Electrical Engineering

Title: Grid Capacity Analysis for Cold Ironing: A Study of Ports and Maritime Vessels 15th of May at 13.00-14.00 in EDIT room number 3364 Opponent: Sima Soltanipour Examinator: Jimmy Ehnberg
This thesis examines the limitations of short-circuit capacity within electrical grids during ship-to-shore power transfers. Utilizing power system analysis software, the study investigates short-circuit scenarios under various conditions, including transient events and potential faults on both the vessel and shore-based installations.&nbsp; The research identifies key factors influencing short-circuit risk in SP systems. These include:
• Voltage stability: Maintaining voltage levels during load transfer between shipboard and shoreside power sources is crucial. Adjustments to transformer tap settings play a vital role in ensuring voltage stability.&nbsp;
• Load sharing: Parallel synchronization methods require careful consideration of combined short-circuit contributions from shipboard generators and shoreside grids to mitigate potential fault currents.&nbsp;
• Worst-case scenarios: Assessing scenarios with unknown shoreside grid parameters is critical. The study highlights the potential for higher short-circuit currents during critical events like large load startups.&nbsp;
This research emphasizes the importance of effective risk management for safe and reliable ship-to-shore power transfers. By evaluating short-circuit capacity limitations and implementing appropriate mitigation measures, such as system upgrades or operational adjustments, the overall safety and reliability of these power transfers can be significantly enhanced.
Welcome! Saman, Tohid and Jimmy

Invariant feature extraction for three-phase power quality disturbances -&nbsp; Large Compact and interpretable features improve performance on downstream tasks
Examinator: Lars Hammarstrand Room: Edit Analysen
Abstract: Feature extraction is a crucial step for tasks such as classification, clustering and predictive risk estimation. In power quality analysis, feature selection is often performed by domain experts. However, crafting a small yet sufficiently informative feature set is often challenging, particularly when evaluation data is scarce.
In this thesis, we present an autoencoder-based feature extraction method tailored for spectrograms of three-phase current and voltage waveforms. The extracted feature set is invariant with respect to time translation and sample length, and we demonstrate that sufficient information is retained to reconstruct the spectrogram with high accuracy. By applying Uniform Manifold Approximation and Projection (UMAP) with a specific pseudometric, invariance with respect to phase permutations can be obtained while further reducing the dimensionality of the extracted features.
The interpretability of the extracted feature sets is evaluated by showing how the reconstructed signals change when the latent variables are perturbed. The usefulness of the features is measured on a root cause disturbance classification task, where they are compared to features selected by a domain expert as well as principal component analysis based features. Our proposed features perform the best for all examined sizes of training sets when training a neural network classifier. Particularly notable improvements are observed for the smallest training sets. In addition, employing a model-free label propagation method on our features reveals further performance improvement. Curiously, we find that pretraining the autoencoder yields better reconstruction fidelity, even when the pretraining dataset consists of audio recordings that are very dissimilar to power quality measurements.
Keywords: Power Quality, Autoencoder, Classification, Feature Extraction, Three-Phase, Invariance, Uniform Manifold Approximation and Projection
Welcome!
Valter, Elias and Lars

Performance Benchmarking between LV BESS and MMC based MV ESS with Grid Forming Control
Master Thesis conducted at Hitachi Energy, under the supervision of Dr. Haofeng Bai Opponents: Ajay Krishna and Viswanathan Ganesh&nbsp; Examinator: Massimo Bongiorno
Online presentation via Teams (please see link below) Abstract&nbsp; FACTS devices are particularly systems which use power electronic switching facilitating faster switching than electro-mechanical switches, to enhance controllability and power transfer capability in the grid. This is done by the injection of appropriate active and reactive power to the grid. An accurate design of FACTS systems provides the grid to be strong and healthy. The advent of renewable-based compensation to the grid, contributes to reduction of grid strength. The reason for this is instability is that the power electronics based compensation devices do not provide the active power injection to the grid, based on its requirement, which necessitates the facility of grid forming control, a method which is the need of today for incorporating renewable sources connected to grid. The thesis work aims at comparing two types of FACTS converter systems namely LV based BESS which is connected by 2 transformer stages to the main grid and MMC based MV ESS connected by a single transformer stage to the main grid utilizing the strategy of grid forming control. The impact of transformers on the control performance between the two types of converter systems is to be investigated in this thesis work.
Welcome!&nbsp;
Reno Joseph and Massimo&nbsp;
Microsoft Teams: <span style="font-size: 11.0pt; font-family: 'Segoe UI',sans-serif; mso-fareast-font-family: Aptos; mso-fareast-theme-font: minor-latin; color: #242424; mso-ansi-language: SV; mso-fareast-language: SV; mso-bidi-language: AR-SA;"><a rel="noopener" href="https://teams.microsoft.com/l/meetup-join/19%3ameeting_NjNkNTAxOTYtOTIzMi00ZTBjLWI3MDgtNWJkMTI5MDY0Mjk5%40thread.v2/0?context=%7b%22Tid%22%3a%2229147a65-536d-43f9-b802-e0a1b5cf9dbf%22%2c%22Oid%22%3a%22b83f7db0-c874-4f34-a5d6-3c8457773823%22%7d" target="_blank" title="Meeting join link">Join the meeting now</a> Meeting ID: 370 979 302 978&nbsp; Passcode: inoizw&nbsp;

Titel: Sensorlösning för att detektera objekt inom ett begränsat arbetsområde. Tid: Måndag den 20 maj, kl 09:00 Plats: Landahlsrummet 7430&nbsp; Examinator: Thomas Eriksson Opponents: Eric Amby and Jared Alexander Tittus&nbsp;
Abstract The following report presents a project assignment for Combitech, tasked with developing a sensor solution to detect objects within a specific work area. The primary purpose is to protect individuals from harm by preventing collisions with a moving unit. This project is more of a preparatory work, where the final product does not need to be ready for mass production, and there are already some existing input values that the sensor solution must be adapted to.
Based on the project’s purpose several questions where asked to clarify what challenges needed to be addressed. These question included everything from, which type to quantity off sensors, as well as how the sensor solution could be constructed to be able to effectively control the sensor while maintaining user-friendliness. The project also contained several objectives. The main focus of those was to be able to measure the sensor’s ability to detect object inside the working area while not show detection for objects outside the are or other disturbances. Other objectives for the project was also set regarding the sensor solution’s adjust-ability and cost-effectiveness.
The project’s workflow began with brief studies and tests of different kind of sensor types. These sensors were controlled using a development board with&nbsp; a microcontroller (programmable control unit) and simple programming codes. This phase was then followed by a final selection of sensors along with construction of the electricalsystem for the chosen sensors. This system would encompass the control logic of the sensors and other important functions of the sensor solution. Based on the electrical system, a circuit board could then be designed and ordered along with the selected&nbsp;electrical components. In the final phase of the project, the work was to solder the components onto the circuit board while simultaneously developing a final program code for the system. Finally, the card was functionally tested to evaluate its performance based on predefined goals.
The project’s final tests showed good results regarding detection within the specific work area, with a 99 percent accurate detection of an object measuring 200 x 200 mm. At the same time, no false detections were recorded despite the fast detection time of 22 milliseconds. The sensor solution’s working range can be adjusted using a push button, and the distance set is indicated by a blue LED on the circuit board. Additionally, there is a red LED on the circuit board indicating when the sensor solution detects objects within the work area.
In summary, the report represents a work of a final solution for a product that largely meets its main objectives and provides good detection reliability. However, there are significant development opportunities in areas such as cost-effectiveness, testing, and performance optimization in various environments, leaving some work&nbsp;for the next version of the product.
Keywords: sensor solution, ultrasonic sensor, circut board, detection, microcontroller.
Welcome!
Martin, Anton and Thomas

Enhancing Battery Life in the Finnish FCR-N Market: Evaluating the Potential of Flywheel Technology Date: 21st of May Room: Analysen Opponent: Arthur Vankeirsbilck
Abstract: The integration of flywheel technology with battery energy storage systems (BESS) presents a promising strategy to improve both the operational lifetime and economic viability of energy storage solutions for providing ancillary services. In this study, Mixed Integer Linear Programming (MILP) optimisation modelling is employed to investigate the benefits of combining batteries with flywheels in the context of grid frequency regulation (FCR-N market) while considering battery degradation and varying ratios of flywheel to battery capacity. The results reveal that battery degradation has little impact on the optimal dispatch of a hybrid system. highlighting the robustness of the flywheel-battery combination in mitigating battery wear during ancillary services provision. The findings demonstrate that integrating flywheels into battery systems can significantly extend the operational lifetime of the battery. Specifically, a hybrid system with a flywheel-to-battery capacity ratio of 0.2 is recommended and exhibits a notable 2.7-fold extension of battery lifetime. Moreover, the incorporation of flywheels unlocks diverse business opportunities that are not feasible with standalone battery systems, enhancing the overall economic value of the energy storage assets.
Welcome!
Douwe and Jimmy

Wind power design for high capacity factors - A techno-economic analysis of specific power reduction and wind-solar hybrid plants
Date: 21 of May at 11:00 Room: EDIT-room 3364 or TEAMS (see below)
Opponent: Matilda Karlsson Examinator: Ola Carlson Supervisor: Anders Wickström, RISE
Abstract: Wind power production is the fastest growing electricity producing technology in Sweden today. One of its challenges is its intermittent nature and rather low capacity factor. Therefore, this thesis investigate the effects of increasing the wind power capacity factor beyond values of 0.5. Alternatives for hourly production estimates for a single turbine, based on historical data, have been proposed, analysed, and validated.  Two studies have been conducted. The first increases the capacity factor by decreasing the specific power, while the second consists of complementing a wind turbine with solar power. The work has analysed the consequences by these design changes on both costs and production, and the results are continuous functions of LCOE, value factor, and profit with respect to an increased capacity factor. From this, conclusions are drawn regarding the feasibility of the proposed design changes.
Most welcome!  Emma Albinsson and Ola Carlson
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Title: Antenna Obstruction Cloaking Room: E2 Room 7430 Landahlsrummet
Opponent: Filip Aldebrink and Rikard Carlsson Examinator: Rob Maaskant Supervisor: Andreas Wikström, Saab AB
Abstract: This report theoretically investigates different techniques of electromagnetic cloaking and anti-scattering on a cylindrical metallic object, e.g. a cord or a pole, along the vertical axis obstructing a vertically polarized antenna (i.e. a worst case scenario in terms of scattering) at 9.5 GHz/X-band. Multiple 'shells' around the pole obstructions have been designed with different materials and shapes, for simulations around metallic poles of diameters 5 cm and 10 cm at different distances from the antenna. A total of 5 designed shells have been simulated in Ansys 3D High Frequency Simulation Software (HFSS) in order to evaluate their performance in terms of realized gain and average sidelobe levels for different steering angles in the H-plane/azimuth plane. The evaluated shells around the poles are 1) a layer of thin radiation absorbent material made out of ferrites (narrowband absorbent), 2) a rhomb made out of PEC, 3) a rhomb made out thick radiation absorbent material with increasing conductivity (wideband absorbent), 4) a rhomb made out of PEC supplemented with a dielectric outer edge and PEC strips around the circumference of the structure, and 5) a theoretical layered meta-material cloak together with means to obtain such a solution in practice. In terms of realized gain and average sidelobe levels the rhomb shaped shells perform the best (shells 2, 3 and 4), with emphasis on the design absorbing scattering (shell 3) and the design that to some extent steers electromagnetic waves around its circumference (shell 4). The theoretical layered meta-material cloak had likely performed best if the antenna had been TM polarized.
 Most welcome!&nbsp; Dennis Lundqvist, Agnes Wilhelmsson and Rob Maaskant
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Self Driving Bike Project - Implementing a Speed-Controller in a Self Driving Bike
Examinator: Jonas Sjöberg Plats: Rum 5430 E-huset, Femman Opponents: Anton Olsson and Martin Bengts
Abstract: The Autobike project, launched at Chalmers University of Technology in 2017, aims to create a self-driving bicycle that mimics regular biking. Its purpose is for testing with autonomous cars and the project includes several bikes developed by different students.
The project previously encountered challenges related to slow response for the bike to overcome the friction between the ground and the bikes wheels. This led to a significant delay between setting a reference speed and the bike reaching it. To overcome these obstacles our contribution focused on developing a two-phased speed controller. This controller aimed to minimize both dead-time and overshoot/undershoot, while ensuring smooth transition between the start-up and rolling phase. Additionally a simulation-based speed controller was implemented to accelerate parameter identification for the PI controller used on the real-time system.
A new approach has been implemented in the simulation to ensure the bike reaches a predetermined destination at a specific time, employing a time-trajectory. This trajectory changes the bike's speed depending on its distance to the set referenced points along the route. The time-trajectory has only been integrated into the simulation and not tested on the real-time system.
Welcome!
Eric, Jared and Jonas

Welcome to the Master Thesis Presentation &nbsp; &nbsp; Humidity Dependent Surface Charging In Air For HVDC Applications&nbsp; by Jin Wang &nbsp; Master Thesis conducted at Hitachi Energy, Chalmers University of Technology
Conducted at Chalmers, under the supervision of Olof Hjortstam and Xiangdong Xu Examiner: Xiangdong Xu
Opponents: Abhishek Subramanya, Ali Koseoglu and Linhua Lai Time: 10:00-11:00 on Tuesday, May 28, 2024&nbsp; Place: Fredrik Lamm, Department of Electric Power Engineering&nbsp; &nbsp;&nbsp; Abstract The performance of polymeric insulation holds a critical role in ensuring the safety and stability of high voltage direct current (HVDC) systems, which is particularly sensitive to environmental conditions, especially in outdoor applications.&nbsp;
This thesis explores the dynamic interaction between surface charge accumulation and atmospheric humidity at polymer-air interfaces, crucial for improving insulation performance in HVDC applications. Given their essential role in HVDC systems, the underlying mechanisms of surface charging, influenced significantly by environmental conditions such as humidity, have remained underexplored. This study employs a comprehensive experimental setup to systematically analyze how different humidity levels influence surface charge dynamics across various conditions, including electrical field strength, air gap length, electrode radius, and polarity.
The work utilizes a specially designed experimental setup capable of controlling humidity, accommodating varied configurations, and measuring surface charges. It identifies key factors that differentiate the effects of humidity and elucidates mechanisms driving the charge accumulation dynamics.
This presentation will outline the experimental methodology, key findings, and their potential implications for HVDC systems. It aims to establish a foundation for future research and advancements in high-voltage insulation technology.
Welcome!&nbsp;
Jin, Olof &amp; Xiangdong&nbsp;

Energy system analysis of Volvo Penta’s Microgrid with optimized battery storage
Examiner: David Steen, E2 Supervisor: Niklas Lundin, Volvo Penta Opponents: TBD Date and time: 4 June 2024, 10.00-11.00 Location: Fredrik Lamm, room 2503
Abstract: This thesis investigates the integration of battery storage solutions within marine Microgrid (MG) environments, focusing on the Krossholmen test site operated by Volvo Penta. A systematic literature review employing integrative and meta-analysis approaches establishes the theoretical foundation, covering topics such as linear optimization, energy-systems modeling, and future energy scenarios. Detailed descriptions of the Krossholmen MG's technical specifications, including demand profiles and energy system components, are documented to facilitate accurate modeling.
Future energy scenarios, reflecting variations in electricity markets and renewable energy adoption, are developed to assess the effectiveness of battery energy storage solutions under different conditions. Linear optimization techniques, implemented through Python-based modeling modules, are utilized to determine the optimal operation of the MG. A minimize-cost objective function, incorporating various constraints, guides the modeling process, with provisions to incorporate non-linear data, such as battery degradation, in later stages. The project encompasses seven major milestones, each aligned with specific deliverables, ensuring the project's successful execution within the allocated timeframe. Through this comprehensive approach, the thesis contributes to advancing understanding and practical applications of battery storage within marine MG contexts.
Welcome!
Jonathan and David

"Pre-flight Mission Simulation Model for Estimating State-of-Energy(SoE) in Hybrid Aircraft"
Abstract: &nbsp; Accurate estimation of state-of-energy (SoE) is critical for the safe and efficient operation of aircraft. The multiple energy sources available in hybrid-electric aircraft make the SoE estimation a highly complex challenge. To address this, a pre-flight mission simulation model for estimating SoE has been developed and validated for hybrid-electric aircraft. This model serves two primary purposes: first, it aids in developing aircraft functions for mission planning in hybrid-electric aircraft; second, it can be used as an analysis tool for developing energy management strategies in hybrid-electric aircraft. The simulation model includes detailed models such as a mission planner, weather model, supervisory controller, aircraft model, both conventional fuel driven and electric propulsion system models and battery models. The methodology for developing and validating this simulation model is described and simulation results for hybrid-electric aircraft mission are presented.&nbsp;
Examiner: Anders Grauers, E2
Opponents: Halime Selimoglu and Bharathi Subramaniam Muthuramalingam
Date and time: 4 June 2024, 15.00-16.00 Location: &nbsp;<span style="font-size: 10.5pt; line-height: 107%; font-family: 'Lato',sans-serif; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; color: black; mso-color-alt: windowtext; background: #F9F9FA; font-weight: normal;"><a href="https://maps.chalmers.se/#ff20a7f0-3b89-11ea-b363-0d727521c5d9">Femman, E2 Room 5430</a>
Welcome!

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Presentation of master thesis

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Presentation of master thesis

Master thesis presentations at Electrical Engineering

15 May 2024

13.00-14.00 Saman Chashm and Fassa Tohid Haddadi, MPEPO

16 May 2024

15.00-16.00 Valter Schütz, MPSYS and Elias Stenhede Johansson, MPENM

17 May 2024

09.00-10.00 Reno Joseph Selvaraj, MPEPO

20 May 2024

09.00-10.00 Martin Bengts and Anton Olsson, TIMEL

21 May 2024

10.00-11.00 Douwe van Alderwerelt van Rosenburgh, Master’s Programme in Innovative Sustainable Energy Engineering (ISEE)

11.00-12.00 Emma Albinsson, MPSES

22 May 2024

14:00-15:00 Dennis Lundqvist and Agnes Wilhelmsson, MPWPS

27 May 2024

09.00-10.00 Eric Amby and Jared Alexander Tittus, TIMEL

28 May 2024

10.00-11.00 Jin Wang, MPEPO

4 June 2024

10.00-11.00 Jonathan Sjölander, MPSES

15.00-16.00: W A Volanka Stepson, MPSYS and Nilantha Dadallage, MPSYS