Bachelor thesis

Most often covered topics in the past and preferential topics for the up-coming theses are listed as follows:

  • Simulation, modelling and analysis of dynamic power-system phenomena,
  • Real-time WAMS measurements analysis,
  • Creating computer algorithms for WAMS-based real-time detection and analysis of disturbances in a power-system,
  • Legislation on power engineering topics,
  • International trends in power engineering,
  • FACTS devices,
  • Direct methods for power-system stability assessment
  • Probability concept in electric power systems,
  • World trends in electrical energy transmission

For further details on possible topics please contact LPEE staff. Students are encouraged to be self-initiative and present their own suggestions for the topic of their theses.

Below, a list of several recent theses is given. Full text can be accessed at the faculty library, or you can search the repository of UL.

 


Electric power-system inertia estimation applying WAMS

Author: Teodora Dimitrovska
Work: Master’s thesis
Mentor: Urban Rudež, co-mentor: Rafael Mihalič

Due to extensive increase and implementation of renewable energy sources into EPS, the share of conventional generation units is constantly decreasing. As a result, the total EPS mechanical inertia is decreasing as well, which is problematic as it represents one of basic mechanisms for assuring stability of EPS. This is why an on-line EPS-inertia estimation became one of high-priority problems all around the world. In the thesis, the algorithm for on-line multi-generator EPS-inertia estimation is verified. The algorithm is analysed on different simulation cases performed on the dynamic 39-bus IEEE test system model. The impact of noise presence in measurements, suitability of different kinds of disturbances for the cause and needs for possible system sectioning concerning coherent generator response to disturbances are also studied. The algorithm is verified also on inertia estimation of NEK for different real-life cases, captured by WAMS system in the past.

 


Electrical distances calculation in large electric power systems

Author: Uroš Simovič
Work: Bachelor’s thesis
Mentor: Rafael Mihalič, co-mentor: Urban Rudež

This thesis presents the problem of calculating electrical distances in large electricity networks. The calculation is essentially not mathematically complex as power distance can also be obtained from the inversion of the nodal admittance matrix, which is, however, due to the large number of busbars in a power network and thus the dimensions of a single matrix, computationally consuming, so the thesis also presents the possibilities of accelerating the calculation of electrical distances. An example of a large electricity grid is provided, more precisely European ENTSO-E network. Finally a web application is presented, which depicts the electricity grid of ENTSO-E on the geographical map and enables a rapid calculation of electrical distances to any selected reference busbar.

 


Impact of photovoltaic power plants on frequency stability

Author: Miha Flegar
Work: Master’s thesis
Co-mentor: Urban Rudež

The  objective  of  this  master  thesis  was  to  verify  solar  stations  response  to  mains  frequency deviations  and  their  impact  on  frequency  stability.  The focus was given on transition into islanded operation and island operation itself. One of most up-to-date focus of the electrical engineering professionals, when dealing with frequency stability, is the so-called »50.2 Hz« problem. The essence of the whole problem is the inverters over-frequency protection setting which causes disconnection of the solar station from the grid if frequency exceeds 50.2 Hz threshold. Dynamic analyses are based on PSS®NETOMAC model of Medvode – Mavčiče island. The solar stations impact on frequency stability was tested for multiple  grid operating scenarios, while checking the impact  of  immediate  disconnection  at  50.2  Hz  and  frequency  controlled  feed-in active power reduction.

 


Detecting ferroresonance in electric power systems

Author: Gregor Maležič
Work: Bachelor’s thesis
Mentor: Rafael Mihalič, co-mentor: Urban Rudež

Ferroresonance occurs rather seldom in electric power-systems. However, the constant growth and development of power-systems made ferroresonance become more important each day. The thesis analyses physical background of series as well as parallel ferroresonance. In addition, corresponding oscillation modes are also investigated. Several possible indications of the phenomenon taking place are provided and typical power-system conditions that enable its occurrence are described. By using simulation software PSS®NETOMAC occurrence of ferroresonance is simulated and its specifics explained.

 


Underfrequency load shedding protection testing with a real-time digital simulation hardware

Author: Matej Bratič
Work: Bachelor’s thesis
Mentor: Rafael Mihalič, co-mentor: Urban Rudež

Underfrequency load shedding (UFLS) is a last-resort measure for power-system blackout prevention in cases when larger imbalances between active power generation and consumption occur. Traditional UFLS schemes, currently in use in actual power-systems, in many situations affect much more consumers as actually needed. However, by applying adaptive UFLS schemes, such unnecessary disconnections can be avoided. In the thesis, several adaptive UFLS schemes are analysed. By applying a modern protection relay from manufacturer ABB, both traditional and adaptive concepts are programmed. For programming, parameterization and testing purposes, closed-loop simulations are conducted by using a real-time digital simulation hardware RTDS.