The use of renewable energy sources increases the energy self-sustainability of cities, enabling citizens to reduce energy costs, which results in an increase in their standard of living. However, solar energy penetration in Bosnia and Herzegovina, and its capital Sarajevo, is not in line with the possibilities. Furthermore, the Sarajevo Canton is extremely polluted during the winter months because of the use of unacceptable heating fuel. The aim of this paper is to introduce photovoltaic power systems use in heating electrification system. In this paper AQI is calculated based on historical data and the hybrid model EMD-SARIMA for air pollution and a solar production forecast is presented. The methodology was tested in the Sarajevo Canton, taking into account 35,000 households. In order to ensure clean air, renewable electric energy use for household heating should be implemented. The widespread use of inefficient individual heating systems characterized by inefficient and expensive use of firewood and the use of coal in individual furnaces in populated areas are the main problems of internal and urban air pollution in Sarajevo Canton. In order to reduce energy poverty in Sarajevo Canton, the use of a floating photovoltaic power plant located on Lake Jablanica with a capacity of 30 MW and the solar prosumers with capacity of 115 MW to provide the 196 GWh necessary for heating electrification of 35,000 households is implemented in this paper. Finally, based on correlation between AQI forecast and solar production it was calculated that the values of the AQI, considering the application of solar energy during 150 days (five months) in one heating season, have significantly decreased. Also renewable energy sources have a very important role in reducing carbon dioxide (CO2) emissions into the atmosphere and reducing urban pollution. With this approach, households would be heated by renewable electricity, which would make Sarajevo a cleaner, smarter city.

Abstract This paper introduces and compares the various techniques for identification and analysis of low frequency oscillations in a power system. Inter-area electromechanical oscillations are the focus of this paper. After multiresolution decomposition of characteristic signals, physical characteristics of system oscillations in signal components are identified and presented using the Fourier transform, Prony’s method, Matrix Pencil Analysis Method, S-transform, Global Wavelet Spectrum and Hilbert Huang transform (Hilbert Marginal Spectrum) in time-frequency domain representation. The analyses were performed on real frequency signals obtained from FNET/GridEye system during the earthquake that triggered the shutdown of the North Anna Nuclear Generating Station in the east coast of the United States. In addition, according to the obtained results the proposed methods have proven to be reliable for identification of the model parameters of low-frequency oscillation in power systems. The relevant analyses are carried out in MATLAB coding environment.

In this paper impact of the tower arrangements on the mitigation of the increased values of the electric field intensity at high-voltage transmission line conductors was investigated. Several configurations of high-voltage towers (horizontal, delta, reverse delta, vertical and split-phase configurations) were analyzed. It assumed that the same height of the lowest phase conductors above the ground and the same value of the connected 400 kV voltage. The calculations were carried out for the values of the electric field intensity on the surface of the conductor and its immediate vicinity. A charge simulation method was used to calculate the electric field intensity on the surface of the stranded conductors and their immediate vicinity.

Ferroresonance is a nonlinear dynamic phenomenon that appears in the electric power system between a non-linear inductances and system capacities excited by a sinusoidal voltage source. The most common non-linear elements of the electric power system are the iron core inductances of power and measuring transformers, reactors, etc. in which saturation of non-linear elements can occur. As a consequence of ferroresonance there may be a significant increase in the voltage value and under the certain conditions an excessive increase of the current value across the transformer terminals. This phenomenon can lead to damage of the measuring transformers and other equipment used in the network. Ferroresonance is one of the most common low-frequency electromagnetic transient phenomena that appear in the isolated power networks. Therefore, special attention must be on analyzing the probability of ferroresonance occurrence in electric power systems. In this paper, ferroresonance measurement results will be given. The waveform of the phase to ground voltage and wave form of the open delta voltage is obtained. Also, the Fourier transformation is performed on these signals. Proposed

ABSTRACT The main purpose of the substations grounding systems is to ensure integrity of substations equipment and safety of personnel in and outside of substation at the maximum fault currents. To meet safety requirements, grounding system should have a low as possible resistance. In order to achieve low resistance, grounding systems are designed in a way to achieve as large as possible contact surface between the grounding system conductors and the surrounding soil. On the other hand, cost – efficiency of the proposed solution must be taken into account. Therefore, to meet the technical criteria on the one hand and economic criteria on the other hand, grounding systems are composed from large number of horizontal, vertical and inclined galvanic connected unisolated conductors that in most practical cases form complex geometries. Additionally, soil in which grounding systems are placed is almost always composed of a number of layers with different electric conductivity. In this paper, numerical model based on the indirect boundary element method is presented for calculation of grounding system parameters placed into the vertically layered soil.