Vjollca Komoni

Universiteti I Prishtines, Sistemet Elektroenergjetike, Faculty Member

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kamal mohammedi

David Quansah

Kwame Nkrumah University of Science and Technology

Mohammed Zeehan Saleheen

Sohar University

Medical University Innsbruck

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Papers by Vjollca Komoni

Performance evaluation of grid connected photovoltaic systems

Mediterranean Conference on Power Generation, Transmission, Distribution and Energy Conversion (MedPower 2016), 2016

The aim of this paper is to evaluate grid-connected photovoltaic systems based on two kinds of ph... more The aim of this paper is to evaluate grid-connected photovoltaic systems based on two kinds of photovoltaic module technologies. This study presents a one-year evaluation of four grid-connected photovoltaic systems installed at the National Institute of Advanced Industrial Science and Technology, in Tsukuba in the northern Kantō region of Japan. Two grid-connected systems based on multi-crystalline: mc-Si and two other ones based on thin film technology namely copper indium selenium: CIS modules. The monitoring data have been collected for one year to make an evaluation of all possible changes in climate environment. The goal of this study is to define the characteristics, the behavior and the sensitivity of the grid-connected PV system to the environmental parameters. Various parameters were used for the outdoor performance evaluation of the four grid-connected PV systems; including performance ratio, temperature losses, final yield, reference yield, AC energy generated and system efficiency. It was found that the grid-connected PV systems based on mc-Si technology perform much better than the systems based on CIS. The annual average daily performance ratios of the systems based on mc-Si modules were found to be about 5.53% higher compared to those of the systems based on CIS module, and an annual average daily AC energy production about 42.85% higher than CIS.

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Vlerësimi I Humbjeve Të Energjisë Elektrike Në Sistemin Shpërndarës Të Korporatës Energjetike Të Kosovës Sh. A. Dhe Masat Të Cilat Duhet Të Zbatohen Për Zvogëlimin e Humbjeve Të Energjisë Elektrike

Calculation and analysis of technical power losses, as well as measures to reduce them represent ... more Calculation and analysis of technical power losses, as well as measures to reduce them represent important task and challenge to the distribution system. Assessment and analysis are usually based on data which we possess on the measurement of power, which may have been not very accurate because is not possible to measure simultaneously at all measurement points, and at various levels voltage. In this paper is assessment of power losses in Power Distribution system in Kosovo with the software application GREDOS, and measures which are proposed to be applied in order to reduce power losses, which are much higher than in the EU states.

Shfrytëzimi i linjës 400 kV NS Kosovë B – NS Tiranë në eliminimin e avarive në rrjet (contingency) dhe ndikimi i saj në shkëmbimin e energjisë ndërmjet SEE të Kosovës dhe Shqipërisë

Transmission of electricity in a safe and quality manner is the main task of each Transmission Sy... more Transmission of electricity in a safe and quality manner is the main task of each Transmission System Operator which is connected to an interconnection system. Each TSO is required to be managed at any time of its security system in the best manner possible, especially when the network failure occurs (contingency). With the liberalization of the electricity market, the TSO is obligated to create conducive conditions to the electricity market. Exchanges of electricity will affect: the flows of power, voltage levels, contingencies and loss of electric power. In the paper an analysis of what will happen in the event of unforeseen fault of the 220 kV-line has happened, in one of the main nodes TSO of Kosovo. Based on analysis and simulations made for this case, the proposed solution is building of a new substation, 400 kV/220 kV, near SS Prizren 2, in the new 400 kV line, SS Kosovo B -SS Tirana. Thus will be fulfilled at any time of the operation criterion "N-1".

Analizë e implementimit të paneleve solare fotovoltaike Isuf Krasniqi , Vjollca Komoni, Arbër Perçuku, Sylë Tahirsylaj

Abstrakti Fotovoltaikët janë duke u bërë një nga investimet më të mëdha në fushën e njësive gjene... more Abstrakti Fotovoltaikët janë duke u bërë një nga investimet më të mëdha në fushën e njësive gjeneruese ripërtëritëse. Përmirësimi i besueshmërisë në Sistemin Elektroenergjetik është një nga impaktet shumë të rëndësishme të instalimit të fotovoltaikëve (PV). Duke ditur se Kosova ka karakterstika shumë të mira sa i përket rrezatimit të diellit (rreth 1300 – 1400 kW/m2), ky punim ofron një analizë të detajuar të instalimit dhe implementimit të paneleve fotovoltaike solare në ndërtesën e Fakultetit të Inxhinierisë Elektrike dhe Kompjuterike (FIEK). Ky instalim i paneleve fotovoltaike solare do të mund të përdorej për studime dhe hulumtime të mëtejshme të fenomeneve dhe dukurive të kësaj teknologjie nga studentët e FIEK. Fjalët çelës: panelet solare fotovoltaike, rrezatimi diellor, baza e të dhënave e Institutit Hidrometeorologjik të Kosovës, ndërtesa e FIEK

Wind Farm Modeling For Steady State And Dynamic Analysis

This paper focuses on PSS/E modeling of wind farms of Doubly-fed Induction Generator (DFIG) type ... more This paper focuses on PSS/E modeling of wind farms of Doubly-fed Induction Generator (DFIG) type and their impact on issues of power system operation. Since Wind Turbine Generators (WTG) don-t have the same characteristics as synchronous generators, the appropriate modeling of wind farms is essential for transmission system operators to analyze the best options of transmission grid reinforcements as well as to evaluate the wind power impact on reliability and security of supply. With the high excepted penetration of wind power into the power system a simultaneous loss of Wind Farm generation will put at risk power system security and reliability. Therefore, the main wind grid code requirements concern the fault ride through capability and frequency operation range of wind turbines. In case of grid faults wind turbines have to supply a definite reactive power depending on the instantaneous voltage and to return quickly to normal operation.

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Mitigation methods for over-voltage occurrence in Kosovo power transmission network

2018 53rd International Universities Power Engineering Conference (UPEC), 2018

Kosovo power transmission network has been suffering from over-voltage problems manifested over t... more Kosovo power transmission network has been suffering from over-voltage problems manifested over the last few years. The latter were recorded especially during light load period. Considering the existing long-term planning objective of Kosovo Transmission System and Market Operator (KOSTT) towards the enhancement of transmission network by integrating compensation devices the demonstrated scientific analysis is considered as of significant importance. Therefore, the impact of integration of various compensation devices for over-voltage mitigation on voltage profile in high voltage power transmission lines of Kosovo was addressed in this paper. The whole power transmission network was monitored for more than a year and then the analysis with the placement of compensation devices was conducted for the worst case associated with the highest voltage values recorded. The real-time data for the selected period was taken from SCADA system and then deployed in the model of Kosovo power system in PSS/E software. Three types of compensation devices as Fixed shunt reactors, Switched shunt reactors and FACTS devices (Static synchronous compensator STATCOM) were used for a profound assessment of the current problem. The analysis was conducted using PSS/E software as a simulation tool. The obtained results showed the good performance of these devices to improve the voltage profile in the system highlighting STATCOM shunt devices. An overall cost analysis of the studied compensation devices is also presented in this work.

KOSTT-Transmission System and Market Operator of Kosovo KOSOVO isuf

This paper presents possibility to decrease the corona power losses in overhead transmission line... more This paper presents possibility to decrease the corona power losses in overhead transmission lines. Corona power losses can be reduced by increasing the diameter of the conductor and used bundled conductors per phase. The objectives were to determine the corona power losses depend on conductors diameters. The simulation is completed using the corona model for one 400 kV and 220 kV overhead transmission line is developed in Matlab/Simulink. The objectives are to determine the corona effect in high voltage transmission lines, and to identify factors of decreasing the corona losses, such as increasing the diameter of conductors, and thus have to increase the critical disruptive voltage. The paper describes the analytical approach, computational tools and simulations models. Key-Words: Electric discharge, Electric field, Corona model, Critical disruptive voltage, Power losses, Transmission line.

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Performance analysis of a 3.9 kWp grid connected photovoltaic system with different types of module, and different slope angles

2018 UBT International Conference, 2018

Energy Efficiency Assessment of University Buildings - Case Study: Technical Faculties Building

Generating energy, as a key factor for the development of the country, implies a number of factor... more Generating energy, as a key factor for the development of the country, implies a number of factors that requires solving its rational use in the context of sustainable economic, social, environmental and cultural issues. The aim of our research described in this paper is to investigate and evaluate several aspects of energy efficiency, such as source and use of energy and its loss in education buildings, when it comes to lighting and heating of the building during the learning process; as well as medium-term strategies for alternative energy sources for these items. The key issue in this study is based on analysis and assessment of enclosed architectural space and its constructive elements, electrical and heating installations of the case study building, the Faculty of Electrical and Computer Engineering, Faculty of Civil Engineering and Architecture and Faculty of Mechanical Engineering, so-called Technical Faculties Building (TFB). This paper is based on comparing the analysis fro...

A comparison of the performance of mono-Si and poly-Si photovoltaic modules operating under Kosovo climate condition

Journal of Renewable and Sustainable Energy, 2018

The performance analysis and evaluation of a real grid-connected photovoltaic system operating un... more The performance analysis and evaluation of a real grid-connected photovoltaic system operating under mild continental climate condition of Kosovo is conducted in this paper. The PV system is installed on a flat roof of the laboratory building at Faculty of Electrical and Computer Engineering. With fixed monocrystalline silicon (m-Si) and polycrystalline silicon (p-Si) module types with an installed capacity of 1.76 kWp and 2.16 kWp respectively, inclined at an angle of 45 • C, facing south and through two solar inverters, the latter feds the low voltage distribution grid with electricity. Performance and meteorological data for each type of modules were collected and analyzed for the period between December 2014 to November 2015. The m-Si PV modules have shown higher performance compared with p-Si PV modules. Electricity production during the monitoring period was 1286.57 kWh/kWp from p-Si modules and 1328.21 kWh/kWp from m-Si modules. The annually average daily final yield (Y f), the annual average value of performance ratio (PR) and system efficiency (η sys), for the p-Si PV modules were found to be 3.53 kWh/kWp/day, 80% and 11.67% respectively. In addition, corresponding values for the m-Si modules were 3.64 kWh/kWp/day, 84% and 12.78% respectively. Furthermore, a comparative analysis of the performance of the photovoltaic system under study with other photovoltaic systems installed in various countries worldwide was carefully investigated and presented in this paper.

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ANALIZA E PERFORMANCËS SË SISTEMIT FOTOVOLTAIK ME FUQI 3.9 kWp TË PALIDHUR NË RRJETIN ELEKTRIK

ABSTRAKT: Sistemi fotovoltaike i pa lidhur në rrjet montohet me qëllim të furnizimit me energji e... more ABSTRAKT: Sistemi fotovoltaike i pa lidhur në rrjet montohet me qëllim të furnizimit me energji elektrike të shpenzuesve, si dhe zvogëlimin e energjisë të marrë nga rrjeti elektrik. Ky sistem forovoltaik përmban edhe bateri të akumulatorëve, e që mundëson të furnizoj shpenzuesve me energji elektrike edhe në rastin kur mungon energjia elektrike nga rrjeti elektrik, si edhe gjatë kohës kur nuk kemi diell dhe nuk ka mundësi të gjenerohet energji nga fotovoltaikët. Punimi përmban përshkrim e sistemit fotovoltaik të palidhur në rrjetin elektrike me fuqi 3.9 kWp, me panele monokristalore dhe polikristalore, të instaluar në UP – FIEK, si dhe monitorimin e tij. Sistemi është monitoruar për një periudhë disa mujore, dhe energjia elektrike e prodhuar ka furnizuar me energji elektrike ndriçimin e jashtëm të objektit. Janë vlerësuar këto parametra ditore dhe mujore të sistemit: gjenerimi mesatare kWh për ditë, rrezatimi diellor, temperatura ditore. Rezultatet e fituara do të mundësojnë vlerësim...

Control Active and Reactive Power Flow with UPFC connected in Transmission Line

8th Mediterranean Conference on Power Generation, Transmission, Distribution and Energy Conversion (MEDPOWER 2012), 2012

Flexible alternating current transmission systems (FACTS) technology opens up new opportunities f... more Flexible alternating current transmission systems (FACTS) technology opens up new opportunities for controlling power flow and enhancing the usable capacity of present, as well as new lines. The Unified Power Flow Controller (UPFC) is a most complex power electronic device, which can simultaneously control a local bus voltage and optimization power flows in electrical power transmission system. This paper presents real and reactive power flow control through a 400 kV transmission line by connected the UPFC at the sending and receiving end. The objective are to determine control and performance of UPFC who is intended for installation on that transmission line to control active and reactive power flow. When no UPFC is installed, active and reactive power through the transmission line can not be controlled. Simulations are carried out in Matlab/Simulink environment to evaluate the performance of the UPFC.

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Performance analysis of 3.9 kW grid connected photovoltaic systems in Kosova

2014 5th International Renewable Energy Congress (IREC), 2014

ABSTRACT Abstract— This paper presents results obtained from monitoring a 3.9 kWp grid connected ... more ABSTRACT Abstract— This paper presents results obtained from monitoring a 3.9 kWp grid connected photovoltaic system installed on a flat roof of a laboratory building of FECE in Prishtina, Kosovo (Latitude 42.6667°N and longitude 21.1667°E ). System was monitored between the May 2013 to November 2013, and all the electricity generated was fed into the low voltage network supply to the building. This system consists of two types of photovoltaic modules, monocrystalline and polycristalline, inverter, and devices for measurement and monitoring. During this period are measured and analyzed daily and monthly parameters of system, such as: power generation, daily solar radiation, air temperature, PV module temperature and wind speed. Monthly average daily performance parameters of the PV systems evaluated include: final yield, reference yield, system efficiency, and performance ratio and capacity factor. These results will be enabling to evaluation and used the photovoltaic systems in Kosovo climatic conditions.

Design optimization and simulation of the Photovoltaic Systems on buildings in Southeast Europe

ABSTRACT The favourable climate conditions of the Southeast Europe and the recent legislation for... more ABSTRACT The favourable climate conditions of the Southeast Europe and the recent legislation for the utilization of renewable energy sources provide a substantial incentive for the installation of photovoltaic (PV) systems. In this paper, the simulation of a grid-connected photovoltaic system is presented with the use of the computer software package PVsyst and its performance is evaluated. The performance ratio and the various power losses (temperature, soiling, internal network, power electronics) are calculated. There is also calculated the positive effects on the environment by reducing the release of gases that cause greenhouse effect.

Performance evaluation of grid-connected photovoltaic system with battery energy storage

PECon 2012 - 2012 IEEE International Conference on Power and Energy, 2012

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PERFORMANCA E MONITORIMIT TË SISTEMIT FOTOVOLTAIK 3.9 kWp TË LIDHUR NË RRJETIN ELEKTRIK

Abstract The paper presents results obtained from monitoring a 3.9 kWp on grid photovoltaic syste... more Abstract The paper presents results obtained from monitoring a 3.9 kWp on grid photovoltaic system installed on a flat roof of a laboratory building of FECE. System was monitored between the May 2013 to August 2013, and all the electricity generated was fed into the low voltage network supply to the building. The photovoltaic system is able to work as a stand alone system or grid connected. This system consists of two types of photovoltaic modules, monocrystalline and polycristalline, batteries, inverter, battery chargers and devices for measurement and monitoring. During this period are measured and analyzed daily and monthly parameters of system, such as: power generation, daily solar radiation, air temperature, PV module temperature and wind speed. With the data collected are calculated all power generation, monthly average solar radiation, monthly average air temperature, monthly average PV modules temperature and monthly average wind speed. These results will be enabling to eva...

Kursimi Potencial i Energjisë Elektrike në Amvisëri me Përdorimin e Llambave Efiçiente CFL

Sipas statistikave të Agjencisë Ndërkombëtare të Energjisë për ndriçim në Evropë konsumohet 14% t... more Sipas statistikave të Agjencisë Ndërkombëtare të Energjisë për ndriçim në Evropë konsumohet 14% të energjisë elektrike të prodhuar, ndërsa në tërë botën kjo është 19% të prodhimit të përgjithshëm të energjisë elektrike. Nga 1 shtatori 2009 është në fuqi ligji, i sponsorizuar nga Komisioni Evropian, që poçet inkandeshente dhe llambat e tjera jo efiçiente, sipas të cilit në Evropë fillohet të bëhet zëvendësimi i tyre me llamba efiçiente. Me kalim në përdorimin e prodhimeve me efiçiente të ndriçimit, amvisëritë e Evropës do të kursejnë energjinë elektrike dhe më këtë do të kontribuojnë në arritjen e objektivave për klimën në Evropë. Gjatë këtij viti MEM dhe GTZ kanë pas një projekt për zëvendësimin e poçeve e poçeve inkandeshente me llamba kompakte fluoreshente CFL në 200 amvisëri në Kosovë.

Increase power transfer capability and controlling line power flow in power system installed the FACTS

7th Mediterranean Conference and Exhibition on Power Generation, Transmission, Distribution and Energy Conversion (MedPower 2010), 2010

This paper presents possibility to increase power system capability and controlling line power fl... more This paper presents possibility to increase power system capability and controlling line power flow in power system with FACTS controllers. FACTS enhance power system performance, improve quality of supply and also provide an optimal utilization of existing resources. Various FACTS controllers devices, especially SVC and STATCOM, enable load flow on parallel circuits to be optimized and controlled, with a minimum of power wheeling, the best possible utilization of line, and a minimizing of overall system losses at the same time. The objectives were to determine the power transfer capability in power system, identify means of increasing the transfer limit, and test the potential application of FACTS devices. The paper describes the analytical approach, computational tools and simulations models.

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Wind grid code requirements regarding connection and operation of wind turbine in Kosovo

7th Mediterranean Conference and Exhibition on Power Generation, Transmission, Distribution and Energy Conversion (MedPower 2010), 2010

Abstract This paper discusses aspects of Kosovo Grid Codes relating to wind turbines. All Generat... more Abstract This paper discusses aspects of Kosovo Grid Codes relating to wind turbines. All Generators connecting to the Kosovo Transmission System are required to comply with the Grid Code. The Grid Code was originally developed with conventional synchronous generators. Since Wind Turbine Generators (WTG) don't have the same characteristics as synchronous generators, it was considered appropriate to develop a new set of Grid Code provisions specifically for Wind Farm Power Stations in relation with specific characteristic ...

Performance evaluation of grid connected photovoltaic systems

Mediterranean Conference on Power Generation, Transmission, Distribution and Energy Conversion (MedPower 2016), 2016

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