Today, 60% of the European mainline railway network is electrified with 80% of total traffic. It will further increase driven by The Trans-European Transport Network (TEN-T) and sustainability initiatives. As electricity consumption by railway networks increases, quantification of rail transport’s actual energy consumption is essential. Currently, railways’ energy consumption is measured at the supply side, i.e., the grid, which includes the network’s losses. This measurement does not give actual energy consumption. The European Union demanded an on-board energy measurement system for railways from 2019 onward.

The existing energy measurement systems designed for transmission and distribution networks are not suitable for railway applications due to the harsh conditions. The voltage and current signals are highly distorted and need a more sophisticated measurement system. The energy measurement can be divided into current measurement, voltage measurement, and energy calculation. This thesis project is part of the ongoing research in the current measurement for the on-board energy measurement system focusing on the DC current measurement.

The primary objective is to measure the energy dissipated during braking of the train. Therefore, we need to measure the current flowing through the braking rheostat during the braking of the train. This current measurement is difficult due to the fast switching of high current (in order of 500 A-600 A) termed as chopped current.

VSL has developed a test setup to measure the chopped current flowing through the braking rheostat. The test setup is modified to eliminate distortions and achieve the project requirement of 600 A current measurement. Intermediate tests are performed during the modification to analyze the components’ performance. Finally, the modified setup is tested up to load current of 600 A, and uncertainty calculation performed on the measurement results.

The Medium Voltage (MV) network in the Netherlands is almost entirely composed of underground cables. The failure statistics show that the interruptions in the medium voltage have a high contribution in the mean outage time per year per customer. The interruptions in the medium voltage grid are often caused by failure of circuit components mainly the cables, joints, and terminations which account for 73% of the failures. The occurrence of these interruptions and their duration can be limited by proper maintenance measures. Partial discharge diagnostics provide a way for the condition assessment of the circuit insulation. The Smart Cable Guard (SCG) systems from DNV GL help in continuous monitoring of the medium voltage cable circuits during the circuit operation and aid the network operators in maintaining the MV grid. With its non-intrusive monitoring characteristic, we see that the SCG systems provide the measurement of partial discharges (PD) occurring in the cable circuit. Moreover, the partial discharge measurements consists of the information about the location of each observed discharge event along with the time of its occurrence and its corresponding discharge magnitude observed in picocoulombs for every minute. The partial discharge events occurring in the circuit are subjected to evaluation from an expert at DNV GL control rooms who qualitatively assigns a warning level (Level 1, 2, 3, or Noise) to the observed pattern of discharge events. This manual process of evaluation of PD events and assignment of warnings to them is a laborious task and the network operator has to rely on the availability of the expert and his/her accurate assessment. To reduce this dependence for the network operator, Alliander in collaboration with the DNV GL experts is developing an automated decision support tool to identify the partial discharge events and to aid the operator and the expert in evaluating the condition assessment of the cable network. This thesis proposes a clustering methodology using the ST-DBSCAN density-based technique for identifying high-density discharge events or `areas of interest' in the PD data obtained from the SCG systems. The clusters identified from the method are further evaluated by extracting their features or characteristics using the PD data attributes as well as describing their
characteristics based on the context of the circuit. The performance of the clustering method is validated using the DNV GL warnings by formulating performance indicators and metrics to measure the performance. The clustering method along with the features extracted from the cluster contribute towards the development of the automated decision support tool.

Destructive consequences of trapped space charges within HVDC coaxial cable insulation, such as accelerated aging, degradation, and breakdown, are some of the most significant challenges that manufacturers and users usually come up with. Pulsed Electro-Acoustic (PEA) method is a widely-used method for space charge detection and measurement, in which the space charge profile is mapped through acoustic waves that are excited by applied pulsed-voltage. There are a few practices for pulse application into PEA circuit. Pros and cons of the different injection practices have been remained unknown due to limited accessibility to the critical points like the core conductor. Modeling of the pulse injection setups can help us with simulating the essential parameters, like voltage and current, at the unreachable spots. The way how the circuit can be modeled, selecting adequate software and transmission line model, strengths and weaknesses of the injection practices and the changes required for possible optimization in the practices are challenging questions that need to be answered. This thesis develops frequency-dependent models for all the PEA injection setups that are usually deployed for Medium Voltage (MV) mini-cables geometry. It shows, through a validation
process, that PSCAD/EMTDC phase model can yield sufficiently accurate results with reference to the lab measurements. In the next stage, the questioned strengths and weaknesses of each original design setup are determined through a series of lab tests and computer-aided simulations by utilizing of which the best setup is recognized. Seeking some approaches for further optimization of the setups is also another aim of this research. This thesis proves that the PSCAD/EMTDC phase model is capable to present an acceptably exact model for the circuits, despite having some limitations that will be explained. Operational
versions of all setups, in which the fundamental problems are cleared up, will also be proposed in this thesis. Among all the setups, Core Pulse Injection (CPI) and Table Pulse Injection (TPI) practices offer the best non-optimized (original design) and optimized results, in terms of quality of the delivered voltage across the target dielectric respectively, while the original design of Double Side Pulse Injection (DSPI) and Single Side Pulse Injection (SSPI) seem to be unreliable due to severe oscillatory behaviors. Nevertheless, two modified versions for DSPI and SSPI show quality results.

Most ocean-going ships are fitted with an impressed current cathodic protection (ICCP) system. The currents impressed by this system onto the seawater find their way to corroding parts of the ship’s hull, and prevent the hull from corroding. The electric field resulting from the currents around the ship is called the electric signature. This signature is a threat in seas with mines, as mines explode when they detect this signature. Therefore controlling the signature is important, especially to naval ships. In order to be able to control the signature the location and size of corrosion damage needs to be known. Today no method exists for corrosion damage estimation on a sailing ship. This study aims to develop a method for corrosion damage estimation using only measurements of an ICCP system. The research question is: To what accuracy and with what measurements can the damage distribution on a ship’s hull be reconstructed? The quality of the damage reconstruction is evaluated by how well the signature is estimated. First an analytical model is used to explore the theoretical limits of damage reconstruction. This shows damage reconstruction is limited by the number of measurement electrodes. Then damage reconstruction by numeric model inversion is attempted, but is shown to be unattainable. The proposed solution is damage reconstruction by repeatedly calculating for different damage configurations, comparing the calculated measurements to the true ones, and iterating until an optimum is found. This method works well on a ship geometry if 140 measurement sensors are used. In order to verify the damage reconstruction algorithm a scale model facility is developed. The produced field sensors show shifting offsets that are not explained, but good linearity with the electric field. Simulations and measurements with a calibration source show good similarity, but a factor of 1.6 difference that is not explained. Test with sacrificial anodes show large variations over time and a large dependency on the sailing speed. The results show that corrosion damage reconstruction using only on-ship measurements can be achieved. The resolution of damage reconstruction is limited by the number of measurement electrodes, at least one hundred are needed for the signature to be resolved. Current ships have between one and eight measurement electrodes; it is recommended future ships will have at least one hundred. These results furthermore indicate that time-dependent effects should be included in the physical model used for the simulations.

This thesis investigates the performance of distance protection function of actual relay placed on high voltage 400 kV transmission line in a system with high photovoltaic (PV) sources penetration. The benchmark model of system with radial connection of PV plant and conventional power plant was designed in the platform of RSCAD software. By hardware-in-the-loop (HiL) test setup two commercial relays were connected to the Real-Time Digital Simulator (RTDS) and linked to two virtual breakers in transmission line ends modelled in RSCAD. Special logic for correct signal processing of analogical inputs and binary outputs of relays was designed and employed in RSCAD. Several test scenarios were recreated and analysed. Distance protection function was tested with radial connection of synchronous generator to check response of benchmark system and validate correct settings of the relays. Afterwards synchronous generator was substituted by generic PV farm model. Impact of different fault locations, types of fault, power generation level and fault impedance values were studied on a basis of the benchmark model. The goal of this research was to determine the extreme scenarios in the power system when real relay would fail to detect the fault conditions. Failures of distance protection function operation were detected and explained from mathematical side. On the basis of this research the author revealed the cases of relay maloperation and suggested possible ways of solution to this problem by the set of recommendations.

There is a rapid increase in the off-shore wind farms and the interconnection between countries which results in an increased energy transfer over longer distances. High voltage DC (HVDC) cables can transfer this energy in a reduced cost and efficient way in contrast with high voltage AC (HVAC) along with many other benefits. For the HVDC cables extruded cross linked polyethylene (XLPE) insulation is preferred over the mass impregnated paper oil cable due to advantages such as low costs, simplicity, no use of oil and high operating temperatures.
One of the main degradation mechanism for such insulation type is weak electrical conduction of charges due to the material conductivity. Due to a local inhomogeneity of the insulation the ow of these charges is non-uniform. This results in the charge owing inside of a region not equal to the charge owing out of that region which causes a local charge build up. These charges are known as space charges. These create region(s) of high electrical stress which can result in partial breakdown or in some cases complete breakdown of the insulation material as well. Hence, space charge accumulation in cable insulation material governs the failure behaviour and life time of the cable.
This thesis look into the possibility of carrying out an off-line space charge measurements for real-sized HVDC polymeric cable insulation samples using the electrostatic probe technique. The first objective is to develop a calibrated sample using which it is possible to carry out the space charge measurement. Secondly, the possibility to convert the measurements obtained from the sample into the space charge distribution is looked into. A calibrated sample (prototype) is prepared and both the objectives are evaluated using it.

Wind constitutes a dominant form of sustainable energy that is expected to grow rapidly in the years to come. Increased inverter-based wind power penetration may however endanger grid stability and reliability, if not enriched with the capability to provide crucial ancillary services to the grid, such as frequency regulation. In order for the wind turbine technology to participate in the ancillary service provision, a more in depth understanding of the wind turbine dynamic behavior is acquired. Therefore, this Master Thesis Project was formulated to study how the wind turbine technology can assist in providing ancillary services under increased renewable penetration levels with a concentration on the frequency support. This project proposes the frequency controllers both at the single wind turbine level and the wind farm level to facilitate the provision of ancillary services. The power system transient simulation package PSCADTM/EMTDCTM V4.6.2 is used for the controller design and the simulation study. The single wind turbine frequency controller enables the provision of the necessary positive or negative active power reserves in proportion to the measured grid frequency, via the kinetic energy stored in the rotating masses and pitch control. Thus, the wind turbine generator power output is enabled to increase or decrease respectively. The full potential offered by the technology is exploited, while the limitations associated with the provision of active power reserves are identified and respected by the implemented controller. The wind farm controller allows for the coordination and control of the available wind turbines within a wind farm, despite several barriers identified in this project. A list of parameters is used to this end, which can be varied to achieve a more sustained frequency response, despite the barriers introduced by the available limitations of the electrical and mechanical components of the wind energy conversion system. An offshore wind farm case study was performed to test the performance of the implemented controllers and investigate the impact of the wind farm frequency response on the grid frequency, in various scenarios. The successful response of the implemented controllers is proven, while no violation of physical or safe limits is identified thanks to the frequency controller designed in this project. The allowable ranges within which the controller parameters can be varied without unwanted situations are analytically discussed and summarized as important lessons learned. Finally, the active power product that can be provided within the Ancillary Service Market is quantified and described, while recommendations are made at the Ancillary Service Market level that reflect the capabilities of the wind turbine technology, if enriched with the designed controller. Overall, a positive effect of the frequency response provided by the wind turbine technology on the grid frequency is observed. Significant improvements have been achieved on the frequency nadir and the rate of change of frequency by the wind farm controller parametrization under different severity of the frequency deviations. In general, the frequency response that can be achieved through the wind turbine technology is in any case proportional to the amount of power that is generated by a certain wind farm (i.e. proportional to the wind speed conditions). The response provided can last for several seconds, thus constituting a “Fast Frequency Response” service the most appropriate option for the wind turbine technology. A trade-off between the maximum reserves provided and the duration of the response provided is seen. However, in the cases that a certain wind turbine needs to recover following a period of reserves provision, a compromise between the aggressiveness and the duration of the recovery period is also observed.

Increasing wind generation causes displacement of conventional power plants with Synchronous Generators in electrical power systems. This condition leads to less inertia, less controllability and a degraded damping performance in the electrical systems. Studies of stability of the power system attempt to analyze this issues. Rotor angle stability studies using real time digital simulation requires the use of data mining to obtain an insight about the coherency of the system with the variation of the time series data. However, the limitations of the simulation systems as well as the magnitude of the models can lead into difficult study scenarios. By modeling the power systems in real time simulators, electrical studies can be performed faster than with conventional offline simulators. In this thesis project, the Britain baseline system was modeled in the Real Time Digital Simulator (RTDS) using as a starting point and initialization reference, the electrical power model developed for the simulator Power Factory. The model then was reduced using coherency analysis by clustering time-series-data. The same modeling considerations were applied for implementing future scenarios of the GB in the RTDS. For reduction purposes, three main areas describing the North, Central, and South parts of the system were considered in the GB model. The results show that while the area of study is considered constant the other two areas can be replaced by the coherent areas. Thus, less use of racks is required for analyzing the model in the simulator. This study contributes to the analysis of the power electrical systems, by providing valuable insights in how to reduce electrical models for their study in the RTDS.

The founders of Momo Medical envisioned a health care product that would help nurses worldwide with pressure ulcer prevention. Pressure ulcers are a chronic wound that affects the skin of patients who do not regularly change bed posture. As it currently stands, nurses lack the manpower and time to change the postureof patients in a timely manor. Thus, a goal was set to create a product that would reduce this strain on nurses.The goal was to design a non-intrusive product that keeps track of the posture of a patient on a hospital bed, and send an alarm if this has not changed in a set amount of time. A constraint with this was that the product has to lay directly underneath the mattress of the patient. Furthermore, the product has to make use of as few sensors as possible. With these constrains, the project group was divided in three subgroups: the sensor, the algorithm, and the testing subgroup.This report will focus on the design, implementation, and evaluation of the algorithm. The algorithm has to be designed to process the sensor data and return, with 90% accuracy, the posture of the patient. It also has to be able to determine with 99% accuracy whether or not there is a patient on the bed. An optional objective was to design an algorithm to determine the heart and respiration rate of the patient, with 80% accuracy, but this was of lower priority. It was soon decided to give priority to posture detection and not further investigate detection of the heart and respiration rate.In the final product, the information about the patient’s posture will be displayed in a graphical user interface (GUI). This GUI has to be user-friendly and intuitive to use by the nurses. During the prototyping phase, however, a different GUI was used, one that displayed various debugging information. This prototype GUI was necessary to test the various algorithms.Several different mathematical models have been investigated, implemented, and tested. These models range from taking the variance of the sensor data, to deploying a Fourier transform on a polynomial curve based on the sensor data. With preliminary test data, an accuracy of 93% was achieved using a neural network. With the final testing data however, only the neural network reached the required accuracy of 90%, though only just, at 90.8%. With future iterations of the algorithm, more research and data collection is advised, as neural networks work better with larger data sets.

Problem Definition
This bachelor final project was an assignment given by the start up Momo Medical named: "Improving health care with technology". This project was to use their existing technology and ideas to create a system to prevent pressure ulcers. Pressure ulcer are the medical condition that happens when a patient is left too long in the same position in bed. In order to combat this the nurses turn the patient onto a new posture every 3 to 4 hours. To improve upon this Momo Medical decided to built a sensor pad that has to be placed under the mattress in order to track the patients bed posture and to alarm the nurses when a patient has been on a side too long. The project group was divided into three parts: the sensor group who would look at the sensor pad, the algorithm group who would use the data from the sensor pad to determine the bed posture and the test group that had to built a system that could verify the algorithm. This report will talk about the test group. Based upon the data that Momo Medical acquired it was also possible to acquire the heart rate and the respiratory rate from the sensor data. A way to acquire this data was also looked at. The design requirement that were set were 95% accuracy for bed posture and 90% for respiratory rate and heart rate.
Design Description
In order achieve these requirements a few different types of reference signals were looked at that could be used in order to detect the bed posture, respiratory rate and heart rate. In the end an accelerometer and an commercial grade ECG chest strap were chosen. The accelerometer could measure the patients orientation and thus his bed posture. When the accelerometer is attached to the chest it is also able to measure the chest compressing as a result of breathing. The ECG chest strap was chosen as this gave a good platform upon which the accelerometer and the micro controller could be attached.
Evaluation
A prototype was built upon our design and it was tested in different situations. In the end the accuracy for the bed posture detection was 99%, the accuracy of the respiratory rate was 91% and of the heart rate it was 95%. With these accuracies it meant that the design requirements were met. The disadvantage was that the system influences the sensor pad while the patient is wearing the prototype. Another disadvantage was that due to the low sampling speed it was not possible to attach the heart rate receiver to the testing group's prototype, but had to be attached to the sensor group's prototype. These two disadvantages could be improved in the future by making the prototype smaller and faster.

There are two existing surface passivation principles. Passivation of unsaturated Si bonds is called chemical passivation. Surface passivation can also be achieved by shielding the minority charge carriers from the semiconductor interface by means of an electric field. This method is referred to as field-effect passivation.
To test the effect of the field-effect passivation provided by the passivation layer, fixed charge density is the most important parameter. Delft Spectral Technologies (DST) developed a new Corona Charging System used to measure this value. It integrates the corona charging and Kelvin probe into one box. As the corona charging system is still in prototype, several improvements are made to the system, especially the improvements of the charge uniformity. In the thesis four different charging plans are compared to acquire the best charge uniformity.
Several passivation layers are tested with the DST corona charging system to measure their fixed charge density, including Atomic Layer Deposition (ALD) Al2O3, Plasma Enhanced Chemical Vapor Deposition (PECVD) SiNx, Low Pressure Chemical Vapor Deposition (LPCVD) poly-Si. Morphology of the c-Si bulk influence on the fixed charge density in ALD Al2O3 has also been studied.
Finally, research on the charge decaying properties has been done, to find out the stability of the corona charges on different passivation layers.

As the primary protection of high voltage (HV) and Extra high voltage (EHV) transmission networks, distance protection needs to operate properly under all possible fault conditions. It needs to operate as fast as possible for internal fault, while it also must be able to discriminate between the internal and the external faults to prevent unnecessary trip of the normal system. In real life application, the operational characteristic of commercial distance relays such as operating time and reach accuracy are usually defined using the steady state conditions. This leads to difficulty in understanding the operational characteristic of the relay under the dynamic conditions such as faults.
In this thesis, a dynamic test tool based on the latest IEC 60255-121 standard, suitable for performance analysis of distance protection during dynamic condition was developed and validated. The tools are built by using the ATP-EMTP Software and the Omicron secondary injection kit. The test results of two distance relays show that depending on the dynamic conditions, the operational performance of the relay might be affected. In some situations, the operating time of the relays was delayed, while, in other conditions, the accuracy of impedance measurement is affected causing the relay to overreach. Furthermore, this delayed tripping or overreach of distance protection could cause both security and dependability issue in power transmission protection. The dynamic test tool which has been developed can be expanded further to study other dynamic conditions that are not covered in this thesis.

In order to make the bifacial yield prediction models commercially available, a lot of work their development, improvement and validation is being done by many research institutes. At Energy research center of the Netherlands (ECN), one such model is under development. In this project, couple of aspects were investigated to give better insight into improving the model. The two main aspects of the model that were investigated were the rear irradiance estimation and the temperature prediction of the model.
Analysis of rear irradiance aspect of the bifacial yield model through simulations at low tilt angles and elevations should in practice result low rear irradiance but the results showed the opposite. From the literature, a new factor called acceptance was implemented in the rear irradiance model which led to correction in estimation of rear irradiance. For the temperature model, initially indoor measurements of three laminates of bifacial cells and three laminates of monofacial cells were performed under solar simulator. The experiment resulted in finding differences in measured and cell temperatures for all six laminates. According to measured temperatures, the bifacial cell laminates were hotter than their monofacial counterparts, which may not be correct due to higher absorption of irradiance by backsheets in bifacial cell laminates. The differences in calculated cell temperature and measured temperature were investigated and were found to be different. The heating behavior of all laminates was modelled and heat capacity and heat transfer coefficient found through modelling were found to be in good agreement with literature values. Outdoor measurements were used for temperature analysis of bifacial panels and again the differences in calculated cell temperature and measured temperature were found. Non-steady state temperature model was found to be more accurate for low resolution meteorological and insolation data of less than ten minutes as compared to the steady state model used by current ECN model. The difference between measured and cell temperature was translated in terms of heat transfer coefficient and for this difference, the annual energy yield results showed a variation of 1.45 %.
The results of the project showed improvement of the bifacial yield model by ECN through an improved rear irradiance estimation. Furthermore, non-steady model should be used in case the input meteorological and insolation data is in less than ten-minute interval.