Improve Stability Operations in Kosovo´s Electrical Energy Distribution Network

A Case Study of Northern Prishtina

Thesis (M.A.), 2010

48 Pages




2.1. Energy technical losses in Kosovo
2.2. Energy technical losses in Europe
2.3. Northern Prishtina as a study case
2.3.1. Middle voltage network in SS 110/10(20)kV Prishtina 5
2.3.2. Low Voltage Network in northern Prishtina
2.3.3. SS 35/10kV Besia

3.1. Voltage quality regulation in Europe
3.2. Voltage quality regulation in Kosovo
3.3. Technical losses and drop voltages in Northern Prishtina as a study case

4.1. Simulations with Gredos and Power Factory software
4.2. Data collections
4.3. Contractual arrangements

5.1. Improve stability in middle voltage network – provide the transition from level of voltage 10kV into 20kV
5.1.1. Upgrade the cross section of the conductors and built lines for reserve supply
5.1.2. Transition from voltage level 10kV into 20kV.
5.2.Improve stability in LVN
5.2.1. Establishing phase symmetry
5.2.2. Rehabilitation of LVN
5.2.3. New SS 20/0.4kV
5.2.4. Compensation of the reactive energy
5.3. Besia SS 35/10kV
5.4. Summary of chapter 5 - priorities

6.1. Project supports
6.2. Managerial approaches
6.3. Human Resources and Team Selection
6.4. Training Needs and Security Procedures
6.5. Communication with Internal and External stakeholders

7.1. Identify and mitigate risks
7.1.1. Strengths
7.1.2. Weaknesses
7.1.3. Opportunities
7.1.4. Threats
7.2. Budgeting and cost estimation

8.1. Determining cost benefit
8.2. Social benefits
8.3. Environmental protection
8.4. Growing interests of businesses

9.1. Technical Future Works
9.2. Financial Future Considerations
9.3. Northern Prishtina Recommendations
9.4. Activities in Long Term Plans
9.5. Future Project Selection Criteria
9.6. Recommendations Having Highest Priorities
9.7. Summary

10. References

11. Annexes

List of aberrations

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This Capstone Project addresses an important problem regarding the power quality which is very common in Kosovo. It describes the context of power quality in distribution systems and deals more specifically with the corresponding diagnostics and implementation. It develops a precise and effective technique and method for the analysis how to improve a quality of electrical energy in Kosovo. The challenge of this project was to upgrade the existing design of network, and bring and build a new design of distribution system electric energy in Prishtina, saving energy which is being lost in distribution networks and improve the stability of particularly the electrical energy in Prishtina area.

This project involves technical and managerial prospects for solving the problems which are facing KEK employees and the customers in northern Prishtina. Moreover, the project provides experiences from other countries for making comparison with those in Kosovo.

This project based on the very latest studies, on increasing the reliability of quality of power energy supply up to the last customer. This project also considers the reduction of technical losses. The main goals of this project concerns the need for increasing the high level of voltage, necessary number of lines, substations and improve low voltage networks.

If it is possible to establish a scale of human needs, giving importance to the achievements of modern time and the way of living of modern human being, then for sure the electrical energy would take one of the top positions.


The distribution network situation during 90’s in Kosovo was as a status quo. Due to the political situation there was no interest to invest in Kosovo. This resulted in gradual deterioration of the distribution network area.

In 1999, after the war in Kosovo, new developments took place affecting the electrical infrastructure, the same as other infrastructures in Kosovo. Households began to concentrate in the city and its suburb areas. This situation led to an increased demand for electric energy supply. On the other hand, the existing network was not designed to respond to such a flux of increased of customers.

It can be calculated that this old network cannot endure the current demand on electrical energy. The middle low voltage network in Kosovo is shown in figure.2.1 where each district is represented by a different color.

Figure.2.1 Middle voltage network of Kosovo

illustration not visible in this excerpt

Source; Estap, 2002

As consequence to this, KEK faces with the problems presented in box 1.

Box.1 Problems leading to poor quality of energy supply which both KEK and customers are facing with

- Old Network Equipments.The electrical energy distribution network is very old. Most of the equipment is older than forty years. E.g. old cables are mostly copper oil-filled which need several interventions during the winter season. Towers are mostly installed from impregnated wood and decay is a present risk for the environment because of their age in some areas.
- Small cross sectionThe network on 10kV level is mainly constructed with Al/Fe conductors of 25 mm2 and 35 mm2. This cross-section technically cannot endure higher loads in long lines
- Radial Design.10kV feeders from main substations are usually very long in rural areas, thus giving rise to high voltage drops (up to 40% of the nominal voltage) and considerable technical losses.
- No reserve supplies due to the radial structure of the 10kV network (particularly in the rural areas); it is not possible to have reserved supply from SS during outages of feeders. As a result of the delicate 10 kV network, it is sometimes necessary to disconnect individual feeders due to the operations in them. Figure 2.4 shows middle voltage network with feeders in Prishtina.
- Bottlenecks;When the loads are higher and the capacity of network to endure such loads is lower, bottlenecks are experienced through the network.
- Employees are facing with a lot of network problems,due to the problems mention above. The majority of their works in the field are under risk circumstances. In some cases towers are over weighted with conductors (annex 1)
- Lack of Business investmentsdue to the quality of voltage. Businessmen, who want to perform their activities, often cannot accomplish their daily activities due to interruptions and quality of voltage. New investors hesitate to invest in such places where there is lack of electrical energy , because it is impossible to use uninterrupted, stable and qualitative electrical energy.
- No electrical energy for 24 hours/day.Customers cannot use their equipment in some areas in Kosovo because of the lack of electrical energy.

The length of network state in Kosovo shown in numbers is highlighted in Table 2.1. Based on this table, 11,411km belong to the low voltage network 0.4kV and 674 km to the level 35km. 411 km can work as a 20kV, but for the moment they work as 10kV and 5,783km belong to 10kV. Both 10kV and 20kV are currently working as 10kV which means 6,974km in 10kV. The level of voltage 6kV is mainly used by the industry.

Table 2.1 highlights that 1,407km are cables, which mean that only 7.7% of distribution network in Kosovo is cable. The rest,92.3% of network , is over head lines.

Table 2.1 Length of distribution network in Kosovo

illustration not visible in this excerpt

Source:Development Department KEK, 2009

Table 2.2 emphases the distribution network based on the number of substations, transformers and installed power according to the level of voltages. E.g. there are 5098 substations with transformation 10/0.4kV while there is just one SS 220/35/10(20) kV. The capacities in the main substations (first five rows) are 1208 MVA; while in substation 10(20) /0.4kV are 1679MVA.

Table 2.2 Number of SS in network distribution and their installed power

illustration not visible in this excerpt

Source:Development Department KEK, 2009

2.1. Energy Technical Losses in KEK

Technical losses in Kosovo were 17% last year. These losses are due to resistance in lines, transformers etc. Those are the losses in general in all network districts, but in Prishtina separately they are around 14%. Table 2.3 shows technical energy losses in Kosovo per each district. Based on this table, the highest energy received in Prishtina was 1,302GWh or about 28% of all consumption goes to Prishtina [(1,302/4,681)*100=28%]. The technical losses expressed in MWh (184,799MWh) were the highest in Prishtina, but in percentage these were the lowest compared to other districts (14.19%)

Drop voltages at the ending points are more than 40% in some regions around Kosovo. It means that the voltage reaching the customer is not 220V but often it is below - 140V. In northern Prishtina during the peak load the value of drop voltages is from 0.5% to 30%. An analysis taken from Section of Analysis and technical losses is shown in Annex 2. It shows the drop voltages in some areas in a 10kV feeder for the highest loads.

As the result of technical issues mention above, KEK technical losses expressed in energy were 800,445MWh in 2009. Having in mind that the average costs per MWh was 57 euro last year, the results shows that KEK, due to these technical losses, lost about 45.6 million € last year.

Table 2.3 Annual reports of technical losses 2009

illustration not visible in this excerpt

Source:Section for Technical Losses and Analysis, Development Department, Network Division, 2009

Figure 2.2 shows technical losses in 2009 graphically. During summer, technical losses are smaller compared to losses in winter. They are depended on the loads which always get higher in the winter season, due to the use of electric energy for heating.

Figure 2.2 Technical energy losses diagram

illustration not visible in this excerpt

Source: Sector for Technical Loss Calculations

2.2. Energy Technical Losses in Europe

Technical losses in Albania are 22.74%, in Georgia 7.3% [i] in Serbia in 2008 (10,5-11,5)% assumed[ii], Croatia 6% [iii], Austria 5.44%, Belgium 4.79%, Finland 3.5%, Greece 8.34%, France 7%, Spain 5.71%, Italy 6.65, Netherland 4.14%, Germany 5.4% Slovenia 6,42. These technical losses are shown in figure 2.3.

Figure 2.3 Technical losses around Europe

Abbildung in dieser Leseprobe nicht enthalten

Source: Energy Regulatory Office (2007)

2.3. Northern Prishtina as a study case

In this research, northern Prishtina has been used as a case for analysis. The reasons why northern Prishtina has been chosen as a study case are:

- There is no need to invest in the main supply or substation 110/10(20) kV, because this substation exists. Existing SS has the possibility of transformation from 110/10kV and 110/20kV which is needed for the project.
- The main idea of this research is to promote the transition from level 10kV into 20kV. In Prishtina 5, about 50% of the existing equipment in middle voltage network can work as 20kV
- The structure for studying is more interesting because of its urban and rural areas
- The network in this part of Prishtina looks like ‘a spider network’, due to many air conductors through the roads
- The technical losses in this part of Prishtina are the highest compared to the other areas in Prishtina

The region of northern Prishtina is supplied by substation SS 110/10(20) kV Prishtina 5. This substation supplies about twelve thousands customers. It has sixteen feeders 10kV with 111 SS 10/0.4kV. The northern Prishtina is shown in figure 2.4.

Figure 2.4.The view of middle voltage network and the 10kV feeders in northern Prishtina.

illustration not visible in this excerpt

Source:District of Prishtina, Engineering Section, taken from Gredos software

The feeders which supply the city are not visible in this figure, but the feeders in rural areas yes. Therefore, feeders Barshoshi and Rezervoaret are shown in the figure while substations in the city are shown with small circles (like points).

2.3.1. Middle voltage network in SS 110/10(20)kV Prishtina 5

The main substation with transformation of voltage from 110kV to 10kV with the possibilities to transform to 20kV was built in 2003 in northern Prishtina to supply that area.

The 10kV feeders are lines which come from 10kV bus bars in 110/10kV and they supply the substations SS 10/0.4kV. The table 2.4 shows the name of each feeder in Prishtina 5, number of cubicles, nominal power of SS 10/0.4kV, the number of SS 10/0.4kV and 20/0.4kV.

Some of the customers use the entire line just for their needs, for example pumps. The table below shows includes three feeders which belong to SS Besia 35/10kV needed for further studies below.

Table 2.4 Data of 10kV feeders in northern Prishtina

illustration not visible in this excerpt

Source:District of Prishtina, Engineering Section, Maintenance Section, CCP software, 2009

20 kV lines that still function as 10 kV after the war have been mainly used as 10 kV lines, until they are transferred to level 20 kV.

630kVA and 1000kVA transformers are mainly installed in the city; the others are mainly installed in rural area. Some businesses have their owns substation to cover their needs, for example sawmill, plastic factories, college, drink factories, hotel, cantonment, Medical Ministry, gas pumps etc.

2.3.2. Low Voltage Network in northern Prishtina

Low voltage network or 0.4kV network, supplies customers from substation 10/0.4kV through conductors and other LVN elements. Here the lines have a cross section of 4x25 mm2 Al, 4x35 mm2 Al and in rare cases cables of PP-41 4x150 Al. There are cases with extreme asymmetries in certain locations.

Figure.2.5 Low Voltage Network in SS 10/0.4kV Kodra e Trimave Abbildung in dieser Leseprobe nicht enthalten

Source:Section for Analysis, Development Department, 2007

Figure 2.5 shows a LVN in SS 10/0.4kV in the so-called Kodra e Trimave 9 with installed power 1000kVA. There are five feeders of 0.4kV which emerge from this SS and proceed to supply the customers through lines and poles (shown in small circles).


[i] World Bank Technical Paper No.423 Non-Payment in the electrical energy sector in eastern Europe and the Former Soviet Union pg 48

[ii] Despotovic Nebojssa & Mladen Petronijevic ‘Commercial Losses and Bad Debts” January 2010, Amman

[iii] Pavic Ante, Kruno Trupinic, ELECTRICAL ENERGY LOSSES IN THE DISTRIBUTION NETWORK, pg.214, 2007

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Improve Stability Operations in Kosovo´s Electrical Energy Distribution Network
A Case Study of Northern Prishtina
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MSc. Lutfije Dervishi (Author), 2010, Improve Stability Operations in Kosovo´s Electrical Energy Distribution Network, Munich, GRIN Verlag,


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