KOMUNALNA ENERGETIKA / POWER ENGINERING 2011
KOMUNALNA ENERGETIKA, _.
PROGRAMME 2011
KOMUNALNA ENERGETIKA / POWER ENGINERING, 0
Programme of the meeting
KOMUNALNA ENERGETIKA 2011, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 000
SENČAR, M., FURJAN, P.
ELECTRIC VEHICLE FOR EVERYDAY USE: SOME EARLY PHASE OBSTACLES AND RESTRICTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 1
In this article we discuss the economic use of electric car in private life and identify the problems that will obviously appear in the initial phase of economic use of electric car, for example, the problem of infrastructure and the billing the services like charging or switching of batteries. Nevertheless, the status of electricity as fuel and the legal barriers that appear in case of providing the service of charging batteries are discussed. Some answers to the questions which arise while proposing the solutions are presented. Furthermore, we try to identify the barriers in the present legislation and propose how to modify or amend it, so that it would be ready for introduction of economic use of electric car and encourage their use. The conditions that a person or an entity must meet to provide the service of charging batteries are discussed, furthermore the way the billing of charging should look like, and the aspect of excise duty and other taxes. Some proposals for researches in the non-technical areas are presented, such as energy pricing model for electricity used as fuel and development of pre-paid smart meters to simplify the charging of batteries in public places.
SEME, S., ORGULAN, A., VORŠIČ, J.
AN OVERVIEW OF THE TECHNOLOGIES AND DEVICES FOR ENERGY STORAGE SYSTEMS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 2
The growing need for energy on the one hand and the growing desire for integrating the units for production from renewable sources, on the other hand, inspired the development of energy storage systems. Electric energy production from renewable sources such as solar and wind, primarily depends on the current conditions and there is no possibility of the production in stock. Therefore, the abovementioned sources require the reserve in conventional sources or appropriate energy storage systems. An overview of the technologies and devices for energy storage systems that are most promising nowadays will be presented in this work.
DEŽELAK, K.
ANALYSIS OF HYDRO POWER PLANT BY THE HILL-CHART DIAGRAM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 3
In the paper the operational analysis of hydro power plant is represented. The turbine model, as one of the main part in hydro power plant, is obtained by the hill-chart diagram of the turbine. The whole model is built in program package Matlab/Simulink. The operational analysis of the hydro power plant is performed at the hill-chart basis regards on any flow and head, whilst the output parameters of model are turbine efficiency and power. The proposed model can be used as useful tool in the different operational regime estimation, even within the optimization algorithms.
SENEGAČNIK, A.
FEASIBILITY STUDY OF COMBINED FIRING IN ANNULAR SHAFT KILN FOR LIME BURNING
KOMUNALNA ENERGETIKA / POWER ENGINERING, 4
The article deals with combined firing of wood chips and natural gas in the annular shaft kiln for lime production. Wood chips are gasified separately in the autonomous gasifier. Hot syngas from the gasifier is mixed with natural gas in the existing combustion chamber and then burned completely. The moisture content in the wood chips dictates the amount and calorific value of syngas. The simulation of syngas and natural gas co-combustion in the lower combustion chambers shows that can be up to 50 % of natural gas supplemented with the wood syngas made from the fresh wood chips.
PLANTIĆ, Ž., ŠTUMBERGER, G.
ENERGY SAVING HIGH EFFICIENT FANS AND BLOWERS DRIVEN BY PERMANENT MAGNET SYNCHRONOUS MACHINE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 5
This paper deals with the energy saving high efficient fans and blowers driven by permanent magnet synchronous machine (PMSM). In order to improve the efficiency of fans and blower, the losses due to the non-optimal operation should be minimized. A proper control of the PMSM can help to reach this goal. The fans an blower often operate under operating conditions where operation without position sensor is desired. In such cases the rotor position required in the PMSM control can be determined using appropriate models and measured currents and voltages, which leads to the sensorless control realizations. Successful implementation of the sensorless control requires a very good knowledge of PMSM parameters. Some of the methods appropriate for their determination are discussed in this paper.
AL MANSOUR, F.
ENERGY EFFICIENCY IN AGRICULTURE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 6
Strategic objectives of the EU energy-climate policies are achieving 20 percent energy saving, 20-percent share of renewable energy sources (RES) in final energy consumption and reducing greenhouse gas emissions for at least 20% by 2020. The agricultural sector is important in order to increase the use of renewable energy from biomass. The adopted National Action Plan for Energy Efficiency in Slovenia for the period 2008 - 2016 does not address energy efficiency in the agriculture sector. The article analyses the users (technology and processes) in agriculture and the proposed appropriate measures to improve their energy efficiency. It is established that there is sufficient potential to reduce energy consumption in agriculture: in buildings, land cultivation, milk production, animal breeding, drying of hay and grain and other measures.
BELAK, L., JAKL, F.
INTRODUCTION OF CRITERIA FOR THE ASSESSMENT OF OVERHEAD LINES IN THE APPLICATION »CALPOS MAIN«
KOMUNALNA ENERGETIKA / POWER ENGINERING, 7
Calpos Main is a software tool for the realization of the RCM methodology (Reliability centered maintenance), that is a reliability centered maintenance. The maintenance of high-voltage equipment according to this methodology does not only monitor the status of the device, but also the power flow through a high-voltage network element. The higher the energy flow through the element and the lesser the network redundancy in a certain point, the more important is the element for the system. Therefore a reliability analysis is performed, which arranges all devices in I accordance with their importance for the system. To each device the RCM methodology thus allocates its value of importance as well as its value of technical condition. For the determination of the condition of a device the application Calpos Main is using a series of criteria, which have to be estimated. Each criterion has a certain weight. When all parameters of criteria are entered, the complete technical state of a device is reflected in a single assesment which is the so called index »c« (condition). The data is obtained from multiple sources: Maximo, diagnostics, CVZ (maintenance centers). Calpos Main now considers four types of devices: circuit breakers, disconnectors, measuring and power transformers. This paper provides a new introduction of criteria for evaluating the technical condition of "C" overhead lines owned by ELES.
BENEŠOVÁ, Z., HALLER, R. F., MÜHLBACHER, J.
ASPECTS OF INCREASING THE AMPACITY OF OVERHEAD LINES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 8
The forced trade activities within the European electrical grid as well as the increased number of connected large wind power equipments lead to a higher loading of existing UHV- overhead transmission lines (OHL). To increase the ampacity of existing OHL´s some possible methods were discussed. The dynamic load method could be very perspective, but for its implementation in a real transmission system a lot of investigations seem to be necessary.
DEŽELAK, K., OGOREVC, K., ŠTUMBERGER, G.
COMPARISON OF HYDROELECTRIC POWER PLANTS BOŠTANJ AND BLANCA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 9
This paper presents a comparison between two hydroelectric power plants (HEPP), HEPP Boštanj and HEPP Blanca. This comparison consists of two parts. The first part is based on the comparison of their dam structures with the mechanical and electric equipment installed, while the second part contains an economic analysis performed with the RETScreen software. The results of proposed analysis show the financial pointers of both hydroelectric plants.
VELEBA, J., NOHÁČOVÁ, L., KŘÍŽ, J.
ELECTRIC POWER SYSTEM OPERATION – STEADY–STATE VOLTAGE STABILITY
KOMUNALNA ENERGETIKA / POWER ENGINERING, 10
There are many software possibilities capable to solve demanding power engineering problems. Continuation load flow analysis is shown along with Author's developed computational software in Matlab environment for full-scale voltage stability analysis of larger power systems. Steady-state system stability is defined as the capability of the network to withstand a small disturbance (fault occurrence, small change of parameters, topology modification) without leaving its stable equilibrium point.
For comparison, alternative approach is further introduced for voltage stability solution using the non-commercial optimization tool. This paper deals with steady-state voltage stability problem as one of the main topics of interest in today's power system operation and control worldwide.
VORŠIČ, Ž., PIHLER, J., VORŠIČ, J.
ELECTRIC FIELD OF OVERHEAD LINE PUAC 2150/495/65 FOR 400KV
KOMUNALNA ENERGETIKA / POWER ENGINERING, 11
Covered conductors are not so vulnerable, because of the outer coat. This fact allows it to reduce the space between the phase conductors of covered conductor to only third of the space, which is the case by uninsulated conductors.
AŽBE, V., MIHALIČ, R.
CHARACTERISTICS OF DOUBLY-FED MOTOR-GENERATOR DURING THE FAULT
KOMUNALNA ENERGETIKA / POWER ENGINERING, 12
Doubly-fed motor-generator (DFMG) will be included in pumping-storage plants in Slovenia—one of them is already in operation— and they will become an important part of Slovenian electric-power system, so it is important to know the behavior of these machines. This paper presents the characteristics of a large doubly-fed motor-generator during and after the fault. During the fault—where DFMG operates as an asynchronous machine—the machine meets the saturation and in combination with the network-voltage reduction this largely affect the electrical torque of the machine. The difference between static and dynamic power-to-speed characteristic is presented with the application of trajectories of rotor speeds. Besides various resistances of crow-bar protection were considered. Results of simulations show that during a fault a crow-bar resistance has an important role—in order to increase the transient stability of DFMG, proper value of crow-bar resistance should be applied.
MORI, M., SEKAVČNIK, M.
EMPIRICAL MODEL FOR CONVECTIVE HEAT TRANSFER IN ROTATING AXIAL CASCADE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 13
This paper presents a method of combining numerical and experimental results and empirical model for convective heat transfer in rotating axial cascade. The method is a combination of infrared thermography and numerical simulations and is useful in rotating environments, which are highly problematic to implement any measurement. The method represents a considerable simplification of the acquisition of the distribution of Nusselt numbers at the observed surface and allows the study of convective heat transfer. The observed surface temperature is measured by infrared thermography. Experimentally obtained temperature distributions are evaluated by numerical obtained by using statistical method. To calculate the Nu number is further used numerically calculated heat flux and measured temperature distribution for the known geometry of the axial cascade. The results are presented as a 2D distribution of Nu numbers for different flow conditions (Re) and at different rotational speeds (Ro). The empirical model is derived, which gives the dependence of Nu number distribution from the influence of rotation (Ro) and flow conditions (Re).
MUHAREMOVIĆ, A., TURKOVIĆ, I., MUHAREMOVIĆ, A., TASAKOVIĆ, S., MUJEZINOVIĆ, A.
CALCULATION METHODS OF CATHODIC PROTECTION SYSTEM PARAMETERS WITH VERTICAL ANODIE ZINC STRINGS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 14
In this paper we analyze protection potential/current distribution for cathodic protection systems (CP systems) with vertical galvanic anode strings. Analytical calculation in case of so called primary current distribution is shown in this paper. In this case, the potential on electrodes, which is the boundary condition, is constant and we only consider the effects of electrical field. Also, the numerical calculation of so called secondary distribution of current and potential is described in the paper. In this case, the boundary conditions on electrodes are nonlinear and alongside the effects of electric field, we must consider the kinetic effects on electrodes. The calculation of current/potential distribution in CP system with galvanic anodes is based on defining the mathematical model of solving Poisson or Laplace equation. Solving of second term partial differential equation in soil and its boundaries requires the precise defining of boundary conditions on anode and cathode surface. Boundary conditions on electrode surfaces represent the functional relationships between current and potential. After the installation of cathodic protection system and multiple year measurement on the given object, the results of numerical calculations of cathodic protection parameters on a concrete object are compared with the measured values. Numerical and measured values correspond to each other.
SENEGAČNIK, A., GLAVINA, U., SEKAVČNIK, M.
ORC – ORGANIC RANKINE CYCLE ALSO IN SLOVENIA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
The article deals with ORC (Organic Rankine Cycle) process. This is a thermodynamic power cycle for conversion low temperature heat into mechanical work. The working media is an organic refrigerant. Operating parameters are lower than in water cycle. Due to specific properties of refrigerant also the ORC process has some peculiarities. The article presents the ORC process, which is applied in the Slovenian industry. Generator power is 125 kW, working media is HFC245 fa (R245 fa). Some specific features and operating experience of ORC processes are addressed in this article.
DEŽELAK, K., DEŽELAK, D., ŠTUMBERGER, G., JAKL, F.
CALCULATION OF THE TEMPERATURE OF THE OVERHEAD POWER LINE CONDUCTOR
KOMUNALNA ENERGETIKA / POWER ENGINERING, 16
Temperature of the overhead power line conductor during operation represents one of the basic limit parameter for overhead power line operating. The allowed conductor heating must be under the limit values, because of high impact to the mechanical parameters of the conductors and conductor sagging. In the paper, all of the results are obtained with the CIGRE method, while obtained results are shown in program package Matlab.
DŽANANOVIĆ, I., MALKOČEVIĆ, D., SARAJLIĆ, N.
EXPERIENCE OF AUTOMATED METER READING SYSTEM BASED ON ECHELON METERS - PILOT PROJECT IMPLEMENTED IN JP ELEKTROPRIVREDA BIH, ELEKTRODISTRIBUCIJA TUZLA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 17
In order to achieve energy efficiency and lower their costs essential for economic operation at liberalized energy market, there is a rising need for power distribution companies to implement automated meter reading/management (AMR/AMM) system. This paper presents experiences from Pilot project of AMR system implementation based on Echelon meters. As many AMM systems are based on PLC technology – JP Elektroprivreda BiH has also recently implemented several projects with PLC, but the specific significance of the subject project is that GPRS is used as communication channel between data concentrator and AMM center.
LUKAČ, N., ŽLAUS, D., TRSTENJAK, N., ŽALIK, B.
ESTIMATION OF OBJECTS SOLAR POTENTIAL USING LIDAR DATA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 18
Solar energy is an attractive resource to gain electrical energy. Although this resource is renewable and available every day, the maximum amount of incoming energy depends on various factors. In this paper, a method to calculate solar potential of the buildings roofs, for a given location and time frame is given. The proposed method considers position and orientation of Earth in respect to the Sun, inclination of objects and surfaces using detailed topography obtained from LiDAR, influence from shadowing and meteorological effects. The maximum solar energy is adjusted according to the shadowing and meteorological influence. In this way, proposed method gives a better approximation of the real world solar energy potential.
RUDEŽ, U., MIHALIČ, R.
POSSIBILITIES FOR UPDATING UNDERFREQUENCY LOAD SHEDDING PROTECTION IN THE SLOVENIAN POWER SYSTEM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 19
In recent decades, the advantages of a fast development in the communication and computer technology have been successfully harvested in the majority of technological areas for updating various mechanisms and processes. Power system control and protection is no exception. However, in certain other countries actual implementation of modern technologies into power system control and protection mechanisms takes less time compared to Slovenia. In case of a sudden major generation unit outage severe underfrequency conditions appear in the power system and only a centralized gathering of measurements and global actions (e.g. use of WAMS and GPS technology) can represent an appropriate approach to a global problem. In such circumstances, underfrequency load shedding is in many times the last resort tool for avoiding a total power system blackout. Consequently, its appropriate actions are of great importance both from technological and economical point of view. As a current status of an underfrequency load shedding protection in the Slovenian power system is still on the traditional level, in this paper authors summarize some of known developed mechanisms, among which some of them might be considered as an actual possibility for an upgrade of current underfrequency scheme in the Slovenian power system to an adaptive level.
ŠTRICELJ, A.
HYDROPOWER PLANTS ON LOWER SAVA RIVER – SYSTEM FOR DETECTING NAVIGATION AND DRIFT-WOOD BASED ON COLOR SPACE ELIMINATION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 20
This article presents a method of detecting objects on water surface using color elimination based on image eroding with morphological variable. Term color area represents a complex enlistment of color spectra distinctive for a specific observed area. System of detecting object on water surface presents initiation of different methods of processing image on water surface and is so adapted to colorful water spectrum.
The method of recognition which is introduced in this article, initiates phases of image pre-processing, determining color area, suitable for this kind of system and defining color deviation with Euclidean distance. It also initiates procedure of eroding on the image.
Plan of that kind of system enables robust and efficient detection of objects on water surface and gives as comparable results with systems that base above all on optimization of image contrast and edge detection.
ŠKRLEC, J.
NEW MATERIALS IN POWER ENGINEERING AND NEW SMALL POWER ENERGY SOURCES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 21
VORŠIČ, J., VOH, J.
POWER SYSTEMS PROBABILITY CALCULATIONS SOFTWARE DEVELOPMENT
KOMUNALNA ENERGETIKA / POWER ENGINERING, 22
Method for planning and operation of power system which considers changes of operational conditions is described in this work. Input parameters - node loads in the load flow probability calculation are passed as probability function resulting from former operation careful analysis.
Based on described method calculation software has been developed. Node voltages, load flows, element currents and losses are calculated from node loads random vector considering connectedness among working and reactive power of same and adjoining nodes. Results (node voltages, load flows, currents and losses) are shown with expected value (arithmetical mean value) and mean square deviation in tabulated form. At the same time elements (lines, transformers) load control according to the natural (lines) and thermic power has been performed. Load flow histograms are real value of this method.