Utjecaj vjetroelektrana na rad elektroenergetskog sustava – 1. dio: Pogon vjetroelektrana i kriteriji priključenja na mrežu

For the purpose of a comprehensive review of power system operation with the connection of wind power plants, this review is presented in two articles. The first article presents the main concepts of wind power plants, technical possibilities of wind power plant operation and all requested criteria for connecting the wind power plant to the power system. In the second article the power quality after connecting wind power plant to the distribution network, energy losses in distribution network with connected wind power plant and feasibility and development of electrical energy production with wind power plants in the power system of the Republic Croatia are considered.Zbog sveobuhvatnosti pregleda rada elektroenergetskog sustava s priključenim vjetroelektranama pregled se prikazuje u dva članka. U prvom članku prikazani su osnovni pojmovi o vjetroelektranama, tehničke mogućnosti pogona vjetroelektrana i svi zahtijevani kriteriji priključenja vjetroelektrane na elektroenergetski sustav. U drugom članku razmatra se kvaliteta električne energije nakon priključenja vjetroelektrane na distribucijsku mrežu, gubici energije u distribucijskoj mreži s priključenom vjetroelektranom, te mogućnost proizvodnje i razvoj proizvodnje električne energije s vjetroelektranama u elektroenergetskom sustavu Republike Hrvatske

Influence of Distributed Power Generation from Renewable Energy Sources on Reliability of Distribution Networks

The paper deals with the impact of renewable energy sources on reliability of distribution networks. It is determined through four case studies in which reliability indices are calculated. Island mode operation in the network is allowed with several assumptions. The authors assumed that the reliability of the system can be improved by islanded operation of distributed generation and showed an advantage of proposed islanding in relation to supply availability

Model of supply restoration of energy consumers by Markov state space models

Rad prikazuje utvrđivanje funkcije gustoće trajanja uspostave napajanja za primjenu Markovljevih modela prostora stanja. Istraživanje uspostave napajanja je provedeno u mreži pod nadležnošću hrvatskog Operatora prijenosnog sustava i Prijenosnog područja Osijek. Na temelju istraživanja procesa uspostave napajanja i utvrđenih parametara distribucije gustoće dan je prijedlog poboljšanog modela uspostave napajanja na sučelju između operatora prijenosa i distribucije. Primjenom ovog modela uspostave napajanja u analizi pouzdanosti značajno se doprinosi kvaliteti rezultata pokazatelja pouzdanosti napajanja korisnika električne energije.The paper presents the determination of a density function of supply restoration duration for the application of Markov state space models. The study of supply restoration was performed in Croatian transmission system operator and transmission area of Osijek. An improved model of the supply restoration at the interface between the transmission and distribution system operator networks is given, based on the research of the supply restoration process and the determined supply restoration distribution density parameters. The use of the proposed model in a reliability analysis significantly contributes to the quality of electricity supply reliability indicators results

The possibilities of increasing the energy efficiency in the city of Tuzla

U radu se analizira potrošnja svih oblika energije u gradu Tuzli kao i ukupna potrošnja energije. Prvi aspekt analize je veliki problem neracionalne potrošnje energije u gradu Tuzli. Zbog toga postoji hitna potreba smanjenja potrošnje svih oblika energije u gradu Tuzli. Ostali aspekti potrošnje svih oblika energije u gradu Tuzli su veliki energetski intenzitet, zagađenje okoliša, povećanje energetske efikasnosti novim investicijama kroz povoljne kreditne linije na temelju uštede energije.The paper analyzes the consumption of all forms of energy in the city of Tuzla as well as the total energy consumption. The first aspect of the analysis is a major problem of irrational consumption of energy in the city of Tuzla. There is an urgent need to reduce consumption of all forms of energy in the city of Tuzla in this way. Other aspects of all forms of energy consumption in the city of Tuzla are the huge energy intensity, environmental pollution, increasing the energy efficiency of new investments through affordable credit lines based on energy savings

Analysis of Transitional Occurrences of Low Voltage Welding Transformer

The purpose of this paper is to demonstrate and analyse transition events that occur when the loaded transformer is turned on and off within the welding device. The purpose of the welder is to provide a high quality and stable voltage during the ignition of the arc, and often during the ignition of the arc the transformer comes from its no-load state to the work-load state, depending on the diameter of the electrode that the arc melts. The welding currents of the MIG/MAG (Metal Inert/Active Gas) process are not less than 100 A, about 350 A, at a voltage of the arc of 35 V (DC). In this paper, the MATLAB/PSB programme package is used to analyse the no-load inrush currents and the loaded inrush currents of welding transformers. Current and voltage waveforms were recorded on the primary side of the transformer, as well as the harmonic content of the transformer primary currents, with indicator calculation of the current waveform distortion - THDi

System Control and Data Acquisition of University Photovoltaic Power Plant

The paper deals with design of System Control and Data Acquisition (SCADA) of Photovoltaic power plant FERIT 1, its configuration and connection with server unit for data archiving and removal approach by either android or PC devices. SCADA is developed according to ideas and need for scientific research of data generated by photovoltaic power plant built on the roof of the Faculty of Electrical Engineering, Computer Science and Information Technology Osijek in Osijek, Croatia. Designed system enables real-time analysis and of course subsequent time analyses based on storing data of high frequency measurement samples of photovoltaic (PV) power plant. The first part of the paper describes hardware components and system configuration and the second part deals with software background. Measurements of PV parameters and meteorological conditions are continuously performed, and these data are stored locally and instantaneously stored also on remote servers. Acquired measurement data is presented by graphics on developed web server platform. Developed SCADA presented in the paper is unique, adaptable open source which enables long-term performance of power plant and its components\u27 function

THE IMPACT OF THE LARGER NUMBER OF NON-LINEAR CONSUMERS ON THE QUALITY OF ELECTRICITY

Theoretically this paper will explain the formation of higher harmonic components in the electricity network, their causes, consequences on consumers and the ways of their elimination. Transformer role in the Dyg connection will be explained on the concrete example. For a specific example the waveform of primary (R) phase at 10 kV voltage level, the current of the secondary (r) phase and the neutral conductor at the 0.4 kV voltage level will be determined as shown in the concrete example in the work. Harmonic content will be determined up to 15 harmonics and the effective value of all these currents (phases R and r).  THD for current of primary (R) phase and secondary (r) fase will be calculated. In this paper, the dimensional three-phase filter is set to eliminate the maximum harmonic component of current of the primary (R) phase on the 10 kV side of the transformer. The waveform, the corresponding harmonic content for the current and THD of primary (R) phase will be determined. Additional measures have been proposed to reduce the THD. Another parallel filter has been realized to eliminate the second by size harmonic components of primary (R) phase current. It will also compare THD for primary (R) phase as in the previous cases. For the total duration of the simulation, the used time is Tstop = 0.1 sec. All of the above simulations will be realized in the MATLAB / PSB program package and simulation models will be displayed

Exploitation of the hydrokinetic potential of rivers by combining the traditional water wheel and the Darrieus turbine

Kinetička energija riječnih struja slabo je istražena za mogućnost proizvodnje električne energije. Zbog toga ima malo novih prijedloga za iskorištavanje tog oblika energije. Ovdje se prikazuje metoda iskorištavanja hidrokinetičke energije riječne struje koja je nastala kombinacijom tradicionalnog vodnog kola i Darrieus turbine. Vodno kolo koristi se zbog povijesno-turističkog značaja, a Darrieus turbina dodaje se zbog povećanja ukupne snage takvog postrojenja. S obzirom na male dimenzije mikro hidroelektrane tog tipa potrebno je precizno odrediti najpovoljnije lokacije. Za te lokacije najvažniji je podatak o brzini i dubini vodotoka jer snaga pri iskorištavanju hidrokinetičke energije ovisi o trećoj potenciji brzine, a dubina je bitna zbog toga jer se Darrieus turbina uranja u vodu. Stoga se model optimizacije lokacija radi na temelju podataka dobivenih mjerenjem hidroloških karakteristika vodotoka pomoću ADCP (Acoustic Doppler Current Profiler) uređaja.The kinetic energy of river currents is weakly researched for the possibility of production of electrical energy. Thus there are very few new suggestions for the exploitation of this energy form. This paper shows a method of exploiting the hydrokinetic energy of river currents created by combining the traditional water wheel and the Darrieus turbine. The water wheel is used due to its historic and traditional meaning and the Darrieus turbine is added due to the increase of the overall power of such a facility. Considering the small dimensions of a micro hydroenergy power plant of this type it is necessary to precisely determine the most favorable locations. For these locations the most important data are the speed and depth of the water flow because the power in using hydrokinetic energy depends upon the third exponent of speed, and depth is important because the Darrieus turbine is immersed in water. Thus, the model of optimizing locations is done based on the data received by measuring the hydrological characteristics of the watercourse using the ADCP (Acoustic Doppler Current Profiler) device

Positive and Negative Impacts of Renewable Energy Sources

In this paper, positive and negative impacts of renewable energy sources are presented. Impacts of solar power, biomass power, fuel cells, hydro power, wind power and geothermal power are described. Ecological, social and political impacts of different renewable energy sources are described. Impacts of power plants using different renewable energy sources on the power grid are also described

Stability Testing of a Small Biogas Plant in an Electric Power System

The aim of this paper is to test stability of a small biogas plant in an electric power system and the possibility of island mode as well. A short description of a biogas plant with two 1 MW generators is given in the introductory part. Furthermore, generator and regulator modeling as well as modeling of the surrounding electrical grid in software package PowerWorld Simulator are described. Operation simulations of this power system show that the system is stable in terms of short-period disturbances. Finally, the possibility of island mode operation of the biogas plant loaded with part of the surrounding electrical grid in the case of blackout is tested. It is shown that island mode is possible and reasonable in the case of longer blackout