This thesis aimed to process and characterize hydrogenated germanium (Ge:H) films to use them as a low-bandgap intrinsic absorber layer. The bandgap of Germanium can go down to 0.67 eV. A p-i-n solar cell consisting of intrinsic germanium film produced using Plasma Enhanced Chemical Vapour Deposition (PECVD) can be inexpensively paired with crystalline silicon and other semiconductor materials to produce a multi-junction solar cell with high efficiencies. Such a cell would utilize the lower part of the solar spectrum currently untapped in commercially available mass-produced solar modules. Previous research had deposited Ge:H films using a counterflow PECVD reactor, as compared to a showerhead configuration in the reactor used in this research.

The study consisted of experiments that explored the properties of the germanium film deposited. First, the deposition parameters of PECVD were varied to study its effect on important film properties. Since the germanium layer will be used in a solar cell as the absorber layer, the band-gap and activation energy were the most critical parameters to monitor film intrinsicity. Experiments were performed by depositing germanium layers on glass substrates and silicon wafers to understand the properties of the films when deposited at different temperatures and also when the germane flow was altered. The effect of the power and pressure on the properties of the germanium samples was studied too. In all these experiments, the deposition time and electrode gap are kept constant. The processing window of 3-4.5 mbar and 12-20 W where intrinsic amorphous germanium (a-Ge:H) films can be produced was identified.

Single junction solar cells in p-i-n and n-i-p configuration were then incorporated with the intrinsic amorphous germanium. The p-i-n configuration displayed solar cell characteristics, whereas the n-i-p configuration cells did not, despite the changes in doping of the p-layer. Further experiments were carried out to look into the stability of the material by repeating the J-V curve measurement of the first cell that showed solar cell characteristics, but similar behaviour was not observed. Additionally, Raman spectroscopy was carried out, which revealed that the material is amorphous.

In summary, the results look promising in proving these films as a suitable material for an intrinsic absorber layer. It also strongly suggests that the showerhead PECVD configuration can lead to better control of reaction mechanics, giving films with desired material properties. The layer can be used as an intrinsic layer in a p-i-n structure device, but further investigation is required to look into the interaction of the layers of the solar cells.

The world is currently undergoing an unprecedented energy transition from fossil fuel-based energy sources to renewable energy sources. Additionally, advancements in power electronics technology have made High Voltage DC (HVDC) the most cost-effective method for long-distance electrical power transmission over both sea and land. These developments have led to an increased presence of Power Electronic Interfaces (PEIs) in the electricity grid. The insulation of High Voltage (HV) equipment in the electrical power grid is subjected to various electrical stresses due to the solid-state switching of PEIs. This can weaken the dielectric material of the HV equipment and therefore reduce the reliability of the electrical power system. Conventional test sources cannot replicate complex waveforms. Therefore, it is necessary to develop an Arbitrary Waveform Generator (AWG) capable of testing HV equipment with complex waveform shapes. A Modular Multilevel Converter (MMC) is a promising topology for this purpose, where each submodule (SM) requires auxiliary power to supply the Gate Drive Units (GDUs) and Distributed Control Units (DCUs). The objective of this thesis is to design the Auxiliary Power Supply (APS).

This thesis proposes using a flyback-based Input Series Converter as an APS. The proposed converter offers advantages such as integrated active Input Voltage Sharing (IVS), a scalable design, wide-input operation, and a minimal component count. The proposed converter topology is compared with other topologies discussed in the literature through SPICE simulations. Furthermore, various synchronous switch driving methodologies are studied and compared, given the necessity of series-connected switches with the currently available devices on the market.

A critical aspect of the design of a flyback-based Input Series Converter is the multi-winding transformer; hence, this thesis places special emphasis on the electrical and mechanical design of the flyback transformer. The transformer provides HV insulation between the SM capacitor and the output of the APS, as well as active IVS for balancing the voltage across the input stage capacitors and the MOSFETs. A prototype of the multi-winding transformer has been developed and used to assemble an open-loop converter. The converter's performance is tested with an input voltage range of 300V–3600V, and the design is further refined with an output diode snubber circuit.

A scalable, compact, and reliable topology has been identified for an HV-wide input APS for an MMC-based AWG. The topology provides suitable HV isolation between the SM capacitor and the APS output, as well as between the gate pulse generator circuit and the APS power stage. However, the transformer winding design led to a mismatch in leakage inductance between the different converter primary side stages. This resulted in a slight discrepancy in the voltage shared between the series-connected MOSFETs during the converter's turn-off stage. Future work should focus on employing a winding design that ensures equal coupling of all primary windings to the secondary winding in the flyback transformer. Additionally, it is recommended to use a coupled inductor-based passive LC snubber rather than an RCD snubber across the primary windings to introduce an active IVS process during the turn-off stage of the converter as well.

Energy arbitrage is a key activity in privately-owned energy storage system portfolios. However, the profitability of battery energy storage systems in this domain is limited by two primary challenges: the high cost of battery manufacturing and the insufficient temporal volatility of electricity prices within individual bidding area.

In this context, this study explores the economic viability of relocating the utility-scale battery energy storage systems. To enhance profitability, the proposed portable energy storage system integrates a semi-empirical battery degradation model to accurately account for degradation costs, while its mobility
allows for travel between different bidding zones to exploit inter-zonal electricity price differences.

A mixed-integer linear programming model is built to optimize the system’s daily charging/discharging and transportation scheduling. The system’s daily operations within the Norwegian day-ahead market are simulated using a Python model.

The investigation includes comparative analyses to assess how battery location, chemistry, and degradation models influence system profitability. The study compares stationary and portable battery energy storage systems: in the stationary case, it evaluates profitability with different battery chemistries (lithium ferrophosphate and lithium manganese) in different locations, while the portable case explores the impact of different battery chemistries and degradation models (semi-empirical vs. conventional energy throughput).

The findings reveal that none of the stationary energy storage systems can achieve break-even through conventional temporal arbitrage in the Norwegian day-ahead market. In contrast, relocating the battery proves profitable for all four portable energy storage systems.

Additionally, the application of the depth-of-discharge-aware semi-empirical model enhances profitability of portable systems with both battery chemistries, with the lithium manganese system showing a more than 15% increase in investment return rate. This makes lithium manganese a more attractive option than the lithium ferrophosphate battery due to its lower investment cost, shorter payback period, and higher return on investment.

For the delivery of Shore to Ship power, the 'status quo' of shore power delivered just from the grid results in the overcapacity of power installation, these resources need to be more optimally utilized.
This research investigates what configuration of electrical components to deliver shore power to vessels is the most cost-effective at the quay-side of Royal Roos.
This thesis ends with the answers to the research questions that guided the research, and thereby help explain under which conditions an implementation for shore power supply is more cost-effective than another

For the delivery of Shore to Ship power, the 'status quo' of shore power delivered just from the grid results in the overcapacity of power installation, these resources need to be more optimally utilized.
This research investigates what configuration of electrical components to deliver shore power to vessels is the most cost-effective at the quay-side of Royal Roos.
This thesis ends with the answers to the research questions that guided the research, and thereby help explain under which conditions an implementation for shore power supply is more cost-effective than another

The increasing penetration of renewable energy sources, such as wind and solar power, introduces significant uncertainties and challenges to conventional power grids. These challenges primarily arise from system frequency instability and voltage fluctuations due to the lack of inertia typically provided by conventional synchronous generators (SG). To enhance grid resilience and mitigate potential power quality issues, synthetic inertia is emulated by Grid-Forming (GFM) inverters, imitating the dynamics of conventional synchronous generators.

This thesis addresses these challenges by investigating the integration of supercapacitors (SC) and the implementation of advanced GFM control strategies, such as Virtual Synchronous Generator (VSG) control, within solar power generators. The primary objective is to ensure power quality and enhance system stability, particularly in scenarios involving high penetration of renewable energy, where the absence of conventional inertia can lead to significant voltage and frequency deviations. In this research, a comprehensive solar power generation system is designed, integrating a 200kW photovoltaic (PV) system with a 100kW SC storage system on the DC bus. The design aims to mitigate the adverse effects of frequency and voltage fluctuations while providing synthetic inertia through the integration of the SC energy storage system and the implementation of VSG control. These strategies are crucial for maintaining system stability and ensuring a rapid response to grid disturbances.

Extensive simulations and analyses are conducted to evaluate the performance of the proposed system under various operational scenarios. Case studies are performed under different assumptions. The results demonstrate that the synthetic virtual inertia significantly enhances the system’s ability to manage voltage and frequency deviations, providing a robust and reliable solution to maintain grid stability in the GFM solar power generator.

This thesis implements the proposed design of a solar power generator that can effectively ensure system stability in power systems with high levels of renewable energy penetration.

Fault ride-through capability studies of MMCHVDC connected wind power plants have focused primarily on the DC link and onshore AC grid faults. Offshore AC faults, mainly asymmetrical faults have not gained much attention in the literature despite being included in the future development at national levels in the ENTSO-E HVDC code. The proposed work gives an event-triggered control to stabilize the system once the offshore AC fault has occurred, identified, and isolated. Different types of control actions such as proportional-integral (PI) controller and super-twisted sliding mode control (STSMC) are used to smoothly transition the post-fault system to a new steady state operating point by suppressing the negative sequence control. Initially, the effect of a negative sequence current control scheme on the transient behavior of the power system with a PI controller is discussed in this paper. Further, a non-linear control strategy (STSMC) is proposed which gives quicker convergence of the system post-fault in comparison to PI control action. These post-fault control operations are only triggered in the presence of a fault in the system, i.e., they are event-triggered. The validity of the proposed strategy is demonstrated by simulation on a 525 kV, three-terminal meshed MMC-HVDC system model in Real Time Digital Simulator (RTDS).

The thermal rating of power cables is a critical aspect of electrical cable design that determines their safe operational limits. Traditional rating methods rely on worst-case assumptions for weather conditions, such as constant ambient temperatures or steady-state loading with a 100% load factor. Given the significant thermal masses and variations in ambient conditions, these assumptions often do not reflect actual operational scenarios. As the integration of fluctuating renewable energy sources into power systems increases, the dynamic nature of these systems becomes more pronounced. Consequently, the thermal rating of the power cables must be considered dynamic to accommodate these changing conditions. In this thesis, an improvement of dynamic cyclic rating predictions is explored for cable temperatures using the Finite Element Method (FEM). This improvement is performed by incorporating detailed weather and environmental data into the model. The study begins with a comprehensive literature review that provides an overview of existing dynamic rating systems and their applications. Subsequently, an analytical and numerical thermal model was developed and compared with COMSOL and CIGRE standards. It is concluded that the developed numerical model demonstrates greater accuracy and usefulness. This numerical model is integrated into a web-based tool called Ampwise, which serves as the basis for all future improvements. Cable data from the Windpark Fryslân project is used to validate the predicted temperature against the measured cable temperature. The research demonstrates that incorporating weather data significantly improves the precision of dynamic cyclic ratings, especially the inclusion of the real external air temperature and solar radiation of the location. Validation of the predicted conductor temperatures against measured DTS cable temperatures from the Windpark Fryslân project showed a mean absolute error (MAE) of 1.9 °C and a root mean square error (RMSE) of 2.3 °C. These results show the enhanced accuracy and reliability of the dynamic cyclic ratings when real weather data are incorporated. However, the rate of change in the real temperature is significantly higher than the predicted temperature, leading to short-term differences between the predicted and actual temperatures. In addition, a sensitivity analysis is conducted to assess the impact of various factors. The analysis highlights the importance of correct initial conditions, particularly ground temperature gradients and seasonal environmental variations. The thesis concludes that integrating weather and environmental data into dynamic rating models is crucial to achieving reliable and precise cable performance predictions over an extended period, thus supporting better operational decisions and infrastructure management.

As the global shift towards renewable energy accelerates, it is crucial to address the inherent challenges and fully leverage its potential. Electric power systems have undergone significant transformations, transitioning from traditional generation methods to those incorporating renewable energy sources and power electronic interfaces (PEI). This transition necessitates extensive research to ensure future grid stability and reliability. This thesis work aimed to enhance a Root Mean Square (RMS) synthetic model of the future 380 kVDutch power system and conducted comprehensive research using this model. A scenario analysis was conducted to evaluate various future scenarios for the Dutch power system, highlighting deviations and uncertainties. The national scenario from the II3050-2 project was selected as the baseline for further work. This approach ensured a comprehensive understanding of potential future developments and their implications for policy and planning. The synthetic model was developed by updating the existing model with new dynamic models and parameters as defined by IEEE and CIGRE standards and aligning it with future public projections and investment plans for the Dutch power system towards 2050, rooted in the scenario analysis. This included upgrading infrastructure such as transmission lines and substations and incorporating new generation and flexibility resources. The model was designed to enhance the dynamic characteristics and facilitate extensive research by integrating DigSilent PowerFactory, Python, and Excel. Three different case studies were performed using the enhanced synthetic model to analyze the system’s response to various perturbations. These studies evaluated the impact of varying levels of renewable generation and load, the role of grid-forming converters, and the effects of different kinetic energy and inertia constant levels on system stability with respect to frequency and rotor angle stability. The findings underscored the significant potential of grid-forming converters to enhance frequency stability and system damping, the influence of controller parameters on system performance, and the critical role of kinetic energy and inertia in maintaining system resilience. By leveraging the capabilities of PowerFactory, Python, and Excel, the research demonstrated the utility of the enhanced synthetic model in facilitating a broad range of stability studies and other analyses. This work provides a valuable foundation for future research and regulatory planning, contributing to the ongoing efforts of Dr. J.L. Rueda Torres’ team. The findings have been submitted to international journals and conferences, emphasizing the importance of continued technological adaptation and research to ensure stable and resilient power grids. Future work should focus on developing smart control strategies, optimizing dynamic control settings, investigating the impacts of kinetic energy and inertia constants, enhancing the synthetic dynamic model with additional features, and assessing the role of flexibility resources in future scenarios. This research offers crucial insights into the evolving dynamics of power systems and sets the stage for further advancements to ensure their stability and resilience.

This paper presents the design and development of an Electrical Discharge Machining (EDM) device aimed at achieving precise hole creation in diverse metal materials. The EDM device was conceptu- alized and constructed based on specific requirements identified by the group. The design process encompassed four main stages: dielectric fluid selection, electrode design, control system develop- ment and power supply. In the dielectric fluid stage, the importance and criteria for selecting an appropriate fluid were discussed, resulting in the choice of distilled water for its superior dielectric properties. The electrode design stage followed a similar methodology, leading to the selection of a copper rod as the optimal electrode material. The control system stage detailed the development of an open-loop, manual, and closed-loop control system, emphasizing the utilization of Klipper software for precise electrode control. The power supply section outlined three primary circuits: the power source, power amplification circuit, and square wave generator circuit. Detailed schematics, component justifications, and optimization values for key parameters were provided to enhance power supply efficiency. Experimental evaluation demonstrated the capability of the EDM device to effectively create holes in various metals using an open-loop control system. Additional experiments focused on parameter variations within the power supply setup further illustrated their impact on machining performance. The discussion highlights the challenges encountered throughout the project, particularly the constraints imposed by limited time, which prevented the realization of all initially set requirements. Despite these challenges, the EDM device successfully met most of the specified objectives, showcasing promising results for future refinements and applications in precision machining.

The goal of this project is to create a power supply for an electrical discharge machine (EDM). This machine can drill holes and create shapes in metal objects by evaporating material using discharges from the electrode to the workpiece. The electrode should be supplied with a high-voltage pulse wave in order to initate sparks. The power supply produces this waveform by turning a DC source on and off using a transistor as a switch. A current-limiting resistor that is placed between the source of the MOSFET and the electrode prevents short circuits during discharges. The circuit was first created with a DC voltage of 15V. A gate driver circuit to drive this MOSFET was designed to reduce power losses and to make the frequency and duty cycle adjustable. Then the design was improved by adding a diode to remove oscillations caused by the parasitic inductance of the power resistor. Afterwards, the circuit was built on a custom PCB to reduce parasitics. A filtering capacitor was added to remove high-frequency noise, after which a stable 15V pulse signal was obtained. A microcontroller is employed to regulate the pulse duration, detect spark occurrences, and relay this information to a speed regulator. This establishes a closed-loop system aimed at optimizing the overall system operation. To achieve this, circuitry is employed to convert the power supply output into a digital format, enabling the utilization of the microcontroller’s specialized hardware for rapid sampling.

Many functional photovoltaic (PV) modules are decommissioned prematurely, often due to the financially motivated repowering of PV systems. This study assesses under which circumstances there is an environmental incentive to reuse these modules as opposed to recycling and replacing them with new, more efficient modules. A life cycle assessment was conducted, covering the end-of-life treatment, manufacturing, transport and use phase of decommissioned and new modules. The decommissioned modules had an efficiency of 14.7% in 2011, the new modules have an efficiency of 19.79%. The analysis covers two different reuse scenarios (local and export) and two different replacement scenarios, based on the quality of the recycling and the manufacturing country of the new modules.

The impacts are quantified in three categories: global warming potential, eco-cost of resource scarcity and total eco-cost. The findings indicate that, because of rapid technological advancements, the recycling and replacement of 10-year old decommissioned modules generally yield greater environmental benefits than local reuse: the net benefit in terms of global warming is greater after only 5 years. In addition, the calculations show that reusing decommissioned modules in a new PV system is only the preferred strategy from a global warming perspective if the modules are less than 5 years old, if that system is intended to have a (financial) lifetime of 10 years or longer.
However, reuse in a selected European Union member state can provide greater benefits in the global warming potential and total eco-cost impact categories than recycling and replacement. The advantage of export is driven by higher annual irradiation as well as a higher emissions intensity of the electricity mix.

These results contrast the conventional belief that reuse is always environmentally preferable to recycling. Based on this research it can be argued that in most cases of premature decommissioning, there is no strong environmental incentive to reuse the modules, provided that new PV modules are widely available or that the materials go directly to the production of new modules. The annual efficiency increase of PV technology was identified as a key parameter for this outcome.