Bachelor Projects

Abstract: The rapid expansion of electric vehicle (EV) charging infrastructure has increased the integration of high-power electronic converters into electrical distribution networks. While high-power DC fast chargers are essential for supporting widespread EV adoption, their nonlinear operating characteristics may introduce harmonic distortion and other power quality challenges. This project investigates the impact of a high-power DC fast charging installation on power quality and evaluates the effectiveness of passive and active harmonic filtering solutions. A seven-day measurement campaign was conducted at the Point of Connection (POC) of a 250–300 kW DC fast-charging installation using a Class A power-quality analyser. The measured data were used to characterise the electrical behaviour of the charging system and to develop a measurement-driven MATLAB/Simulink model for harmonic and power quality analysis. The study focused on harmonic distortion, voltage distortion, active and reactive power behaviour, and power factor. Passive and active harmonic filtering solutions were subsequently implemented and evaluated under comparable operating conditions. The measurements showed that the charging installation behaves as a nonlinear load with dominant 5th- and 7th-harmonic components. However, the measured voltage distortion remained within the limits defined by applicable power quality standards, with an average total harmonic distortion (THDV) of 2.49% and a maximum of 3.27%. Simulation results demonstrated that passive harmonic filtering reduced the total harmonic distortion (THDI) from 3.81 % to 2.26 %, while active harmonic filtering reduced THDI to 0.38 %. The active filter achieved the greatest harmonic mitigation while maintaining operating conditions close to the baseline system..

The results show that both passive and active filtering methods can significantly improve power quality performance. However, the investigated charging installation already operated within applicable power quality limits, indicating that additional harmonic mitigation is not currently required at the studied site. The findings suggest that harmonic filtering may become increasingly relevant as charging infrastructure expands and charging power levels continue to increase.

Abstract: When working with the simulation software PV*SOL, a problem related to battery simulation was identified. In the results, the battery system is only presented as aggregated sum values, making it difficult to evaluate battery performance in detail. Therefore, the objective of this project is to develop a program capable of importing hourly CSV data from a PV system simulated in PV*SOL and using it to perform a simplified battery simulation based on a discrete hourly simulation model.

The optimization of the simulation is based on the hourly import price, calculating the potential savings achieved through battery discharge. The system is easily configurable through the main.py function and reveals the cost-saving potential of a given lithium-ion battery system. The program is intended for engineers, meaning that knowledge of the physical characteristics of batteries and PV systems is a prerequisite for its use.

The program utilizes real-life electricity prices from previous years, battery parameters, and the hourly PV*SOL CSV export as inputs. As output, it provides day-by-day results in the run window for detailed analysis, a yearly economic overview, and a PV*SOL-style summary of PV coverage and consumption including the battery.

Testing of the system demonstrates that it functions as intended. For the evaluated 12.6 kWh / 6 kW lithium-ion battery system, the total annual savings were calculated to be 5523 DKK/year under the given price conditions. In particular, when export levels are high, the battery system performs well, as it charges only from energy that would otherwise be exported. However, during periods with little or no export—such as winter weeks in the presented test case—the system remains largely inactive. The conclusion is therefore that future development should include the possibility of grid charging when export is not expected.

Abstract: This report investigates the design and analysis of a low-voltage electrical supply for a medium customer project, including the integration of electric vehicle charging infrastructure and a photovoltaic (PV) system. The project is based on a real case provided by Nexel, a Danish distribution system operator, and concerns the electrical supply of a renovated bus station owned by Gladsaxe Municipality. The increasing power demand caused by electrification of transport and local renewable generation forms the background for the study.

The electrical system consists of a 10 kV medium-voltage grid, a 10/0.4 kV, 630 kVA distribution transformer, a low-voltage distribution network, a building with a 144 kWp photovoltaic system, and two electric vehicle charging points. The system is analysed using both analytical calculations and simulations performed in DIgSILENT PowerFactory. Load flow calculations are carried out to evaluate voltage levels, transformer loading, and cable loading under normal operating conditions, while short-circuit calculations according to IEC 60909 are used to assess system safety under fault conditions.

The results show that the voltage levels at all buses remain within acceptable limits, despite the presence of significant local PV generation. The transformer operates with a low loading of approximately 17%, indicating sufficient capacity for current demand and future expansion. Cable loading under normal operation is highest for the building feeder but remains below thermal limits. However, short-circuit calculations reveal that the initially selected 150 mm² aluminium cables exceed their thermal withstand capability for conservative fault clearing times.

To improve system robustness, the feeder cable cross-section is increased to 240 mm². Both hand calculations and PowerFactory simulations confirm that this upgrade ensures adequate thermal withstand capability under short-circuit conditions and also reduces cable loading during normal operation. A close agreement between analytical calculations and simulation results is observed throughout the study.

Overall, the project demonstrates that the proposed electrical system design fulfills operational and safety requirements and highlights the importance of considering both normal operation and fault conditions when integrating electric vehicle charging and photovoltaic generation into low-voltage distribution networks.

Abstract: This project presents a comparative analysis of two medium-voltage internal power distribution systems operating at 10 kV and 20 kV, respectively, for a future decentralized heating station operated by Vestforbrændingen. The study investigates whether operating at a higher voltage level provides technical, economic, and environmental advantages. Both systems were dimensioned based on identical load requirements and simulated under steady-state operating conditions to evaluate voltage quality, power losses, and equipment loading. In addition, installation costs, long-term energy losses, and associated CO2 emissions were assessed over a 30-year period. The results demonstrate that the 20 kV system enables smaller cable cross-sections, reduced losses, longer feasible feeder lengths, and lower total costs, with the advantages becoming more pronounced as feeder length increases. The study concludes that a 20 kV internal grid is the preferable solution for the proposed application.

It should be noted, that Chatgpt 5.2 has been used throughout the written project as a grammar tool to correct grammar and semantics, but not to generate standalone text. The language model has been used as a citation twice in section 2.3.3 Medium voltage switchgear and section 4.3 Cost of installation 10kV vs. 20kV. It also assisted in generating the Matlab scripts used in section 4.3 Cost of installation 10kV vs. 20kV and in the subsection 3.3.3 Thermal check.

Abstract: The continued expansion of offshore wind power toward larger wind farms, higher turbine ratings, and greater distances from shore places increasing demands on electrical system architecture. Conventional AC-based collection systems rely on offshore substations equipped with large transformers and reactive power compensation, which introduces high capital expenditure, increased system complexity, and additional electrical losses. At the same time, modern offshore wind turbines are already heavily dependent on power electronic interfaces, creating the technical basis for alternative electrical architectures beyond traditional AC solutions.

Against this background, this bachelor's project examines the feasibility of an All-DC offshore wind farm architecture as a potential alternative to conventional hybrid AC/DC systems. The study is conducted in collaboration with Siemens Energy and focuses on system-level design rather than component-level optimisation. The central question addressed is whether an All-DC architecture can deliver predictable electrical behaviour and competitive economic performance while remaining compatible with current industrial constraints. The project investigates an All-DC wind farm concept based on 14 MW offshore wind turbines and a bipolar medium-voltage DC (MVDC) collection grid operating at ±25 kV per pole (50 kV DC). Voltage scaling is performed at the turbine level using turbine-integrated power electronic converters, which enable a direct connection to the MVDC collection grid. A radial string topology is adopted to minimise system complexity and support protection zoning, while the bipolar configuration is selected to enhance operational robustness and align with established HVDC practices.

The study begins with a structured literature review covering DC transmission for offshore wind, MVDC collection grids, and the associated challenges related to protection and standardisation. While HVDC export systems are well established, the review shows that DC collection grids remain an active research area, particularly due to unresolved issues related to fault handling, protection coordination, and the absence of dedicated IEC standards. Nevertheless, multiple studies indicate that DC-based architectures may offer tangible advantages for large offshore wind farms, especially through reduced electrical losses and simplified offshore infrastructure.

Based on the identified research gaps, a concrete All-DC wind farm architecture is developed and analysed using a simplified steady-state simulation model implemented in DIgSILENT PowerFactory. Wind turbines are represented as aggregated DC power injections, and MVDC array cables are modelled using resistive elements. The simulation focuses on DC voltage profiles, current distribution, and resistive cable losses under rated and partial-load operating conditions. Dynamic behaviour and detailed protection modelling are explicitly excluded from the scope of the study.

Abstract: The increasing penetration of renewable energy sources has significantly altered the dynamic behavior of modern power systems, leading to reduced system inertia, increased rate of change of frequency (RoCoF) and increased risks to frequency stability. These challenges are particularly pronounced in small or weakly interconnected systems with high shares of inverter-based generation. This project investigates the role of battery energy storage systems (BESS) in providing primary frequency control, using the Danish island of Bornholm as a representative case study.

A detailed electrical model of the Bornholm power system was developed in Digsilent power factory, incorporating conventional generation, renewable energy sources, aggregated load and a utility scale BESS. The BESS was equipped with frequency droop control, voltage droop control and a charge/discharge management strategy to ensure realistic operation within state of charge constraints. Quasi dynamic simulations were conducted to evaluate long term operational behavior, while RMS simulations were used to assess frequency stability and RoCoF performance under minor and major generation outage scenarios.

The simulation results demonstrate that BESS can significantly enhance frequency stability during large disturbances by rapidly injecting active power, reducing RoCoF and improving frequency nadia. While minor disturbances did not always trigger substantial BESS activation, major outage led to severe system instability in the absence of BESS, where as stable operation was maintained when BESS is a technically effective solution for providing primary frequency control specially FCR-D in renewable dominated, low inertia power systems and highlight its importance in the future Danish and Nordic power system.

Abstract: This project has set out to evaluate the accuracy of 400A and 800A current transformers, with regards to earth faults. At first the theory of earth faults, as well as the method of detecting them was explored. The watt metric relay is often used for this purpose, and relies on detecting the sign of the active power flowing through the feeder. Therefore the phase error of the current transformers used, has to be kept at a minimum as the angle defining the sign is often within a couple of degrees.

A practical experiment simulating a smaller earth fault was conducted, using an old distribution power transformer. The transformer has generously been donated by NEXEL to DTU, who in the future can utilize it in experiments. The experiment simulated an earth fault of around 5A and 10A. The experiment proved that the 400A CT is more precise at the lower currents. This is because the 400A CT is operating at a higher percentage of it’s rated current, where the 800A in the same condition is operating at half that. This results in the ratio and phase error becoming significantly larger.

After the experiment was conducted, the CT’s where tested with an OMICRON CT analyzer. The CT analyzer proved what the experiment had shown, and clearly highlighted the difference in accuracy. Not only does the general accuracy of the CT setup reduce at low currents, but also the individual CT’s differ in error which further magnifies the error. The final verdict made as a result of the project, is that the 800A CT’s by themselves will not detect earth faults as accurately as 400A CT’s. This will then result in the need of a core balance current transformer. The project has then answered what it set out to research, concluding that the accuracy of 800A CT’s does not guarantee earth fault detection as good as 400A CT’s.

Abstract: This BEng bachelor’s project analyses the impact of a large heat pump installation on electrical power quality, focusing on harmonic distortion. The study considers a system consisting of two 500 kW heat pumps driven by Active Front End (AFE) converters connected to a 15 kV busbar. The objective is to evaluate whether the installation complies with relevant harmonic limits at the Point of Common Coupling (PCC) and to explore potential mitigation options.

A detailed model was developed in MATLAB/Simulink using actual network and equipment data, including the 15 kV grid, transformer, cables, converters, and asynchronous motors. Two base cases were investigated - strong and weak grid conditions - both simulated at 50 % load. Harmonic performance was evaluated using FFT analysis, with key indicators THDV , THDI , and TDD calculated at PCC. The results indicate very low voltage distortion and moderate current harmonics in both grid cases, with TDD and THDV well below the IEEE 519 limits. Therefore, no grid-side filter is required under the examined conditions. A selective Active Harmonic Filter (SAHF) is, however, proposed as a future-oriented solution in case of grid expansion, higher loading, or reduced grid strength. The study concludes that the modelled system does not exceed the harmonic content limits at the PCC and provides a practical approach for analysing similar converter-based heat pump installations within future district heating electrification.

Abstract: This report investigates the topological optimization of switching devices in onshore substations, focusing on the interaction between harmonic filters, shunt reactors, and circuit breaker arrangements. Three scenarios were analyzed: varying cable with fixed reactor, varying harmonic filter with fixed reactor, and varying reactor with fixed cable and filter. In addition, two case configurations were compared: a shared circuit breaker arrangement, where the harmonic filter and reactor are connected through a common circuit breaker, and a dedicated circuit breaker arrangement, where each component is equipped with its own circuit breaker.

The scenario analysis shows that the zero-miss phenomenon becomes most critical when capacitive and inductive reactive power are nearly balanced. Under these conditions, the alternating current component is minimized and the transient direct current component dominates, resulting in extended interruption times. The case comparison show that the shared circuit breaker setup reduces equipment count, footprint, installation time, and maintenance, but experience reduced fault clearing reliability. The dedicated circuit breaker setup, while more costly and space consuming, ensures robust interruption capability by allowing each breaker to operate independently at natural zero crossings.

In conclusion, the study demonstrates that breaker topology directly influences both technical reliability and economic efficiency. Case 1 offers a compact and cost efficient solution, whereas Case 2 provides better fault clearing performance. The optimal choice depends on project priorities, requiring a balance between investment constraints and operational robustness in substation design.

Abstract: This bachelor thesis explores the transient stability of the generator situated at Køge Kraftvarmeværk. This is done by simulating and calculating the critical breaking times for the generator to stay synchronised to the grid in case of a local, symmatrical, threephase fault by the generator as well as a single-phase to ground fault. The purpose of simulating the two different fault types is to ascertain whether a differentiation of breaking times based on fault type would be enough of a boon to justify the potentially increased costs of implementation. This thesis makes no attempt at the specific economic calculations. In addition to the technical basis of the calculations, a number of factors are examined which, from a technical, economic and legal perspective, are relevant to the medium-sized production facility located at Køge Kraftvarmeværk.

The simulations are done through DigiSilent’s Power Factory. The results are verified continuously throughout the thesis with relevant calculations. The results show a significant difference in the critical breaking times for the generator in different fault scenarios. This indicates that a differentiation of the breaking times would offer a significant increase in stability, provided motivation to stay synchronised for as long as possible during a fault scenario, whether those be for grid stabilising or economic purposes.

Abstract: This project examines how an industrial-scale photovoltaic system and a Battery Energy Storage System can be safely integrated into a modern low-voltage distribution grid. A complete electrical installation has been designed based on a real industrial case, including cable dimensioning, main switchboard configuration, protection coordination, and thermal performance evaluation. Both analytical calculations and professional simulation tools such as Caneco BT [35], VAS-EL [15], and PowerFactory [7] were applied to verify short-circuit levels, protective device selectivity, harmonic compliance, and grid interaction. Calculations were performed using both sequence-based and impedance-based methods. The results showed that the simpler impedance method produced negligible differences compared to the sequence method, while remaining just as accurate for low-voltage short-circuit analysis.

This supports why the impedance method is widely used in practical low-voltage design. The results show that the system can operate efficiently within Danish grid requirements, with low arc-flash risk and no thermal derating needed when active ventilation is applied. Economical and operational perspectives for the BESS, such as peak shaving, ancillary services and energy arbitrage, were evaluated to assess potential benefits for future industrial applications, and the analysis indicates that the BESS can form a financially attractive business case under typical Danish energy price conditions. The project concludes that inverter-based resources can be integrated reliably when proper standards are followed, and it highlights opportunities for further improvements in battery control strategies and transformer design for renewable-dominated grids.

Abstract: NHN Hospital is supplied by a 10 kV distribution network with two independent incomers originating from the TRO and HIL substations. Under normal operation, the hospital is supplied via a closed ring formed by Radials 1 and 3, energized from the TRO substation. In contrast, Radials 2 and 4 operate in an open-loop configuration and remain energized from TRO but are normally disconnected. The Automatic Transfer Switch (ATS) system facilitates transitions between closed-ring operation (R1 and R3) and open-loop operation (R2 and R4), ensuring continuity of supply. Generator synchronization and load transfer are managed by InteliMains units, which ensure proper voltage, frequency, and phase alignment during transitions. Continuous operation is furthermore constrained by a long-term current limit of 600 A [2], imposed by the public network operator to prevent overloading and unintended relay tripping.

The present thesis therefore seeks to document and analyse, in a systematic manner, to what extent the combined distribution and standby power installation can guarantee uninterrupted, selective and reliable supply under all realistic scenarios—namely: (i) the loss of a single incomer (N−1) concept, (ii) complete grid failure necessitating emergency generator operation, and (iii) subsequent resynchronisation with the grid. The investigation focuses on three principal problem areas: (1) the installation’s ability to maintain supply to all critical loads without undue voltage disturbances, (2) the stability and control of the generators in parallel operation and their smooth reintegration into the grid, and (3) correct protection coordination that enables selective tripping while enforcing the 600 A limit.

Abstract: This project focuses on the design and optimization of 10 kV medium-voltage cables and associated grounding systems as part of a Site Energy Upgrade (SEU) at Novo Nordisk in Hillerød. The aim is to analyze and validate the electrical and thermal loading of the concentric conductor and assess the impact of various bonding and grounding methods under realistic operating conditions.

The study is based on a three-phase cable system using single-core cables in trefoil configuration, each with a 50 mm2 copper concentric screen and a parallel Ground Continuity Conductor (GCC). Theoretical calculations are performed to determine system impedance, short-circuit currents, and thermal capacity of the screen, with particular focus on the most critical fault scenario which is a two-phase-to-ground fault. The project includes an in-depth analysis of grounding systems, comparing isolated and impedance grounded networks. The study evaluates how the choice of grounding method affects fault current magnitudes, protection settings, and dimensioning of the concentric conductor. These insights form the basis for determining the most robust and operationally reliable grounding strategy.

Different bonding methods single-point bonding, solid bonding, and cross bonding are analyzed in relation to their impact on induced voltages, circulating screen currents, and power losses. The system is modeled in both DIgSILENT PowerFactory and COMSOL Multiphysics, with simulation results benchmarked against theoretical expectations and relevant international standards. The simulations show that single-point bonding eliminates circulating currents and reduces thermal losses but requires overvoltage protection using Sheath Voltage Limiters (SVLs), while solid bonding ensures equalized potential but results in increased losses. Cross bonding is assessed theoretically but not implemented due to the scope of the project.

The project concludes that correct screen dimensioning and careful selection of grounding and bonding methods are essential to ensure system reliability, personal safety, and efficient operation in medium-voltage installations. The results provide a technical foundation for future grounding design in large-scale electrification projects.

Abstract: This project explores the automation of early-phase design deliverables for high-voltage air-insulated switchgear substations. Traditionally, creating single-line diagrams, 3D layouts, and bills of quantity requires significant manual effort, especially in the initial proposal stage. The aim of this project is to develop a proof-of-concept tool that generates these deliverables based on a structured input file describing a substation configuration. The tool was built using Revit, Dynamo, and Excel, and relies on a library of predefined bay typicals to generate consistent outputs. It was tested on three representative cases, each increasing in complexity. Validation focused on verifying the tool’s output against known standards and expected configurations, including electrical accuracy, dimensional alignment, and component completeness.

The results show that the tool significantly reduces manual workload, ensures consistency across deliverables, and supports faster iterations in early project phases. However, the tool also depends heavily on the quality of input data and requires ongoing maintenance to remain aligned with evolving standards and employers requirements. The project concludes that automation of substation design is feasible and beneficial when implemented with proper governance. Future work should focus on expanding the scope of deliverables, including more parts of a substation, and standardizing input formats to support broader adoption.

Abstract: The primary objective of this study is to analyze and evaluate the effectiveness of the Static VAR Support (SVS) as a reactive power compensation device in grid-connected photovoltaic (PV) systems using DIgSILENT PowerFactory as the simulation platform. The increasing penetration of PV farms into modern power grids has introduced challenges such as voltage instability, power quality deterioration, and reactive power management deficiencies. This research aims to address these issues by integrating the SVS into a grid-connected PV system and assessing its impact on grid stability, efficiency, and compliance with grid codes through modeling, simulation, and performance analysis in DIgSILENT PowerFactory.

To achieve this, the study focuses on the following specific objectives:

To investigate the role of reactive power compensation in grid-connected PV systems and its impact on voltage stability, power factor correction, and overall power quality in

modern power grids.

To analyze the working principles, control strategies, and technical capabilities of the Static VAR Support (SVS) as a reactive power compensator for PV farms.

To develop a comprehensive simulation model of a grid-integrated PV system with an SVS in DIgSILENT PowerFactory, considering real-world grid conditions, solar variability, and load fluctuations.

To evaluate the performance of SVS-based reactive power compensation under various operational scenarios, including voltage disturbances, grid faults, varying solar irradiance, and dynamic load conditions.

To assess the economic feasibility and technical viability of implementing SVS technology in grid-connected PV systems, considering cost-benefit analysis, energy losses, and grid compliance with regulatory requirements.

To provide recommendations for integrating the VAR Support into future grid-connected PV farms, addressing technical, economic, and policy considerations to enhance grid stability and power quality.

By accomplishing these objectives, this research aims to contribute to the optimization of reactive power management strategies for PV-integrated power systems and support the development of resilient and efficient renewable energy-based grids.

Design and Integration of Solar-Wind Hybrid Power Plants with Battery Storage

Meron Embaye

Abstract: Moving to renewable energy is essential for a sustainable future and reducing our reliance on fossil fuels. This project designs a hybrid power plant that uses wind, solar PV, and battery storage to make Bornholm, Denmark, energy self-sufficient. The system was modeled in DIgSILENT PowerFactory, using wind and solar data along with load profiles to evaluate performance. Calculations for the Levelized Cost of Energy (LCOE) and curtailment were done in Excel. The most cost-effective setup found was 90% wind and 10% PV, with an LCOE of e0.1433/kWh. At higher solar shares, the LCOE increases significantly due to higher curtailment and the need for larger battery storage. At very low solar shares (around 5%), the LCOE is also slightly higher because wind energy alone has a higher LCOE compared to solar. These results show the importance of balancing wind, solar, and storage to reduce costs and keep the system stable. Future work should use real-time wind and solar data to improve accuracy and apply advanced optimization methods like Artificial Bee Colony (ABC) or Particle Swarm Optimization (PSO) to enhance performance.

Abstract: This thesis presents the design and development of a 1.5 kW T-type inverter for uninterrupted power supply (UPS) applications, utilizing wide-bandgap semiconductors. These semiconductors enable high efficiency and reliability through their ability to operate at elevated voltages and switching frequencies. The inverter’s T-type topology was selected for its reduced conduction and switching losses compared to NPC and H-bridge designs. While the intended control strategy was space vector pulse-width modulation (SVPWM), simulations were conducted using a simplified sinusoidal pulse-width modulation (SPWM) approach. Simulations in PLECS informed the selection of components for the prototype. However, due to difficulties in interfacing the Simulink control model with the Speedgoat I/O module, experimental testing was not completed.

Abstract: In recent years, the increasing demand for clean and sustainable energy sources has led to a rapid advancement of renewable energy technologies. Among these, photovoltaics and wind power have emerged as highly viable options, offering abundant and easily accessible energy resources. However, the intermittent nature of both solar and wind energy poses a challenge in ensuring reliable and consistent power generation. To overcome this limitation and enhance the efficiency of renewable energy systems, the concept of hybrid energy parks, which combine multiple renewable energy sources, has gained significant attention.

In this thesis, the hybrid energy park will integrate solar and wind power, along with a battery storage system, to maximize energy production and system reliability. By harnessing the complementary nature of solar and wind, and incorporating battery storage to store excess energy during peak production periods, the hybrid energy park offers several advantages such as: improved overall energy output, enhanced grid stability, and a reduction of reliance on conventional power sources. Battery storage also ensures a more reliable energy supply by addressing fluctuations in power generation and demand, further solidifying the viability of hybrid energy parks as a cornerstone of sustainable energy solutions.

Abstract: This Bachelor thesis explores the potential of using an electrode boiler to provide ancillary services for the transmission grid. The research focuses on how electrode boilers can contribute to resolving system stability challenges, particularly frequency regulation, in a power system increasingly reliant on renewable energy sources. By leveraging the flexibility of electrode boilers, the study examines their role in supporting frequency containment reserve (FCR) services and addressing the inherent variability of renewable generation. The project includes an in-depth analysis of the technical and regulatory requirements for ancillary services, focusing on the DK2 region in Denmark. Simulations are performed using PowerFactory to model the dynamic behavior of an electrode boiler under various operational scenarios, assessing its ability to stabilize the grid during disturbances and frequency deviations. The study evaluates Frequency Containment Reserve - Normal (FCR-N) services, examining the boiler’s ability to operate within the defined frequency and power regulation parameters.

The results highlight the feasibility of using electrode boilers as effective tools for grid stabilization and ancillary service provision. By integrating this technology into the energy system, the research demonstrates its potential to improve flexibility, enhance system stability, and support Denmark’s transition to a sustainable energy future. This work provides valuable insights into the design and operation of electrode boilers for ancillary services and offers practical recommendations for their implementation in modern power systems.

Modelling and Assessing the Impact of PtX Plant on Grid Frequency Stability

Nuri Sezer Sahan

Abstract: Renewable energy plays a significant role in Denmark’s future power system, with PtX (Power to X) plants expected to significantly contribute to grid stability. In this bachelor thesis focuses on the integration of PtX plants into the power grid, particularly their role in providing ancillary services to stabilize grid frequency. As the penetration of renewable energy increases, grid fluctuations and frequency instability pose challenges to the power system. This project addresses these challenges by modeling PtX plants in the context of Denmark’s future grid, focusing on their contribution to frequency stabilization in the FCR (Frequency Containment Reserve) market. The research emphasizes the modeling of PtX plant components, specifically electrolysers and fuel cells, using DigSILENT PowerFactory’s DSL (DIgSILENT Simulation Language). These components are modeled to assess their dynamic performance and their capacity to stabilize frequency by consuming power during periods of overproduction and generating power when necessary to support the grid. The technologies modeled are based on PEM (Proton Exchange Membrane) systems, which are well-suited for the fast, dynamic responses required for grid stabilization.

At the heart of the project is the simulation of these PtX components in PowerFactory, evaluating their behavior in different scenarios. The performed simulations discussed in the latter part of the thesis and evaluating their performance by analyzing how electrolysers and fuel cells interact with the grid. The simulation examines their overall impact on stabilizing grid frequency. This investigation provides valuable insights into the integration of PtX plants into the power grid, specifically their role in stabilizing grid frequency under varying operational conditions. The results underscore the potential of PtX plants to enhance grid reliability and stability in Denmark’s energy landscape, particularly as renewable energy sources continue to expand.

Abstract:

This report outlines an essential study on integrating wind-driven pump storage system into the electrical grid of Suðuroy in the Faroe Islands. Utilizing the island's considerable wind resources, this project aims to enhance grid stability and energy storage capabilities, essential for the sustainable transition of the energy system in the Faroe Islands. The project evaluates the environmental viability, technical feasibility, and economic effects of implementing advanced wind turbine technologies alongside existing hydroelectric infrastructure.

A detailed assessment of wind resources, appropriate wind turbines, pumps and water turbines for the circumstances, economic optimization of the design and assessment of the effects on the electrical grid upon implementing a wind-powered storage system on Suðuroy in the Faroe Islands, underpins the project.

It addresses critical technical challenges, such as maintaining grid stability, managing power quality, and optimizing energy storage. These issues are tackled through innovative engineering solutions designed to enhance the reliability and efficiency of the grid.

Furthermore, the project explores the optimal design of a wind-powered storage system, viewed from a economic perspective, including cost-benefit analyses, investment evaluations, and potential revenue streams from energy production. The economic optimization aims to establish the best financial design combination of a wind-powered storage system, considering the significant upfront costs associated with infrastructure development and technological integration.

The hoped outcome of this study are to contribute substantially to the Faroe Islands' renewable energy goals for 2030, to be free of all fossil fuels in the energy sector (Christensen [3]), providing a robust framework for sustainable energy development that can be replicated in other regions with similar geographic and climatic conditions. By demonstrating the feasibility and benefits of such integration, the project supports policy decisions and promotes broader adoption of renewable energy technologies, thereby enhancing energy security and reducing environmental impact.

Abstract: This project delves into the economic viability of implementing 1KOMMA5° Danmark A/S’s Heartbeat-enabled Residential Battery Energy Storage Systems (R-BESS) and its associated services in Small and Medium Businesses (SMBs) to leverage market opportunities within the Danish power grid. Market analysis findings indicate that 1KOMMA5° Danmark A/S is well-positioned to enter the SMB market with minimal direct competition. However, the economic viability of Heartbeatenabled R-BESS implementation is influenced by uncertainties in the electricity market, driven by political incentives and economic recovery post-Ukraine invasion. Despite these uncertainties, the results of a data-driven electricity market analysis based on findings from the market analysis conclude that market conditions are favourable for R-BESS adoption, as historical and projected electricity prices indicate continued volatility. This is primarily constituted by the Danish government’s initiative to shift to renewable energy sources for all electricity generation by 2030, which enhances price volatility and demand for ancillary services to maintain power grid stability.

Business case results aggregating analysis results from an optimisation model used to simulate the revenue from the technology stack demonstrate that Heartbeat-enabled R-BESS systems can leverage price volatility for arbitrage opportunities. Additionally, participation in ancillary services through Heartbeat’s Virtual Power Plant (VPP) functionality adds a secondary revenue stream. Particularly, the Frequency Containment Reserve for Disturbances (FCR-D) service shows promising economic results due to its low impact on battery degradation and high monetary rewards.

The results ultimately conclude that implementation is profitable, showing a return on investment (ROI) at end-of-life (EOL) ranging from 178% to 304%, with a payback period of 3.32 and 4.9 years, respectively. This profitability is primarily driven by the VPP functionality, with the remaining generated by the Energy Trader through load shifting and arbitrage. The conclusion also emphasises the significance of accurate system configuration to maximise profitability, particularly the need to scale the R-BESS to the load headroom of the SMB facility. Moreover, it also highlights the importance of restricting daily charge cycles to an average of 1.1 cycles/day to ensure the long-term operation of the system and continuous revenue generation.

Abstract: The aim of this project is to investigate the capabilities of two smart meters, the NES G4 and Kamstrup OMNIPOWER, in power quality monitoring. The investigation is first done theoretically by means of comparing the claimed capabilities of the two smart meters and thereafter a comparison of their measurement data using an advanced PQ analyser, the UniPower UP-2210, as a benchmark for the actual state of the power quality in the point of supply where the three meters are connected in series.

The desired outcome of the project is to gain an understanding of to what extent the integrated power quality monitoring functions of the two smart meters can be used in monitoring power quality. If some of the functions of the smart meters prove capable to a certain extent, this can prove valuble because of the fact that smart meters are already installed in all supply points in the danish grid. This means that potentially a wider understanding of the state of the power quality in the grid can be gained by collecting data from these smart meters and analysing the data without having to install expensive PQ analysers. Knowledge about the state of the power quality in an electrical grid is valuable information because the state of the power quality can have a great impact on society. Poor power quality can result in expensive outages for consumers, it can damage electrical equipment and shorten the life of components in the grid. Good power quality is generally a very desirable trait in any given electrical grid, which is why monitoring it is also important. Having an understanding of when and where the power quality is poor is a core aspect in determining the causes of poor power quality. When the causes are known, it is easier to fix the circumstances that result in poor power quality.

Abstract: This study presents a comprehensive analysis of the performance and fault diagnosis of two three-phase, three-winding transformers, designated EG1 and EG2, at Østerport Converter Station. The goal of the study is to evaluate the general condition and performance of these transformers, which are plagued by serious problems such irregular transformation ratios and frequent diode fuse blowouts under high load. A number of specialized tests are included in the technique, including the following: Turns Ratio (Prim-Sec and Prim-Tert), Exciting Current, Short Circuit Impedance (Prim-Sec, Prim-Tert, and Sec-Tert), and Winding Dissipation Factor and Capacitance (DF & CAP). Every test is thoroughly carried out to assess distinct facets of transformer performance, ranging from impedance characteristics and winding condition to insulation integrity.

The analysis gives us information about the problems the transformers are facing and includes diagnosing faults, interpreting data, and explaining the theory behind each test. Furthermore, MATLAB-Simulink modeling is implemented in the study to get a more profound comprehension of the behavior of the transformers in different operational scenario. The study specifically concentrates on the load distribution in single and parallel operations as well as the selection of the best operating steps. The results highlight the necessity for focused maintenance and operational optimization by exposing serious insulation system problems, including core lamination concerns, winding deformations, voltage control difficulties, harmonic distortions, and electrical losses. The paper ends with practical suggestions for improving the transformers’ reliability and efficiency, which will protect the electrical system of the Østerport Converter Station against instability and deterioration.

Abstract: This thesis aims to develop and compare two battery interfaces for Uninterruptible Power Supply (UPS) applications. One interface is based on standard semiconductor technologies, while the other utilizes Gallium Nitride (GaN) semiconductors. The chosen topology is a nonisolated, bi-directional buck-boost with two controllable switches. The project encompasses creating PLECS simulation models, constructing mock-ups for each interface, testing, and measuring key parameters such as input/output waveforms, efficiency, and thermal behavior. The converter specifications include a 3 kW rated power, input voltage ranging from 300V to 500V, and output voltage from 200V to 300V. The switching frequency varies between 24kHz and 40kHz for standard semiconductor technologies and 50kHz to 500kHz for GaN semiconductors. The study provides insights into the performance of these interfaces, offering valuable contributions to the field of power electronics for UPS systems.

Abstract: The purpose of this paper was to see if a BESS could comply with the grid codes for frequency-related ancillary services, as well as understand its impact in an electrical grid when participating. This paper examines BESS, and its capability to provide ancillary services in the electrical grid. To do so, a template model has been modified and used in the software program DIgSILENT PowerFactory (PF), to replicate a real BESS.

In the paper, there will be a brief introduction to ancillary services, frequency regulation and the current status on energy storage systems as a whole. The PF BESS model will be described in great detail, validated, and then be used for simulating different over- and under frequency events in a case study system. Neither the PF model or BESS model claims to be an exact representation of reality, but efforts have been made to come close. Among these efforts are a change of cell voltage and internal resistance to be non-linear in relation to the SoC, whereas the BESS template assumptions were a linear voltage change and a constant internal resistance.

The results of the paper show that the BESS is capable of providing FCR-D ancillary service in DK2, as well as contributing to a positive impact on the severity of faults. It also shows how the amount of inertia affects the frequency behaviour of the grid after a fault. Besides this, the BESS model has been described and modified in such a way, that it is easily implementable in other projects related to frequency regulation.

Abstract: This graduation project focuses on the design and analysis of a data center for the Danish defense with the aim of enhancing IT security. The project involves establishing redundant supplies using two separate transformer stations, each providing a 10 kV supply. These supplies ensure a reliable and stable power delivery to the data center, even in the event of a failure or interruption. The project is divided into three stages with a gradual increase in power requirements over a period of 15 years. A primary goal is to attain a TIER 3 security standard for all power supply elements within the data center. In pursuit of this objective, 10 units of 1600 kVA dry transformers have been integrated within the existing structures, earmarked as the eventual site for the data center. These 10 transformers are distributed across two transformer stations, with each station housing 5 transformers. In an effort to optimize safety, these stations are separated by a firewall. The two transformer stations are interlinked with a double busbar configuration situated within the "transformer room," the designated location for the internal transformer stations.

In the event of a disruption to both 10 kV supplies, eight 1000 kVA UPS systems have been implemented for temporary power supply. These UPS systems ensure continuous power supply until eight diesel generators, each with a capacity of 1.25 MW, can take over and supply the data center. The project also includes simulations using Power Factory software to analyze short circuits and UPS systems with associated battery banks. Furthermore, main power diagrams and layout plans have been prepared for the placement of transformers, 0.4 kV switchboards, and 10 kV systems in the transformer stations, as well as floor plans of the "Utility building" where the eight diesel generators are located.

The project results will contribute to an improved understanding of the design and analysis of emergency power supply systems for data centers, as well as methods to achieve high security and reliability. The gradual implementation of components in the three stages demonstrates a strategy for flexible and scalable expansion of the data center’s power requirements over time.

Abstract: This report presents an analysis of the impacts of upgrading the cables from 66 kV to 132 kV in wind farm NS1 in the North Sea. The report provides a description of the power supply network, and the necessary theory to conduct the analysis. Following this, the construction of a single line model of the simulation program Power Factory was presented, forming the basis for the required simulations and analysis. A central aspect of the analysis is the possibility of doubling the voltage level in the array cables, which potentially opens for the implementation of larger turbines in the wind farm, for example, with a capacity of 20 MW. This would result in increased efficiency and a greater amount of extracted energy. Lastly, the report includes an examination of the feasibility of a wind farm with 15MW and 20MW WTGs without an offshore substation. A short-circuit analysis for different scenarios has been conducted using Power Factory.

Abstract: This paper revolves around the ability of the type of gravity energy storage system developed by the UK company Gravitricity to deliver certain ancillary services in the electrical grid. This is done by creating and simulating both the energy storage system, as well as the grid connection of the upcoming Gravitricity Project Beta in the simulation tool DIgSILENT PowerFactory. The paper will introduce the technical aspects of ancillary services and gravity energy storage as well as cover the entire process of modelling the Project Beta in PowerFactory and the results of the simulations carried out in said model. The PowerFactory model is not a perfect representation of the actual Project Beta. However, great strides are made in order for it to be a good approximation in the aspects relevant to the results.

At the end of the paper, it is concluded that the Gravitricity energy storage system in the Project Beta, as well as in future projects, is able to meet the response-based requirements for all of the ancillary services in which Gravitricity has shown interest in providing. As such, the Gravitricity energy storage system is well suited to provideing these services. However, in order to provide these services, Gravitricity will have to partner with an aggregator or another type of energy partner in order to meet the required capacity for these services.

Stability enhancement in Suðuroy using ancillary services through converters 

Krista Maria Meinhardsdóttir

Abstract: The optimization techniques for converter-based-integration to be able to be more involved in regulatory services of the power system is a hot topic today as renewable energy shares are increasing rapidly. The purpose of this paper is to review control strategies for PV systems, and based on this, the possibility of providing ancillary services on the grid – mainly frequency support. The analysis in this paper is conducted on the hybrid power system of the island Suðuroy, in the Faroe Islands. Two methods of providing ancillary services are chosen to investigate further, and one is implemented in the grid on. Grid stability analysis is done where the impact of increasing renewable energy shares is investigated. The grid in Suðuroy is RMS simulated in PowerFactory. The simulated scenarios show signs of a stable grid, even as the penetration of PV increases. The scenarios of active power curtailment show that this is positively affecting the frequency of the grid and makes a difference.