KOMUNALNA ENERGETIKA / POWER ENGINERING 2010
KOMUNALNA ENERGETIKA, _.
PROGRAMME 2010
KOMUNALNA ENERGETIKA / POWER ENGINERING, 0
Programme of the meeting
KOMUNALNA ENERGETIKA 2010, _.
KOMUNALNA ENERGETIKA / POWER ENGINERING, 000
KOPAČ, J.
RELIABLE ENERGY SUPPLY IN SLOVENIA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 1
KOSEC, M.
NEW MATERIALS IN POWER ENGINEERING AND NEW ELECTRIC ENERGY SOURCES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 2
MAVEC, T., KOŠNJEK, E.
IKT AND ACTIVE NETWORKS FOR ELECTRIC ENERGY DISTRIBUTION TODAY – AND TOMORROW?
KOMUNALNA ENERGETIKA / POWER ENGINERING, 3
LUGSCHITZ, H.
ENVIRONMENTAL IMPACT ASSESSMENT AND PUBLIC DISCUSSION FOR THE "380KV STEIERMARKLEITUNG KAINACHTAL - SÜDBURGENLAND" IN AUSTRIA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 4
HUDOKLIN, J.
PLACING ELECTRIC ENERGY TRANSMISSION AND ENVIRONMENTAL IMPACT
KOMUNALNA ENERGETIKA / POWER ENGINERING, 5
SENEGAČNIK, A., SEKAVČNIK, M.
REPOWERING OF WASTE HEAT USING ORC IN SLOVENIA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 6
The article deals with ORC (Organic Rankine Cycle) process. This is a working cycle for
conversion of low temperature heat into mechanical work. The working fluid is an organic
refrigerant. Due to specific properties of refrigerant also the ORC process has some
peculiarities. The article presents the ORC process, which will be applied in the Slovenian
industry providing a generator power of 120 kW. Some specific features of ORC processes
are addressed and the impact of implementation of heat exchangers is analysed. Analysis of
the impact of cooling water temperature on the operation of ORC process is also provided.
PIRC, A., SEKAVČNIK, M.
ANALYSIS OF ENERGY SUPPLY SYSTEMS DECENTRALIZATION IN URBAN AREA
KOMUNALNA ENERGETIKA / POWER ENGINERING, 7
In this paper analysis of energy supply systems decentralization was made. Energy supply
of real urban area with heat and electricity depends on energy efficiency, investment and
operational costs. At the beginning biogas plant, hot water and gas network planning are
presented. Analysis consist of three examples: firstly, biogas plant generates electricity and
distributes heat by hot water network; secondly, biogas plant distributes biogas to smaller
cogeneration units inside of urban area; finally, produced biogas is burned in internal
combustion engine and distributed to individual users boilers. On the basis of investment and
operating costs, the calculation of cost prices of heat and electricity was made at the end.
KOVAČ KRALJ, A.
ELECTRIC ENERGY PRODUCTION IN CHEMICAL PROCESSES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 8
Our main purpose is to use existing gases during chemical processes, in order to drive a
turbine. Processes, that operate under high pressures, followed the cleaning at low pressures,
can be exploited for electricity cogeneration. The high operating pressure at a reactor’s
outlet can be exploited to produce electricity using the open gas turbine system.
SENEGAČNIK, A.
FEASIBILITY STUDY OF A WOOD SYNGAS CO-FIRING IN ANNULAR SHAFT KILN FOR LIME BURNING
KOMUNALNA ENERGETIKA / POWER ENGINERING, 9
The article deals with the wood syngas as a partial supplementary fuel for lime burning in
the annular shaft kiln. Natural gas is a primary fuel. Wood chips are gasified with approved
technology in the counter current gasificator. As an oxidizer the mixture of air with recycled
flue gas with ~10 % oxygen is used. The moisture content in the wood chips dictates the
amount and calorific value of syngas. The simulation of syngas and natural gas cocombustion
in the lower combustion chambers shows that can be 20 % to 50 % of natural gas
supplemented with the wood syngas.
ANDREJAŠIČ, T., BRECL, K., NEMAC, F., TOPIČ, M.
BIVP – ENERGY POTENCIAL AND INTEGRATION OF SOLAR POWER PLANTS IN TOWN AREAS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 10
Given a high degree of solar irradiation in Slovenia, which is between 1150 and 1400 kWh/m2 on a horizontal plane, the potential for installing solar power plants is high in fragmented urban areas as sources of BIPV. The paper is based on the database of solar irradiation, depending on the location. Quantification of losses is presented due to the nonideal angle and orientation of photovoltaic generator and the effects of partial shading.
Furthermore the influence of reduction of natural convection in BIPV is presented as temperature raise and consequent decrease of annual energy yield. Finally, losses in the process of voltage conversion in the inverter and protection elements are presented.
SEME, S., ŠTUMBERGER, G., VORŠIČ, J., TOMAŽIČ, A.
MEASUREMENT OF THE U-I CHARACTERISTICS OF PHOTOVOLTAIC MODULES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 11
This paper deals with measurement of the U-I characteristics of photovoltaic modules. Measurements of the U-I characteristics of photovoltaic modules are defined in standards developed by the Technical Committee IEC TC 82. Unfortunately, we do not have equipment required to perform measurements of U-I characteristics of photovoltaic modules in accordance with the standard. Therefore, a comparative analysis of U-I characteristics measured on different modules under the same technical and weather conditions is performed. The results are given for the photovoltaic modules made of monocrystalline silicon, polycrystalline silicon and amorphous silicon.
TOROŠ, Z.
OPTIMAL AMOUNT OF INVESTMENT IN ORDER TO ARCHIVE MAXIMUM QUALITY WITHIN DISTRIBUTION POWER SYSTEM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 12
The present article deals with quality of electrical energy within distribution power system connected to the cost. Two objective functions were determined: for hybrid quality index Q and costs C. The proposed two criteria of optimization can be used to calculate the optimal amount of investment in order to archive maximum quality.
SENEGAČNIK, A., ZBAŠNIK SENEGAČNIK, M.
ENERGY EFFICIENT BUILDINGS ARE ALSO AN ENERGY STRATEGY
KOMUNALNA ENERGETIKA / POWER ENGINERING, 13
Passive house is an energy optimal building. It has very low energy demands for heating the building and sanitary water, with affordable expenses. In the paper a comparison of energy savings between buildings, built by Regulations about isolation and energy efficient use in buildings from 2002 and buildings, built by passive house standard. The calculations are based on new buildings built between 2003 and 2008. The same buildings, built by passive house standard would consume a lot less energy for heating, but electric energy consumption would increase a bit because of the heating pump usage.
SCHMAUTZER, E., PACK, S.
NEW WAYS TO INTEGRATE GROUNDING, EQUIPOTENTIAL BONDING, SHIELDING AND LIGHTNING PROTECTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 14
The safe and reliable operation of electronic equipment in modern low-voltage electrical, suitable for bidirectional energy and information flows, requires - starting from the transformer stations via the mains connection to the location of the equipment in the buildings - special attention with regard to the integration of grounding, equipotential bonding, shielding and lightning protection. As these themes so far in the planning, implementation and verification are considered mostly separately, in practice a variety of electro technical problems such as with stray currents, unwanted interference fields and inductive interference caused by low-frequency and transient currents result. In the following article new and old methods for a functional, comprehensive approach to planning and construction of electrical installations are combined, which takes into account the needs of various grid-bound supply systems such as electricity, gas, water and telecommunications.
SALKIĆ, H., SIKIRA, Z., SALKIĆ, Z., SOFTIĆ, A., BAČINOVIĆ, D.
ELIMINATION OF ELECTROMAGNETIC INTERFERENCE IN TRANSFORMER STATION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
The paper presents maximum values calculations of electric and magnetic fields intensity, emitted by TS 10(20)/0.4 kV, 3x1250 kVA, obtained in software package EFC-400 that allows the simulation in three-dimensional space. Calculations of effective values of the magnetic flow density (magnetic induction) and analysis of electromagnetic compatibility are obtained for height of 4.5 m above the ground surface, in the x-y plane, in parts of offices located above the substation, where the highest levels of the field intensity are expected, with a maximum current load at some equipment pieces. This load rarely appears in real operation, so the calculation results are on the side of safety. Substation is modelled without walls and other obstacles that significantly affects on the reduction of the electric field intensity. In this way, the results of the electric field intensity are largely on the side of safety, since an external wall of transformer stations damping down the same field on negligible values. These values can be verified by measuring on the substation location. The results are shown in diagrams that describes the 2D and 3D distribution of the magnetic flow density and electric field intensity, in the continuous distribution and using isolines. Recommendations for a new model of substation which realizes the reduction of electromagnetic interference are given.
DEŽELAK, K., KADIŠ, J., ŠTUMBERGER, G.
CALCULATION OF AUDIBLE NOISE EMISSIONS CAUSED BY HIGH VOLTAGE OVERHEAD POWER LINES
KOMUNALNA ENERGETIKA / POWER ENGINERING, 16
The paper deals with the calculation of audible noise emissions caused by high voltage overhead power lines due to corona. The first part describes the theoretical basis of corona occurrence and its consequences. Furthermore, the paper presents frequently used methods for the calculation of audible noise emissions caused by high voltage overhead power lines. Electric field strength values around conductor are essential for audible noise emissions and the occurrence of corona, therefore, the comparison of three methods for the calculation of electric field was performed. All of the methods were used for calculating the audible noise emissions caused by various overhead power lines.
ŠTERBENK, E., MAVEC, M., MLJAČ, L., DEBELJAK, B.
ENVIRONMENTAL IMPROVEMENT OF FLY ASH DEPOSITION IN THE ŠALEK VALLEY
KOMUNALNA ENERGETIKA / POWER ENGINERING, 17
The Šoštanj TPP (installed power of 809 MW) is the biggest thermal power plant in Slovenia. In the facility lignite coal from the Velenje Colliery is burned. Approximately 700 000 tonnes of fly ash results from electric power production every year. Fly ash is used for remediation of subsidence area damaged by coalmining. Fly ash was transported as slurry directly into the Lake Velenje up to 1982. After 1982 a dry landfill was constructed, while transport water still entered the lake. In 1994 the closed loop system for ash transport water was built and it has been operated since than. The previous high alkalinity of water from the Lake Velenje decreased in 3 years of operation of the closed loop system from pH over 12 to pH approximately 8. In 1995 the flue gas desulphurisation plants on unit 4 and in 2000 on the unit 5 were built. The product of desulphurisation is gypsum. Fly ash and gypsum have been mixed together as so-called stabilisat and transported to the subsidence area. The material is used for remediation of damaged area. Negative environmental impacts have been significantly reduced since the early nineties. The Šoštanj TPP management adopted an environmental improvement programme. The Velenje local community adopted a law, which required the Šoštanj TPP to reduce the degree of pollution from fly ash landfill. An ecological monitoring programme for solid waste disposal started in 1996 and has been performed on a regular yearly basis. It covers the most important pathways, so it comprises measurements of air, surface and underground water, water sediments, soil, and some vegetation. The results show very locally limited environmental impacts. The main impact has been observed in the surface water. In the early nineties of the 20th century the area used to be an ash dump. Over last two decades it has become a well-maintained site of remediation. The major part of site is grassed and partly used as a recreational area, although works are still in process.
POLAJŽER, B.
METHODS FOR VOLTAGE SAG SOURCE DETECTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 18
This paper describes and evaluates methods for voltage sag source detection. These methods are based on different criteria, i.e. disturbance energy, current change, and incremental impedance. Extensive simulation tests are performed, whereas the methods for voltage sag source detection are also tested through laboratory measurements, and field data. Based on the analysis of the obtained results, an evaluation of the discussed methods is performed. It is found that in the cases of symmetrical voltage sags, all methods give satisfactory results. However, in the cases of asymmetrical voltage sags, which are the most frequent ones, the effectiveness of almost all methods is insufficient. Furthermore, using positive-sequence components for voltages and currents, the effectiveness of all the discussed methods is considerably increased.
AIGNER, M., RAUNIG, C., SCHMAUTZER, E., FICKERT, L.
SMART GRIDS – CONSIDERATIONS REGARDING PROTECTION OF ELECTRICAL INSTALLATIONS AND SAFETY IN CASE OF DECENTRALIZED POWER SUPPLY
KOMUNALNA ENERGETIKA / POWER ENGINERING, 19
Parallel to the progress of information- and communication technology in recent years, energy production and energy distribution get more economic and efficient; so called Smart Grids get more attention. The focus of the Smart Grid infrastructure lies in the increased involvement of decentralized power generation, exemplarily photovoltaic plants, small hydro power generators or stirling engines in the low-voltage or medium-voltage network. Due to the increased integration of distributed (renewable) energy generation systems, a significant contribution concerning the reduction of CO2 emissions claimed in the 20-20-20 targets and transmission losses is provided.
An important advantage of Smart Grids is the possibility of a multivalent up to a fully independent power supply for islanded grids and microgrids. In case of a failing (separation from the distribution network) a certain degree of power can be principally maintained by decentralized feed-in. Short circuit currents from distribution transformers and additional short circuit currents from decentralized sources (bidirectional current flow) can lead to a incompatibility with existing protection systems.
Therefore the increased integration of decentralized generation requires new considerations regarding protection systems in terms of personal safety and safety of electrical equipment.
The neutral point treatment of decentralized sources, transformers and uninterrupted supply units in combination with distribution transformer is important for security of networks and personal safety.
This paper shows exemplary the effects of a missing neutral point to earth connection (earthing) of decentralized generators in case of parallel supply.
PEŠUT, D., KINDERMAN LONČAREVIĆ, A.
ENERGY PLANNING ON THE ISLANDS - CASE: ISLAND OF BRAČ
KOMUNALNA ENERGETIKA / POWER ENGINERING, 20
According to the modern perception local planning is one of the key prerequisite of well-balanced, quality and sustainable development, both in energy sector and other sectors. Energy planning at local level sets up a firm basis for decentralization and security of supply; helps achieve competitiveness, rational use of energy resources and environmental protection. Islands are particular natural resources in every country, so they require special attention and care even when defining future energy system development. The island of Brač presents specific case where crucial conditions for establishing sustainable energy development were created. Authorities, energy suppliers and others recognize importance of their involvement in creation of energy development plan of the island and its implementation in order to achieve balanced and optimizing supply from old and new conventional and renewable energy sources. Application of various integrated measures results with sophisticated energy planning methodology applicable not only on islands level but in local communities in general. The procedure for sustainable energy planning on the island of Brač is developed in the frame of the IEE EASY project – energy actions and systems for the Mediterranean local communities.
AŽBE, V., MIHALIČ, R.
A SOFTWARE TOOL FOR PRESENTING FACTS DEVICES IN AN ELECTRIC POWER SYSTEM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 21
The effects of Flexible AC Transmission System (FACTS) devices on an electric-power system (EPS) depend on many parameters. As a result, an easily understood and at the same time comprehensive explanation of these effects can be a difficult task. For this reason we have developed a computer program that can graphically represent the active and the reactive power and the phasors of the voltages and currents in a longitudinal EPS incorporating various FACTS devices. The design of the program makes it easy to change the parameters of the FACTS devices and the parameters of the EPS while the charts are simultaneously refreshed. The program is available, free of charge, on the web (http://lpee.fe.uni-lj.si/index.php?option=com_content&view=category&layout=blog&id=42&Itemid=29). To demonstrate the applicability of the program, a comparison between two similar—but when considering certain parameters, very different—FACTS devices has been performed. Using this program a user can gain a new insight into the effect of FACTS devices on an EPS, i.e., by changing the EPS's parameters and the parameter of a FACTS device, and by observing the changes in the power flow and the movement of the phasors of the voltages and currents. As the numerical results are also available "on-line", the program can be used as a simple control of plausibility of the results for other—more detailed— calculations.
POLAJŽER, B., PETRUN, M., PULKO, R., GRČAR, B.
TURN-TO-TURN SHORT CIRCUITS ON TRANSFORMERS AND PROTECTION
KOMUNALNA ENERGETIKA / POWER ENGINERING, 22
This paper describes turn-to-turn short circuits on single and three-phase transformers. Measurement results are given for the developing turn-to-turn fault on a laboratory transformer. The obtained results are in complete agreement with the findings from the literature. Furthermore, criterion for a turn-to-turn three-phase transformer protection is described, which is based on a negative-sequence component of differential currents. The preliminary testing results of the discussed turn-to-turn protection are promising.