genetic Algorithms (GA) is presented in this paper. Results (power losses, operating conditions and annual benefits) are compared with that obtained from radial and loop distribution systems. Computational results obtained showed that the harmonic component affects the optimal capacitor placement and sizing in all system configurations. When all loads were assumed to be linear, interconnected and Loop system configurations offer lowest power losses and best operating conditions rather than the radial system configuration while radial system configuration offer best annual benefits due to capacitor placement. In distorted networks, interconnected systems configuration offer lower power losses, best operating conditions and best annual benefits due to capacitor placement.
Computer Relaying Software Reliability Evaluation Using Event Tree
Aditya Anil, Dusmanta Kumar Mohanta, Diptendu Sinha Roy, and Ajit Kumar Panda
Software reliability evaluation has emerged as an area of importance in recent times with the proliferation of software based systems. But highly dependable software systems used for safety critical application, such as computer relays for power system transmission line protection produce little failure data. Hence a statistical method known as statistics of extreme is used for reliability evaluation. This paper deals with calculation of exceedance probability of computer relay for decision making purposes using an event tree for software used in computer relaying.
Relationship between Production Capacity of Wind Power Stations and Needs of Ancillary Services
Vaclav Cerny, Andrea Fialova, Lucie Houdova, Petr Janecek, and Eduard Janecek
Number of wind power stations has been increasing in the world for last years. Of course, this causes that electrical power amount produced by this kind of power station and subsequently delivered to electricity transmission systems has also been growing. On one hand, this brings positive effects with respect to living environment because production of coal, gas or nuclear power stations can temporarily be reduced while wind blows. On the other hand, this sets enhanced demands on needs of ancillary services. This paper deals with these connections and demonstrates obvious consequences that arise from them.
Extracting Electricity from Groundwater Flow - A New Environment Friendly Source of Energy Case Study: Iran
Majid Labbaf Khaneiki and Ali Asghar Semsar Yazdi
In Iran, extracting energy from groundwater flow was an ancient technical tradition which unfortunately has been abolished in the wake of the advent of modern means of power generating. The subterranean irrigational canals called Qanat in Persia made it possible to build many watermills rotating with the force of groundwater. Qanat is a gently sloping subterranean canal, which tap a water-bearing zone at a higher elevation than cultivated lands. At present there exist some 32000 active qanats running all over Iran, discharging about 9 billion cubic meters groundwater a year. The head of water in a qanat canal with a discharge of 80 liters per second is such that the flow can spin a millstone weighing over 800 kilos, in a traditional way in which the friction is so high. In this paper we depict the possibility of replacing the abandoned traditional watermills with the modern optimized turbines to generate electricity in an environment friendly way. The qanat holding countries like Iran, Oman, Afghanistan, China and Iraq can consider the qanat system a new source of energy, which not only can supply water to the rural communities but also can provide them with cheap, renewable and clean electricity. In closing, we describe some considerable initiatives taken in Iran to make use of the groundwater flow in the qanat canals to generate electricity.
Fault Liability and Maintenance Cost Modeling of a Steam Turbine
Lenka Houdova, Libor Jelinek, and Eduard Janecek
This paper focuses on modeling of power stations
technological equipment reliability. There is described a method
of failure model creation, based on failure and repairs data of a
particular components, and cost model creation, based on costs
specification. At first there is mentioned the data processing
procedure, problems of appropriate stochastic parameters
inference and total characterization of failure model connected
with small number of data and their dependence on operational
conditions in concrete. This model should be able to predict the
future conditions and to estimate important evaluation indicators.
For that reason it is necessary to introduce the software, which is
used for simulation, visualization and optimization future
development of evaluation indicators possibilities. This work is a
part of the joint project of the UWB and Škoda Power company
called “Operational availability and maintenance cost
optimization with the computer support”.
Voltage Stability Analysis of Grid Connected Wind Generators
Nguyen Tung Linh
Wind generators can have a significant impact on the power flow, voltage profile and the power quality for customers and electricity suppliers. This requires a suitable tool to analyze the influence of wind generators on the distribution system. This paper presents a method to find the steady-state voltage stability region for each bus of a distribution power system, considering the presence of windpower generation. The maximum permissible load of each bus is calculated, so that it can operate with the voltage within the limits allowed by the power system utilities.
Keywords: Wind generator, Voltage stability
Organic solar cells based on ZnO nanowires layer
Jiri Podzemsky and Wolfgang Schade
In our research we are looking for alternative to solar cells based on silicon. We are using zinc oxide (ZnO) which is N type semiconductor instead of silicon. To reach PN junction P type polymer is used. ZnO is in form of well aligned nanowires. Since the distance between nanowires is smaller than the mean free path of electrons almost all emitted electrons are collected. We use vapor-liquid-solid (VLS) method to create ZnO nanowires. Used substrate was sapphire, silicon and silica glass. Small solar cell was manufactured and its open circuit voltage under light was measured.
Wind Turbine Cylinders with Spiral Fins
Radomir Gono, Stanislav Rusek, and Miroslav Hrabcik
Paper describe the world’s first wind turbine system that rotates with cylinders which have spiral-shaped fins coiled around instead of common propeller-type blades. When the spiral cylinders catch the wind, rotating force is generated due to the aerodynamic properties caused by Magnus Effect. On the basis of experiments make by MECARO Co.Ltd it is possible to state that this type of power station is better than propeller type - more effective, cheaper the construction cost and stronger in the strong wind.
Reliability Standards for Large Interconnections
Petr Horacek and Petr Havel
Different interconnections may have chosen and use slightly different performance criteria for evaluating the reliability of system services in terms of power balancing which is the essential task of all bodies including electricity market players and namely balancing authorities like Independent System Operators in the US and Transmission System Operators in Europe.
The paper describes the history of performance standards and he state of-the-art applied to several large interconnections in North America and Europe (UCTE Interconnection). Performance indices and standards proposed for the Czech Control Area of the UCTE Interconnection is discussed in more detail. The use of performance standards in Ancillary Services planning is shown.
Shields of Electromagnetic Wave Based on Amorphous and Nanocrystalline Soft Magnetic Materials
Mariusz Ozimek, Dominika Gaworska-Koniarek, and Wieslaw Wilczynski
The paper presents results of measurement of electromagnetic wave shielding effectiveness by shields based on Fe73,5Cu1Nb3Si13,5B9 soft magnetic material in nanocrystalline and amorphous form. Manufactured shields were characterised by good elastic properties. The research was carried out in frequency band of 150 MHz – 1 GHz. The highest shielding effectiveness was obtained for sample made of amorphous tape - at frequency of 700 MHz it equals 42 dB.
Impedance-Source Inverter-Based High-Power DC/DC Converter for Fuel Cell Applications
Mikhail Egorov, Dmitri Vinnikov, Ryszard Strzelecki, and Marek Adamowicz
This paper presents the possibility of implementation of fuel cells with low output voltage range for supplying the high-voltage loads. For matching the different voltage levels and for the providing of galvanic insulation the isolated DC/DC interface converter is required. For increasing of power density, efficiency and flexibility the interface DC/DC converter with three-phase intermediate AC-link is proposed. The one of features of the proposed topology is the impedance source inverter utilized in the input stage of the converter. The paper is devoted to study of theoretical background of the topology proposed, which is verified by the simulations.
Voltage division over the interrupter units of a high voltage circuit breaker without grading capacitors
Henryk Stuermer
In a modern high-voltage circuit breaker in lower voltage levels (up to 300kV) one interrupter unit is used per phase. In higher levels two, three or four switching lines in serial circuit are used.
Both in off-position and disconnection of the load or short circuit current the interrupter units are stressed by different voltages. In order to be able to stress a specified number of interrupter units by high voltage, the voltage is equally divided by grading capacitors to all interrupter units. The grading capacitors are connected in parallel to the interrupter units. For example for a quad breaking circuit breaker a voltage division of 25/25/25/25% is aspired and for a twice breaking circuit breaker a division of 50/50% is aspired. Using available grading capacitors the voltage division is 53/47% and 27/26/24/23%.
Because the grading capacitors are an important expense factor for high-voltage circuit breakers for several years it’s tried to apply multiple breaking circuit breakers without grading capacitors. The voltage division is the most important factor. The result from the calculation of a twice breaking switch is 80/20%, for a quad breaking switch without grading capacitors it is 80/10/5/5%. In both cases one interrupter unit has 80% of the voltage; the other units have only a small voltage.
If you make a dielectric or switching capacity testing you can see, the switch is able to keep a higher voltage like the calculation showed.
The following facts could be the reasons:
- The calculation is too inexact.
- Only the capacities are considered; other effects could be the reason.
It’s difficult to measure the voltage division between the interrupting units by common measurement equipment because the measurement equipment has a noticeable influence to the voltage division. A possibility could be the usage of measuring probes which have no or only a small effect to the voltage division because of the contact less measurement.
The following problems are to research:
- Development of a qualified measuring method: measurement of circuit breaker-
capacities by measurement of capacitive current and with bridge, measurement of
earth capacities by measurement of capacitive current, voltage measurement
- Simulation of circuit breaker and measurements: field an transient simulations
- Several High Voltage Tests: ac-tests and impulse tests
- Analysis of the effects, which determine the voltage division and which
determine the several forms of the voltage stress
- Comparison of the findings and the test readings and declare, why the switch
operates better than in the calculation
- Test problems: capacities between test object and measuring equipment/environment
Adjustable Speed Generation System For Wind Turbine Power Quality Improvement
Wlodzimierz Koczara, Grzegorz Iwanski, and Zdzislaw Chlodnicki
The paper presents an emerging technology of electricity
generation based on decoupled theory. The decoupled generation
system operates in wide speed range and control strategy is
oriented to select regions of high efficiency of the driving engine.
This system is used to operate parallel to renewable energy source
that is unstable and not reliable. In case of high power available
from the renewable the decoupled adjustable speed generation
reduces it speed what results in low fuel consumption. However
when the renewable source power is decreasing the adjustable
speed generation system increases its speed following points of
high efficiency of the driving Diesel engine. The paper presents
topologies of the combined systems including variable speed wind
powered generation system and adjustable speed generation
system driven by Diesel engine. Moreover ability of the adjustable
speed to provide power is discussed.
Current progress in ambient energy harvesting using piezoelectric materials and electroactive polymers
Pawel Zylka
A review on current progress in energy harnessing
micro-generators using active materials (ceramic and polymeric
piezoelectric materials as well as electroactive polymers) is presented.
A problem of effective electrostatic energy extraction from those
capacitive-in-nature energy supplies is illustrated experimentally. It
is shown that using Macro Fiber Composite (MFC) piezoelectric
transducers working in resonant mode and matching the load to the
MFC impedance it is possible to attain 10 % generation efficiency.
Thin Film Adhesion Measuring of Conductive Silicon Rubber Depending on Power and Coating Time in Magnetic Sputtering Method
Artur Napierala and Jan Ziaja
Coating silicon rubber with another material is not facile task due to the fact, that this substance exhibits very poor adhesiveness coming from the low surface tension. Adhesion properties can be improved by means of addition filler and plasma treatment. The analyzed sample is a conductive silicon rubber, which was coated using magnetic sputtering method. This method bases on plasma activity in strong magnetic fields. The adhesion in modificatied material was evaluated on the basis of cross-cut test by different coating time and target power.
Electrical behaviour of current conducting silicon rubber
Artur Napierala
Conductive plastic gain more and more interest in
electrical industry due to few advantages in comparison to metal
like light weight and rustles properties and to some extent lower
material price. The idea of using such materials is not new. These
kinds of materials have been applied for many years in fields like
electromagnetic shielding or voltage grading, where there strongly
entrench his position. Recently new possible applications are
being taking into consideration, which have in common that
conductive plastic should conducting significant among of current.
This paper inspects a mechanism of current conducting be means
of percolation theory and resulting with that consequence.
On Hilbert Transform and its application to assessment of electrical signal waveform distortion
Tomasz Sikorski and Piotr Ruczewski
In order to achieve full description of the distorted signals applied method of analysis should take into consideration two kind of desirable parameters: those which characterizes time behavior of the waveform, and those which gives information about frequency components. This paper follows by the idea of Hilbert Transform (HT) which allows to construct analytic signal and introduce the term of instantaneous amplitude (IA), instantaneous phase (IP) and instantaneous frequency (IF). Unfortunately, application of HT, especially in point of instantaneous frequency, gives meaningful results for restrictive class of signals. The accurate representation is achieved for monocomponents signals. Practical application of HT can be preprocessed by selected signal decomposition method. This paper provides some analytic derivation of HT and its digital application for not decomposed and decomposed signals.
Voltage Dependence of Hologram Generation Dynamics in Nematic Liquid Crystal Hybrid Panels
Agata Anczykowska, Stanislaw Bartkiewicz, Lech Sznitko, and Jaroslaw Mysliwiec
In this paper we present results of the study of dynamics of diffraction efficiency in hybrid liquid crystal panels (HLCP) dependent on applied voltage. In the experiment we used laser to write a hologram by modifying the alignment of liquid crystal molecules. Simultaneously we used a second laser to read the recorded gratings. We proposed the model explaining the dynamics of the gratings formation which is composed of three different following processes related to the charge carriers generation and their mobility in the photo conducting polymer.
Relevance of a Safety Factor for Wind Power Trading in Comparison with the Utilization of a Storage
Steve Völler and J. F. Verstege
In Germany renewable energy sources are paid by law with a constant amount for the supplied energy. Thus, the operators of such plants have no intention to take part at the energy market yet, but there exists possibilities to earn a better payment, so already some facilities act in the market and in the future this participation will be more and also necessary.
This work analyses the opportunities for the participation at an energy exchange and at the control power market. To interact with the market, wind farms have to supply a constant power for a specified time. Due to the fluctuations of wind energy it is not possibly to guarantee a constant power based on wind forecasts. Thus, the wind farm cannot sell their maximal estimated energy but only a reduced value. The aim of the work is to figure out this specific \"safety factor\". Later on, the results are compared both technically and economically with the use of a storage unit, where the full amount of energy can be traded.
The Probabilistic Integration of Demand-Side Load and Generation in a Representatntive Irish Distribution Network
Keith Sunderland and Michael Conlon
This paper follows-on from work developed in the modelling of the Irish distribution network with increasing penetration of micro generation (more specifically focused on micro wind generation) [1] in the context of voltage profile analysis. The Representative Irish Network [2] is comprised:
One 500MVA Source
Two 10 MVA Transformer (YY0, 38/10.5kV)
Five, 10kV Distribution feeders with one modelled in detail
o The detailed feeder contains ten 10/0.433kV Substations, each substation having four LV feeders.
o One of these LV feeders is further highlighted in detail.
Each substation, serves 312 customers (over three phases) and each customer is modelled as having an ADMD of 1.28kVA and the potential of affording a micro-generation technology with capacity of 1.1kVA. Each substation was modelled with a load factor of 50%. One of the LV Feeders is modelled in detail. The representative Irish Network was specifically modelled in terms of the Distflow. Distflow was applied as the optimal load flow technique to derive the voltage profile for the network being considered as standard load flow approaches have difficulties in converging given the challenges posed by distribution networks – specifically the high X/R ratios.
The next stage of development for the model is to integrate recorded wind data and investigate system reaction when said data is employed to vary power output from the network connected micro wind generation. The approach previously considered [1] was to model load/generation mix in terms of:
• Maximum Demand on each substation (of each 10kV feeder), 0% Generation
• Minimum Demand on each substation (of each 10kV feeder), 0% Generation
• Minimum Demand on each substation (of each 10kV feeder), 100% Generation
A probabilistic approach has now been developed which was initially employed to the connected generation. This was then applied to the network in conjunction with the LV loading which was based on measured load profiles of a sample of domestic installations. Therefore the cumulative effect of variable generation and load can be observed and a voltage profile from a dynamic and realistic perspective ascertained. The approach adopted is summarised by:
1. The data set being organised so as to be represented in terms of a probability density function
a. This is compared to a Rayleigh Distribution Function to ascertain correlation
2. A cumulative distribution function is produced and by using a random number generator a representative wind speed value from the data set is acquired
3. This wind speed is then applied to derive the power output for the range of wind generators.
The approach to apply a single wind speed to all connected generation is considered acceptable as the land coverage the representative Distribution Network would encompass is consistent with the hypothesis that there would be little variation of wind (excluding consideration towards obstruction or shading). Independently varying ‘bulk’ connected load of the connected consumers at the sectionalized connections of the LV feeder was also considered acceptable as a compromise to individual manipulation of each consumer’s load.
This paper details this approach and goes on to describe the methodology employed in synergizing a load/generation variation which is autonomous and accurate in its representation. This development of the model is also applicable to any micro generation technology that can export electricity on to the Distribution Network.
REFERENCES
[1] Sunderland K., Conlon M.F., "The Role of Micro Wind Generation in Ireland's Energy Future”. Proceedings of 43rd Int. Universities Power Engineering Conference (UPEC2008), paper No. 258, Padova 1-4 Sept.
[2] Ingram. S., P.S.a.J.K., Impact of Small Scale Embedded Generation on the Operating Parameters of Distribution Networks, Department of Trade and Industry. June 2003.
[3] D. D. S. Ghosh, "Method for load-flow solution of radial distribution networks", IEE. Proc.- Gener. Transm. Distrib. Vol. 146, No. 6, November 1999, 1999.
Planning of Ancillary Services Securing Power System Operation
Ondrej Novak, Tomas Strnad, Petr Horacek, and Josef Fantik
The paper deals with procurement of AS categories used by the Transmission System Operator except voltage control and black start. Performance standards are specified and set for a control area of the UCTE following general requests for all interconnected areas defined in the Operation Handbook. AS are planned meeting the performance standards and purchased in yearly auction under the lowest cost. Operation of the control area under Automatic Generation Control and Energy Management System run by the TSO dispatching balancing power on minute-by-minute basis for one year is simulated in Monte-Carlo simulation scheme. Several approaches used for planning AS are presented, compared and experience from CEPS, the Czech Transmission System Operator will be shared.
Biofuels- the power from plants
Grzegorz Pawel Maliga and Amar Mohan Patil
In this paper I try to review five fundamental groups of biofuels which are used as a power source for mechanical engines. However engines could be use as a propulsion in cars or other machines and as a current source when engines cooperate with generators.
The basics biofuels which belong to the fundamental group are: rapeoil, biodiesel, biomethanol, methan from biogas and synthetic biofuel. I present calorificvalue of these kind of biofuels and compare to earthfuels.
In Europe the leader of production biofueals is Germany. On the basic of this country I present how the biofuel industry deweloped in the last ten years and what kind of benefits is possible to gain. I describe also political and law conditions which influece by using biofuels.
Finally, I pay attention to the most important result of using biofuels which is influence to environment, because producing and burning biofuels take a part in the same carbon dioxide cycle.
Keywords: biofuels, biodiesel, biomethanol, rapeoil, fuels from biomass
Guideline for the Investigation of PEM Fuel Cell Systems in Automotive Applications
Maik Heuer, Mathias Kaebisch, Guenter Heideck, and Zbigniew Styczynski
In the context of a research project in the field of
energy conversion and drive systems at the Otto-von-Guericke
University Magdeburg, four proton exchange membrane (PEM)
fuel cell systems of the newest generation have been put into
operation. The investigations refer to stationary and mobile
applications as well as to lifetime tests of the fuel cell. The plants
are presented and scheduled measurements plus the research
goals are described. The operational behaviour of the fuel cell and
the overall system are evaluated for long-term investigations. A
further emphasis is on the behavior of several fuel cells, which are
operated with different gas compositions. Because the
measurements are still in the early stages, the report mainly
describes the project goals and gives an overview of fuel cell
technology.
Wind Turbine Driven Doubly-Fed Induction Generator With Grid Disconnection
Chitti Babu B, Mohanty K B, and Poongothai C
This paper describes the transient behavior of a doubly-fed induction generator (DFIG) driven by wind turbine after its disconnection from the grid. The induction machine runs at a specific speed with the stator disconnected from the grid (Is=0), the rotor is suddenly excited with slip-frequency voltages derived from voltage regulators so as to produce commended open-circuit stator terminal voltage. Behavior under varying rotor speed typically observed in wind turbines is also reported. A MATLAB computer simulation study was undertaken and results on 1.5 kW wind turbine are presented.
Possibilities of Utilization of Energy Briquettes
Gabriel Borowski
The analysis of mineral coal briquettes from charcoal and biomass together with molasses as a binding agent for utilization in industrial energy were presented. The physical-chemical properties of the material investigated, consisting of raw waste material, are described. The process for preparing the material into briquettes comprised of crumbled and mixed constituents, together with the specific reduction of moisture of the mixture, are presented. The effect of the selected parameters of the consolidation process in the pressing stamp on the toughness of briquettes is investigated. Analysis was made of such parameters as: contribution of the biomass in the mixture of charcoal and binder, moisture in the mixture, press pressure on the formation, and seasoning. The results confirm the possibility of utilizing high quality energy briquettes. They possess the high material strength as well as high value combustible fuel, which qualifies them for utilization in industrial energy.
Optimum location and sizing of passive filters in distribution networks using genetic algorithm
Mahdi Ghiasi Varzeghan, Vahid Rashtchi, and Sied Hadi Hoseini
The harmonic distortion of voltage has became an important subject in power quality, especially after use of power electronic equipment and nonlinear loads. Simple method to limitation of harmonic distortion is using of passive filters. The objective of this paper is to determine the location and size of passive filters in distribution networks economically, by using genetic algorithm. With using of genetic algorithm and new coding here some of other methods limits for passive filters locations are removed. The purpose of the genetic algorithm is to minimize the cost of passive filters and, at the same time, to reach the harmonic limitations defined by standard IEEE-519. This algorithm is applied to IEEE 13-bus distribution network and the results are shown, finally.
Balancing Voltage Source Direct Torque Control of Induction Motor with Three level Inverter
Aberrahmane Berkani and Hacene Rezine
The object of this paper is to study a new control structure for sensor-less induction machine dedicated to electrical drive using three-level voltage source inverter. The amplitude and rotating speed of the flux vector can be controlled freely. Both fast torque response and optimal switching logic can be archived; the selection is based on the value of the stator flux and the torque.
A novel direct torque control scheme of induction motors is proposed in order to develop a suitable dynamic. We propose an approach, in which we enhance the response of torque and flux with optimal switching strategies. However, the middle point voltage of the input DC voltage of the three-level NPC voltage source inverter presents serious problems caused by fluctuation of the DC voltage source. As consequence to these problems we obtain an output voltage of the inverter which is asymmetric and with average value different from zero, in this paper, we will present one solution to minimize this fluctuation. This solution uses
a hysteresis comparator to regulate the input voltage of the three level inverter the results obtained indicate superior performance over the FOC one without need to any mechanical sensor.
Remote Irrigation controller under photovoltaic energy
Mohamed Lassaâd Benzaoui
Water is an important thing in the earth, so we must use it economically, especially in the irrigation of fields in the dry areas and in summer days. So that we present in this paper, a conception of a device which permits us to control automatically the uses of water in irrigation. This is by microcontroller. We applied this device in the Sahara of Algeria (oasis).
And to get autonomy of the system, we have preferred to use the Photovoltaic systems as an electrical supply of the installation and a power for water pumping.
The greet problem in irrigation is to specify water needs for each plant, which depends of temperature, land humidity, air humidity, wind and the nature of the plant.
In first we have used in the controller device many sensors to get the in formations about these parameters which are used as inputs of the test conditions to irrigate.
And next an electronic device based on the microcontroller 16F877 was realised in order to get an automatic control and commands.
Finely we have tested this device to irrigate tomato, between June and July, and results were good.
Implementation of Inter-area Angle Stability Prediction in Wide Area Control
Ahmed A. Daoud
This paper proposes a new interarea angle stability prediction algorithm. This proposed algorithm does not require any prior knowledge of system state as it operates directly from measurements drawn from PMUs. The proposed predictor foresee the system stability state for 500 ms in advanve. Applying the COI angle concept for the interconnected power systems, inter-area stability can be predicted in a proper time. The proposed method was applied for two standard test systems, two area 4 generator system and IEEE 50 generators test system. The results showed that the prediction accuracy in most cases converges around 1 %. At the worest case the predicted values approaches 7%.
Some aspects of technical, economical and wind simplified analysis for 18 MW wind farm in Poland
Waldemar Dolega
In this paper, simplyfied analysis of different conditions of wind power expansion in Poland is shown. This analysis is made on basis simplyfied computational example of 18 MW wind farm in Poland from the point of view of different group of parameters. Four groups of conditions: wind, geographical, technical and economical are taken into consideration. Introduction is contained short analysis of wind energy expansion in Poland in last times. First group of conditions is contained wind regime (consistent with mesoscale) as: yearly wind speed and Weibull distribution. Second group of consider conditions is geographical conditions as: localisation of wind farm, surface class, roughness and height. Third group of consider conditions were technical conditions connecting with selected unit of wind turbine for wind farm. Fourth group of consider conditions were economical factors as: wind turbine price, installation cost of turbine, operational & maintenance cost, price per kWh, price of property rigths connecting with certificates of origin, rate of discount etc. In frames this project two main groups of calculations were realised. First group were year energy output calculations of 18 MW wind farm for applied wind units, wind speeds and surface classes. Second group were calculations of electricity cost per kWh produced electric energy for mentioned earlier factors and for assumed prizes per kWh electric energy sale for distribution company. Results of realised computational calculations are placed in shape of tables. Conclusions contain analysis of impact of inquired conditions for key parameters of wind farm – magnitude of year energy output and electricity cost per kWh produced electric energy, which decide about wind farm effectivity.
The aspects of combustion and co-combustion biomass
Grzegorz Pawel Maliga and Amar Mohan Patil
Growing world population, increasing energy use, emission carbon dioxide (CO2) and climate changing are the reasons for searching alternative sources of power. Recently we are vested with numerously alternative sources of energy but biomass is considered as a most powerfull and easiest to access.
The bigest problems with burning raw biomass are: first the calorificvalue of biomass is average half compare to coal, second problem is a big contents of moisture for example in coal 10% of weight is water but biomass include even 35% of water.
For these reasons in huge power plants complete displacing stone fossil and lignite by biomass is not workable. Coal-fired furnaces which are used in power plants are not adapted to burn raw biomass, hence in powerplants co-combustion biomass and coal for power production is most efficiency because this process does not require additional energy. Precious advantage of co-combutstion is that technical range of change the fuel feed system is less. Preparing the fuel mixture based on blending biomass with coal on storehaus or in coal mills. The most efficient dose biomass to coal is about 10% weight.
Otherwise in small domestic heat furnace burning a raw biomass with high efficience is possible for example wood pellets furnaces are popularly used in onefamily houses. These kind of combustion occure, because the furnaces are specific adapted. The calorific value of wood pellets is near 19 MJ/kg which is compare to coal. Wood pellets are assembled for example numerous from energy willow or other kinds of waste wood and preparing the pellets form reqires energy addition.
In this paper I demonstrate two ways of burning biomass: combustion and co-combustion. I try to show that selecting the way of burning is depended by size of furnace.
Control and Stability Analysis of Doubly Fed Induction during Voltage Sags
Kairous Djilali Djilali, B. Belmadani, and M. Benghanem
Large wind turbines are often equipped with Doubly Fed Induction Generator -DFIG-.
Today the penetration level of wind power on the network is high. The power system stability defined as the ability of the system, for given initial operation condition, to regain a normal state of equilibrium after being subjected to a disturbance is the major problem.
In this paper we study dynamic behavior of the DFIG during voltage sag. Also we study the ability f the Control to remind the stability of the system
Application and Comparison of LQR and Robust Sliding Mode Controllers to Improve Power System Stability
Sahar Saffar Shamshirgar, Mohammad Golkhah, Hojat Rahmati, and Mohammad Ali Nekoui
Heffron-Philips model has had great popularity to simulate mono or multi machine power systems. Since the stability of this model is related to operating point of synchronous generator(s), many efforts have been made in research papers to design robust and reliable controllers to ensure the stability of the system. A typical mono-machine power system is presented in this paper to make a comparison between behaviors of traditional power system stabilizer and LQR based pss. Characteristics and fundamental concepts of each controller are stated. At the termination of the paper, Sliding Mode method has been engaged so that the power system can be stable in uncertain condition. The results of LQR base and sliding mode based PSSs have been compared under uncertainty.
A Survey of Solar Energy Power Systems
Adekunle Babatope Ajayi
This paper presents the survey of the free gift of nature (THE SUN) called solar energy and it is globally utilized as a form of power generation. Using the direct space SUN – RAY energy, solar energy power system is to link up Industrial to Domestic usage (I2D) such that each nation can identify an effective power generation, which brings development to a developing nation and also stability to the developed nation in every facet of her economy.
This paper highlights the opportunities for sustaining the developed nations and the developing nations in the implementation of Renewable Energy Sources by taking the Free Gift of Nature (FGN) sun. Concerns over global warming are causing shifts in energy policy and energy sourcing around the world. Citizens and governments are carefully weighing their impacts on the environment, which makes many begin to convert to clean renewable energy sources. The European countries are leaders amongst the continents of the world, as well as a nest for the minds of young independent thinkers and countries. Exploration of the renewable energy options will allow any country to understand its potential for reducing its impact on global warming, such that it can weigh the costs of Climate Change with those of upfront economic investment in renewable energy.
Energy has always existed in one form or another. It can be transformed into other forms, but it can neither be created nor destroyed.
Reducing the Short Circuit Levels in Kuwait Transmission Network. (A Case Study)
Mahmoud Gilany and Wael Al-Hasawi
Preliminary studies on Kuwait high voltage
transmission system show significant increase in the short circuit
level at some of the grid substations and some generating stations.
This increase results from the growth in the power transmission
systems in size and complexity. ew generating stations are
expected to be added to the system within the next few years. This
paper describes the study analysis performed to evaluate the
available and potential solutions to control SC levels in Kuwait
power system. It also presents a modified planning of the
transmission network in order to fulfill this task.
Impact of Inverter-fed Multi-Motor Drives on the Quality of Electric Power in the Mains
Maciej Stanislaw Pawlowski
An increased share of power of non-linear receivers on the power network gives rise to significant transfiguration of the feeding power sine waves. The performed analyses clearly indicate that the degree of transfiguration of the feeding power is higher at definite times of day. This refers to user supply networks, on which the number of small recipients, like PC users, significantly increases. Upper harmonics are common in electric networks Their sources are all sorts of non-linear receivers like converter systems, arc furnaces etc. The receivers get a transmuted current and thus become sources of upper harmonic currents. Those currents cause voltage drops at network impedance and distort voltage sinusoid. However, it seems important to suggest a relevant model of power supply network including linear and non-linear receivers and a capacitor set. It is even more vital to discuss the practicality of applying some proposed models. In converter drives, the rectifier load current is an oscillating one since the value of inductance in a DC circuit is limited. The phenomenon has a significant impact on the harmonic spectrum of the input current fed to the rectifier from the mains. Of course, converters are usually equipped with commutation reactors, so the commutation angle γ is not zero. Those factors are especially important with some electric drives, as due to the high circuit dynamics required, the drives have commutation reactors but no smoothing reactors in the load circuits. The article presents the results of analysis of higher harmonics of current and voltage in networks feeding six-puls rectifier.analitycal dependences of this phenomena at inductance in a dc cir-cuit is also given. evaluation of this applicability of the analysis for practical purposes, verification measurements is taken. It is done measurements on the reel cutter of a paper-making machine.
Modeling analysis and solution of Power Quality Problems
Mahesh Singh, Vaibhav Tivari, and Rajkumar Jhapte
Abstract-- A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a mis-operation of end use equipments. Utility distribution networks, sensitive industrial loads, and critical commercial operations all suffer from various types of outages and service interruptions which can cost significant financial 1oss per incident based on process down-time, lost production, idle work forces, and other factors. With the restructuring of Power Systems and with shifting trend towards Distributed and Dispersed Generation, the issue of Power Quality is going to take newer dimensions. The aim therefore, in this work, is to identify the prominent concerns in the area and thereby to recommend measures that can enhance the quality of the power, keeping in mind their economic viability and technical repercussions. In this paper electromagnetic transient studies are presented for the following two custom power controllers: the distribution static compensator (D-STATCOM), and the dynamic voltage restorer (DVR). Comprehensive results are presented to assess the performance of each device as a potential custom power solution.
Power System Real Time Simulation Testing Using IEC 61850
Yogesh Devidas Sonawane, Pankaj M. Patil, Naresh D. Sonawane, and Sayali Y. Sonawane
Abstract—
IEC-61850 becomes more widely accepted in the electrical engineering community, it is important that the testing tools keep pace with this development. IEC 61850 presents new challenges to real time simulation and closed-loop testing of protective relays. Electrical interfaces used for binary signaling and voltage/current amplifiers must be replaced by an Ethernet connection and an IEC 61850 protocol stack. The electrical interfaces of a real time simulator are engineered to provide low latency and deterministic performance appropriate for a real time simulation. Similar attention must be given to IEC 61850 interfaces. Latency must be minimized so that the IEC 61850 interface does not add unacceptable delays to the operation of the simulator. Also, protocol processing must be deterministic to allow real time simulations to be repeatable and dependable. In addition, IEC 61850 specifies new configuration parameters and a new method for configuration called the Substation Configuration Language (SCL). These must be implemented in such a way that they fit within the typical modes of operation of the simulator. The paper presents a successful hardware implementation for IEC 61850 messaging on a real time simulator and discusses the key design criteria. The software required to configure the IEC 61850 will also be addressed along with the advantages in using the IEC 61850 protocol. One of the biggest advantages is brought about by the realization of the IEC 61850-9-2 sampled values, removing the need for amplifiers as the standard interface to protection devices. Sampled values of the voltage and current signals can be sent via Ethernet, making it even more practical to perform testing on a protective relaying scheme rather than just individual devices.
Keywords: IEC 61850, GOOSE, GSSE, closed-loop testing, real time, power system simulation.
Economical Benefits by Contribution of Large Wind Farms to Voltage Control
Ahmad-Rami Al-Awaad
Wind energy is the main installed type of renewable energies in Germany. Wind farms owner gets a fix payment for the generated energy. This payment is much higher than the average variable costs of conventional power plants. Wind farms do not participate at voltage control till now. Although, they can supply reactive power into the network. In this study it is assumed, that there is a reactive power market. Large wind farms are connected to high voltage networks. It is shown, that fed reactive power from wind farms can contribute to minimization of the network losses in high and very high voltage networks. This fed reactive power leads to reduction of the complete demanded reactive power to support the voltage control by strong load too. Thereby, a part of costs of transmission system operator will be saved. These saved costs can be a contribution to reduce the fix payment of the generated energy of wind farms.
Optical properties of thin films of polyazomethine with triphenylamine unit in the main chain prepared by spin-coating method
Marcin Palewicz, A. Iwan, J. Doskocz, W. Strek, and D. Sek
Thin films of a polyazomethine (PAZ) were prepared from a chloroform solution by spin-coating technique. The solution of the polymer was spread on microscopic cover glass and quartz under nitrogen atmosphere at room temperature and atmospheric pressure. The optical properties of the PAZ were investigated at room temperature under atmospheric pressure. An absorbance, transmittance and reflectance were determined from spectrophotometric measurements. The absorption coefficients and bang gap of films material were developed. Surface structure of the PAZ thin layer was checked by AFM measurements. Thickness of the PAZ thin layer on the glass and quartz were determined with ellipsometer at the range from 150 to 220 nm.
A new approach to a solar cell problem
Bronislaw Swistacz
In this paper a new concept for a space charge
transport through a solid placed between the two electrodes is
presented. The effect of the light on the electric field distribution
and on the shape of current – voltage characteristic is determined.
For a space charge distribution some new singular solutions are
obtained. In this paper it is found that the system can act as a
blocking diode.
Proposed Techniques for Identifying Faulty Sections in Closed-Loop Distribution Networks
Wael Al-Hasawi and Mahmoud Gilany
This paper deals with three problems in closed loop distribution systems. The first problem is how to detect and identify the faulty section after a short-circuit fault is successfully isolated by the protection system. The second problem is how to identify a section affected with undetected open-circuit fault. A novel circuit is suggested in this paper to solve these two problems. The third problem addressed in this paper is the undetected short-circuit fault which may lead to a complete shut down of the substation. An effective modification in the trip circuits of the relays protecting the main feeders of the closed loop is suggested to minimize the occurrence of this problem. The validity of the proposed circuits is checked against the specifications of the available equipment used in the network.
Index Terms-- Distribution networks, open-circuit faults, Fault identification, fault detection.
Charcoals Used as Electrode Material in Supercapacitors
B. Szubzda and R. Kulinski
In this paper we have been described biomimetical
structured charcoals based on acacia, sycamore, coconut and pine,
in which capacitance arises in consequence of separation of
charges in electrode/electrolyte interface (so-called electrical
double layer), due to it's biomimetical structure, are proven to
have high porosity and capacitance.
Influence of biomimetical structure on supercapacitive behaviour
has been tested by cyclic voltammetry, galvanostatic chargedischarge
and self-discharge tests.
Wavelets for detection of voltage dips and micro interruptions
Zbigniew Leonowicz
In electrical energy power network, disturbances can cause problems in electronic devices therefore their monitoring is fundamental in Power Quality field both to properly dimension protections and to calculate compensations in case of malfunction of the apparatus. In this paper we address the problem of disturbances estimation by using Wavelets signal processing for detection of short, impulse-like voltage dips and micro-interruptions.
Index Terms—Power Quality, Wavelets, voltage dips, micro interruptions..
Two Modified Methods for Harmonic and Flicker Measurement based on RWPC considering spectral leakage and edge effects
Marjan Saadati and Seyed Saeidollah Mortazavi
Harmonic is an important issue in electric power systems. A wavelet packet transform (WPT) method is introduced as a powerful tool for detectionHarmonics and Flicker. The proposed methodscan simultaneously measure the distribution of RMS quantities with respect to individual frequency bands directly from the wavelet transform coefficients. Uniform frequency bands result from the WPTdecomposition of power system waveforms can be used for identification of harmonic frequency bands. This paper presents twonovel modified methodsfor harmonic detection and measurement.However, use of wavelet packet coefficients has some errors such as the edge effects of wavelet filters and spectral leakage. In first method paper proposes to combine two adjacent frequency bands to reduce error caused by spectral leakage. In the recently methods they place frequency of main harmonics on the edge of the bands. It provides huge errors because of non-ideal characteristics of the filters. In second methodpaper proposes to change the band width ofoutput to 40 Hz. This causes that the main harmonics be in the band no on the edge. This method has got the chance to measure flicker also.Use of Wavelet Packet Coefficients for harmonic measurement because of Downsampling reduces number of sampling points and energy content of signal making huge error. This paper also offers the use of a compensation method by use of Reconstructed WPC to prevent energy reduction. In addition, it introduces a modification method to reduce edge effects and spectral leakage. Methodsaresimulated and experimented. Parameters are compared with true values that it shows satisfactory results. I.INT
Combustion Characteristics of Palm Wastes in Fluidized Bed Combustor
Rosyida Permatasari, Kang Kin Hui, and Mohammad Nazri Mohd. Ja'afar
Fluidized bed combustion (FBC) is one of the most
promising energy conversion options available today. The
emissions from FBC are very dependent on a number of
operating conditions (temperature, staged air, excess air, fuel
feed rate, etc.) and fuel properties. This paper described the
experimental results taken in a staged air fluidized bed
combustion scale laboratory, using palm shell and palm fiber as
fuels and silica sand as the inert bed material. The silica sand
was used for ensuring sustainable fuel ignition and combustion
in FBC. The variation of excess air and fuel feeding rate were
taken in these experiments. Gaseous emissions of CO
concentrations, combustion efficiency and temperature along
the combustor height as well as in flue gas were measured in the
experimental tests. The experimental results showed that the
axial temperature profiles decrease successively related along
the FBC height. The CO emission obtained results lower for
staged air condition than for un-staged air condition. And the
combustion efficiencies give satisfied value. The palm wastes
combustion give significant contribution for reduction of CO
emission from combustion process.
Dynamic Brake Regulator and Protection System in Locomotive
Farzad Takbiri and Siamak Farshad
In this paper, dynamic braking system of locomotive is simulated by ORCAD software. Locomotive dynamic braking is a system which is used to retard locomotive speed through the conversion of kinetic energy to electrical energy. This energy conversion is accomplished by connecting the traction motors as separately excited generators with field current being provided by the main generator. This system consists of two modules DR and DP. Excitation current to the motor fields is controlled by the braking lever position and by the dynamic braking regulator module DR. The dynamic brake protection module DP provides backup protection for the traction motor fields and the dynamic braking resistor grids in case a fault develops in the dynamic braking regulator module DR.
Signal Processing Techniques used in Power Quality Monitoring
Umar Naseem Khan
This paper gives a general review of different signal processing techniques which are widely used for the power quality monitoring. The majority of power quality problems can be characterized through measurements of voltage and current. To distinguish the type of disturbances, monitoring systems require the processing of signals, which concern the extraction of features and information from measured digital signals. In fact, the use of signal processing techniques can influence the way that voltage and current signals are measured and analyzed in power system field.
Evaluation of Chaotic Ferroresonance in Power Transformers Including Nonlinear Core Losses
Ataollah Abbasi, Mehrdad Rostami, Hamid Radmanesh, and Hamid Reza Abbasi
Abstract
This paper investigates the effect of nonlinear core on the
onset of chaotic ferroresonance and duration of transient
chaos in a power transformer. The transformer chosen for
investigation has a rating of 50 MVA, 635.1 kV, the data for
which is given by Dommel etal. (Tutorial Course on Digital
Simulation of Transients in Power Systems (Chapter 14),
IISc, Bangalore, 1983, pp. 17_/38). The magnetization
characteristic of the transformer is modeled by a singlevalue
two-term polynomial. The core loss is modeled by a
third order power series in voltage. With nonlinearities in
core loss included, two effects are clear: (i) onset of chaos
at larger values of open phase voltage, (ii) shorter duration
of transient chaos. It also shown that nonlinear core can cause
ferroresonance drop out.
Primary Energy Market and Electric Market interaction
Nuno Soares Domingues
A liberalised market is a market where customers can freely choose their supplier. This market model came with the introduction of competition into non-competitive regulated markets. In a non competitive environment, supply and prices are regulated, while in a liberalized market regulation aims at avoiding the abuse of market power. In the case of electricity, the starting point was the rigorous analysis of the sectors of the industry which were natural monopolies and the identification of the activities where the barriers to entry were such that no competition will develop naturally. It had been assumed in former market organization that the whole of the electricity industry was a natural monopoly which led to the acceptance of vertically integrated monopoly supply utilities. On a closer inspection it was found that only certain activities were natural monopolies, in particular the transmission and distribution networks. This discovery led reformers to search for mechanisms of introducing competition wherever this seemed possible. Bearing in mind the upcoming Iberian Electricity Market – MIBEL, we studied the sensitivity of the Market Clearing Price to changes in the production inputs, such as coal, natural gas and fuel.
Distributed Generation and Power Quality
Umar Naseem Khan
The main purpose of this paper is to discuss the basic understanding of power quality in relation to the distributed gen-eration. Due to considerable overlap between two technologies, disturbances affecting the power quality, which are mainly cause by the addition of Distributed Generation (DG) on the existing power system network. Injection of the DG into an electric power grid can affect the voltage quality. Distributed generation of dif-ferent voltage levels when connected to the power system network could influence the voltage regulation, sustained interruptions, harmonics, sags, swells, etc. All the information given here is col-lected from different references by keeping in mind the students at the beginning level of the concerned topic.
Using Ultracapacitors for Saving Energy in Regenerative Braking in Hybrid Vehicles
Amar Mohan Patil and Gregor Pawel Maliga
Abstract: An ultracapacitor bank control system for an Electric Vehicle has been
simulated. The purpose of this device is to allow higher accelerations and
decelerations of the vehicle with minimal loss of energy, and minimal degradation
of the main battery pack. The control of the system measures the battery voltage,
the battery state-of-charge, the car speed, the instantaneous currents in both the
terminals (load and ultracapacitor), and the actual voltage of the ultracapacitor.
This last indication allows knowing the amount of energy stored in the
ultracapacitor. When the car runs at high speeds, the control keeps the capacitor
discharged. If the car is not running, the capacitor bank remains charged at full
voltage. Medium speeds keep the ultracapacitors at medium voltages, to allow
future accelerations or decelerations. The battery voltage is an indication of the car
instantaneous situation. When the vehicle is accelerating, the battery voltage goes
down, which is an indication for the control to take energy from the ultracapacitor.
In the opposite situation (regenerative braking), the battery voltage goes up, and
then the control needs to store the kinetic energy of the vehicle inside the
ultracapacitor. The measurement of the currents in both sides allows keeping the
current levels inside maximum ratings. The battery state-of-charge is used to
change the voltage level of the ultracapacitor at particular values. If the battery is
fully charged, the voltage level of the capacitors is kept at lower levels than when
the battery is partially discharged.
Keywords: Hybrid vehicles, Ultracapacitor, Regenerative braking, energy
modelling, Battery pack.
Solar energy in Spain
Dariusz Szymanski
The article shows what kind of solar power plants
is used in Spain. It describes what technologies are used to build
this objects and how do they work.
Single Phase STATCOM-Its Control Algorthim
Linju Jose
In this paper, a new type of single phase static compensator (STATCOM) for low rating used in customer side is proposed. This new STATCOM is constructed by cascading a full-bridge (H Bridge) voltage-source inverter (VSI’s) to the point of common coupling (PCC.) A so-called sinusoidal pulse width modulation (SPWM) unipolar voltage switching scheme is applied to control the switching devices of each VSI. A new control strategy is adopted for compensating the harmonics and reactive current required by the load. The proposed STATCOM has the advantage of a fewer number of VSI’s, the VSI’s being identical and extremely fast in response to reactive power change and the control strategy adopted shows a good response.
Power quality in automatic restoration systems using stand alone generators
Piotr Danielski and Marcin Dębowski
The aim of this paper is to give an introduction to
automatic restoration of voltage techniques and technology. There
is also basic generator power quality test presented, with
specification of typical small power stand-by usage. All the tests
were taken with Fluke 345 PQ meter. Introduction concerns also
basic European Directives for power quality measurements and
requirements.
Ocean Power: tidal and wave energy
Dennis Grzelak, Nico Brose, and Lennardt Schünemann
The growing necessity of a sustainable energy
supply requires a great expansion of renewable
energy production. While developing and realizing
different concepts of energy usage like
photovoltaic, wind, geothermal or biomass energy,
another big potential energy source has got very
low attention – energy from tidal power. Tidal
power allows many ways of electricity production
and can be classified into two different main types:
Overvoltage Protection Devices
Cezary Pawel Szafron
This article states about overvoltage
protection methods, especially lightning overvoltages.
Different types of lightning protection devices are
presented and described, according to their
construction and application methods. The pressure
was put on protection in accordance with European standards.
High-voltage direct current technology
Tomasz Drobik
This article treat about HVDC (high-voltage direct current) technology. In history of energy transmission, crucial moment was “War of Currents” in XIX century . From conflict between supporters of AC and DC was winning Nikola Tesla. In effect, the most popular way to transmission energy are AC transmission lines. Despite many advantages of AC transmission, in some conditions better is DC transmission, which demand presence of high-voltage. The serious acceleration in development of this technology was 1954 when was built the first such system. Since those time, HVDC has developed very intensive, and will be very important technology in problem of transmission energy.
Transient response of doubly fed induction generator under voltage sag using an accurate model
Alireza Abbaszadeh, Saeed Lesan, and Vahid Mortezapour
In order to investigate the transient response of doubly fed induction generator (DFIG) under grid disturbances, an accurate model is required. In this paper transient response of DFIG during voltage sag considering saturation effect of leakage flux for different order models is simulated. Then, rotor over-current due to voltage sag and factors that affect it, is investigated.
Reverse electrodialysis for power generation
Sameer Deshmukh
Abstract:
The use of reverse electrodialysis, to derive energy from the difference between the chemical potentials of concentrated and dilute salt solutions is reviewed. The process employ the flows of brine and dilute solutions through alternating cells bounded by cation- and anion-exchange membranes in a stack placed between two electrodes to generate a voltage by the passage of salt through the membranes. Potential sources of brine include the salt domes of oil and gas wells, salt water lakes, and geothermal brines. This paper also reviews the ion exchange membranes in the application of RED.
Keywords: Power generation, Reverse electrodialysis, membranes for RED.
Microbial Fuel Cells to produce electricity
Sameer Deshmukh and Yogesh Khambia
Microbial fuel cell (MFC) provides a new opportunity for the sustainable production of energy in the form of direct electricity from biodegradable compounds present in the wastewater achieving the simultaneous water treatment. MFC is a device that converts chemical energy to electrical energy with the aid of the catalytic reaction of microorganism. This article provides a brief introduction to MFC along with its envisaged applications as one of the class of biological fuel cell.
Keywords: Microbial fuel cells, electricity.
Cable Shielding to Minimize Electromagnetic Interference
Anke Fröbel
A cable shield is necessary to prevent emission of electromagnetic waves from the cable respectively to protect data and signal conductors from external electromagnetic interference (EMI). The effectiveness of a cable shield installation depends on the kind of EMI to be shielded and the type of termination at both ends. This paper depicts the different types of cable shielding. Moreover shielding effectiveness is analyzed.
Fault Location System for Transmission Lines in One-terminal By using Impedance-Traveling Wave Assembled Algorithm
Sachin Ramrao Yerekar
Considering roundly reliability and accuracy of one terminal fault location system for transmission lines, an impedance-traveling wave assembled algorithm, which combines measurement impedance method with traveling wave method, is presented. At first, it uses measurement impedance method to calculate roughly fault distance. Then regions of reflected waves from fault point and opposite bus to detective bus are confirmed respectively through the distance. At last, exact time of reflected wave from fault point to detective bus and that of reflected wave from opposite bus to detective bus are identified respectively in corresponding regions, and fault location is implemented according to the result detected. It has complementarities of both methods, because measurement impedance method guarantees reliability and traveling wave method improves accuracy. Results of simulation are that located errors are within 100m if fault location based on traveling wave algorithm is available. It is improved that assembled algorithm proposed is correct.
Market behaviour to promote renewable energy
Nuno Soares Domingues
This paper presents results of a study concerning the generation strategic bids for a single hour.
In this study I incorporated the price and quantity bids.
I considered an elastic demand curve, approximated by an affine function, assuming that there is consumer’s reaction and that the market price and the demand are related. Also, I consider the competitors reaction using a parameter that represents the conjectural variation.
I studied the market behaviour assuming that the market price is represented by a normal probability function.
I studied and compared the market behaviour for two price markets types, the MCP (Market Clearing Pay) and PAB (Pay As Bid), in two situations: without incorporating the externalities and taking account with the emissions.
The future goes offshore…
Robert Hoyer, Henry Römer, and Jonathan Saudhof
Within the renewable energies wind parks are playing an important role. Since onshore wind energy market is already high developed and concerns are more about repowering, offshore wind plants have gained enormous popularity. In consideration of the high potential German government set the target to accommodate 15 percent of the energy demand with the help of offshore wind plants in 2030. Despite the high potential there are still risks and problems hindering the installation of huge offshore plants. In fact there is still no such wind park completely installed in Germany.
Index Terms—Economic potential, offshore, Renewable energy, wind energy
Strong Electromagnetic Impulse Generation
Daniel Pyda
Electromagnetic fields can have not only disturbing but also damaging influence on equipment. There are many ways to generate such electromagnetic field. In this paper some of electromagnetic field generators will be introduced and how dangerous such field is for today electric and electronic equipment.
Detection of Fault Position with Respect to the Compensating Bank in Series Compensated Line by Measurement of Phase Shift for Distance Relay Input Currents
Piotr Mazniewski and Jan Izykowski
In the paper, an analysis of possibility of detection of a fault position with respect to the compensating bank in a series compensating transmission line is investigated. Knowledge of the fault position, i.e. whether a fault has occurred in front of the compensating bank or behind it, is important for a distance relay protecting the series compensated line. In case of identifying that the fault is behind the bank, the fault loop impedance has to be calculated with compensation for the voltage drop across the compensating
bank. In turn, for faults occurring in front of the compensating bank, there is no need for eflecting the compensating bank and the fault loop impedance is calculated as in a distance relay designed for uncompensated lines.
The presented algorithm for detecting the fault position is based on determining the change of phase shift for the distance relay input currents. The phase shift is evaluated with fuzzy logic technique. The delivered algorithm has been tested and evaluated with the fault data obtained from
versatile ATP-EMTP simulations of faults in the test power network containing the 400 kV, 300 km transmission line, compensated at the rate of 70%. Different specifications of faults and prefault power flows have been considered in the study. The sample results of the evaluation are
reported and discussed.
Elimination of Chaotic Ferroresonance in Power Transformers Including Nonlinear Core Losses Applying of Neutral Resistance
Ataollah Abbasi, Mehrdad Rostami, Hamid Radmanesh, and Hamid Reza Abbasi
This paper studies the effect of neutral resistance on the onset of chaotic ferroresonance and chaotic transient in a power transformer including nonlinear core losses. It is expected that this resistance cause ferroresonance ‘dropout'. Time-domain study has been carried out to study this effect. Simulation has been done on a three phase power transformer rated 50 MVA, 635.1 kV with one open phase. The magnetization characteristic of the transformer is modeled by a single-value two-terms polynomial. The core loss is modeled by third order power series in terms of voltage includes nonlinearities in core model.The simulation results reveal that connecting the neutral resistance to the transformer, exhibits a great mitigating effect on voltage ferroresonance. Phase plane along with bifurcation diagrams are also derived. Having Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance voltages has been obtained and presented
Geothermal energy as a renewable energy source
Stefanie Kitscha, Jürgen Schmeckebier, and Marcel Steckel
The earth is a dynamic planet and can be described as a
gigantic thermal engine. The available heat is called
geothermal energy.1 Geothermal energy is a renewable energy
source just like wind, hydro or solar power. By using
geothermal energy, greenhouse gas emissions can be reduced
significantly. However, other than solar or wind power,
geothermal energy is neither dependent on climatic influences,
nor daytime or season and is available at almost any place and
time. Although as a renewable energy source geothermal
energy offers many advantages and is available at many
potential sites, it has so only a comparatively low proportion of
the total energy supply so far. As experts assume, geothermal
energy consists of approximately 30% residual heat caused by
the earth´s formation process about 5 billion years ago, when
gases, rocks and dust were condensed. In this process a huge
amount of energy was released. Temperatures of about 6000
°C are reached in the earth´s core.2
Slot harmonics in stator current as syptoms of reparation of induction motors
Jan Stanislaw Pytlarz and Paweł Ewert
Nowadays in many industry branches all over the world more than 90% of all installed motors are of induction motor type. During induction motor operation in electrical parts of stator and rotor circuits (windings) and in mechanical part of the motor and cooperating machine together with coupling elements there occur numerous failures. Every failure brings disturbances in technological process and in worst case leads to whole plant stoppage, what in consequence leads to rise of production costs. In this connection early failure detection on the electrical drives monitoring basis has a great weight. In the paper the attention will be focused on one of the mechanical failures – eccentricity, that is non-axial rotor to stator orientation. There will be presented theoretical considerations and examination results connected with this problem. On the basis of carried out theoretical and experimental considerations there will be made an assessment of stator current signal usability in induction motor operation diagnostics.
Model of a Wind Turbine with PMSG and Wind Park Configuration
Michal Piotr Jankow
Nowadays the number of dispersed generators (DG)
is growing rapidly. This change will greatly influence the power
system dynamics. A distribution network, where DG are
connected to the grid, cannot be considered as passive anymore.
So in future it will not be possible to use simple equivalents of
distribution networks for power system dynamic modeling as it
was before. In dynamic studies the whole power system cannot be
represented in a detailed manner because of huge system
dimensions. Therefore special techniques have to be applied for
aggregation and order-reduction of distribution networks with
DG. Future of power generation which is cleaner and more
efficient to meet the targets of the Kyoto protocol is a head of us.
Distributed energy resources systems are small-scale power
generation technologies used to provide an alternative to or an
enhancement of the traditional electric power system. Therefore,
distributed generation will play a vital part in the future of
electricity generation. However the connection of distributed
generation may pose several problems to local distribution
networks, therefore, analysis and tackling these problem areas
will be needed to address new challenges for a network design,
operation and modeling of a power system is required of utmost
importance. In this paper brief review of load and generation
models have been given.
Load Modeling For Power System Analysis
Jakub Kepka
This paper covers overview of the load models for
distribution systems. The basic concepts for static, dynamic
and combined models are introduced. The following discussion
shows importance of accurate system parameters modeling for
analysing power system stability. The accurate load
representation is not easy issue regarding to its changeable
nature and variety. Basic load classification is described.
Loads and Synchronous Generator Modeling
Robert Pliszczak
This paper survey of different accurate models of
load and synchronous generator model. I would like to described
one out of two basic types of load modeling. One is component-based
load modeling which contain ‘ZIP’ (polynomial) model,
exponential model, combination of this two called exponential-
‘ZIP’ model and ETMSP & EPRI model as an example of
combination of fundamental models. Second one is measurementbased
load modeling, however, this is not on my consideration.
The second part survey consists synchronous generator modeling
by electrical circuits. Moreover, there are dc generators, but this
model is not covered in this paper.
Renewable energy from the oceans – Wave power, tidal power and ocean streams
Lars Bork, Bastian Garnitz, Thomas Krisch, and Carsten Schwartze
When thinking about renewable energies, wind, solar and hydro energy typically come to mind.
To tackle climate change and all the challenges imposed by the need to find alternative and reliable energy sources, there is one major resource that has remained untapped until now: marine energy.
The potential of wave energy has been recognized for long, and mostly associated with a destructive nature. The following paper will give the reader a short overview about using wave and tidal energy as a renewable energy source.
Wave energy is a concentrated form of solar energy: the sun
produces temperature differences across the globe, causing winds that blow over the ocean surface. These cause ripples, which grow into swells. Such waves can then travel thousands of miles with virtually no loss of energy.
The total wave energy resource is as large as world electricity consumption, approximately 2 TW. About 10-25 % of this resource is economically usable. [1]
Tidal power occurs because gravities of the moon and sun combined with the rotation of the earth cause periodic changes of the oceans. These changes are called tidal range. The considerable level difference between high tide and ebb at many coasts of the earth generates an enormous energetic potential, which can be opened and used by the mankind.
Furthermore, it is possible to use the energy of ocean streams which are caused by the complex interactions between warm and cold layers of water.
The global theoretic potential of tidal energy is approximated at 3000 GW, but about 100 GW are realistically recoverable.
Carbon Capture and Storage – Part of the solution to the climate change problem?
Robin Kuscheck, Sören Schlüter, and Martin Noack
Focusing the state-of-the-art of renewable energy science and technology, you are forced to advance the established energy sources. Today, it’s not possible to substitute coal-burning power plants, nuclear power plants or gas-fired power plants for solar power stations or wind power stations.
The task is also to explore environmentally compatible technologies for reduce the carbon dioxide emission and uncouple it of the economic growth. The energy demand grows because of the emerging markets like China or India and their coal deposits. The Kyoto Protocol or the objectives of the European Union are confronted the countries with the problem of global warming resulting from the greenhouse gases.
FFT algorithm optimization using Stream SIMD Extension instruction set
Pawel Dawidowski
This paper explain how to perform Cooley and Tukey fast Fourier transform for sequence length being power of 2 using modern Stream SIMD Extension known as SSE. Basis of FFT algorithm will be shown pointing on which parts can be significantly speed up using SSE focusing on programming side rather than FFT algorithm itself. Also basic SSE instruction will be introduced.
Abuse of transmission congestion existing naturally or created by bidding strategies in order to exert market power
Abouzar Estebsari, Seyyed Mohammad Sadeghzadeh, and Mehrdad Rostami
Market power refers to conditions where the providers of a service can consistently charge prices above those that would be established by a competitive market. Market power assessment within electric power markets requires the consideration of the ever-changing network conditions that result from congestion. This paper explores the effect of changes in network congestion conditions on competitive market. Bidding strategies, such as withholding capacity and bidding at higher price, influence the network and cause transmission congestion. These strategic biddings are analyzed and the impacts of the congestion on the locational marginal price (LMP) are demonstrated in detail. Congestion will cause relative scarcity of generating capacities in the congested areas, so generation companies in these areas have locational market power. A 9-bus system is used to evaluate the impacts of congestion caused either by low transmission capacity or suppliers' strategic biddings. Focuses are on a transmission network with six sellers in which network constraints give rise to market power opportunities. Finally we compare two bidding strategies which exert market power by abuse of transmission limits and show enhance of locational market power in congested area.
"Banning of Incandescent Bulbs” and Its Influence to Electromagnetic Compatibility
Yan Lu
This paper presents worldwide “Banning of incandescent bulbs” campaign, which aims to replace traditional incandescent bulbs that have long been known as inefficient sources of electrical lighting, with compact fluorescent lamps (CFLs). Controversy, operations and comparisons between these two alternatives are introduced in succession. Electromagnetic compatibility (EMC) issues, such as light flicker, which emerge more apparently because of the coming popularization of CFLs, will be discussed. Additionally, precautionary senses and steps to limit adverse interferences are mentioned when installing lighting systems.
Reactive power in one-phase circuits with periodical voltages – reactive power compensation
Sebastian Słabosz
The article states about reactive power
compensation methods for circuits with non-sinusoidal voltages,
there have been presented selected theories application in order
to compensate the reactive power in one-phase circuits. Also
measurement results after compensation of an actual object
supplied from an non-sinusoidal voltage source were presented.
Also algorithms of optimal capacity selection were given, which
connected in parallel to the circuit with inductive character will
cause current root-mean-square value minimization.
Grid integration of renewable energy sources
P. Kammer and Andreas Kober
The growing lack of fossil fuels, the increasing demand for
electricity and the harmful effect of carbon dioxide output on
the climate force nations - especially industrialized countries
and their governments - to find new ways of producing the
amount of energy in demand. The integration of alternative
energies to reduce emissions and to conserve available fossil
sources is a known political aim. EU directive 2001/77/EC
requires feeding in renewable energies into electricity grids.
Although the potential of renewables is very high and the
technical conditions to produce electricity are achieved, the
current generated rates are clearly lower. A key problem is the
integration of renewable energies into the existing grid. This
paper analyzes the reasons for this deficit and assesses possible
solutions.
Solar potential of the Sahara Desert with an introduction to solar updraft power plants
Stefanie Fiedermann, Jadranka Halilovic, and Torsten Bogacz
Considering the rising energy demand, it is necessary to support new sources and possibilities for energy extraction. Renewable energies play a determining role. Amongst others, it is inescapable to regard geographic regions with extreme climatic circumstances. The desert Sahara has a huge potential of solar energy. Its dimension and climatic circumstances give cause to inspect those factors, which would permit solar power generation. An excellent way to use the premises is e.g. solar updraft power plants.
Index Terms— Sahara, updraft, Renewable energy, solar potential, wind
Power Quality in distribution power networks with photovoltaic energy sources
Ricardo Albarracin Sanchez and Hortensia Amaris
Solar radiation is characterized by short fluctuations
introduced by passing clouds. These solar fluctuations will
produce Voltage and power fluctuations at the PCC (Point of
common coupling). Flicker level should be evaluated by using a
flickermeter according to the standard IEC 61000-4-15. Models of
the solar fluctuation, photovoltaic modules and power converter
are shown in this paper and the flickermeter model is tested
according to the IEC requirements and the CIGRE/CIRED/UIE
test protocol.
Index Terms – Power quality, Flicker, PV.