Increased climate changes and environmental pollution cause a decrease of available quality water quantities and increase differences in precipitation amounts by seasons. The question is how to provide sufficient quantities of water to supply the population, agriculture, industry, and electricity generation. Sources of quality water are most often located in areas far from the centers of consumption, so it is necessary to construct large water management systems. In order to mitigate the variations in the available quantities of water during the year, reservoirs of significant, seasonal capacity must be built. The power system stability is additionally endangered by the growing impact of renewable sources with extremely variable electricity generation, which is manifested both on an intraday and seasonal level. Therefore, seasonal accumulations, with multi-purpose and even multiple use of the same amount of water, represent a winning option and a stronghold on which power supply, economic and social security and stability should be built. In the case of Serbia, apart from seasonal ones, there are also a spatial differences in the quantities and quality of water in the river basins. In the areas of Zapadna and Velika Morava, Šumadija, Kolubara and Belgrade, the required quantities of water for the supply exceed their own resources. On the other hand, the Drina basin is rich in water of significantly higher quality, and the possibilities of leveling the waters of river Lim are extremely limited. This paper reaffirms the old idea of building a multi-purpose hydro system „Lim-Zapadna Morava“, which would solve these problems. Beside those in power industry, other positive effects that would be achieved by the realization of this strategic project are also presented in this paper.

This paper presents and elaborates the proposal for reorganization of district heating sector in the Republic of Serbia, in order to increase its efficiency, as well as the proposal for the introduction of a self-sustaining incentives system for investments in infrastructure and thermal systems using renewable energy sources (RES). The goal is to reduce the use of non-renewable energy sources, in order to mitigate environmental pollution, as well as to decrease the share of electricity used for space heating. That way, also the electric power system (EPS) would be relaxed and the degree of primary energy utilization would be increased, by avoiding its conversion into electric and then back into thermal energy. As a comparative example of the applicability of the reorganization proposal, the paper presents experiences from the process of reorganization of the electricity sector in the Republic of Serbia. Within the presented proposal of the incentives system, descriptions of the methods necessary for the establishment of such a system are given, too. Acceptance and implementation of these proposals would contribute to increasing the participation of RES in district heating systems and result in achieving the aforementioned, positive effects of wider social impact and significance.

Modern approach to the modernization of the power generation capacities in the hydropower sector of PE Electric Power Industry of Serbia (EPS) is seen through intensive rehabilitations and building new hydropower plants (HPPs). Although these priorities are defined by long-term investment plan, there are also improvements that are seen through the optimization of the operational regimes of HPPs. EPS technical expert team, after several months of adjustment and investigation has prepared monthly reports with the operational parameters of the HPP. In this paper, as an example, investigated parameters and results for one particular aggregate of the HPP Iron Gate 1 (ser. Đerdap 1/ rom. Portile de Fier I) are presented. Generally, in the current phase of investigation, monthly report is prepared which includes selected parameters that are archived (such as headrace and tailrace water level, the aggregates’ power and discharge) and based on data from the hill charts, losses in pipeline, generator etc. output parameters are defined. Output parameters which are considered as important for the presentation are efficiency of the turbine, generator, hence aggregate, and losses in the operational regimes with the elevation lower than the maximum headrace level. Basic parameters of the aggregates, and generally HPPs’ operational regimes, are retrieved through SCADA system, averaged on minute time intervals, and presented for the one month period.

Kratak sadržaj: Verodostojnost modela nekog objekta ocenjuje se prema veličini odstupanja rezultata simulacije od rezultata ispitivanja sprovedenih na stvarnom objektu. Veličina odstupanja rezultata simulacije od rezultata ispitivanja, kao i prihvatljivost veličine odstupanja za određenu namenu modela, određuje se u postupku potvrde verodostojnosti, odnosno verifikacije. U ovom radu prikazani su rezultati ispitivanja, model i verifikacija modela jednog hidropostrojenja. Osnovu za verifikaciju čine rezultati ispitivanja kvaliteta rada hidroagregata R2 u RHE "Bajina Bašta" u primarnoj regulaciji učestanosti i snage razmene. Ključne reči: model turbine, turbinski regulator, primarna regulacija učestanosti UvodIspitivanje rada agregata u primarnoj regulaciji napona i učestanosti vrši se za potrebe JP Elektroprivrede Srbije (EPS) u okviru realizacije studije "Sistemski parametri regulatora pobude i turbinske regulacije u elektranama EPS-a". Studijom je predviđeno da se na određenim agregatima izvrše ispitivanja sistema pobude i sistema turbinske regulacije i da se na osnovu podataka iz dostupne tehničke dokumentacije i rezultata ispitivanja formira matematički, odnosno simulacioni model postrojenja koji bi kao takav bio uvršten u opštiji model elektroenergetskog sistema (EES) Srbije i njegove interkonekcije sa susednim elektroenergetskim sistemima. Korišćenjem 145

Kratak sadržaj: Kao posledica značaja primarne regulacije učestanosti, kao i raznovrsnosti realizacija sistema turbinske regulacije, njihovih mogućnosti, podešenja parametara, različitih uslova, načina i dužine eksploatacije opreme javila se potreba za prikupljanjem i sistematizacijom relevantnih podataka o učešću svakog proizvodnog agregata EPS-a u primarnoj regulaciji učestanosti. Sa tim ciljem pristupilo se eksperimentalnom određivanju stanja i podešenja sistema turbinske regulacije agregata. Predmet ovog rada su rezultati ispitivanja kvaliteta učešća jednog termoagregata u primarnoj regulaciji učestanosti elektroenergetskog sistema i rezultati merenja parametara sistema turbinske regulacije na osnovu kojih se izračunavaju parametri matematičkog modela turbinskog regulatora i agregata kao elementa elektroenergetskog sistema.Ključne reči: turbinski regulator, primarna regulacija učestanosti, statizam, parametri UvodU radu su prikazani rezultati ispitivanja kvaliteta rada agregata A5 u TE "Kolubara" u primarnoj regulaciji učestanosti u elektroenergetskom sistemu. Istovremeno je prikazan pregled rezultata ispitivanja koja su izvršena i na agregatima u drugim termoelektranama koje posluju u okviru Elektroprivrede Srbije (EPS). Ispitivanja su deo studije koja je sprovedena sa ciljem da se ostvari uvid u postojeće stanje sistema turbinske regulacije agregata i izvrši 75