Infrastructure of a distribution systems is facing major challenges with deregulated power system. Reactive power compensation can reduce energy losses in system, improve voltage profile and release feeder capacity. Installation of capacitors in distribution network is ensuring more efficient systems, but also provides economic benefit to utility and users. Vital task for capacitor implementation is to determine the best locations and size of capacitors. Hence, capacitor placement has an important role in distribution system planning. In this paper, using the professional software tool DigSILENT Power Factory, optimal capacitor placement is analysed in real low voltage distribution network. Results and analysis show that by optimal capacitor placement annual losses and adequate size for installed capacitors can be calculated. The capacitor placement problem consists of objective function which is composed of power losses and capacitor installation costs subject to bus voltage constraints. Optimization placement calculation is compared to installation of four capacitors in given case study distribution grid. Simulation results show that with appropriate software techniques optimal capacitor placement can be achieved in distribution grid.

The paper analyzes the problem of the construction of utility-scale solar photovoltaic power plants (US-PV). Two main problems of this construction are: occupying usable areas and the connection and integration of the power plant into the electricity system. The construction of US-PV power plants on water accumulations of existing hydro power plants was analyzed, as one of the solutions to these problems. The Jablanica Lake was taken as an example. Jablanica Lake is an artificial accumulation lake on the river Neretva with an area of 13 km2 within the hydroelectric power plant (HPP) Jablanica with 180 MW of installed power. It was shown that on a surface of less than 3% of the total area of the accumulation of HPP Jablanica, there could be built a floating photovoltaic (PV) plant with a power of 30 MW. This power would add another generator of 30 MW to HPP Jablanica, which would increase the current number of the 6 generators to 7. This would enable significantly better exploitation of the Neretva and Rama river basins, and increase production in the summer period with a decrease in lake level oscillations. Suitable locations for the installation of floating solar power plant were analyzed. Locations are selected on the basis of requirements for the preservation of existing lake functions, and provide the possibility of installing a 3 MW power plant. 10 of these plants, connected by a 20 kV power grid, represent one US-PV 30 MW plant, which at one point connects to the transmission network of 220 kV. The specifications of one 3 MW power plant are given in terms of the required area, number of modules and number of inverters. A preliminary techno-economic analysis of the total plant was carried out. In this analysis, the possible production, the indicative price of the plant, and the price of the produced kWh of electricity are calculated.