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PIHLER, J.

KOMUNALNA ENERGETIKA / POWER ENGINERING, 0

SARAJLIĆ, M., KITAK, P., SARAJLIĆ, N., PIHLER, J.
Electric Field Strength of the Medium Voltage Post Insulator with Different Number of Ribs
KOMUNALNA ENERGETIKA / POWER ENGINERING, 239
The paper describes the designing of a medium voltage post insulator. The insulator model was designed in Matlab software and calculations of the electric field were in Elefant software. The emphasis is on the external shape of the insulator. The paper presents examples of the insulator with different number of ribs and their influence on the insulator’s electric field strength.

SARAJLIĆ, M., PIHLER, J., RIBIČ, J., KITAK, P.
APPLICATION OF MAYR MODEL IN THE SIMULATION OF ELECTRIC ARC
KOMUNALNA ENERGETIKA / POWER ENGINERING, 23
The paper describes application of Mayr model in the simulation of electric arc. The Mayr simulation model is a part of the MATLAB – SIMULINK, where the simulations of an open electric were performed. The experimental part was performed in the ICEM laboratory at the circuit breaker and switch disconnectors. A comparative analysis has been made of simulation calculations and laboratory measurements.

STOPAR, K., PIHLER, J., KITAK, P.
MEASUREMENT OF ARC FURNACE ELECTRICAL PARAMETERS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 24
Electric-arc furnace is one of the most importance pieces of equipment in the liquid steel production. An electric arc furnace enables a plant to melt scrap as fast as possible with the maximum energy input. An electrical energy input depends on the secondary current and secondary voltage of the furnace transformer tap, influencing the electric-arc burning stability. Electric arc furnace should be driven as efficiently as possible. Therefore, we want to measure electrical parameters during operation of the electric arc furnace to obtain information on its behavior. A measurement of arc furnace electrical parameters is the subject of this article.

VORŠIČ, Ž., PIHLER, J., MARUŠA, R.
HEATING OF CONDUCTORS IN STEADY STATE II
KOMUNALNA ENERGETIKA / POWER ENGINERING, 26
Factors such as voltage drop, power losses, stability, protection etc are important when selecting conductors cross-section in distribution and transmission networks. Important factor is also the rise of the temperature over the surrounding temperature: it is necessary to know the maximum continuous conductor current since it determines the maximum permissible temperature of conductor. The temperature of the conductor affects the conductor sag between the columns and determines the change in tensile strength due to warming. For short connection lines conductor temperature in emergency conditions is relevant for selection of the conductors cross-section.

TRBUŠIĆ, M., PIHLER, J., HAMLER, A.
MATHEMATICAL MODEL OF THE MARX GENERATOR WITH SURGE WAVE TAIL COMPENSATION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 28
This Paper presents a mathematical model of the Marx generator with surge wave tail compensation. Due to small inductance of low-voltage transformers windings, the tail of the impulse voltage decreases in such a manner that the impulse voltage shape no longer meets the IEC standards. In this case it is necessary to modify the Marx connection with the Glaninger circuit, which increases the time to half value.

SOMI, L., DEŽELAK, K., PIHLER, J.
ACCUMULATION SMALL HYDRO POWER PLANT ON THE EXISTENT LAKE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 8
An article presents an Accumulation small hydro power plant on existent lake. The project could be built on an already existing infrastructure, consisting of an embankment, a tower and a lake outflow. In the paper the potential of the river Ledava in the western part of Goričko with the placement of the hydro power plant is dealt. The choice of technical equipment, location and the planned operation regime, as well as the construction and investment cost of the project are presented in the work.

DEŽELAK, K., JAKL, F., MARUŠA, R., PIHLER, J., ŠTUMBERGER, G.
IMPACT OF NON-ELASTIC EXTENSION OF CONDUCTORS ON THE OVERHEAD POWER LINE CONDUCTOR SAGS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 14
Proposed paper deals with the problems regarding a non-elastic elongation of overhead conductors known as creep phenomena on account of mechanical yielding of material. Impact of non-elastic elongations of conductors is directly connected with the conductor sags and with smaller clearances between conductors and ground. Some results related to the researches in permanent elongations of conductors of the ACSR 490/65 type are presented, where compesation methods are applied as well.

VORŠIČ, Ž., KUMPERŠČAK, V., PIHLER, J.
HEATING OF CONDUCTORS IN STEADY STATE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
Several factors influence the choice of conductor cross-section when planning distribution and transmission networks, such as voltage drop, loss of power, stability, protection and others. Important factor is also conductor temperature rise above surrounding temperature. To determine it one must know maximum continuous current which determines maximum allowed conductor temperature. The temperature of the conductor affects the conductor sag between the pillars and determines the change in tensile strength due to heating. Conductor temperature is authoritative guide for selecting conductors for short connecting lines in extreme condition. Three temperatures are relevant: Joule heating depends on average conductor temperature and convection and radiation depends on conductors’ surface temperature. Change (decrease) of tensile strength is in first approximation dependent on temperature of strands in the middle of conductor. Article shows how individual influencing factors act on conductor by heating or cooling it in steady operation.

MARUŠA, R., VORŠIČ, J., PIHLER, J., KOBAL, I., MARUŠA, L.
SELECTION OF A SUITABLE CONDUCTOR FOR GROUNDING THE CABLE SHIELD TO THE TRANSMISSION LINE TOWER
KOMUNALNA ENERGETIKA / POWER ENGINERING, 16
This paper describes which factors to consider when faced with choosing conductor for grounding of surge arresters and high-voltage cables on powerline construction, where transition between powerline construction and powerline cable takes place. For proper grounding of surge arrester and shielded cable, the grounding cables have to be designed to ensure efficient high frequency current flow to the ground that can reach up to 10 kA. During our research and measurements we have chosen such a conductor that at the same time ensures recommended parameters and is not of any particular value to vandalism.

SOTLAR, T., PIHLER, J., ROŠER, M.
IMPACT OF THE GENERATOR TO SHORT-CIRCUIT CONDITIONS IN THE DISTRIBUTION NETWORK
KOMUNALNA ENERGETIKA / POWER ENGINERING, 27
The article deals with the analysis of the impact of the generator to short-circuit conditions in the distribution network. The aim is to determine the effect of synchronous generator on short-circuit currents, which are at the point of connection baseline data for the design and sizing of individual network elements. Short-circuit currents will be in point of short circuit determined using a DMS software tool that is developed for the analysis of the actual situation in the network and also enables the calculation of the parameters of all types of short circuits. Analysis of the impact of the generator to the short-circuit currents in the distribution network is carried out in point near the generator and point away from the generator by comparing the results with the generator on and off.

JAHIĆ, A., KONJIĆ, T., PIHLER, J.
DISTRIBUTION SYSTEM PLANNING USING GENETIC ALGORITHM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 6
Optimal configuration of a distribution system implies topology of the network with adequate conductor cross sections (power line sizes), and active and the reactive powers of source nodes which will simultaneously optimize several objective functions. At the same time all technical constraints must be satisfied like: voltage level limitations, radiality of the network, allowable continuous current limitations, as well as the limitations of the power delivered by the source nodes. The method of multi-objective optimization, as used in this work, is based on a Genetic algorithm and the Pareto principle of optimality. The obtained results verify the applicability of the proposed algorithm for a wide-range of distribution system planning problems.

BELAK, L., MARUŠA, R., FERLIČ, R., RIBIČ, J., PIHLER, J.
ANALYSIS OF THE SLEET CONSEQUENCES IN 2014 IN THE ELES TRANSMISSION SYSTEM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
Republic of Slovenia and part of the neighboring countries in the end of January and beginning of February cover weather storm snow, sleet and rain. LED is a natural weather phenomenon that occurs periodically in different parts of Slovenia, particularly in mountain bulkheads where they encounter different climates. LED 2014 hit large parts of Slovenia and the large amount of ice, which cling variety of items including paralyzed. Most damage is caused to forests, power, rail and road infrastructure. During this period, around 10% of Slovenia's population were been without electricity. In this article we summarize the weather situation, past experience and damage to the transmission network. At the end of the article we show an analysis of the transmission network for the period before and after the ice 2014.

KITAK, P., PIHLER, J., l GLOTIĆ, A., HORVAT, D., ŠPELIČ, D., ŽALIK, B., TIČAR, I.
APPROACHES TO SPATIAL VISUALIZATION OF OVERHEAD LINES ELECTROMAGNETIC FIELD
KOMUNALNA ENERGETIKA / POWER ENGINERING, 17
This paper deals with the art of voxel visualization technique of electromagnetic radiation on the high voltage transmission line. Results are useful for the electrical engineering society, in education, for environmental agencies and other non-experts. Paper covers three main subjects, i.e. the numerical analysis of electromagnetic field by the finite element method, classical electromagnetic field presentation in postprocessor of numerical program tool and visualization of the electromagnetic field with the volume ray casting technique. In the last representation, for each pixel of the displayed image a ray of sight is shot into voxel space and intersection is calculated. This method enables the representation of results independently of the numerical program tools.

VORŠIČ, Ž., PIHLER, J., KITAK, P.
ENVIRONMENTAL IMPACT OF SEMIINSULATED CONDUCTORS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 18
For overhead power lines, there are increasingly used compact conductors with carbon core. If such a conductor is »incomplete« isolated, we get covered conductorm which is mechanically stronger and what is even more important, it is spatially less wasteful. Furthermore, because of the isolation the electric field strength is lower near such a conductor. There is a design of a covered conductor given in this article, which we could install on the existing 220 kV columns and so increase the transmission capacity of the Slovenian electricity network. The integration of regular energy infrastructure is increasingly demanding, therefore we investigated the impact of such covered conductor for the highest voltage levels to the environment. We compared the analytical calculation of the electric field strength near the proposed covered conductor with the method of finite elements. The results were evaluated according to the regulation on electrictromagnetic radiation in the natural and living environment.

MARUŠA, R., VORŠIČ, J., PIHLER, J., FERLIČ, R., BELAK, L., RIBIČ, J., MARUŠA, L.
TESTING SLIDING GROUNDING CLAMP FOR EARTHING CONDUCTORS TO DOUBLE-CIRCUIT 110 KV TRANSMISSION LINE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 20
This paper presents the testing Sliding clamps for grounding conductor transmission line. For the purpose of an effective transmission line grounding in working with vicinity of high voltage a special form of sliding clamps for grounding has been designed. Grounding device is intended for grounding transmission line conductors, which are dragged along conductor installation on a double-circuit transmission line, the second system operates normally which represents a significant risk for single-phase ground fault . The device must provide such a connection during the sliding along the guide, so that it prevents the arc and effectively discharges ground current into the ground. Prior to regular usage, it was necessary for grounding the device to perform a series of tests, which are described in this article. A test with the realization of single-phase ground fault was also carried out on the transmission network of 110 kV ELES. All tests have been successful and positive.

TRBUŠIĆ, M., PIHLER, J.
PLANNING OF LABORATORY TESLA TRANSFORMER
KOMUNALNA ENERGETIKA / POWER ENGINERING, 21
Paper presents a calculation of the Tesla transformer, which was built in Powerlab at the Faculty of Electrical Engineering and Computer Science at the University of Maribor. The mathematical model is defined using differential equations and is solved by finding the eigenvalues and the corresponding eigenvectors in Matlab. Inductances and ground capacitance of the HV winding are obtained from the magnetostatic and electrostatic energies, respectively, and calculated using FEMM 4.2. The calculation method described represents the basis for the construction of the Tesla transformer.

MARUŠA, R., VORŠIČ, J., PIHLER, J., FERLIČ, R., BEČAN, M., ZAGORIČNIK, A., ULAGA, M.
CORONA AND RADIO-INTERFERENC PHENOMENON REDUCTION ON 220 KV BUSBAR IN PODLOG SUBSTATION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 9
The restoration and the occurrence of corona and radiointerference on the primary high-voltage equipment busbar 220 kV in substation 400/220/110 kV Podlog is presented in this paper. On the busbars 220 kV substation in Podlog was due to wear fully replaced jointing and insulation equipment, including elements of design electric field. After performing assembly work, measurements were taken corona and radiointerference. The results are showed poor results, it was necessary to approach the restoration status. To perform to the repair, were made laboratory measurements of partial discharges and radiointerference. On the basis of tests and comparative measurements have been developed and tested prototypes corona rings. Based on the measurement results, it was concluded that the remediation carried out by corona rings, which have been designed and a prototype was confirmed by measuring the conformity of the appropriate form of the electric field to be replaced suspension and insulation equipment busbar 220 kV substation Podlog.

RIBIČ, J., PIHLER, J., VORŠIČ, J., VORŠIČ, Ž.
MODELING TRANSFORMER IN ELECTRIC NETWORK CALCULATIONS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
Computer aided load flow calculations and short-cicuit analyses are well known and technically soficticated software for with solutions for planing and operating are available on market. Deficiency of such software is usually lack of possibility to significantly modify elements. Three windigs transformers are mainly presented as two windings tranmsformers and sometimes lack of data is the obsticle for calculations. Article presents results of the research on how including third windings influence load flow and short-circuit calculations.

DEŽELAK, K., PIHLER, J., FLUHER, B., ŠTUMBERGER, G.
COMPARISON OF SMALL HYDRO POWER PLANTS: HYDRO MATRIX TURBINE VS. MOVING HYDRO POWER PLANT
KOMUNALNA ENERGETIKA / POWER ENGINERING, 11
In proposed paper the comparison of two possible solutions for small hydro power plant construction is dealt. In that way the technical, as well as financial parts are observed. The first proposed solution is hydro power plant with the hydro matrix turbine, whilst the second solution is construction of so called moving hydro power plant. The choice of such solutions depends on particular water flow.

BELAK, L., MARUŠA, R., PIHLER, J., ZAGORIČNIK, A.
RECONSTRUCTION OF 220 KV BUS IN THE SUBSTATION 400/220/110 KV PODLOG
KOMUNALNA ENERGETIKA / POWER ENGINERING, 21
This Article describes the reconstruction of 220 kV bus (isolation and the corresponding material) in the substation 400/220/110 kV Podlog. The switching substation 220 kV has been in operation since the early seventies. Due to the long year operation and to the worn out equipment, the operations are no longer reliable. Because of this, the bus reconstruction was made in 2011. At that time, there was a primary objective that during the reconstruction the electro energetic system would be as less disturbed as possible. For this purpose, has been analyzed the operation of the 400 and 220 kV network during the reconstruction. The focus was on the implementation of the reconstruction to ensure the least disturbed electro energetic system and consequently the uninterrupted supply of electricity to consumers.

MARUŠA, R., VORŠIČ, J., PIHLER, J., ZUPAN, B., GRADNIK, T., BELAK, L., FERLIČ, R.
DETECTION OF COMBUSTIBLE GASES IN THE POWER TRANSFORMER
KOMUNALNA ENERGETIKA / POWER ENGINERING, 22
The paper presents an upgrade of existing gas (Buchholz) relay with a gas detection device, which is used for fault detection and protection of power transformers. The upgrade refers to a sensor for detection of combustible gases in (Buchholz) relay, which are formed during thermal and electrical defects in active parts of power transformer. In the first part paper focuses on describing mechanisms of production of combustible gases in oil, as well as intrusion of air bubbles into transformer tank due to leaking dilatation system. The second part provides description of the simulation setup for testing performance of the gas detection device in real-life conditions. The final section describes the sensor and automation of the transfer and processing of measurement data. It also presents useful practical advantages and opportunities that the upgrade brings for various transformer sizes as well as provides an estimate of installation costs and benefits through analysis of operational reliability increase of the upgraded transformer.

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.

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