Supraharmonics are present in low-voltage (LV) networks, and they can cause interference with equipment and power line communication. The propagation of supraharmonics is defined by the network impedance which in turn depends on the impedance of the devices connected to the network. The probability of interference due to supraharmonics is then dependent on the customers’ behavior. This article presents a case study for the evaluation of the probability of interference considering the uncertainty in LV customers’ supraharmonic emission and impedance. A stochastic analysis of the system characteristics and supraharmonic emission is used. The results for the case study presented in the paper show that there could be a 40% probability of surpassing the compatibility levels in certain nodes which translates into a risk of interference due to supraharmonics. The simulation results are supported by measurements performed in a laboratory, which can emulate a network like the simulated one. The simulation and measurements show that in the frequency range of 27 kHz to 150 kHz the compatibility levels are surpassed.

The induced primary emission leads to changes in the primary emission of a device and the induced secondary emission leads to changes in the propagation of supraharmonics in the adjacent phase due to the connection of single-phase loads spread over three phases in an installation. The induced primary emission and induced secondary emission are shown to give a significant contribution to the total emission measured at a given point in an installation. The induction of the emission is caused by the inductive and capacitive coupling among the conductors within the cables. This paper presents an analysis of four parameters that impact the magnitude of the induced emissions. Simulations carried out in COMSOL, show that the type of cable used impacts the induced emission and studies show that shielded cable with a stranded conductor with the shield grounded will lead to a reduction in the induced emissions. Among the other parameters, i.e., the load and transformer impedance and the length of the cable, the length of the cable is dominating in deciding the magnitude of the induced emissions. Analysis is carried out using Monte Carlo simulation and varying parameters stochastically. For all investigated parameters there is a strong frequency dependency. The stochastic variation of the load impedance in one phase causes a variation of 5% whereas the change in length of the cable leads to a maximum 40% variation in the considered frequency range for induced primary emission. Measurement results are presented to validate the results.

Society has increasingly started depending on the continuity of internet services, the interruption can be crucial for vital societal functions. It is therefore important to maintain continuous and reliable operations of e.g., installations housing sensitive IT (Information Technology) loads. The establishment of a data center attracts huge investments, thereby boosting the economy. The electrical load within the data center is more structured with a similar type of load, i.e., power supplies supplying the servers connected repetitively. They also use power-conditioning equipment such as an uninterruptible power supply (UPS), which ensures uninterrupted power to the servers. The power supplies use switching techniques to modulate and condition the power supplied to the IT load. The switching residues from the power supplies are often in the frequency range from 2 kHz to 150 kHz, known as supraharmonics. The switching frequency of power electronic converters and power line communication are identified as the main contributors to supraharmonics. The increase in the number of power electronic converters in the power system has sparked interest in supraharmonics. Limited standards are available on the magnitude of supraharmonics allowed in the system. For installations that house multiple power converters, prior knowledge about the propagation and consequences of the supraharmonics can be an advantage in increasing their reliability. This work is focused on supraharmonics within data centers, but the results of the study can be applied to other installations.

The data centers are usually three-phase installations where single-phase devices, i.e., servers are distributed over three phases. To understand the holistic view of the system, it is important to understand the spread of supraharmonics in phase, neutral, and protective earth conductors. A perspective on the behaviour of supraharmonics in three-phase installation is presented in this work. The focal point of the work is the summation of supraharmonics in the neutral conductor and conductor crosstalk. The behaviour of the device connected in single-phase installation and when the same devices are spread over three phases may differ depending on the design of the installation. Since the focus is on a greater number of devices, analysis for the change in the magnitude of supraharmonics in a neutral conductor with the change in the number of devices is also undertaken. The IT workload in a data center changes continuously, thus a constant unbalance in the electrical load between the three phases can exist. The thesis aims to understand the factors influencing the change in supraharmonic magnitude and propagation in phase and neutral conductors according to a balanced and unbalanced voltage supply and loading conditions. The presence of a supraharmonic emitting load in one phase can cause interference on the adjacent phase due to conductor crosstalk. Crosstalk leads to the propagation of supraharmonics between the phases. The work focuses on the parameters influencing the crosstalk phenomena for supraharmonics. Among the parameters studied, the type of cable used in an installation and the cable length is dominating. The measurement of supraharmonic emission from the device connected as single-phase and connected as three-phase would differ because of crosstalk.

A large number of servers in data centers connected close by may lead to an increased leakage current. The composite leakage current can comprise subharmonics, harmonics, and supraharmonics. This can cause unwanted tripping of the residual current device (RCD), which is installed for human protection. The work aims to understand the impact of the composite residual current on the operation of the residual current devices.

The main contributions of this work are summarized as:

• A sensitivity analysis is presented based on the parameters impacting the propagation of supraharmonics for different operating modes of a UPS.

• A characterization of supraharmonics emission from different devices according to their time and frequency varying behaviour.

• A mathematical model to predict the change in the supraharmonic emission in the neutral conductor.

• An increased understanding of the behaviour of supraharmonics for constant powerloads under voltage reduction conditions in three-phase installations.

• Introduction and definition of the terms induced primary emission and induced secondary emission to explain conductor crosstalk for supraharmonic emission.

• A mathematical model to show the factors influencing the magnitude of induced primary emission and induced secondary emission.

• The frequency response of RCDs of type AC, A, B, and F under residual currents comprising pure tones and composite currents is presented by measurements andmodeling.

The journey towards sustainable transportation has significantly increased the grid penetration of electric vehicles (EV) around the world. The connection of EVs to the power grid poses a series of new challenges for network operators, such as network loading, voltage profile perturbation, voltage unbalance, and other power quality issues. This paper presents a coalescence of knowledge on the impact that electro-mobility can impose on the grid, and identifies gaps for further research. Further, the study investigates the impact of electric vehicle charging on the medium-voltage network and low-voltage distribution network, keeping in mind the role of network operators, utilities, and customers. From this, the impacts, challenges, and recommendations are summarized. This paper will be a valuable resource to research entities, industry professionals, and network operators, as a ready reference of all possible power quality challenges posed by electro-mobility on the distribution network.

A data center is a major hub of different converters ensuring continuous power to the server loads. The pulse width modulation switching techniques with frequency emission from 2 to 150 kHz (i.e., supraharmonics) in these converters call for a study of the magnitude and propagation of this emission within data centers where UPS is one of the main contributors of supraharmonics. The paper shows, with measurements and model, the change in magnitude and propagation of supraharmonics with the change in the operating mode of the UPS. The magnitude of supraharmonics shows a non-linear dependency on the power consumed in the online mode. In bypass mode, the magnitude of supraharmonics shows a dependency on the type of load connected. The filter connected between PE-N at the input side of the UPS can cause resonance in the phase conductors. The results show that to study the emission, immunity, and electromagnetic compatibility of supraharmonics for UPS, the factors such as operating mode, the type of load connected, and the input and output impedance need to be considered.

Interaction in the supraharmonic range of 1-ϕ device connected in 1-ϕ or 3-ϕ installations will differ according to the design of the installation. Power factor corrected devices employing switched mode power supplies produce supraharmonics in the range 2–150 kHz. The impact of e.g. voltage unbalance, load unbalance and conductor crosstalk on supraharmonics from these devices connected in a 3-ϕ installation are still somewhat unknown. The paper aims to show with measurements and mathematical models the impact of voltage unbalance, load unbalance, and conductor crosstalk on supraharmonics. The impact of voltage unbalance for constant power loads was seen to increase the emission of supraharmonics. Two new terms induced primary and induced secondary emission showing the impact of conductor crosstalk have been introduced. The induced primary emission leads to an increase in the self-emission of the device. The induced secondary emission on the other hand influences the propagation of the emission. The impact of the voltage unbalance, load unbalance, and conductor crosstalk on the addition of supraharmonics emission in the neutral conductor is shown.

Supraharmonics (waveform distortion between 2 and 150 kHz) proliferate in electrical installations due to the increasing use of power electronics converters and power-line communication. Due to the wide range that the supraharmonics cover and the high frequency resolution needed to measure them, a considerable amount of data is acquired. The analysis is usually done manually by experts. More efficient methods for data mapping and analysis are needed. Machine learning methods are explored in this paper for the analysis of supraharmonics data.

Residual current devices (RCDs) are a common means of protection against shock due to indirect contact in low voltage (LV) systems. Due to the increasing penetration of power electronics equipment in LV systems, higher amounts of waveform distortion at a broad range of frequencies, from dc, subharmonics up to hundreds of kHz (supraharmonics), are expected to be present both during normal operation and during faults. The standardization committees and manufacturers have responded to this challenge by proposing different types of RCDs that are expected to function under given conditions of fault current waveform. However, subharmonic and supraharmonic frequency components are not considered in the standards for most of the RCD types. This article studies the effect of these frequency components on RCDs type AC, A, B and F. An assessment is made in terms of two types of RCD failure: blinding and nuisance tripping, for which both magnitude of the current and breaking time is considered. A frequency mapping of the RCDs is performed, and an assessment of these results based on the frequency-dependent response of the human body to currents is performed. Finally, a frequency model for RCDs type A, F and B is developed.

The reliability of the electrical and cooling systems is of utmost importance for the uninterrupted operation of the data center information technology (IT) load. The electrical distribution of the data center includes many subsystems starting with the utility and building transformers, uninterruptible power supply (UPS), power distribution units (PDUs), and power supplies ultimately powering the fans and the internal components of IT equipment. The various converters in data centers emit switching frequency residue due to PWM (pulse width modulation) techniques. The switching frequency range falls within the supraharmonic range, i.e., 2 to 150 kHz. This paper aims to show, with measurements, the different types of supraharmonic emissions measured in the data center, and the difference between their maximum and average magnitudes. The paper shows a method to identify the equipment emitting supraharmonic emission and possible disturbances caused by it. The paper traces the propagation of supraharmonic emission from the source through the transformer to the grid. Lastly, a comparison of measurements is made with the compatibility levels given by standard IEC 61000-2-2.

Data centers are believed to be a significant part of the load in many areas in the future. The future trend of energy usage in datacenters depends on many factors including the efficiency of the equipment used and IT usage. Loads such as residential loads,office loads, agriculture loads, etc. show a daily, weekly and seasonal variation in the power consumption. The behavior of datacenters w.r.t power consumption may differ. The paper, therefore, characterizes data centers from the grid perspective in termsof their power consumption and power quality. An example grid consisting of data center and renewable energy sources is usedas a reference and the impact on power quality, in terms of harmonics and their propagation for the system is presented. Thepaper also shows how different power generating sources (E.g. wind, solar, hydro, etc.) perceive the data center as a load.