KOMUNALNA ENERGETIKA / POWER ENGINERING 2016
KOMUNALNA ENERGETIKA 2016, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 00
KOMUNALNA ENERGETIKA 2016, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 0
KOMUNALNA ENERGETIKA 2016, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 000
LEVIČAR, D.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 1
OTOREPEC, R.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 2
MIHALIČ, R.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 3
OMAHEN, G.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 4
ŠTUMBERGER, G.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 5
ŠTOK, T.
PRICE REGULATION OF A DISTRICT HEATING
KOMUNALNA ENERGETIKA / POWER ENGINERING, 6
With the new Energy Act (from now on referred to as EA-1) the area of district heating and cooling and the area of the distribution of other energy gases from isolated distribution systems are treated within the regulatory framework. The heat price regulation is namely passed from the Price Control Act to the EA-1; price regulation for district heating must be done by a distributor carrying out a service of general economic interest and by regulated heat producer. Distribution of heat can be carried out as commercial distribution, or as an optional local service of general economic interest, depending on the number of connected household consumers, and with a view to satisfying the public needs.
KOKOT KRAJNC, M.
SLOVENIAN ENERGY EFFICIENCY OBLIGATION SCHEME
KOMUNALNA ENERGETIKA / POWER ENGINERING, 7
The Energy Agency has in the year 2016 started to monitor for the first time the reporting of the achieved energy savings, which are reached by the suppliers of electricity, gas, heat, solid and liquid fuels in the year 2015. With this, in Slovenia the monitoring of the energy efficiency obligation scheme of suppliers begins, which is carried out by the Energy Agency. The paper presents the characteristics of the energy efficiency obligation scheme in Slovenia by suppliers and the legal basis for this obligation system. In conclusion, we provide the first information on the activities of suppliers in increasing energy efficiency.
MEZGA, Z., ĆATIĆ, D.
CHP AS A POWER BACKUP FOR THE DISTRIBUTION MANAGEMENT CENTER AND AS AN EXAMPLE OF COST-EFFICIENT ENERGY MANAGEMENT AT THE OFFICE BUILDING OF ELEKTRO MARIBOR
KOMUNALNA ENERGETIKA / POWER ENGINERING, 8
The installation of combined heat and power (CHP) as a power backup for the users of Elektro Maribor’s Distribution Management Center (DMC) at the office building at Vetrinjska ulica 2 was the result of analyses of synergetic effects of two independent projects. The first project was the modernisation of the existing system of DMC uninterrupted power supply providing redundant backup power. The second project came about due to the requirements of an energy audit of the building. One of the priority investments was the renovation of the boiler room. Besides the replacement of the energy inefficient old boiler with a modern gas condensing boiler it was also proposed to install a small CHP gas unit.
By combining these projects after drawing up an investment programme, we decided to renovate the boiler room and to implement CHP as a permanent source of heat and also as backup power supply for DMC. CHP can operate in isolated operation mode in emergencies which provides a continuous electricity supply for DMC. This kind of CHP operation has many benefits: it is a unit for the production of electricity for DMC, the total electricity consumption at the production location is lower, heat production during the operation of CHP is constant and there is a guaranteed state grant for production sources. This CHP operating model represents a technically and technologically advanced process in the company which also provides financial savings.
ROŽMAN, M., GERMIČ, L., KOKALJ, F.
PLANNING NEW RES ENERGY FACILITY OF ENERGETIKA MARIBOR BASED ON HIGH EFFICIENT HEAT AND ELECTRICITY PRODUCTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 9
Advanced heat production center, based on high efficient heat production, which would consist of a set of production and combined heat and power systems (heat and electricity), will provide for the region's largest district heating system additional quota of heat generated from high-efficiency systems and renewable energy sources.
The purpose of the center is to provide an optimized - real time heat production from renewable energy sources and combined heat and power production in line with real and momentary heat consumption of the system.
Advanced center will include:
• high performance, low-emission biomass boiler – 5 MW,
• combined heat and power production system powered by natural gas – 2.3 MWe
• high temperature heat pumps for the utilization of low temperature energy flows – 0.84 MW and
• public learning center on biomass energy utilization and advanced energy systems for efficient use of energy.
POZZETTO, D., ALVAREZ SERRANO, Y. M., CEFALO, R., GRAZIOLI, A., TOMMASI, A.
COMPARATIVE ANALYSIS OF TECHNICAL, ECONOMICAL AND ENVIRONMENTAL FEASIBILITY OF COGENERATION PLANT USING WOOD BIOMASS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 10
After having identified, in a previous work [6], the possible sites for the location of a new cogeneration plant using wood biomass in the Mountain Community of Carnia, Friuli Venezia Giulia Region (Italy), the technical and economic feasibility and environmental sustainability of such a system has been carried out in order to evaluate the feasibility of the proposed solution.
In this paper are presented:
- the design of a cogeneration plant and the district heating network serving the thermal loads;
- the economic evaluation of the investment among the alternative;
- the environmental sustainability of the cogeneration plant and the district heating network compared to the conventional systems.
HEBAR, B.
SYSTEM FOR WASTE HEAT RECOVERY FROM COMPRESSORS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 11
In the group Talum heating of production and business premises and sanitary water is largely carried out by steam, bought from the company Silkem. Produced at our gas boiler, steam is conducted to individual heating stations throughout the facilities in the above-ground and underground steam lines. In the substations heat from steam is via the heat exchanger handed over to hot water, which then through the radiators, fan-heaters and floor heating emits its energy to the premises, and heats sanitary water in boilers. The condensate is in the vast majority returned back to the company Silkem.
HEBAR, B.
MODERNIZATION OF THE CENTRAL SYSTEM FOR PRODUCTION OF COMPRESSED AIR
KOMUNALNA ENERGETIKA / POWER ENGINERING, 12
In Talum, especially in electrolysis C as the largest consumer of this energy, compressed air is utmost importance. Supply interruptions longer than 10 minutes can already be fatal for the electrolysis process, so the production and supply of air is under the strict supervision of the managers. Another reason for the modernization of the system of compressed air production is the cost of electricity consumption for the compressors. The objective set for the project was next to update of key equipment also to reduce the specific energy used (kWh / Nm3) for 25%.
PAPLER, D.
REDISTRIBUTION OF SUPPLIERS' MARKET SHARES DUE TO THE DECREASE IN ENERGY PRICES AND AN INCREASE IN REGULATED NETWORK CHARGES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 13
Supply of electricity is a commercial activity. Supply and demand meet on the energy market. The liberalisation of the electricity market caused changes in supply, bringing about an initial increase in the number of competitors. The concentration of electricity sales to industrial and household customers fluctuated over the years, recording a downward trend. Market shares of individual suppliers changed and typically reduced, having been redistributed among several suppliers. The structure of the electricity market changed with a drop in market shares of suppliers from the group of distribution companies and a rise in market shares of new traders. The provider holds the role of energy supplier, freely agreeing with the customer on the quantity and price of energy supplied, whereas the other part of the bill is determined by the state by setting of network charges, contributions, excise duty and value added tax. We have analysed the trends in the final price of electricity charged to various consumer groups in the industry and households in Slovenia in the 2005–2015 period. We have presented the shares indicating the liberalised market part (energy price), the regulated infrastructural part (use-of-system charge) and the mandatory national duties on trading in electricity (duties, excise duty and value added tax). At average electricity prices applying to industrial customers in Slovenia, the share of energy price in the structure of elements dropped by 10.12 percentage points, the share of use-of-system charge increased by 2.23 percentage points and the share of total duties: contributions, excise duty and value added tax rose by 7.90 percentage points. At average electricity prices applying to household customers in Slovenia, the share of energy price in the structure of elements grew by 1.15 percentage points, the share of use-of-system charge decreased by 7.91 percentage points and the share of total duties: contributions, excise duty and value added tax rose by 6.75 percentage points. By regression analysis we established that the consumption by industrial customers is positively related to gross domestic product and substitute energy products, and negatively related to liberalisation of the electricity market. The household consumption is positively related to household income and negatively related to liberalisation of the electricity market.
PAPLER, D.
ENERGY EFFICENCY ACHIEVED BY SYSTEMATIC ENERGY MANAGEMENT MEASURES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 14
In the Gorenjske elektrarne company, using the concept of energy efficiency we have systematically monitored the consumption of energy by energy accounting, costs from the financial aspect and the CO2 emissions from the ecological aspect. With systematic approach using our own example we have presented an example of a municipal energetics. After the decline of profitable subsidies for solar power plants, the interest in terms of the energy efficiency concept was aroused by the construction of a 12.3 kWp solar power station with own internal connection based on PX3 type scheme and use of electricity to satisfy own needs, with generated savings in network charges and duties owing to own electricity production. Since 2005, efforts have been devoted to increasing energy efficiency by use of heat pump for heating during transitional period and since 2011 by switching from heating oil to natural gas for heating in the winter. The introduction of energy accounting, the optimisation of consumption of all energy products, the energy performance certificate and energy audit measures are aimed at a comprehensive supervision over the consumption and costs of energy products and the acquisition of the ISO 50001 quality certificate for energy management. We have calculated greenhouse gas emission savings of the energy efficiency development concept comprising own solar power plant and a heat pump. We have developed an energy control information system GEKenergija, which is based on monitoring the consumption of a specific energy product, the valuation of use and savings, both in terms of energy product and money. The results have proven the effects expected. Using the regression analysis we have explained the effect of external temperature on the consumption of heat energy.
KRMELJ, V.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
Ministrstvo za javno upravo, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 16
ZIETNEK, J.
E-Mobility in the City of Klagenfurt on Lake Wörthersee – CEMOBIL project
KOMUNALNA ENERGETIKA / POWER ENGINERING, 17
KONTIĆ, V.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 18
PETERŽINEK, M.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 19
Pošta Slovenije, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 21
MUJEZINOVIĆ, A., MARTINEZ, S., MUHAREMOVIĆ, A.
MATHEMATICAL MODEL FOR CATHODIC PROTECTION OF THE UNDERGROUND PIPELINES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 22
Cathodic protection is most often used technique for protection of underground or underwater metallic infrastructure from corrosion. Design of the cathodic protection system implies determination of the potential distribution on the protected object surface which meets given criterions. This paper presents a mathematical model for calculating cathodic protection system parameters. Presented mathematical model was used to conduct the analysis of the impact of soil resistivity and coating resistivity on the level of polarization.
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.
KITAK, P.
STEP VOLTAGE DETERMINING BY USING DIFFERENT PROGRAM TOOLS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 25
For the earth rod three processes of the potentials calculations on the ground surface are presented. On the base of potential difference the step voltage is determined. Theoretical calculation of potential distribution can be applied according some assumptions and simplifications. For complex earthing systems a software tool based on an analytical approach of solving the grounding systems can be used (e.g. WinIGS software tool). Third approach is based on a numerical process on finite elements method that enables more complex analysis of potential distribution on the surface and below the surface inhomogeneous earth. For this approach some measures will be shown which reduce the step voltage.
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.
SOTLAR, T.
SIMULATION OF THE REAL SHORT-CIRCUIT IN THE DISTRIBUTION NETWORK WITH MATLAB
KOMUNALNA ENERGETIKA / POWER ENGINERING, 27
The article deals with the simulation of the real short-circuit in the distribution network with Matlab. The purpose is to show how in simulation of the real short-circuit in software package Matlab determine model parameters. Assuming that we know all the parameters of network elements can in principle produce a model of the distribution network that is completely identical to the actual network. Nevertheless, we have in any real short circuit variables that need to be taken into account in the simulation. In conclusion, is by comparing the timings of effective short-circuit currents in single-phase, two-phase and three-phase short circuit, illustrate the correlation of simulation results and actual measurement.
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.
NOHÁČOVÁ, L., ŽÁK, F., KROPÁČEK, V.
CAPACITIVE EARTH-FAULT CURRENT IN DISTRIBUTION NETWORKS OPERATED WITH THE ISOLATED NEUTRAL POINT
KOMUNALNA ENERGETIKA / POWER ENGINERING, 29
This paper deals with the method of solution of capacitive earth-fault current in distribution. The value of phase earth capacity in the network can be determined using the voltage ratio in the network and the capacity value of the connected capacitor. The new indirect method of measurement and calculation of phase-earth capacity in networks with isolated neutral point is based on creation of short-term phase capacity asymmetry in the network. When expanded, the method can be also used for leakage current estimation. Furthermore, this method can be applied to periodic controls of the earth capacitive current value. For the evaluation of the phase earth capacity, a single-purpose automatic can be used and thus the whole process of measurement and evaluation is conducted with a defined period (at a given hour, day, month…) or on operator’s command.
SRPAK, D., PAJAN, D.
THE IMPACT OF MODULE SHADING AND AZIMUTH ON SOLAR POWER PLANT ELECTRICITY PRODUCTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 30
This article shortly describes the solar power plant built on the roof of Crnec municipality building and shows the difference between actual and designed production of electricity. As example, the selected solar power plant shows the impact of module shading on electricity production and the possibility of their reduction. Moreover, the difference in production is analyzed depending on the position of the module towards the Sun in different seasons.
SUKIČ, P., RODIČ, M., ŠTUMBERGER, G.
ADAPTING CAR CHARGING STATION TO PV PLANT OUTPUT POWER
KOMUNALNA ENERGETIKA / POWER ENGINERING, 31
The increasing number of PV systems increases also their influence on the electricity network in which they are connected. The PV systems operation has often a negative impact on the network voltage profile. Fluctuation of clouds causes a step decrease of a solar irradiation and subsequently leads to drastically changes in PV system’s output power in a very short period of time. In areas with a high concentration of PV systems it is to expect the drop of network voltage or even frequency. Problems related to step changes in output power of PV systems are usually solved by using energy storage devices, which are capable to compensate the output power changes.
Simultaneously with PV systems charging stations for electrical vehicle appeared in electricity networks. The most powerful chargers achieve a power up to 120 kW per installed unit and represent a heavy load in comparison to other loads connected to the network in vicinity. In case of a step reduction in PV system’s output power it is possible to lower the charging of electrical vehicles during the transient behaviour in order reduce the overall impact on the electricity network.
The paper presents simulation of the PV system disturbance compensation with the temporary decrease in charging power of vehicle connected to the charging station. The results presented show that the proposed compensation can improve voltage profile in the electricity network.
SREĆKOVIĆ, N., TRBUŠIČ, M., BELIČ, E., ŠTUMBERGER, G.
PROVIDING THE PROPER VOLTAGE PROFILES WITHIN THE MEDIUM VOLTAGE DISTRIBUTION NETWORK WITH PV SYSTEMS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 32
Proliferation of the distributed electric power generation (DG) units requires the evaluation of different effects that DG units may have on the electricity network operation. Photovoltaic (PV) systems that are properly placed and sized, as well as equipped with the suitable control systems, may have positive impact on the voltage profiles and the reduction of losses of electric energy within the network. This paper discusses the possibility of providing the proper voltage profiles within the medium voltage distribution network, using the optimal reactive power generation and/or optimal reduction of active power generation from PV systems. Time – discrete calculation of the network operating conditions throughout the year were performed on two existing medium voltage distribution networks. Optimal values of reactive power generation and the reduction of active power generation were determined using the differential evolution in time points, where voltage rise, higher than the allowed, occurred. The results obtained suggest that reactive power generation from the existing PV systems should be used in voltage control, followed by the reduction of active power generation when necessary.
BELIČ, E., VOH, J., SUKIČ, P., ŠTUMBERGER, G.
IMPACT OF PHOTOVOLTAIC SYSTEMS’ REACTIVE POWER GENERATION ON ACTIVE POWER GENERATION AND TRANSMISSION LOSSES IN
THE LOW VOLTAGE DISTRIBUTION NETWORK
KOMUNALNA ENERGETIKA / POWER ENGINERING, 33
This paper evaluates the impact of photovoltaic systems’ reactive power generation on active power generation and transmission losses in the low voltage distribution network. The introduced experimental system consists of two major parts. The photovoltaic system represents the first part, in which every photovoltaic module is connected to the low voltage network by the individual microinverter. Two way communication is established to each microinverter by the communication gateway. The second part consists of a control system with data acquisition system. The flexible experimental system offers a possibility to add and establish different network connections of the single-phase or three-phase smart grids. Within the scope of this work, additional cable was installed to establish one phase low voltage network with the photovoltaic system on one side and network on the other. The results of the analysis and measurements performed for operation of experimental low voltage network show that the reactive power generation in photovoltaic systems increases the amount of active power that can be generated in photovoltaic systems without to violate voltage profile. However, with both of these actions transmission losses in the low voltage network increase.
ŽMAVC, M., UNUK, B.
GROUNDS FOR INTRODUCING PERMANENT CONTROL IN
THE TRANSFORMER STATIONS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 34
Electricity consumers are becoming more aware of their rights regarding the quality of electricity. Distribution companies must take care of the uninterrupted supply of electricity, both in terms of ensuring the continuity of supplies and the compliance with the SIST EN 50150. New technologies, used by business users and by households, put distribution companies against new challenges and compel them to ensure the quality of electricity.
In Slovenia the standard EN 50160, which defines 13 parameters of quality of electricity, is used to ensure the quality of electricity and is described in the following paper.
KIRBIŠ, A.
HPP ZLATOLIČJE – SYNCHRONIZATION OF THE SYNCHRONOUS GENERATOR TO THE ELECTRICAL NETWORK
KOMUNALNA ENERGETIKA / POWER ENGINERING, 35
Introducing part of this article explain meaning and theoretical basis of the synchronization of the synchronous generator to the electrical grid. On the basis of theoretical introduction, the mathematical model of hydro power plant in Matlab/Simulink will be created. With the model the different switching conditions of synchronization on grid will be simulated and analyzed.