Modelling of flicker in large real distribution networks has been a challenge until now, due to huge number of flicker sources contributing to total flicker levels in the network. In this paper, voltage flicker is modelled for a large real medium voltage (MV) distribution network. The total flicker is calculated from background flicker resulting from high voltage network and from flicker emission of a large number of sources in the analysed MV network. The flicker emission was modelled by statistical distributions of emission levels. Results of the simulation were compared to flicker measurements from several power quality monitors, installed in the feeders of the analysed MV network. The results show a significant similarity between the model and the measurements. Conclusion of this work is that the voltage flicker can be modelled with sufficient accuracy, even in large real MV networks.

Abstract The aim of this paper is to analyse the stand-alone operation of the microgrid located in Umoljani, Bosnia and Herzegovina. The analysis was performed for two scenarios; one representing a summer day and the other a winter day. The analysed network was modelled using the DIgSilent PowerFactory. The Photovoltaic (PV) system, Wind Generator (WG) and battery sizing were performed using the HOMER software tool. The load data for the location was obtained from JP Elektroprivreda Bosne i Hercegovine. The analysis showed that the network was able to operate in stand-alone mode. Voltage levels were under the voltage limit defined by EN 50160. Line loading was decreased compared to loading in grid-connected mode. As given by the obtained results for the two scenarios, the consumer demand could be satisfied without the inclusion of WG. However, different input data (wind speed data measured on the location) could change the sizing of the production facilities as the results of the optimization calculations in HOMER, which needs to be considered in microgrid configuration.

A microgrid concept for the thermal and electrical energy supply of a Sport-Recreation Center Ajdinovići (S.R.C.A.) has been proposed in this paper. A self-contained and intelligent power distribution grid has been developed for this case, taking into account the location, locally available renewable energy sources and the very purpose of this center. Comparative analyses between independent power supply through the proposed hybrid power system and the supply over the transmission and distribution network were performed. Technical and economical optimization of an energy system with distributed power generation was done by applying HOMER and DIgSILENT PowerFactory professional software tools. As a result, hybrid power system is more cost-effective than the conventional supply by the power distribution network, microgrid meets the technical criteria based on the analysis of power flows and the stability of the network has been achieved. Establishment of energy independence for the existing S.R.C.A. besides economic factor will show several benefits regarding better use of locally available resources, reduction of CO2 emissions and energy efficiency increment as well as an employment opportunity to the local people, thus contributing to the sustainability of the region.

Modelling of harmonics in large medium voltage (MV) distribution networks has so far been a challenge due to the presence of a large number of harmonic sources contributing to total harmonic voltages. This study proposes a deterministic methodology of modelling harmonics in large real MV distribution networks using aggregate harmonic source models parameterised based on measurements and results from the literature. In this research, background harmonic voltages from the sub-transmission system are parameterised based on measurements in the analysed network. Aggregate harmonic current emission of different customer categories in low-voltage (LV) networks (households and small commercial customers) parameterised based on several measurements in LV networks was dominated by residential or office customer type configurations. The harmonic current emission of industrial customers is parameterised based on the results from published literature. Two methods for modelling harmonic sources are used and compared: (i) modelling according to the IEC 61000-3-6 summation law and recommended summation exponents and (ii) modelling using complex phasors. The results of the models show a good match with the measurements from power quality monitors installed in the analysed MV network. Based on these results, the method according to the IEC 61000-3-6 is recommended for large MV distribution networks.

Abstract Distribution network planning is a regular business process for determining optimal construction and reinforcement in the distribution network of a particular area that all power distribution companies are concerned. It is conducted based on techno-economic analyses for purpose of achieving the required safety and quality of power with minimum investment costs. The development of the distribution system should include all the needs of customers and electricity producers for the observed planning period. In addition, the development plan needs to be coordinated with the strategic directions of the development of the electricity distribution network. Among other things, this involves transition to direct transformation and one medium voltage (MV) level. In order to reduce losses and repair voltage conditions, interpolations of secondary TS and shortening of low voltage (LV) networks are planning. The paper presents some of the results of the research carried out in the study “Development projection of distribution networks of PE Elektroprivreda BiH, d.d. Sarajevo for the period 2015 - 2025”.

Abstract A trend of developing electricity distribution networks towards a concept of smart distribution networks has been noted for quite some time. Tendency to integrate all different systems installed in electricity distribution network has also been observed as a part of the trend. This creates the opportunity for distribution system operators to efficiently utilise the data from all the different systems and all the electronic devices, installed in electricity distribution networks, for more comprehensive and accurate network power quality (PQ) monitoring. This paper presents the possibilities of implementation of Integrated Power Quality Monitoring System (IPQMS), which should integrate all the PQ data from all the available systems in smart distribution grids. The concept of advanced IPQMS is also presented. Apart from integration of PQ data, it would also estimate the state of PQ in an analysed area, perform localisation of disturbance sources and suggest mitigation measures. Furthermore, the paper presents the possibilities, advantages and needs for implementation of such a system based on real measurement results from the electricity distribution networks of the Public Electric Utility Elektroprivreda of Bosnia and Herzegovina d.d. - Sarajevo (JP Elektroprivreda BiH d.d. - Sarajevo). The conclusion is that the implementation of IPQMS system is necessary if the complete information about the state of PQ in electricity distribution networks of the future is required.