The research is conducted via collaboration betweenthe Delft University of Technology, Netherlands and Alewijnse Netherlands B.V. The objective of this work is to verify the techno-economic feasibility, of a proposed hybrid marine vessel configuration. This proposed hybrid solution now requires an upgraded Energy Management System, to efficiently make use of the distributed energy resources on the grid. Verification of these results are conducted in real time using the Typhoon Hardware - in - Loop (HIL) platform, to create a Digital Twin of the proposed hybrid marine vessel. The designed digital twin, with modified EMS control, is specifically aimed to optimize vessel operations in the DP2 mode. The designed EMS control ensures the vessel operates it's diesel generators at their optimal loading points, in combination with the battery energy storage system. This operation effectively reduces fuel consumption, reduces maintenance costs for generators and green house gas emissions. The findings of this research contributes to the field of green ships and marine industry decarbonization.

The global shift towards sustainable energy sources, together with rapid technological advancements, has driven a significant increase in the demand for electric vehicles (EVs) over recent years. This surge in EV adoption highlights the critical need for robust supporting infrastructure, particularly in the deployment of efficient and accessible EV chargers. Gallium Nitride (GaN) is a wide bandgap semiconductor material that offers better performance characteristics compared to traditional silicon-based components in medium-power and high-frequency application. Its higher electron mobility, saturation electron velocity and breakdown electric field make GaN an ideal candidate for high-frequency power conversion applications in EV chargers. To explore the potential of GaN technology in EV charging applications, an 11kW GaN based isolated bidirectional multi-port EV charger with a two-stage architecture has been designed to interconnect bipolar DC grid and electric vehicles. The two stages of the charger consist of a three-level triple active bridge converter and a three-level interleaved buck converter. The TAB converter is an extension of conventional dual active bridge (DAB) converter, offering capability to direct power transmission among three ports. However, the addition of a third port introduces complexity in managing power flow. The TAB converter can operate under various modulation schemes, including three-level and five-level modulation. An analysis of the switching modes associated with each modulation scheme has been
erformed. In order or derive the soft switching range of the converter, the current expression
of series inductors of each port are derived based on generalized-harmonic approximation method and equivalent circuit models. A detailed analysis of the commutation process during critical switching transitions has been conducted, leading to the derivation of the soft
witching criteria for both three-level and five-level operations of the TAB converter. To validate the design and verify the soft switching range, simulations have been carried out. Moreover, the prototype of the 11 kW multi-port EV charger is designed based on calculation and simulation results. The prototype employs a top-side cooled GaN high-electron-mobility transistor (HEMT) to enhance thermal dissipation. Testing of the prototype indicates that the converter can transmit 1.2 kW from the primary to the secondary side at the rated voltage
of 700 V.

With the energy transition, electrical energy consumption is increasing heavily. Electric vehicles replace cars with internal combustion engines, and electric heating replaces gas-heated homes. The AC electricity grid becomes congested with the increase in load. Local electricity generation through PV panels or windmills also increases, but there is generally a mismatch in generation and demand. Besides, practically all electrical equipment uses DC directly or in the conversion process. This makes using DC grids much more efficient than AC grids. The distribution grid can not convert directly to AC. DC microgrids could prove an attractive solution to support the distribution grid and to move gradually to a DC grid. These locally operated grids combine load, generation, and energy storage. A bipolar DC microgrid further increases efficiency by providing an additional voltage level and doubling the power compared to a unipolar DC grid with the same pole voltage. A DC/AC converter will interface the LV AC grid and the DC grid to enable energy exchange between the grids.

Research is conducted to the design and modulation techniques for a transformerless bipolar 700 V DC grid interfacing converter. Mitigating the isolation transformer increases efficiency and reduces material usage, but will also provide a path for ground leakage current to flow. An NPC converter topology is selected and an 11-segment modulation scheme is implemented using sub-references and carriers. This scheme mitigates the oscillations in the DC neutral point, while simultaneously reducing the ground leakage current to acceptable levels. Furthermore, a novel dead time compensation method is implemented to reduce the ground leakage current further. Finally, a new concept to provide unbalanced power to the poles based on the pole voltages is introduced. Simulations and experimental tests show that the developed modulation technique can enable a transformerless connection.

The increase in non-linear loads of modern electronics raises concerns over power quality. Additionally, existing power-quality analyzers are expensive and not intended for household use. This thesis aims to develop a single-phase, user-friendly power-quality analyzer using a Raspberry Pi 4 Model B with an emphasis on low cost and class S specifications. The design was split into modules consisting of analog to digital conversion, voltage sensing, and current sensing. Sub-modules were added for circuit protection and PCB. Various approaches are discussed before circuit design, simulation, and testing occur. A functioning prototype was assembled on a dedicated PCB while not exceeding the set budget of €250.00. However, it could not be determined whether the class S specifications were achieved due to insufficient testing. A variety of improvements have been suggested.

This thesis describes the design of a low-cost class-S power quality analyzer based on a Raspberry Pi 4. Capable of detecting power frequency, magnitude, voltage dips and swells, harmonics, and total harmonic distortion, the project consists of four main components: the communication protocol, the interface, the algorithms for power quality parameters, and the database. Each with its subdivisions. The communication module, which uses the I2C protocol, is chosen for its high sampling rates and built-in acknowledgement system, ensuring robust and fast operation. The interface module features a secure login process with two-step verification, a graphical user interface for real-time monitoring, and integration with algorithms for power quality parameter calculation. The algorithm module includes Fast Fourier Transform for harmonic detection, zero crossing method for power factor and frequency, and peak detection for voltage dips and swells. The database, powered by MariaDB on Raspberry Pi 4, securely manages the received data with restricted access for increased security, allowing remote access only from specified IP addresses.

The urgent need to decrease greenhouse gas emissions and enable clean energy transition has driven the power industry to seek compact and eco-friendly solutions for power transmission. Gas Insulated Switchgear has been a key technology in this regard, using Sulphur Hexafluoride gas as an insulating medium. However, is a potent greenhouse gas with high global warming potential, necessitating the search for more environmentally friendly alternatives.
Siemens Energy has proposed "Clean Air" as a substitute for inside high voltage. Clean Air, also called Synthetic Air is a homogeneous mixture of 80% N2 and 20% O2. However, due to its lower electrical strength compared to SF6, the GIS design with Synthetic Air as the insulation gas requires optimization and newer insulation techniques to maintain compactness and reliability.
The goal of this thesis is to analyse the breakdown strength of Synthetic Air as a substitute for SF6 inside the High Voltage GIS and examine the performance of its breakdown strength with dielectric coatings on the surface of the electrodes.
Initially, experimental studies were conducted to investigate the breakdown strength of Synthetic Air under various pressure ranges. Comparisons with compressed air reveal that Synthetic Air demonstrates similar electrical breakdown strength.
Next, the study focused on understanding the influence of dielectric coatings on the breakdown behavior of Synthetic Air for applications in GIS. Methodical optimization of coating thickness and air gap distance were done to effectively minimize the electric stress inside the air gap. The test setup was designed with electrodes coated with neat epoxy and the AC breakdown tests were performed. Compared to the uncoated electrodes, the coated electrodes showed significant improvement in breakdown strength.
Though the coated electrode did not breakdown at the voltage at which the uncoated electrodes broke down, with higher voltages, a new phenomena of surface flashover was observed. The observations of surface flashovers across the dielectric coatings demonstrated the ability of these flashovers to travel longer distances at remarkably low voltage ranges. This research concluded by postulating two hypotheses to explain the observed surface flashover phenomena. These hypotheses were researched and analyzed using FEM simulations and experimental investigations.

The EU strives to lower greenhouse gas emissions. To reach this goal, many energy intensive processes in the residential sector such as heating and transportation will be electrified using heat pumps and electric vehicles (EVs) respectively. Simultaneously, a transition of electricity generation to sustainable sources will take place, necessitating an increased adoption of rooftop photovoltaic (PV) systems.

The adoption of PV systems, heat pumps and EVs, also known as low carbon technologies (LCTs), can increase three-phase unbalance in low voltage (LV) distribution networks as many of these components will be connected to a single phase of the three-phase network. Threephase unbalance is undesirable in a three-phase system, as it causes among others, energy losses and a suboptimal use of network capacity.

The aim of this thesis is to evaluate the impact of different combinations and penetration levels of LCTs on three-phase unbalance in different real LV distribution networks through simulations and how unbalance is affected by LCT location, season and LCT control schemes.

Simulations were performed on six different grids, varying in level of urbanization and loading, with increasing levels of LCT penetration (0%, 50%, 80%, 100%). In these simulations, LCTs were integrated in varying combinations (PV & EV, PV & HP and PV & EV & HP). For every simulation, the maximum and mean voltage unbalance factor (VUF) was determined. Seasonal effects and the effect of an LCT control scheme were also evaluated.

Simulations showed that the voltage unbalance factor exceeded the legal limit of 3% for two of the six grids for high levels of LCT penetration when all LCTs are integrated. Combining all three LCTs resulted in the highest unbalance levels. Varying the locations of the LCTs resulted in significant differences in unbalance levels. Comparing a winter week with a summer week, the overall unbalance is similar, however, the contribution of the PV systems to the unbalance is increased, while the contribution of EV chargers and heat pumps is decreased.
The effect of the LCT control scheme was limited.

As the integration of LCTs will increase considerably in the near future, three-phase unbalance levels exceeding the limit of 3% will occur more often. To prevent unbalance levels from structurally exceeding the legal limit of 3%, more effective control schemes should be designed and implemented.

As the electricity sector transitions towards a low-carbon future, an increasing proportion of synchronous generation in the power system is replaced with inverter-based resources (IBRs). The result is a reduction in the available rotational inertia in the grid, depleting its ability to withstand and arrest frequency changes following disturbances. Consequently, disturbances such as a loss of generation or load have an increasingly larger impact on the system, resulting in higher frequency deviations and increased rate of change of frequency (RoCoF).

On two occasions in 2021, the Continental Europe Synchronous Area (CESA) experienced system splitting events caused by cascading trips of several transmission system elements. In both cases, system defence plans were activated in order to preserve the integrity of the overall system. The amount of disconnected load was limited on both occasions, however, should similar events occur in the future with even lower rotational inertia in the grid, the impact could be more severe. This raises the question of whether the existing defence measures are sufficient to maintain system integrity and stable system operation.

Currently in CESA, containment of system frequency excursions following a severe loss of generation is achieved through low-frequency demand disconnection (LFDD) at a frequency below 49Hz. Due to the reduction in traditional synchronous generation and system inertia, the frequency stability of the system is expected to deteriorate, leading to an elevated impact of major disturbances, a rising probability of forced disconnections at frequencies below 49 Hz, and the potential for cascading loss of generation and blackout events.

The objective of this research is to explore the potential impact of reduced system inertia and increased penetration of renewable generation on the performance of the traditional LFDD scheme. In conjunction, additional proactive measures are proposed and investigated with the aim to reduce the probability of LFDD disconnections, by taking actions at frequency thresholds between 50 and 49Hz, as well as to improve the performance of the LFDD scheme in the event that disconnections are required. As a test case, the LFDD scheme as currently applied by one of the distribution system operators in the Netherlands is considered.

This project is therefore categorised in two primary research directions: (i) improving selection criteria for LFDD load shedding locations, and (ii) improving LFDD performance using alternative load shedding schemes.

Key topics explored in this research include: (i) the use of system strength and real-time DER generation as input parameters to load bus selection criteria for LFDD, and (ii) proactive RoCoF-based disconnection of pre-determined consumers above 49Hz. The findings of this study indicate that adapting the current LFDD implementation based on the local system strength and the level of active DER generation at LFDD buses can improve frequency response and reduce instability following LFDD switching operations. Furthermore, proactive RoCoF-based demand side load management techniques above 49Hz prove effective in reducing frequency deviation during the most severe events while avoiding LFDD over-shedding for smaller contingencies.

This report emphasizes the importance of implementing quality control methods in the production machines at HyET Solar for assessing the quality of deposited materials. The focus is on two key steps: the deposition of the front transparent conductive oxide (TCO) layer and the deposition of silicon layers. Models were developed to characterize the quality of the TCO layer, including layer thickness, carrier concentration, and mobility of the electrons. A Drude model-based approach was chosen for in-line implementation. The sheet resistance of the TCO layer was measured using an improved tool, by enhancing its robustness and accuracy. To assess the quality of the deposited silicon layers, a non-contacting capacitive device was developed and calibrated (to measure the spatial gap between the photovoltaic layer and the device). Results showed that the Drude model fitting provided sensible results for carrier concentration and mobility with the former having a better correlation than the latter, with the standard Hall effect measurements. The results from the optical thickness model showed overestimation of values as compared to the scanning electron microscopy (SEM) results. The electrical sheet resistance values correlated well with Hall effect measurements than the optically obtained sheet resistance values. The calibrated non-contacting capacitive device demonstrated its ability to measure opto-electrical properties of the silicon layers, accurately. This research contributes to enhancing the efficiency and reliability of roll-to-roll production process of thin-film solar modules.

Power Electronics in association with the high voltage technology has the potential to bring out new generation of electrification with well-integrated renewable resources. Various high voltage applications of power electronics include Solid State Transformers (SST), Photovoltaic Inverters (PV), and Shore-to-ship connections. A demand for faster and smarter testing of high voltage components led to the development of an arbitrary waveform generator. It is possible to generate voltage waveforms with varying magnitudes and frequencies using a modular multilevel converter (MMC). Based on the voltage withstand capacity of semiconductor switches and the control complexity of MMCs, the number of levels and maximum voltage at each level in MMC are determined. The commercially available semiconductor switches are capable of withstanding 1.7kV (SiC-MOSFET) and 6.5kV (Si-IGBT). The low current and fast switching requirements of high-voltage (HV) tests argue in favor of SiC MOSFETs.

With the ability to connect commercially available and mature but lower breakdown voltage semiconductor transistors in series, medium-voltage (MV) and high-voltage (HV) converters can be built with a significant reduction in costs. Using the proposed technique, a modular multilevel converter (MMC) can be equipped with a HV switching module. When semiconductor switches are connected in series, the key challenge is to ensure equal voltage sharing in both static and dynamic switching states. There is a clear connection between the asynchronous gate driving signals and the voltage imbalance. Different types of intrinsic and extrinsic capacitive couplings also affect the voltage shared among series-connected SiC MOSFETs. The factors responsible for voltage imbalance are listed below from a dominant influence to a subservient one.
1. Gate delay introduced by the gate driver circuit and associated power supply.
2. Resistance and capacitance to ground introduced by the measurement probes.
3. External capacitance to ground introduced by the heatsink.
4. Parasitic inductance introduced by the interconnects between series-connected devices.
5. Process variation in intrinsic parasitic capacitances.

Stacks of SiC MOSFETs can be controlled synchronously and isolated from the gate driving circuit using a pulse transformer. A common primary winding is made of a HV insulated cable passing through ’N’ toroidal cores carrying ’N’ secondary windings for respective gate terminals of the series-connected SiC MOSFETs.
By resolving the frequency dependency between pulse transformer and stack duty cycle, the proposed technique achieves arbitrary switching function for the series-stack. There are two sets of such pulse transformer arrangements that ensure the fail-safe switching transitions for series-connected SiC MOSFETs. An experimental verification of the proposed technique is performed with a 6kV prototype of five 1.2kV SiC MOSFETs in series. During differential probe measurements across drain-source terminals of the individual series-connected SiC MOSFETs, a significant challenge has been encountered. It is demonstrated that external resistive and capacitive couplings induced by the measurement probes can affect switching function.

The objective of the thesis is partially met, and a low-cost approach to achieve high voltage switching modules with commercially available devices in series connection is proposed. With the conducted research it is possible to build high-voltage isolation between gate driving circuit and series-connected SiC MOSFETs.
The proposed method is an open loop voltage balancing technique which significantly reduces the required number of components by eliminating the need for feedback and its isolation challenge. Furthermore it achieves synchronous switching with the ability to set the duty cycle for the series-connected switch.

This thesis investigates and compares the performance of HVDC protection algorithms in terms of their sensitivity, selectivity, speed, and robustness. The threshold determination process for each algorithm has been described in detail as well. Each algorithm is tested under various fault resistances, and fault distances to test the sensitivity of the algorithm. The trip time for each case in each algorithm is monitored to analyze the speed of the algorithm. Various external faults have been simulated to test the selectivity of the algorithm. Lastly, the resilience of each algorithm against white noise has been tested. Furthermore, the effect of varying the sampling frequency and the inductance of the current limiting inductors on each algorithm is investigated. The HVDC protection algorithms discussed are - current differential deviation-based protection, ROCOV-based protection, ROCOC-based protection, and DC reactor voltage change rate-based protection. All protection algorithms have been implemented in the PSCAD environment. The noise resilience analysis for each algorithm has been performed in MATLAB.

The renewable generation capacity, particularly solar and wind power installations, has increased steadily in the Netherlands over the course of recent years. Due to the local, small-scale nature of these power plants (compared to conventional power plants), a large share of this generation capacity is installed into the medium- and low-voltage distribution grids. This trend acts as the source of several challenges for distribution system operators (DSOs) such as Stedin Netbeheer B.V. (a DSO in the Netherlands, supporting this project). One of the main problems is the fact that voltage limit violations, particularly upper voltage limit violations, become more frequent.
Conventional voltage control schemes assume a unidirectional power flow (i.e., consumption only) in distribution grids and are unable to keep the limits in case a large share of generation capacity is installed. This is further complicated by the fact that underground cable networks, typical in Western European electricity distribution grids, have lines with large R/X ratios, which reduces the effectiveness of reactive power injection-based voltage control methods.
This MSc project intends to solve the issue of voltage limit violations with a model predictive control (MPC) policy. The considered control actions coordinated by the model predictive controller are the switching of the on-load tap changer (OLTC) mechanism mounted to the primary substation’s transformer, setpoint adjustments of the low-level OLTC control relay, and the active power curtailment of larger photovoltaic plants. A linear, sensitivity-matrix-based model is used for the grid’s state prediction; and the sensitivity values are re-calculated at each sampling time step of the MPC. To avoid the curtailment of photovoltaic (PV) plants when not justified, a conditional curtailment logic is incorporated into the MPC policy: PV plants are only allowed to be curtailed if their local voltage magnitude is above a tuneable threshold. This logic is described and incorporated into the model predictive controller’s optimization problem with the help of binary variables and mixed-integer linear (MIL) constraints. The benefit of incorporating knowledge about future disturbances (load, generation, and external grid voltage profiles) is also tested, in order to assess the potential benefit DSOs could get from forecasting these quantities.
A case study was conducted in which the considered controllers were tested on a section of a Stedin grid that carries the characteristics of a typical Western European medium voltage distribution grid: large R/X ratios and a large installed PV generation capacity both in the form of household generation and larger PV plants. All controllers were simulated in 4 different test cases: a typical summer day, a summer day with the external grid’s overvoltage, a summer day with 2 out of 3 large PV plants not operating, and a typical winter day. All test cases have the control goals of mitigating limit violations and ensuring that the nodal voltage magnitudes are as close as possible to the nominal 1 per unit throughout the day. The winter day test case has the additional goal of avoiding excessive curtailment as PV energy is worth considerably more during these days. All profile data is based on real Stedin measurements. The designed model predictive control policies are compared to two simple control schemes: current compounding, i.e. when the primary substation’s automatic voltage control relay’s setpoint is adjusted based on the active power delivery through the substation’s transformer, and another scheme when current compounding is combined with local active power curtailment controllers for large PV plants. The most important metrics used for comparison are voltage root mean square error (RMSE), the total voltage limit violation area, the percentage of curtailed PV energy, and the number of tap changes over the considered day. The simulations were carried out using Python and DIgSILENT PowerFactory.
The simulation results show that the MPC policy can perform better than the simple control schemes but only when exact knowledge of future profiles is available. In this case, the MPC results in lower voltage RMSE, smaller violation areas, and lower curtailment percentage values, at the expense of using more tap changes in all 4 test cases. In 3 of the 4 test cases, MPC was completely able to eliminate voltage limit violations, showing clearly the advantages of good quality forecasts on future disturbances. Since this exact knowledge about the near future fluctuations is quite ideal, more realistic MPC policies were also tested with no future knowledge and tightened voltage constraints. These simulations brought mixed results when compared with the simple schemes, performing better in terms of voltage RMSE, but worse in terms of the total voltage limit violation area.

With the increasing appearance of DC loads and DC sources in the MVAC distribution grids, the need for DC power systems is getting more and more pronounced. As a result, the MMC has become a promising and innovative technology that can serve as the interface between a DC and AC network. The MMC-based MVDC distribution link is one of the solutions to incorporate DC in power grids. This link consists of two back-to-back configured MMCs connecting two possibly asynchronous AC networks. Generally, an MVDC distribution link is operated at a fixed rated DC voltage set through the MMC. This work explores the possibility of enhancing the DC link voltage beyond the nominal value to improve the power transfer capacity of the distribution link. The enhancement is achieved while preserving the average energy stored in the MMC and maintaining the AC-side harmonic performance.
First, a control strategy was developed that qualified for the static operation of back-to-back configured MMCs. This control strategy was designed using multiple sub-control modules, each regulating one or multiple circuit quantities using a closed-loop PI or PR control strategy. Second, the analytical limitation to the DC link voltage enhancement was determined. This provided the enhancement boundary expression, which revealed the dependence between the enhancement limit and the grid-injected reactive power. Third, the MMC control strategy was adapted to dynamically incorporate the DC link voltage enhancement. This was performed using the open-loop DC link voltage control, which dynamically enhanced the link voltage by using the reactive power input reference. The controller is realised using a finite state machine that provides an event-driven control system with conditional state transitions. Simulations verified the performance of this controller. Finally, the dynamic DC link voltage controller is implemented for a lab-scale MMC and optimally tuned using the MO tuning method. This is to provide experimental verification of the DC link voltage enhancement. Three experiments were performed to: demonstrate the workings of the enhancement concept, verify the analytical enhancement boundary expression, and show the performance of the dynamic DC link voltage controller. The experiments concluded that the open-loop dynamic control successfully achieved the DC link voltage enhancement and limited the grid injection of harmonic elements during system transients.
So it is concluded that the power transfer capacity of an MMC-based MVDC distribution link can be enhanced by applying dynamic DC link voltage control. This while operating with the same submodule stresses and preserving the AC-side harmonic performance. When the DC current of the distribution link is fixed at the rated value, the power transfer capacity of the link increases linearly with the controller enhancement function. For system transients, the dynamic controller uses smart control logic to avoid harmonic element injection. Combined, this concludes that the dynamic DC link voltage control achieves a proper DC link capacity enhancement that meets the requirements for both steady state and dynamic conditions.

In recent years, the Wireless Power Transfer (WPT) system has become more and more popular due to its prominent advantages, especially for Electrical Vehicle (EV) charging. The WPT systems are required to follow the EV battery charging profiles, thus more and more voltage control methods with distinctive characteristics are proposed and studied. The goal of this thesis report is to conduct a comprehensive benchmark of the front-end voltage control solutions.

This thesis report focuses on the front-end voltage control solutions including the front-end buck converter and the phase shift control based on the primary inverter. Six different front-end voltage control scenarios are designed and compared in terms of system efficiency. There are four scenarios of the front-end buck converters including the single-phase buck converter working in Continuous Conduction Mode (CCM), the single-phase buck converter working in Triangular Current Mode (TCM), the two-phase interleaved buck converter working in CCM and the two-phase interleaved buck converter working in TCM. There are also two scenarios of primary inverter-based phase shift controls including phase shift with and without phase delay. The single-phase buck converter working in TCM has the highest efficiency reaching 95.5% at a light load. The phase shift control scenario with phase delay has the highest efficiency exceeding 96.5% at a heavy load.

Different from previous research on phase shift control, this thesis report conducts an in-depth harmonic analysis and compares the accuracy of harmonics analysis with the accuracy of fundamental wave analysis. The conclusion not only proves that fundamental wave analysis is reliable and accurate enough to calculate the phase shift parameters for the S-S compensation but also improves the calculation accuracy at a light load by harmonics calibration.

With the development of sustainable energy technology and the increasing emphasis on environmental protection, the popularity of electric vehicles is increasing. However, As the number of electric vehicles increases, so does the pressure on the grid due to charging. If a large number of electric vehicles are charged at the same time, the grid will inevitably be overloaded. For this problem, smart charging can be a good solution. The smart charging algorithm determines when it is optimal to charge the electric vehicles(EVs) based on factors like Photovoltaic(PV) generation, local load consumption, and energy price. For customers, this means the total cost of charging is the lowest, for the power system it means charging when the network is not overloaded. Furthermore, Smart charging can reduce the need for grid infrastructure investments and reduce energy costs. From an energy-friendly and economical perspective, this is worth doing.

Up to now, there is a large amount of literature study about smart charging. However, most of the literature is based on pure software analysis rather than hardware experiments. In this thesis, a hardware-in-the-loop-based simulation is presented. The basic idea of hardware-in-the-loop simulation is to include a part of the real hardware in the simulation loop. The advantages of hardware-in-the-loop simulation are obvious. Compared with pure software simulation, hardware-in-the-loop(HIL) simulation has the real response of the hardware components, and it is not very complicated to set everything up. In this thesis, the testing and the evaluation of the system are carried out in real-time because the HIL setup includes an OPAL-RT OP4510 DRTS. The simulation of the distribution grid is running on the OPAL target by the software ePHASORsim. The rest part of the testbed consists of a Programmable Logic Controller (PLC) and two bidirectional Direct Current(DC) power supplies to form an Alternating Current(AC) source and an Alfen charger. The smart charging algorithm is written in Python code. By calling Gurobi, smart charging algorithms can calculate and decide the optimal current setpoints for each EV connected to the distribution grid in real-time.

Nowadays, electric vehicles (EVs) in the market only travel short distance and are usually charged at home which can be the obstacle in the way of EVs development. As a result, fast charging that can ensure long-distance drive with shorter charging time draws more and more attention.

In emerging fast-charging stations, DC fast chargers (DCFCs) are employed which rely on power electronics and control to achieve the required performance. Harmonic current emission induced by the complex system behavior is of great concern in the DC fast charger (DCFC) system. This thesis proposes a harmonic emission model for the typical DCFC design, i.e., the two-level active front end. The technique is based on the Fourier series method and the impedance model which is able to reveal the harmonic current emission of DCFCs under different grid conditions. Time-domain simulations and experiments are presented subsequently to validate the proposed model.

The analytical model can be implemented in cloud-based charging, which is a popular topic right now because of the lower overall cost. Besides, cloud-based systems have a larger storage capacity and are easier to maintain. Another reason for the appealing cloud-based charging is that all of these Internet of things (IoT) devices are interconnected, and vehicle data are shared. Therefore, an IoT based online harmonic emission estimation tool for DCFC is built based on the aforementioned proposed model in this thesis.

The worldwide adoption of Electric Vehicles (EV) has gained momentum in recent years, with more than 30% of all EVs being sold last year. Additionally, a new trend of 800 V battery architectures has appeared to allow for faster charging than the now common 400 V architectures. Future proof charging topologies should, therefore, be able to provide a wide output voltage range. This study investigates how DC-DC resonant power converters can be employed to achieve a wide output voltage range of 150-1000 V for EV charging. After the literature study, a two-stage topology consisting of a LLC converter and Interleaved TCM Buck converter is selected for this purpose. Additionally, the competitiveness of an IGBT based solution is examined in comparison with a SiC MOSFET based solution. An analytical model is created in MATLAB and verified using LTSpice, after which different configurations of the 11kW two-stage converter are compared analytically. This comparison is performed by developing a method to assess the efficiency of a converter based on real-world Charging cycles. A trade-off is made between efficiency and costs. In the end, one stage is equipped with IGBTs in the final design. After this, a PCB is designed and used to implement the prototype of the final design. The analytical and simulation models are verified experimentally using the prototype. The maximum measured efficiency of the converter is 97.66%, with a 95+% efficiency over the complete 150-1000 V range at full power. The obtained efficiency for the 11 kW-400 V Charging cycle is 96.85% and 95.67% for the 11 kW-800 V Charging cycle. The proposed converter in this study thus proves to be a highly efficient charging solution that is capable of charging existing, and future Electric Vehicles.

Given the urgency to shift to a cleaner energy mix, offshore wind energy is bound to be quickly deployed on a large scale in the next years. In order to meet the Paris Agreement, the current role-out rate of wind energy in the North Sea, that is 2 GW/year, needs to be increased to an average value of 7 GW/year over the period 2023-2040. This rapid increase of the share of uncontrollable, renewable sources in the energy mix raises a certain number of challenges, among which sustaining energy balance and transient stability. To organise the large-scale deployment of offshore wind in a strategic manner, the concept of hub-and-spoke has been introduced. It envisages modular offshore renewable power generation clusters (a.k.a. offshore hubs) designed to be easily and safely operated and interconnected.

Dealing with large power fluctuations constitutes a major challenge for each offshore hub. The variability of power supply needs to be mitigated through the integration of storage solutions. Offshore power-to-gas conversion for storage purposes has been widely investigated in the literature, under techno-economic or power balance points of view. However, detailed analysis of the effective connection of large scale electrolysers in offshore hubs are missing.

This thesis proposes a real-time simulation model of a 2 GW offshore hub integrating electrolysers in order to investigate their impact on the dynamic active power management of the hub. Two locations for the connection of the large-size electrolysers are studied: i) connection of an electrolyser to the AC common bus of the hub and ii) connection of electrolysers to the DC link of the back-to-back converter of each Type-4 wind turbine of the hub. An Electromagnetic Transient (EMT) simulation based analysis, necessary to capture the fast dynamics of the zero-inertia hub, is performed under different severe disturbances, such as a three phase fault and sudden large wind speed fluctuations.

In a second part, the thesis investigates the connection of the hub to the shore via a bipolar High-Voltage Direct Current (HVDC) link. It has been shown in the literature that bipolar links are more reliable than monopolar ones, as they can still be operated to transfer half of their nominal capacity in case of failure of one cable or converter. The work of this thesis is focused on developing and implementing a power sharing strategy between the two Modular Multi-level Converters (MMCs) constituting the offshore terminal of the link.

It was found in this thesis that both investigated locations for the connection of the electrolysers can be beneficial in different ways. Connected at the AC common bus, the electrolyser can provide centralized ancillary services, while an electrolyser connected locally at the wind turbine can consume the power generated during an islanding event. Regarding the power sharing in the HVDC link, two different strategies were developed, both enabling to unload one of the poles of the link. Further studies should be carried out to provide in-depth understanding of the potentialities of the two methods.

The need for efficient power transfer at lower cost is a common requisite for any power con­verter system. When considering the application of wireless power transfer for Electric Vehicle(EV) charging, higher efficiency and lower cost can be achieved by reducing the number of stages of the system at the grid side. This thesis explores the feasibility of an AC/AC matrix converter for wireless power transfer application. To begin with, different existing topologies of the converter module are discussed and qualita­tively compared to the matrix converter. Subsequently, the plausibility of single stage matrix converter is verified through simulation. Due to the converter’s high switching frequency, this configuration results in injection of higher than permitted harmonic content into the grid. Fur­thermore, the feasibility of three phase matrix converter and its advantages are studied. The converter working is verified through simulation. To make the grid current less distorted, closed­ loop control is introduced. This control con­sists of an inner current loop and an outer voltage loop which are both implemented using a PI controller. To conclude, three phase matrix converter acts as a plausible solution for the desired applica­tion. Furthermore, the control ensures balanced grid current and desired output power.

Performance of photovoltaic modules are widely expressed using their efficiency at Standard Test Conditions (STC). Although, real world conditions largely differ from this standard. Energy yield of photovoltaic modules at a certain location gives a clear indication of the performance of the module exposed to varying weather conditions. Photovoltaic Materials and Devices (PVMD) Toolbox developed at Delft University of Technology and implemented in MATLAB®, aims to simulate energy yield of photovoltaic modules while providing the flexibility of modifying cell-level to module-level parameters of the device. Accurately determining the irradiance falling on the module at a certain location and simulating the electrical properties of a solar cell at realistic conditions is crucial in determining the yield generated by a module. Due to the promising results displayed by the technology, in this study, energy yield of perovskite/c-Si tandem modules are simulated using newly developed daylight and parameter extraction models in PVMD toolbox. Due to high computational efficiency and functionality offered, Preetham daylight model is implemented as an improvement to Perez model currently used in PVMD toolbox. The model considers the effect of Rayleigh and Mie scattering, and turbidity of atmosphere in determining the distribution of diffuse irradiance across the skydome. By implementing the model, three factors can now be determined: luminance distribution, RGB co-ordinates and relative spectral power distribution over the skydome for any location. Luminance is calculated for every point in sky using Perez parametric function that use coefficients derived from simulated data for different sun directions and turbidity values. For all locations considered, Preetham model calculates higher luminance over the year by ~2%. Calculated luminance values normalized against zenith luminance is used to derive CIE xyY values and consecutively, the RGB co-ordinates that are rendered real-time to create images of the skydome for every hour in chosen timeframe. By calculating the relative spectral power distribution, analysis of incident light falling on the module from all points of the skydome is possible which especially deems useful for modelling tandem modules. To accurately simulate electrical properties of solar cell under varying operating conditions, parameter extraction model for simulated ASA J-V curves is implemented using an analytical method. For the c-Si and perovskite cells considered in the study, the reconstructed curves using extracted parameters fits ASA curve with RMSE or 1.98% and 3.02% respectively at STC. Using these models introduced in this study, energy yield of mono-facial and bi-facial 2T/4T tandem modules are calculated and analyzed for Rome, Reykjavik and Alice Springs. Depending on air mass of a location, perovskite thickness of mono-facial 2T tandem devices are optimized to produce maximum specific yield. All considered modules generate highest yield at Alice Springs due to high insolation at the location. The yield difference between modules while using the two daylight models is insignificant at <1%. With an increase in perovskite thickness, energy yield of 2T bi-facial modules increase significantly for high albedo while it drops beyond the optimum thickness due to current mismatch for low albedo. Bi-facial 4T module on high albedo (albedo= 0.85) surfaces show best performance out of all the modules producing 36% higher yield than mono-facial 4T module for Rome.