Master Projects

  • Development of portable impulse generator with output up to 1 kV

Master project

Contact Person: Dr. Rafael Alipio ([email protected])

Cloud-to-ground lightning is a natural phenomenon resulting from high levels of electric field established between the cloud and the ground or between the cloud and a grounded structure. In terms of protection engineering, lightning is modeled as a high-intensity current source (of the order of tens of kA) and of an impulse nature (rapid growth from zero to the peak value, in an interval of the order of a few µs). Due to their impulse nature, lightning currents have a wide frequency content, ranging from DC to a few MHz. The main objective of this project is the development of portable voltage generators that produce output signals with an impulse pattern, that is, a rapid increase from zero to the peak value, in the order of a few µs, and decrease to zero, after reaching the peak, in a few hundred or tens of µs. The generator is based on an electronic circuit, including among other components a voltage multiplier and an electronic switch, built with a MOSFET, to trigger the impulse voltage. Such generators will allow the characterization of the experimental response of electrical equipment, such as transformers, cables, and grounding systems, to lightning transients.

 

  • Enabling low-cost far-field imaging thanks to electromagnetic time-reversal and software-defined radios

Master project

Contact Person: Elias Le Boudec ([email protected])

Imaging radiation sources in the far field is a powerful feat that opens many possibilities, such as the localization of electromagnetic interference sources for compatibility debugging. In particular, electromagnetic time reversal takes advantage of the medium complexity to provide a reliable localization technique. However, imaging techniques generally rely on expensive radio-frequency hardware, which can hinder practical applications or limit them to developed countries.
Fortunately, advances in the technical capabilities of software-defined radios (SDRs) make them suitable for engineering or scientific applications. In particular, such platforms can be used for source localization thanks to electromagnetic time reversal. Nevertheless, SDRs present unique challenges related to generating the radio-frequency signal. Therefore, this thesis aims to develop an experimental platform for source localization with an SDR and electromagnetic time reversal, demonstrating the feasibility of low-cost far-field imaging.

 

Master project

Contact Person: Amirhossein Mostajabi ([email protected])

LEMO, a global leader in the design and manufacture of custom precision connectors and cabling solutions, develops a high voltage, high frequency connector for laboratory applications. The project consists of developing a numerical model of the current connector design to improve its performance in terms of withstand voltage and partial discharges.

The project will be co-supervised by LEMO.

  • Design of an electric field sensor for the measurement of lightning electric field. 

Semester or Master project

Contact Person: Antonio Sunjerga ([email protected])

The purpose of this project is the design and calibration of an electric field sensor for the measurement of the wideband electric field radiated by a lightning discharge. Lightning produced electric field is typically observed with electrically small flat plate antenna. The output of such antenna is proportional to the derivative of electric field. The output of the antenna has therefore to be electronically integrated. The design of the integrator is based on a trade-off between the sensitivity and measuring range. The aim of this project is to design a measuring system with two integrators, one with high sensitivity and low range, and second with low sensitivity but high range, connected to the same antenna. The calibration of the system will be performed in the laboratory.

  • Simulation and Scaled Model Measurements of Grounding Systems in Elevated Terrain 

Semester or Master project

Contact Person: Antonio Sunjerga ([email protected])

The quality of a grounding system is measured by the value of its input impedance. The lower the impedance the better the grounding system. Telecommunication towers and wind turbines are usually placed on elevated terrain to either obtain line of sight or a higher power gain. Due to their height, there is high risk of lightning striking those structures. In the case of a non-flat terrain, due to the reduced volume of soil, grounding resistance of such structures at those locations is increased. The aim of this study is to investigate the influence of non-flat terrain by both simulations and measurements on a reduced-scaled model. The student will be provided with measuring setup and the simulation framework.

  • Lightning current waveform analysis

Semester or Master project

Contact Person: Dr. Mohammad Azadifar ([email protected])

The aim of this study is to investigate the dependency of lightning channel-base current waveshape to the channel geometry. In this study, use is made of the Säntis Observatory facilities, specifically the current waveform recording system, lightning broadband interferometry, and high-speed video camera, to analyze different current pulses and get insight into the physics of lightning discharge.

  • Comparison of lightning characteristics over land and ocean

Semester or Master project

Contact Person: Amirhossein Mostajabi ([email protected])

Thanks to the available data from the geostationary satellites, for each 20 seconds time window and over an area of 32580 km x 32580 km covering north and south Americas, we can estimate the number, energy, and spatial coverage of the occurred lightning flashes. Since the covered area by the satellite includes both land and ocean, one can do a statistical analysis on how the aforementioned parameters differ between the lightning flashes occurred over land and ocean.

  • Localisation of multi electromagnetic sources using electromagnetic time reversal (EMTR) and machine learning (ML)

Semester or Master project

Contact Person: Amirhossein Mostajabi ([email protected])

We aim to use the power of EMTR and ML together to localise multiple electromagnetic sources inside a medium. In the EMTR part, we use the data from multiple electric/magnetic sensors and in the ML part the convolutional neural networks will be used.

  • Numerical Validation of Electromagnetic Time Reversal for Geolocation of Lightning Strike Using 3D-FDTD

Master project

Contact Person: Dr. Hamid Karami ([email protected])

Electromagnetic Time Reversal Technique (EMTR) was implemented to locate lightning return stroke using 2D-FDTD based on the entropy criterion. Scatterers are included in the computational domain to emulate the presence of the objects. However, 2D-FDTD cannot model the terrain, lossy ground or antenna factors like directivity. In this work, the student will extend the algorithm to the 3D case to model a lossy ground, terrain and antenna factors. Some new EMTR concept such as 1-bit time-reversal or clipping technique will also embedded in this project.

  • Numerical Validation of Electromagnetic Time Reversal for Partial Discharge in Power Transformers Using Green’s Functions

Semester or Master project

Contact Person: Dr. Hamid Karami ([email protected])

Generally, numerical techniques such as FDTD or FEM are used to detect the partial discharges in the power transformer. In this project, we propose to use Green’s functions for this purpose, which will allow to  significantly decrease the computation times.

  • DORT-Based Method Applied to Locating Resistive electrical faults

Semester or Master project

Contact Person: Zhaoyang Wang ([email protected])

Based on the theory of time reversal, DORT (Décomposition de l’Operateur de Retournement Temporel) is an extended version of the classical time-reversal operation and has been applied to locating soft faults in wired systems. The existing EMTR-based methods are challenged to locate resistive electrical faults, in particular those with relatively high fault impedance. Considering the general principle of TR and fault characteristics, it is promising to apply the DORT-based technique in locating resistive (high impedance) electrical faults.

The objective of the project is twofold:

  1. Study the theory of DORT
  2. Develop a DORT-based electrical fault location method.