Application maintenance is an important part of SDLC (Systems Development Life Cycle). Possible maintenance issues have to be considered during the initial application design and development. The aim of this paper is to present how database and GUI can be designed in an object-oriented way, and to investigate whether such design can contribute to reduction of maintenance costs. Benefits of such approach are expected to be particularly noticeable in large scale applications that are expected to evolve and experience profound changes. Costs of maintenance as well as time required for potential modifications of application which is designed in accordance to the proposed methodology can be significantly reduced. Proposed methodology is compared with traditional application design which is based on relational database and user interface development using Rapid UI tools.

Intermittent renewable generation plays a significant role in power system planning, hence the requirement for more exact data and resource representation for power system modeling is of high interest. It is therefore the aim of this paper to analyze properties of the wind resource in specific operating conditions. As Bosnia-Herzegovina (B&H) abounds with mountain plateaus at high altitudes, the paper will analyze data records of four recording sites located at altitudes ranging from 1250m to 1700m a.s.l. Due to the specific geographic position and topography, the country experiences different climate conditions (Mediterranean, Moderate Continental and Alpine Climate) within a rather small surface area, which also has an effect at the recording sites of interest. The rate of change of diurnal patterns by season is analyzed by means of the Normalized Root-Mean-Square deviation (NRMS), whereby occurrence and intensity of occurring patterns is analyzed by means of the Fast Fourier Transform (FFT). The paper finds interesting results on wind statistics and the related operating conditions, with particular focus on mean diurnal wind profile and variability and the rate of change by season.

Because of the regulatory requirements for the quality of electricity supply being imposed in many countries, power quality is ought to be an important aspect of smart distribution grids. In this context, there is a need for the Integrated Power Quality Monitoring System, which would integrate all the power quality data available from various systems of smart distribution grid, such as Power Quality Monitoring System, Automated Meter Reading/Advanced Metering Infrastructure, Supervisory Control and Data Acquisition, Electric Vehicle Management System etc.

Keywords:Energy efficiency, CO2 emission, coal-based power plants, decarbonisation. ABSTRACT This paper describes measures which are being undertaken by EPBiH power utility, largest public electricity utility in Bosnia and Herzegovina, to improve its energy efficiency and keep on the track of the European targets outlined in the EU strategic documents and laid down by new energy efficiency Directive 2012/27/EU. By modernization its existing power plants performed in last 10 years, EPBiH improved net efficiency and reduced its CO2 emission for 30% compared to 1990 levels. Plan till 2030 is further increasing the net efficiency up to 40.2%. With introducing Energy Management System, energy efficiency has been involved into all sectors of the company; from coalmines, generation and distribution, to the energy supply, to comply the business model with EU energy efficiency targets and legislation.

The current generation capacity structure of the Public Power Company Elektroprivreda B&H (EP B&H) of 70%:30% in favour of TPPs provides some advantages like safe and reliable supply, but promoting RES and their use in the generation portfolio of the company is a commitment in order to contribute to sustainable development plans and environmental preservation. The ongoing measurement campaign performed by EP B&H investigates wind and solar energy potential on the territory of B&H. This creates preconditions for techno-economic evaluations of exploiting wind and solar power, with the final aim of building wind power plants (WPP) and photovoltaic power plants (PVPP) in the country. Particularly in terms of wind power, high altitude abandoned areas are assessed for potential WPP construction. Experience from the three year measurement campaign has shown promissing results in the available wind and solar potential of B&H, providing good preconditions for future techno-economic assessments and planning activities. Keywords: wind potential, solar potential, harsh weather conditions

The smart distribution grids will have to supply the electricity according to power quality standards. Various measurement instruments, currently considered as cornerstones of smart grids (smart meters, protection relays, fault recorders etc.), do not measure all the power quality parameters specified in these standards. Some distribution system operators are already installing Power Quality Monitoring Systems (PQMS), based on fixed power quality monitors. The aim of this paper is to present the possibility of integrating power quality data from PQMS system, AMR/AMI (Automatic Meter Reading/Advanced Metering Infrastructure) system and all the other systems in the distribution network, into an Integrated Power Quality Monitoring System (IPQMS). The results of pilot projects conducted in the Public Electric Utility Elektroprivreda of Bosnia and Herzegovina, in order to test the three power quality monitoring systems, are also presented. The possibility of using data from smart meters in power quality monitoring was analysed.

Most power systems in underdeveloped and developing countries are based on conventional power plants, mainly "slow-response" thermal power plants and a certain number of hydro power plants; characterized by inflexible generating portfolios and traditionally designed to meet own electricity needs. Taking into account operational capabilities of conventional power systems, their development planning will face problems with integration of notable amounts of installed capacities in wind power plants (WPP). This is what highlights the purpose of this work and in that sense, here, possible variations of simulated output power from WPP in the 10 minute and hourly time interval, which need to be balanced, are investigated, presented and discussed. Comparative calculations for the amount of installed power in WPP that can be integrated into a certain power system, according to available secondary balancing power amounts, in case of concentrated and dispersed future WPP are given. The stated has been done using a part of the power system of Bosnia and Herzegovina. In the considered example, by planned geographically distributed WPP construction, even up to cca. 74% more in installed power of WPP can be integrated into the power system than in case of geographically concentrated WPP construction, for the same available amount of (secondary) balancing power. These calculations have shown a significant benefit of planned, geographically distributed WPP construction, as an important recommendation for the development planning of conventional power systems, with limited balancing options.

This paper presents the findings of research into cofiring two Bosnian cola types, brown coal and lignite, with woody biomass, in this case spruce sawdust. The aim of the research was to find the optimal blend of coal and sawdust that may be substituted for 100% coal in large coal-fired power stations in Bosnia and Herzegovina. Two groups of experimental tests were performed in this study: laboratory testing of co-firing and trial runs on a large-scale plant based on the laboratory research results. A laboratory experiment was carried out in an electrically heated and entrained pulverized-fuel flow furnace. Coal-sawdust blends of 93:7% by weight and 80:20% by weight were tested. Co-firing trials were conducted over a range of the following process variables: process temperature, excess air ratio and air distribution. Neither of the two coal-sawdust blends used produced any significant ash-related problems provided the blend volume was 7% by weight sawdust and the process temperature did not exceed 1250oC. It was observed that in addition to the nitrogen content in the co-fired blend, the volatile content and particle size distribution of the mixture also influenced the level of NOx emissions. The brown coal-sawdust blend generated a further reduction of SO2 due to the higher sulphur capture rate than for coal alone. Based on and following the laboratory research findings, a trial run was carried out in a large-scale utility - the Kakanj power station, Unit 5 (110 MWe), using two mixtures; one in which 5%/wt and one in which 7%/wt of brown coal was replaced with sawdust. Compared to a reference firing process with 100% coal, these co-firing trials produced a more intensive redistribution of the alkaline components in the slag in the melting chamber, with a consequential beneficial effect on the deposition of ash on the superheater surfaces of the boiler. The outcome of the tests confirms the feasibility of using 7%wt of sawdust in combination with coal without risk to the efficiency of the unit, its combustion process and with the benefits of emissions reductions. Furthermore, they show that no modification to the existing coal transport system and boiler equipment is necessary to achieve this outcome.

In the past 10 years, very intensive integration of wind power plants (WPP) into power systems worldwide is evident. This phenomenon can have significant impacts on the normal operation of certain power systems. Especially exposed are power systems that do not possess a flexible generation portfolio, where the biggest challenge for power systems with significant amounts of installed capacity in WPP are variations of their output power which need to be balanced. In this paper, possible variations of output power from WPP based on real, measured wind speed data are analyzed. Recommendations for power systems that want to remain/become self-sustaining i.e. independently satisfy consumer needs and enable smooth functioning, in spite of significant amounts of installed capacity in WPP are given. In this sense, some of the characteristics of power systems in the Southeast Europe (SEE) region are presented. Most of these power systems are characterized by dominant electricity generation from "slow-response" generation facilities, such as thermal power plants (TPP) based on coal and nuclear power plants (NPP). On the basis of gained results, a more detailed elaboration of possibilities of integrating WPP into the power system of Bosnia and Herzegovina (B&H) are done in this paper.

Renewable energy systems are becoming a topic of great interest and investment in the world. In recent years wind power generation has experienced a very fast development in the whole world. For planning and successful implementations of good wind power plant projects, wind potential measurements are required. In these projects, of great importance is the effective choice of the micro location for wind potential measurements, installation of the measurement station with the appropriate measuring equipment, its maintenance and analysis of the gained data on wind potential characteristics. In this paper, a wavelet transform has been applied to analyze the wind speed data in the context of insight in the characteristics of the wind and the selection of suitable locations that could be the subject of a wind farm construction. This approach shows that it can be a useful tool in investigation of wind potential. Keywords—Wind potential, Wind speed data, Wavelet transform.

In power system, stability problem and problems with electromechanical oscillations or generators swinging are consistent in power system. Electromechanical oscillations are noticeable in characteristic variables of synchronous generators. Consequences of synchronous generator connecting on grid are physical nature, apropos more generators connecting on one power system. The responses of power system on any system disturbance are electromechanical oscillations. Oscillations can be low damped or undamped with constant or increasing amplitude, so they can achieve value which can disrupt the system operation. The monitoring of power system electromechanical oscillations is very important in the frame of modern power system management and control. This paper presents techniques for identification and analysis of low-frequency oscillations. Simulations and analysis shall be performed on two-area test system.

This paper considers the problem of integrating distributed generators into the Bosnia and Herzegovina's (B&H) distribution system. B&H has a respectable hydro potential accommodation for small hydro power plants (HPP). Today, an imposing number of small hydro power plants (27 units/ 36.5 MW) is connected to the B&H distribution grid and tenths are in the phase of construction (total power cca 300 MW). After receiving positive results from multi-year measurements of wind potential in some regions of B&H, it has become evident that B&H fulfills conditions for the development of wind power plants (WPP). There are some initiatives for constructing WPP on several locations in B&H with generator units between 300 kW and 2 MW. Their integration into the B&H powerless distribution grid presents an important technical problem. This paper is aimed to present some problems which have occured in the B&H distribution system with a large penetration of distribution generation.