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Abstract This paper considers the problem of centralized structural control of power systems in emergency states, when large generation/load disturbances provoke power mismatch in the system, causing a viability crisis. The proposed control strategy with the action on demand and/or generation is initiated by the fast detection and estimation of disturbance magnitudes, using a decentralized low-order observer, based on locally available frequency and tie-line power exchange measurements in control centres of all the areas operating in a large interconnected power system. The paper proposes a suitable control strategy for this type of emergency and presents a systematic procedure for decentralized observer design. Finally, it gives an illustrative example of the application of such a power mismatch estimator in a two-area interconnected power system.

The multi-threaded implementations of the power flow calculation procedures became more and more popular as they decreased calculation speeds. The multi-threaded power flow calculation with the integration of the control strategies of traditional and electronically coupled energy resources in asymmetrical states are the main subject of this paper and the main objectives are as follows: (i) to present the models of traditional and electronically coupled energy resources and to incorporate their control strategies into more accurate bus type classification, and develop the unbalanced power-flow calculation procedure, (ii) to identify which parts of the proposed algorithm could be implemented in the multi-threaded manner, (iii) based on the measured performance data, to further optimize the identified parts of the algorithm using subthreads, and (iv) to develop the multi-threaded power flow procedure for unbalanced large-scale weakly-meshed and meshed networks. These procedures were successfully tested on large-scale unbalanced weakly-meshed and meshed networks.

A new hybrid approach by integrating the support vector machine (SVM) with firefly algorithm (FFA) is proposed to estimate shape (k) and scale (c) parameters of the Weibull distribution function according to previously established analytical methods. The extracted data of two widely successful methods utilized to compute parameters k and c were used as learning and testing information for the SVM‐FFA method. The simulations were performed on both daily and monthly scales to draw further conclusions. The performance of SVM‐FFA method was compared against other existing techniques to demonstrate its efficiency and viability. The results conclusively indicate that SVM‐FFA method provides further precision in the predictions. Nevertheless, for daily estimations, the applicability of proposed method could not be feasible owing to high day‐by‐day fluctuations of parameters k, whereas the results of monthly estimation are completely appealing and precise. In summary, the SVM‐FFA is a highly viable and efficient technique to estimate wind speed distribution on monthly scale. It is expected that the proposed method would be profitable for wind researchers and experts to be used in many practical applications, such as evaluating the wind energy potential and making a proper decision to nominate the optimal wind turbines. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 867–875, 2016

Heating value is an important indicator for assessment of the coal quality. Machine learning models are powerful computational tools that allow for the analysis of various heat and mass transfer phenomena in energy systems. In this paper, Random forest model for determining the lower heating values of coal from the thermal power plant “Kolubara A” is developed based on proximate and ultimate fuel analysis. A database of the proximate and ultimate fuel analysis values and lower heating value of coal was created by experimental measurements in the accredited test laboratory of the Department of Thermal Engineering and Energy (“VINČA” Institute of Nuclear Sciences). The developed Random forest models, applied to a relatively small database, showed acceptable predictions for the lower heating value based on both the proximate analysis (RMSE = 0.22 MJ/kg and MAPE = 2.26%) and the ultimate analysis (RMSE = 0.64 MJ/kg and MAPE = 6.12%), with better accuracy achieved by the model whose input data consisted of the values of technical fuel analysis. Power Plants 2023 : Elektrane 2023; November 8-10, 2023, Zlatibor, Serbia

Two natural alkaloids, methyl (M) and isopropyl (I) N-methylanthranilates, with recently demonstrated significant pharmacological activities, were assayed for their possible overall effect on intact gastric mucosa and their protective properties towards the onset of gastric lesions induced by diclofenac (a non-steroidal anti-inflammatory drug, NSAID) or ethanol.The influence of I and M on gastric mucosa integrity was assessed by oral administration in doses of 200mg/kg. The gastroprotective action of I and M in doses of 50, 100 and 200mg/kg was analyzed in the diclofenac and ethanol-induced gastric lesion models in rats. After the treatment, the stomachs of the animals were analyzed (captured by a digital camera). Ulcer scoring, morphometric and histopathological analyses of the stomachs were done.The oral application of these compounds on their own, even in quite high doses (200mg/kg) did not induce gastric lesions. Both alkaloids exerted a very strong antiulcer activity, even in low doses (50mg/kg), by decreasing the number of lesions caused by the application of either diclofenac or ethanol, eliminating them completely or reducing them to a form of mucosal hyperemia.Their possible mechanism of action was discussed and due to their many positive properties including anxiolytic, antidepressant, antinociceptive, anti-inflammatory and gastroprotective activities, as well as a cheap and simple synthetic route for their preparation, methyl and isopropyl N-methylanthranilates, both alike, might represent a cost effective alternative sought for in the treatment of peptic ulcers and/or new safer NSAIDs for pain management.

SUMMARYAn approach to modelling of electrical and thermo‐physical properties in small cylindrical volumes of cable insulation, that is, insulation spot samples is presented in this paper. Apart from small leakage currents, high currents can flow through these spots under fault conditions, at the same time heating up and destroying the cable insulation in them as well. An introduction of models for electrical and thermo‐physical properties of the insulation to the nonlinear thermal finite element method (FEM) analysis of faults is demonstrated on the examples of short circuits that occurred in buried power cables. Nonlinearity of the thermal FEM model is based on the heat sources, electrical and thermo‐physical properties of polyvinyl‐chloride and cross‐linked polyethylene insulation as functions of temperature and/or time. According to the DIN VDE standards, the cable structures considered herein correspond to the NAYY 4×120 SM 0.6/1 kV and NA2XY 4×120 SM 0.6/1‐kV cables. The proposed models for insulation properties are applicable to the fault thermal FEM analysis of all multi‐core power cables laid in the soils, air or water. Copyright © 2011 John Wiley & Sons, Ltd.

Coal is the main energy source in Serbia. One of the problems associated with the production of energy from coal is the so-called “energy waste”, such as fly-ash and slag (bottomash), which are incombustible and unburt residue from combustion of coal. Fly-ash and slag are TENORM (Technically Enhanced Naturally Occurring Radioactive Material), and if they are released into the environment an increase and/or redistribution of natural radionuclide content can occur. To determine the potential impact of “energy waste” on the environment, samples of coal, fly-ash, and slag from thermal power plant “Nikola Tesla” and “Kolubara” were analyzed. The measured concentrations of natural radionuclides (uranium and thorium series and 40K) in samples of coal as well as in slag and fly-ash produced by combustion of coal are presented in this paper. Sealed samples were measured with a semiconductor HPGe spectrometer (37% relative efficiency) after the radioactive equilibrium was reached. Spectra were recorded and analyzed using software package GENIE 2K, with additional analysis performed by ANGES software. The obtained values of specific activity do not differ significantly compared to the values available in the literature. All the results were further statistically analyzed in order to determine the possible correlation. Ugalj predstavlja glavni izvor energije u Srbiji. Jedan od problema koji prati proizvodnju energije iz uglja je problem tzv. “energetskog otpada”, kao što su leteći pepeo i šljaka, koji predstavljaju nesagorivi i nesagoreli ostatak pri sagorevanju uglja. Leteći pepeo i šljaka predstavljaju TENORM (Technically Enhanced Naturally Occurring Radioactive Material), a u slučaju kada se odlažu u životnu sredinu mogu dovesti do uvećanja i/ili promene raspodele sadržaja prirodnih radionuklida. Da bi se odredio eventualni uticaj “energetskog otpada” na životnu sredinu analizirani su uzorci uglja, pepela i šljake iz termoelektrana “Nikola Tesla” i “Kolubara”. U radu su prikazani rezultati koncentracije prirodnih radionuklida (uranovog i torijumovog niza, kao i 40K) u uzorcima uglja, kao i šljake i pepela nastalih sagorevanjem uglja. Zatopljeni uzorci su mereni nakon uspostavljanja radioaktivne ravnoteže na poluprovodničkom HPGe spektrometru (37% relativne efikasnosti). Spektri uzoraka su snimljeni i analizirani pomoću programskog paketa GENIE 2K, uz dodatnu analizu korišćenjem programa ANGES. Dobijene vrednosti specifičnih aktivnosti ne odstupaju značajno u odnosu na vrednosti dostupne u literaturi. Svi dobijeni rezultati su dodatno statistički obrađeni u cilju određivanje mogućih korelacija. Power Plants 2014 : Elektrane 2014; Oktober 28-30, Zlatibor, 2014.

Unlike developing countries, advanced economies combine top-down and bottom-up approach for strategic planning and consider energy policy in the wider scope of spatial planning. In order to better align planning policies in different sectors, the authorities have transferred decision making from the central government to the local communities. This paper provides a brief overview of the London’s strategic spatial and energy policies, examining how they fit within more general visions and objectives. Past and future approaches to the spatial and energy planning were also analysed, with respect to the legal documents that supported actions of different government levels. This paper presents decentralised energy planning and supply in London, highlighting the significance of experience and lessons learned in the development of decentralised energy options for developing countries, willing to engage their resources to contribute to a low carbon economy in accordance with their financial and other possibilities.

The Republic of Serbia has a significant potential for the electricity production from solar energy, namely the floating photovoltaic (PV) systems, which are not exploited enough. Although there is a large interest in floating photovoltaic systems (FPVS) worldwide, studies related to the assessment of FPVS potential in this part of Europe have not been performed yet. This paper investigates, for the first time, the possibility of implementation of the FPVS on the six largest Serbian lakes and demonstrates the impact of geographical location on the energy output of the FPVS for the selected locations. The possibility of implementation is studied by simulating the energy output of FPVS using "PVGIS" tool. Energy production from the proposed FPVS, for selected locations, is discussed on a monthly and yearly basis. Installment of the FPVS on these water bodies can produce up to 8959 kWh of energy, while saves 164⋅10^6 m3/year of water from evaporation at the same time. In addition, the annual reduction of carbon dioxide emissions was analyzed and found to be up to 6.34 tons per year, which further implies with carbon credit potential of up to 9741 € in 20 years period. Drawn conclusions provides better understanding of FPVS and their applicability in the Republic of Serbia to ensure a sustainable, ecological friendly, secure and reliable supply of green energy, and further the used approach can be easily applied in other countries with similar geographical characteristics.