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

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

Simplified Model for Optimal Sizing of the Off-Grid PV System Regarding Value of Loss of Load Probability

In this paper, a simplified model for optimal sizing of the off-grid PV system regarding value of loss of load probability is described. The model gives optimal size of system in terms of required number of PV modules, peak power, number of batteries and cost of system regarding the defined value of loss of load probability, load curve and period for which optimal size will be determined. The model is applied for determination of optimal size of the off-grid PV system for the city of Osijek. Based on measured load curve, optimal size of the system is determined for values of loss of load probability from 0.00 to 0.10 in steps of 0.01, and additionally for 0.15

Battery energy storage technologies overview

Battery technologies overview for energy storage applications in power systems is given. Lead-acid, lithium-ion, nickel-cadmium, nickel-metal hydride, sodium-sulfur and vanadium-redox flow batteries are overviewed. Description, graphical representation, advantages and disadvantages as well as technical characteristics are given for all technologies. Differences and similarities between different battery technologies are perceived. Battery technologies are considered with respect to peak shaving, load leveling, power reserve, integration of renewable energy, voltage and frequency regulation and uninterruptible power supply applications. According to technical characteristics for overviewed technologies, comparison between battery storage technologies is given through diagrams which are uniformed. Comparison is done according to specific power, specific energy, power density, energy density, power cost, energy cost, lifetime, lifetime cycles, cell voltage and battery technology efficiency

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

Stochastic modelling of pump-storage hydroelectric power plants, Part I

Ovaj članak u dva dijela predstavlja doprinos implementiranju stohastičkog modela crpno-akumulacijskih hidroelektrana u model pouzdanosti sustava elektrana. U prvom dijelu, nakon analize pogona ove vrste elektrana, dan je prikaz određivanja razdiobe vjerojatnosti varijabilne proizvodnje pri isključivom korištenju prirodnog dotoka u gornji bazen, razdiobe vjerojatnosti varijabilne proizvodnje iz crpno-akumulacijskog pogona, te razdiobe vjerojatnosti potrebne energije crpljenja postrojenja s prirodnim dotokom. Pri tome se dotok tretira kao slučajna varijabla, a stohastičko modeliranje oslanja se na poznatu metodu konstantne i varijabilne energije. Razvijeni model je pogodan za stvaranje pomoćnog kriterija odlučivanja pri izradi studija za planiranje izgradnje proizvodnih kapaciteta u elektroenergetskom sustavu. Prikazani stohastički model ilustriran je jednostavnim brojčanim primjerom.Two parts of this paper represent a contribution to the implementation of a pump-storage hydroelectric power plant stochastic model into a power plant system reliability model. After analysis of operation modes of such type of power plants, Part I gives an overview referring to the determination of the probability distribution of variable production when natural hydraulic inflow into the upper storage is exclusively used, the probability distribution of variable production from a pumped-storage drive, as well as the probability distribution of necessary energy of the plant with natural hydraulic inflow. The inflow is thereby treated as a random variable, and stochastic modeling relies on the well-known method of constant and variable energy production. The developed model is suitable for development of an additional determination criterion when it comes to making studies related to planning strategy of production capacities in the power system. The stochastic model presented in the paper is illustrated by a simple numerical example

Modelling of power system reliability assessment

Rad prikazuje način modeliranja podsustava elektroenergetskog sustava s aspekta prekida opskrbe električnom energijom korisnika prijenosne mreže. Rezultati analize pouzdanosti ukazuju na značajnu različitost rezultata ovisno o načinu modeliranja i razumijevanju ulaznih podataka. Kvalitetnu analizu je moguće provesti samo uz vrsno poznavanje promatranog sustava, organizacije i pravila. Za primjer proračuna analizirana je jednostavna trafostanica 110/x kV uzimajući u obzir standardni model i poboljšani model. U radu je dan pregled različitih Markovljevih modela jednostavne trafostanice te usporedba rezultata proračuna pouzdanosti i raspoloživosti. Prikazani poboljšani model bi trebao doprinijeti kvalitetnijim rezultatima analize pouzdanosti i raspoloživosti promatranog podsustava.The paper presents the way of modelling a subsystem of the power system from the power supply interruption consumer’s point. Results of reliability assessment indicate significant differences of results depending on the modelling and understanding of the input data. Valid reliability assessment can be performed only with excellent knowledge of the observed system, organization and rules. As an example of calculation, a simple transformer station 110/x kV analysis is performed, considering the standard and improved model. The paper gives an overview of the different Markov models for simple transformer station and comparison of the results of reliability and availability. The improved model presented should contribute to better reliability and availability assessment results of observed subsystems

Cost-benefit comparison of on-grid photovoltaic systems in Pannonian parts of Croatia and Serbia

Rad predstavlja detaljnu analizu potencijala sunčeve energije i analizu isplativosti instaliranja fotonaponskih sustava u Panonskim dijelovima Hrvatske i Srbije. Uspoređeni su tarifni sustavi za poticanje proizvodnje iz električne energije pomoću mrežnih fotonaponskih sustava i time rezultirajućom dobiti s jedne strane s trenutnim investicijskim i pretpostavljenim troškovima održavanja i pogona tijekom životnog vijeka s druge strane. PVGIS – PhotoVoltaic Geographical Information System korišten je za podatke o sunčevom zračenju i proračunu očekivane proizvodnje električne energije iz fotonaponskih sustava nazivne snage do 10 kW, 30 kW, 300 kW i preko 300 kW (prema različitim poticajnim tarifama u Hrvatskoj) Rezultati pokazuju značajne razlike u razvoju fotonaponskog tržišta u Hrvatskoj i Srbiji i potrebu daljnjeg poboljšanja sustava poticaja i legislative u Srbiji kako bi se instaliranje fotonaponskih sustava učinilo izvodivim.The paper presents detailed comparison of solar energy potentials and cost-benefit analysis of installing photovoltaic power systems in Pannonian parts of Croatia and Serbia. Feed-in tariff systems for incitement of the electricity production from on-grid photovoltaic power systems and the resulting benefits on one side and the current investment and the projected life-time operation and maintenance cost on the other side, have been compared. PVGIS – PhotoVoltaic Geographical Information System have been used for data on solar irradiation and calculation of expected electricity production from PV systems with rated power up to 10 kW, 30 kW, 300 kW and over 300 kW (according to the different feed-in tariffs in Croatia). The results indicate substantial differences in PV markets development in Croatia and Serbia and the necessity to improve feed-in tariffs and legislation in Serbia in order to make the installation of PV systems feasible

Stohastički model crpno-akumulacijskih hidrelektrana, II. dio

Two parts of this paper represent a contribution to implementation of a pump-storage hydroelectric power plant stochastic model into a power plant system reliability model. Part II provides the method for determining the probability distribution of required pumping capacity of a pump-storage plant with natural inflow, and then the insertion of pump-storage hydro plants into the reliability model of the entire electrical energy production system. The inflow is thereby treated as a random variable, and stochastic modelling relies on the well-known method of constant and variable energy production. The model developed is suitable to create an additional decision-making criterion for studies related to expansion planning strategy of generating capacities in power systems. The stochastic models presented in this paper are illustrated by simple numerical examples.Ovaj članak u dva dijela predstavlja doprinos implementiranju stohastičkog modela crpno-akumulacijskih hidroelektrana u model pouzdanosti sustava elektrana. U drugom dijelu dana je metoda određivanja razdiobe vjerojatnosti potrebne snage crpljenja crpno-akumulacijskog postrojenja s prirodnim dotokom, a zatim je prikazan način uvrštenja crpno-akumulacijskih hidroelektrana s prirodnim dotokom u model pouzdanosti cjelokupnog sustava elektrana. Pri tome se dotok tretira kao slučajna varijabla, a stohastičko modeliranje oslanja se na poznatu metodu konstantne i varijabilne energije. Razvijeni model je pogodan za stvaranje pomoćnog kriterija odlučivanja pri izradi studija za planiranje izgradnje proizvodnih kapaciteta u elektroenergetskom sustavu. Prikazani stohastički modeli ilustrirani su jednostavnim brojčanim primjerima

Providing Power Supply to Other Use Cases Integrated in the System of Public Lighting

Smart city is an attractive way of making the city more livable through intelligent solutions that are enabled by information and communication technology. Regarding the lighting system, it achieves the perfect balance between beautiful city ambience and preserving the darkness that makes cities more livable. As a smart city component, a public lighting system offers much more than light itself. Integration of other use cases has given a new dimension to the public lighting system in visual and functional terms. All those features that could be integrated into the public lighting infrastructure require additional power supply. This paper deals with possibilities of providing electricity to other power use cases integrated into the system of public lighting. Simulation results in DIALux showed that it is possible to save energy by a transition to LED lighting technology and establishment of a smart lighting management system using a dynamic operational profile proposed in the paper. By means of that, it is possible to reduce energy consumption in the public lighting system by at least 50 % up to 80 %, which could be enough for power use cases integrated into the public lighting infrastructure