Arbetet utfördes med hjälp av Micropower groups i Växjö. För att få ett förståelse för hur Micropowers batteriladdare beter sig och hur stora övertoner de skapar. Då 5 kW laddaren ej klarade SS-EN IEC 61000-3-12[1] standarden, konstruerades det passiva filter för att reducera övertonerna. Det paralleldämpade filtret klarade att reducera dessa övertoner till rätt nivå. 26 KW laddaren klarar standarden, men det lånades in ett elektroniskt filter av Comsys. Filtret testades för att reducera övertoner till den bästa nivån i standarden och hur många laddare filtret kan hantera. Efter detta gjordes det en enkel beräkning för att se hur stor ekonomisk vinst det är på att införskaffa ett filter istället för att bygga individuella filter för varje laddare.  Nyckelord: Batteriladdare, Filter, Övertoner, Passivt filter, Elektroniskt filter.

The number of solar panel systems and electric vehicle charging in the low voltage grid is increasing rapidly, due to climate- and environmental targets. These nonlinear loads inject harmonics into the grid, which could impact power quality as well as the wear and life of power grid components, such as transformers and cables. The Swedish network operator Ellevio wants to investigate the possible effects that can arise from a largescale introduction of this equipment in the grid, in terms of harmonics. The aim of this master thesis has been to evaluate the compatibility of equipment emission standards and requirements for power quality, and through different calculation methods assess the potential impact from high penetration of devices in the same network. The results show that converters of both EV and PV are able to keep emission levels well below the equipment standard limits. Even by full penetration of a network the aggregated effect of these loads will not alone have a significant impact on neither power quality nor components in terms of wear, losses or capacity. However, in networks experiencing unusually high background levels in combination with high emissions from other loads, the PV and EV emissions could be a contributing factor to a state where individual transformers would be affected or single harmonic voltage limits would be violated. This is considered a very rare case, and thus not something that would serve as a basis for the dimensioning of the low voltage grid. Instead, increased knowledge will help assessing such a scenario and give better support for solving the individual cases that do arise.

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Products produced by a Swedish company are requested to be investigated regarding their harmonic and inter-harmonic currents injected into the public supply system to comply with the Swedish standard SS-EN IEC 61000-3-2, Electromagnetic compatibility (EMC).    On behalf of Systemair Sweden AB, this bachelor thesis aims firstly to investigate if their product, PAFEC 4225 WH (Air Curtain), complies with standard SS-EN IEC 61000-3-2, and if not, what measures should be taken; and secondly to develop a low-cost instrument for the measurement of harmonics and inter-harmonics according to standard IEC 61000-4-7 related to the requirements on equipment used in standard SS-EN IEC 61000-3-2. To this purpose, the standards have been looked into thoroughly, the preconditions for measurements have been studied in detail, and external meetings with a consultant at Delta Development Technology AB have been performed. Measurements of the harmonic spectrum generated by PAFEC 4225 WH have been performed first at Systemair Sweden AB’s Technical center in Skinnskatteberg, and later at Delta Development in Västerås. After this, a low-cost instrument was developed, including hardware and software design and implementation. The hardware implementation consists of a circuit board designed using EasyEDA (an online PCB Design Tool), a NI myDAQ (a data acquisition device made by National Instruments), and an enclosure designed with Solidworks and made with a 3D-printer. The software implementation was conducted using LabVIEW – a graphical programming language.  A few measurements were performed using instruments complying IEC 61000-4-7 at Delta Development, and later with the low-cost instrument. Different line chokes were measured. The results showed that a 15 mH line choke connected in series with each motor would make the PAFEC 4225 WH comply with SS-EN IEC 61000-3-2. The results from the low-cost instrument did not match Delta Developments results regarding harmonic and inter-harmonic content. The difference could be caused by unfinished algorithm, different measurements conditions, and missing anti-aliasing-filter.          For the future work it is recommended that Systemair Sweden AB can either develop the low-cost instrument or buy an existing instrument that complies with IEC 61000-4-7, to enable to do measurements that comply with SS-EN IEC 61000-3-2. One does also need to investigate the grid during low activity or consider buying a signal generator for the purpose of fulfilling the preconditions to enable measurements. It is also recommended that further measurements are performed with the proposed line choke installed to check for any change in performance of the product.

The purpose of this thesis is to evaluate a selection of power quality parameters (harmonic distortion and voltage variations) in the microgrid on Arholma Island in the Stockholm archipelago, Sweden. Measurements of harmonic distortion, total harmonic distortion, and voltage magnitudes is evaluated and compared prior to and after the installation of the microgrid. Furthermore, a comparison is made between grid-connected mode and island operation mode where also the frequency is analysed. The measured values are compared against regulatory limits.  The microgrid is owned and managed by the company Vattenfall, who provides the data used for the evaluation. The microgrid consists of two battery energy storage systems and a small photovoltaic system. The central energy management system has different use cases, for example peak shaving and voltage regulation. At the time when this thesis is conducted, the microgrid has been up and running continuously for approximately 8 months, from September, 2023 to April, 2024. A power quality meter has been collecting data at the point of common coupling (connection to the mainland) for a period of two years, i.e., from April, 2022, which is one year prior to the installation of the microgrid in mid-April, 2023. The microgrid is also operated in island operation mode for three short periods on April 18, 2024.  The data analysis is executed in Excel and Matlab. The results show that all measured harmonics (2nd to 25th), and total harmonic distortion stays well within regulatory limits throughout the whole measuring period. The microgrid does not seem to make the harmonic magnitude increase in general, although there is a slight increase during island operation mode for certain harmonics. Only on one occasion (with the exception of a planned maintenance outage) does the voltage drop below the levels of what is considered as good voltage quality during the two-year measurement period. Also, during island operation mode, the frequency show less variations than during grid-connected mode. / Syftet med detta examensarbete är att utvärdera ett urval av elkvalitetsparametrar (spänningsdistorsion/övertoner och spänningsvariationer) i mikronätet på ön Arholma i Stockholms skärgård, Sverige. Mätdata för övertoner, total övertonsdistorsion och spänningsamplitud utvärderas och jämförs före och efter installationen av mikronätet. Dessutom görs en jämförelse mellan nätanslutet läge och ö-driftläge, där även frekvensen analyseras. De uppmätta värdena jämförs med föreskrivna gränsvärden. Mikronätet ägs och förvaltas av företaget Vattenfall, och tillhandahåller den data som används för utvärderingen. Mikronätet består av två batterilagringssystem och ett litet solcellssystem. Det centrala kontrollsystemet har olika funktioner, till exempel ”peak shaving” och spänningsreglering. Vid t idpunkten då detta examensarbete genomförs har mikronätet varit i drift kontinuerligt i cirka 8 månader, från september 2023 till april 2024. En elkvalitetsmätare har samlat in data vid sammankopplingspunkten mot fastlandet under en period av två år, dvs. från april 2022, vilket är ett år före installationen av mikronätet i mitten av april 2023. Mikronätet körs i ö-drift under tre korta perioder den 18 april 2024. Dataanalysen utförs i Excel och Matlab. Resultaten visar att alla uppmätta övertoner (2:a till och med 25:e) och total övertonsdistorsion håller sig väl inom regulatoriska gränser genom hela mätperioden. Mikronätet verkar inte bidra till att övertonernas magnitud ökar i allmänhet, men en liten ökning för vissa övertoner kan ses i samband med att mikronätet körs i ö-drift. Endast vid ett tillfälle (med undantag för ett planerat underhållsavbrott) under den tvååriga mätperioden sjunker spänningen under nivåerna för vad som anses vara god spänningskvalitet. Resultaten visar även att frekvensen varierar mindre vid ö-drift än när mikronätet är sammankopplat med fastlandsnätet.

This study addresses quality control for Light Emitting Diodes (LED) according to fouraspects, the power factor of LED lamps, their harmonics and total harmonic distortion (THD), the luminosity for total power to radiated power ratio. It focuses on four brands and six different LED lamps, and concludes that IKEA's LED lamps pertain as the quality lamp, with a power factor over 0.9, THD less than 4% and a power to radiated light of over 4%.

<p>One of ABB Power Systems´s business areas is HVDC (High Voltage Direct Current) technology. HVDC is used for transmissions for both short and long distances. One of Power Systems’s products is called HVDC Light. </p><p>HVDC Light is a relatively new technology for power transmission, but have before only been used for motor drives applications. The technology is based on VSC (Voltage Source Converter) that uses a technique called PWM (Pulse Width Modulation). </p><p>There are a lot of PWM patterns that have been examined, but not in the field of power transmission where ABB Power Systems is working. </p><p>The different PWM patterns can be used for reducing switching losses or harmonics, that can cause the need of external filters to decrease or increase. </p><p>The purpose of this report is to give a general picture of the system that generates the PWM patterns. The report describes some main components in the system. T</p><p>he thesis also present amplitude spectrum from various PWM patterns - generated by signals that have been pulse width modulated with a triangle- shaped wave. </p><p>By showing the frequency-content, the decisions are eased for the engineers and technicians that are working with this kind of questions. </p><p>An analysis of different PWM patterns have been done. The kind of reference waves that generate the PWM patterns are called Dead Band PWM and Modified SPWM. </p><p>Comparisons have been done for Dead Band PWM, between harmonics and the width of Dead Band. Comparisons have been done for Modified SPWM, between: </p><p>1. fundamental frequency and modulation index. </p><p>2. different Modified SPWM and their harmonics.</p>

One of ABB Power Systems´s business areas is HVDC (High Voltage Direct Current) technology. HVDC is used for transmissions for both short and long distances. One of Power Systems’s products is called HVDC Light. HVDC Light is a relatively new technology for power transmission, but have before only been used for motor drives applications. The technology is based on VSC (Voltage Source Converter) that uses a technique called PWM (Pulse Width Modulation). There are a lot of PWM patterns that have been examined, but not in the field of power transmission where ABB Power Systems is working. The different PWM patterns can be used for reducing switching losses or harmonics, that can cause the need of external filters to decrease or increase. The purpose of this report is to give a general picture of the system that generates the PWM patterns. The report describes some main components in the system. T he thesis also present amplitude spectrum from various PWM patterns - generated by signals that have been pulse width modulated with a triangle- shaped wave. By showing the frequency-content, the decisions are eased for the engineers and technicians that are working with this kind of questions. An analysis of different PWM patterns have been done. The kind of reference waves that generate the PWM patterns are called Dead Band PWM and Modified SPWM. Comparisons have been done for Dead Band PWM, between harmonics and the width of Dead Band. Comparisons have been done for Modified SPWM, between: 1. fundamental frequency and modulation index. 2. different Modified SPWM and their harmonics.

In this thesis the effect of harmonics on the electrical grid from electric car chargers, specifically the effect on distribution transformers, is analyzed. The study was performed on the electrical grid of two areas provided by the electrical company Dala Energi. Electric car chargers are added to each customer connected to the electrical grid in both areas to examine the effects of harmonics on the distribution transformers. A model of the electrical grid of each area was recreated and simulated with the open source program OpenDSS. The effects of the added harmonic load on the electrical grid was evaluated in a range from 10% to a 100% of the consumers connected to the grid.  The results of this study show an increase in losses due to harmonic distortion. However, the losses are less significant when the added electric car charger load is distributed between all three phases of the grid compared to one phase. All the added harmonics, except the 9th harmonic, maintain acceptable levels set by The Swedish Energy Market Inspectorate. The impact of the 9th harmonic can be reduced by installing filters. The main conclusion of this thesis is that to reduce the effects of harmonic on the grid the harmonic load should be distributed on all three phases. Also scheduling the charging time of the cars can be implemented to further even out the load variations on the electrical grid.

HVDC technologies are very effective on long distance power transmission but generally raise large interrogations as how to determine an effective configuration. This thesis propose part of an optimization process in order to determine an optimal configuration for an HVDC installation, emphasizing in this report the impact of the conductor selection and of the filter design.  The conductor selection, including varying voltages raises concern about the knowledge of the energy cost evolution in order to determine its optimum and a sensitivity analysis is proposed to evaluate the impact of this factor on the final design. The conductor selection approach made it possible to determine the key parameters in choosing a conductor which are the radius and number of conductors. Different types of conductors and configurations were compared with different scenari for energy cost in order to determine the most economical conductor.  Filter design is a matter that concerns both the internal components and the AC components of the HVDC station but can also be considered as an optimization process, considering the total losses of the filters and the total harmonic distortion and using a minimax approach.  The optimization approach, based on a Newton-Raphson algorithm, made it possible to determine an optimal combination of filters in order to account for all the power range in the HVDC link. It was observed that even though the actual choice for the design was close to the final design selected, it was not optimal for low power harmonics. / HVDC är en mycket effektiv teknik för kraftöverföring av elektrisk energi på långa avstånd, men ställer generellt stora krav på hur man genomför en effektiv konfiguration. Denna avhandling föreslår en del av en optimeringsprocess för att bestämma en optimal konfiguration för en HVDC-anläggning. Det som betonas i denna rapport är effekterna av val av ledare och design av filter. Ledarvalet, inklusive val av spänning, kräver en prognostisering av energikostnadernasutvecklingen för att optimera designen och göra en känslighetsanalys för att utvärdera effekterna av dessa faktorer på den slutliga utformningen. Tillvägagångssättet för ledarval gjorde det möjligt att fastställa de viktigaste parametrarna att välja en ledare som är radien och antal delledare. Olika typer av ledare och konfigurationer jämfördes med olika scenario för energikostnaden för att bestämma denmest ekonomiska ledaren. Filterdesignen är en fråga som berör både de inre komponenterna och AC komponenter i HVDC-stationen, men kan också betraktas som en optimeringsprocess, med avseende på de totala förlusterna av filtren och total harmonisk distorsion och med hjälp av en minimax tillvägagångssätt. Optimeringsstrategin som bygger på en Newton-Raphsons algoritm, gjorde det möjligt att fastställa en optimal kombination av filter för att ta hänsyn till alla effektområden i HVDC-förbindelsen. Det observerades att även om det faktiska valet för konstruktionen var nära den slutliga utformning som valdes, så var den inte optimala för låga  övertoner.