1. Zielstellung der Arbeit war die Entwicklung von Musterkennungsmethoden zur automatischen Klassifizierung von Gasen. Um dieses Ziel zu erreichen, wurde die Reduktionsmethode Parameterabschätzung mittels Adaptive-Simulated-Annealing (ASA-PE) und eine Committee machine (CM) zur Klassifikation entwickelt. 2. Mittels PEDOT:PSS-Sensoren wurden mit Hilfe der Impedanzspektroskopie NH3 und NO2 in unterschiedlichen Konzentrationen gemessen. Die aufgenommenen Messdaten wurden durch die ASA-PE, die Komplexe Haupt-komponentenanalyse (CPCA) und die Discriminant analyses via Support Vector (SVDA) reduziert. 3. Der Vergleich der Merkmalsextraktionsmethoden zeigt: Die in dieser Arbeit neu entwickelte Methode ASA-PE liefert im Vergleich dazu ein sicheres Segmentierungs-Ergebnis. 4. Der Vergleich zwischen ASA-PE und ZView zeigt, dass die ASA-PE eine sichere Methode für die automatisierte Gasanalyse ist. Aber bei zweidimensionalen Merkmalen gibt es einen Bereich, in dem sich eine gemeinsame Häufung einstellt, welche zu einer Irritation in der Auswertung von CPCA und SVDA führen kann. Dieses Problem kann durch eine Erhöhung der Anzahl von Merkmalen gelöst werden. 5. Es wurden sechs die Klassifikationsmethoden: Abstandsgewichtete k-Nächste-Nachbarn-Klassifikation (DW-kNN), das mehrlagige Perzeptron (MLP), Support Vector Machine (SVM), CM, CM ohne MLP und CM mit Abstandskontrolle und AAi-Filter untersucht und miteinander verglichen. Um die Klassifikationsmethoden anzulernen wurden alle Merkmalsreduktions-ergebnisse der CPCA, SVDA und der ASA-PE in Trainings- und Testdaten eingeteilt. 6. Die Ergebnisse zeigen, dass die Kombination aus One-Against-All-SVM (OAA-SVM) und ASA-PE die besten Erkennungsraten liefert. Bei 200 Trainingsdatensätzen wird eine Erkennungsrate von bis zu 99.5% erzielt. Durch diese Kombination können jedoch nur 8 Typen ohne Identifikation von unbekannten Typen ermittelt werden. 7. Wenn das MLP aus CM entfernt wird, werden die Resultate von CM leicht verbessert. Mit Hilfe von 6-Sigma zeigt CM ohne MLP eine gute Erkennungsrate für unbekannte Gase und gleichzeitig bleibt die Erkennungsrate auf einem befriedigenden Niveau. 8. Die Streuung der ASA-PE führt zu einer schlechten Abgrenzung zwischen bekannten und unbekannten Gasen. Stattdessen zeigt die Kombination von CM ohne MLP und CPCA in diesem Fall eine gute Abgrenzung.:Abstract II Danksagung III Inhaltsverzeichnis IV Abkürzungen VII 1 Einführung 1.1 Einleitung 1.2 Entwicklungen bei Gassensoren 1.2.1 Fortschritte bei Material und Messmethode 1.2.2 Fortschritte bei Mustererkennungsmethoden 1.3 Motivation 1.4 Struktur der Arbeit 2 Verfahren zur Gasanalyse 2.1 Messverfahren 2.1.1 Impedanzspektroskopie als Detektionsmethode 2.1.1.1 Definition der Impedanz 2.1.1.2 Bauelemente des elektrischen Modells 2.1.2 Optische Verfahren 2.1.3 Elektrochemische Verfahren 2.2 Merkmalerkennung 2.2.1 Merkmalsreduktion 2.2.1.1 Komplexe Hauptkomponentenanalyse (Engl. Complex Principal Component Analysis) 2.2.1.2 Kernel-Diskriminanzanalyse mittels Support Vektoren (engl. kernel Discriminant Analysis via Support Vector) 2.2.2 Klassifikationsverfahren 2.2.2.1 Abstands-gewichtete k-Nächste-Nachbarn-Klassifikation (engl. Distance weighted k-Nearest-Neighbor-Algorithms, DW-kNN) 2.2.2.2 Mehrlagiges Perzeptron (MLP) 2.2.2.3 Support Vektor Maschine (SVM) 3 Eigene Mustererkennungsverfahren 3.1 Parameterschätzung mittels Adaptive-Simulated-Annealing (ASA-PE) 3.1.1 Allgemeines Impedanzspektroskopiemodell eines Gassensors 3.1.2 Parameterschätzung 3.1.3 Die Optimierungsverfahren 3.2 Committee machine 4 Anwendungsbeispiel 4.1 Experiment mit einem Gassensor aus PEDOT:PSS 4.1.1 Sensoraufbau und vereinfachtes Sensormodell 4.2 Experimentelle Ergebnisse 4.2.1 Messaufbau und Versuchsdurchführung 4.2.2 Vorbereitung zur Messung 4.2.3 Durchführung der Messung 4.2.4 Fehlerbetrachtung 4.2.5 Messergebnisse des Gassensors 4.3 Ergebnisse der Merkmalreduktion 4.3.1 CPCA und SVDA 4.3.2 Parameterschätzung mittels Adaptive-Simulated-Annealing (ASA-PE) 4.4 Ergebnisse der Klassifikationen 4.4.1 Ergebnisse der Gasbestimmung mittels Trainingssatz und Testsatz 4.4.1.1 DW-kNN 4.4.1.2 MLP 4.4.1.3 OAO-SVM 4.4.1.4 OAA-SVM 4.4.1.5 Committee machine 4.4.1.6 CM ohne MLP 4.4.1.7 CM mit AAi-Filter 4.4.2 Abhängigkeit der Klassifikationsergebnisse von der Anzahl der Trainingsdaten 5 Zusammenfassung und Ausblick 5.1 Zusammenfassung 5.2 Ausblick Abbildungsverzeichnis Formelverzeichnis Literaturverzeichnis

Detta examensarbete syftar till att svara på ett av Trafikverket fastställt problem: en gemensam regional cykelplanerings process skulle göra dem billigare och mer jämförbara. De erbjuder för närvarande planerarna en modell som utvecklades av Kågeson 2007. Denna modell har formen av en rapport som ger råd om när man ska bygga en cykelväg mellan städer eller platser i en region. Ändå används den bara i endast 6 av de 21 svenska länen. Trafikverket kräver ett nytt planeringsstödverktyg, mer interaktivt och komplett än Kågeson-modellen. Några nya önskade funktioner är separationen av efterfrågan per syfte, införandet av e-cyklar, olika resesyfte och en prioritering av investeringarna.  Examensarbetet är att designa och implementera det här verktyget, även kallat Planning Support System (PSS), som syftar till att jämföra utbud och efterfrågan på cykelväg till prioritering av infrastrukturförbättringar. En huvudbegränsning för modellen är att den måste vara billig datavis, men så komplett och exakt som möjligt. Det baseras på flera öppna dataleverantörer, till exempel OpenStreetMap, den svenska nationella vägdatabasen (NVDB) eller reseundersökningar från Sverige och Nederländerna. Resultatet är en modell, uppdelad efter turändamål och typ av cykel.  Del för efterfrågeuppskattning anpassar en klassisk fyrsteg transportmodell till cykelplanering och begränsad data. För olika resändamål genereras och distribueras resor tack vare en ursprungs begränsad gravitationsmodell. Valet av cykelläge är anpassat till det faktiska resebeteendet genom logistisk regression med en binär logit-modell. Resorna tilldelas sedan nätverket med tilldelnings metoden "allt-eller-ingenting" genom Dijkstras algoritm. För att utvärdera cykelförsörjningen använde vi ett mått som heter Level of Traffic Stress (LTS), som uppskattar den potentiella användningen av en nätverkslänk för olika delar av befolkningen som en funktion av vägnätvariablerna. Prioriteringsrankningen är då förhållandet mellan mått på efterfrågan och utbud.  Detta nya verktyg implementeras med opensource Geographic Information System (GIS) som heter QGIS och med Python 3 och testas i Södermanlands län / This Master Thesis main objective is to answer a problem set by the Swedish Transport Administration: a common regional bicycle planning process would them cheaper and more comparable. They currently offer the planners a model developed by Kågeson in 2007. This model takes the form of a report which advises on when to build a bicycle path between cities or places of a region. Still, it is only used in only 6 of the 21 Swedish counties. Trafikverket requires a new planning support tool, more interactive and complete than the Kågeson model. Some new desired features are the separation of demand per purpose, the inclusion of e-bikes, different trip purposes, and a prioritization of the investments.  The Degree Project work is to design and implement this tool, also called Planning Support System (PSS), which compares supply and demand for bicycle path to prioritizing infrastructure improvements. A main constraint for the model is that it needs to be cheap data-wise, but as complete and precise as possible. It bases on several open data providers, such as OpenStreetMap, the Swedish National Road Database (NVDB), or Travel Surveys from Sweden and the Netherlands. The result is a model, disaggregated by trip purpose and type of bicycle.  The demand estimation part adapts a classic four-step transportation model to bicycle planning and limited data. For different trip purposes, trips are generated and distributed thanks to an origin-constrained gravity model. Bicycle mode choice is fit to actual travel behaviour through logistic regression with a binary logit model. The trips are then assigned to the network using the "all-or-nothing" assignment method through the Dijkstra algorithm. To evaluate bicycle supply, we used a metric called Level of Traffic Stress (LTS), which estimates the potential use of a network link by different parts of the population as a function of the road network variables. The prioritization ranking is then the ratio between demand and supply metrics.  This new tool is implemented with the opensource Geographic Information System (GIS) called QGIS and with Python 3, and it is tested on Södermanland County.

Problem: Public procurement constitutes a large part of the global economy, accounting for 15% of GDP. But it is also responsible for 15% of global greenhouse gas emissions and consumes vast amounts of raw materials as it is strongly focused on linear products. A more circular alternative is the procurement of Product-Service Systems (PSS), which combine products and services. However, research shows that Circular Public Procurements, such as procurements of PSS, are more complex and require deeper procurer-supplier interaction. Yet, the procurer-supplier interaction in the context of public procurement of PSS has not been empirically explored.  Purpose: The purpose of this study is to explore how the interaction between the procurer and supplier throughout the public procurement process can facilitate public procurement of PSS. Method: A qualitative multiple-case study was conducted, exploring four cases of public procurements of PSS between Swedish municipalities and Swedish private companies. Seven semi-structured interviews with interviewees from both sides were conducted. The data was triangulated with case-specific procurement documents.  Results: Procurer-supplier interaction was found to be crucial for procurers and suppliers throughout the public procurement process to make PSS happen and to improve its quality. In both, the preparation and utilisation phase of public procurement, the interaction can bring benefits for procurers as well as for suppliers, thus facilitating PSS.

Purpose: This study aims to examine what is needed by manufacturers and their resellers in thetruck manufacturing industry that wants to pursue a result-oriented PSS. More specifically, thisstudy aims to answer what capabilities are needed for the actors and address what partnershipfactor is needed for collaboration. At the same time, collaboration has been found vital to pursuea PSS, whereas partnership factors can be used to leverage the needed capabilities. Method: This study builds on a qualitative single case study research strategy. The unit of analysisconsists of the European truck manufacturer and its resellers in Singaporean and Malaysianmarkets that want to pursue a product-service system (PSS). The primary data collection wasdone through 24 interviews with decision-makers in a three-phase model, and internalPowerPoint presentations were collected as secondary data. The primary data was then analyzedusing thematic analysis. The main role of theory was to use it to develop interview guides andto be used to code per the thematic analysis. Findings: The result of this study is a framework that shows scholars and practitioners whatcapabilities and partnership factors are needed when planning to pursue a result-oriented PSS inthe truck manufacturing industry. Thirty-three capabilities were identified and categorized acrossvarious business areas, such as capabilities related to the operations of the PSS and innovation.This research further identified six essential partnership factors and explained how these couldbe used to leverage the identified capabilities. Lastly, this research presents a roadmap forprioritizing capabilities and partnership factors for early-stage PSS implementation. The first stepof five is that management should create a clear concept and direction and then create a dedicatedPSS unit to further get the necessary capabilities and partnership factors through iterations. Theoretical- and managerial implications: This study contributes to current PSS literature byexpanding the understanding of what capabilities and partnership factors are needed from amanufacturer-reseller perspective to offer a PSS. Also, it addresses how the partnership factorscan be used to leverage the identified capabilities. Managers can use the framework to evaluatewhich of the capabilities and partnership factors they already have or which they need to get. Itcan further be used to assess the other party before going into a PSS collaboration together. Theroadmap initially guides what is essential so managers can prioritize how to develop or acquirethe necessary capabilities and partnership factors. / Syfte: Denna studie syftar till att undersöka vad som behövs av tillverkare och deras återförsäljare inom lastbilstillverkningsindustrin som vill erbjuda en resultatorienterad PSS. Mer specifikt syftar denna studie till att svara på vilka kapabiliteter som behövs för aktörerna men även villka partnerskapsfaktor som behövs för samverkan. Detta då samarbete visat sig vara avgörande för att driva en PSS, medan partnerskapsfaktorer kan användas för att maximera de nödvändiga kapabiliteterna. Metod: Denna studie bygger på en kvalitativ forskningsstrategi för enskilda fallstudier. Analysenheten består av den europeiska lastbilstillverkaren och dess återförsäljare på singaporeanska och malaysiska marknader som vill erbjuda en PSS. Den primära datainsamlingen gjordes genom 24 intervjuer med beslutsfattare i en trefasmodell och interna PowerPoint-presentationer samlades in som sekundärdata. Primärdata analyserades sedan med hjälp av tematisk analys. Teorins huvudsakliga roll var att använda den för att utveckling intervjuguider och användas även för att koda i den tematiska analysen Resultat: Resultatet av denna studie är ett ramverk som visar forskare och praktiker vilka kapabiliteter och partnerskapsfaktorer som behövs när man planerar att driva en resultatorienterad PSS inom lastbilsindustrin. Trettiotre kapabiliter identifierades och kategoriserades över olika affärsområden, såsom kapabiliteter relaterade till driften av PSS och innovation. Denna forskning identifierade även sex viktiga partnerskapsfaktorer och förklarade hur dessa kunde användas för att utnyttja de identifierade kapabiliteterna maximalt. Slutligen presenterar denna forskning en roadmap för en prioritering av de identifierade kapabiliteterna och partnerskapsfaktorer för PSS-implementering i ett tidigt skede. Det första steget av fem är att ledningen ska skapa ett tydligt koncept och riktning för att sedan skapa en dedikerad PSS-enhet vars upgift är att få tag eller skapa de nödvändiga kapabiliteterna och partnerskapsfaktorerna genom iterationer. Teoretiska och praktiska implikationer: Denna studie bidrar till aktuell PSS-litteratur genom att utöka förståelsen för vilka kapabiliteter och partnerskapsfaktorer som behövs ur ett tillverkare-återförsäljarperspektiv för att erbjuda en PSS. Den tar också upp hur partnerskapsfaktorerna kan användas för att utnyttja de identifierade kapabiliteterna maximalt. Beslutsfattare kan använda ramverket för att utvärdera vilka av de kapabiliteter och partnerskapsfaktorer de redan har eller vilka de behöver skaffa. Den kan vidare användas för att bedöma den andra parten innan man går in i ett PSS-samarbete tillsammans. Roadmappen vägleder initialt vad som är väsentligt så att beslutsfattare kan prioritera hur man ska utvecklar eller införskaffa de nödvändiga kapabiliteterna och partnerskapsfaktorerna.

The furniture industry is an integral part of the European economy and is now facing economic, environmental, and regulatory challenges. Within the European Union (EU), a large amount of furniture every year goes to incineration or landfill, with only 10% being recycled. One of the causes is the increased supply of low-quality furniture that is put on the market, causing increased consumption levels, resulting in an increasing amount of waste. Additionally, most of the climate impact occurs within the extraction of raw materials. From an environmental perspective, vast opportunities present themselves. Simultaneously, new stricter legislation demands decreased use of resources and climate impact, and the introduction of new circular economy guidelines forces companies to act. By adopting a circular approach in the organisation, companies can improve their resource usage and climate impact. However, the adoption itself demands new types of business models, which is a challenge for the corporates in the furniture industry to realize.  The furniture industry can be split into two sections, business to business (B2B) and business to consumer (B2C), where the first one has reached a bit further than the latter, regarding circularity. This can be explained, among other things, by knowledge gaps between the two sections and that Product-Service System (PSS) is more established for B2B. PSS integrates products and services to fulfil the customer’s needs, which is seen as an enabler for circular economy. The aim of this thesis is to explore the furniture industry within B2C in Sweden by identifying which circular business practices are offered today, as well as exploring the challenges and opportunities for furniture companies to implement more circular business practices. In addition, it examines which prerequisites are central to a more circular furniture industry. To achieve the purpose of this thesis, a qualitative approach has been used through a case study at a large Swedish B2C furniture company. Data has been collected through a literature study and an interview study where a total of 14 respondents have been interviewed. The interviewees consisted of both internal respondents at the case company as well as external parties consisting of experts and suppliers. In addition, a mapping consisting of a website study has been conducted to identify the current circular business practices that B2C furniture companies offer in Sweden today. The result indicates that linear business models are currently dominating in the furniture industry and that there is an extensive demand for low-priced furniture, which often lacks quality. Regarding circular business practices, there is a limited amount that is being offered on the market. Out of 40 companies considered, four offered two circular business practices, 18 companies offered one circular business practice and 18 companies offered none. The offers included furniture care guides, reconditioning services, furniture leasing, recycling guides and second-hand sales. The most central obstacles a circular furniture industry faces are the price aspect and the consumer attitude, where circular initiatives in many cases can be more expensive compared to buying new products. Cheap furniture has worse prerequisites for circularity due to the inadequate design and lack of spare parts. In addition, the hygiene aspect and logistical issues were found to be central barriers as well. On the other hand, one major opportunity for circular business practices is changes in consumer attitudes, which is changing with the coming generation due to an increasing interest in sustainability. Furthermore, there are upcoming directives and legal requirements as well as benefits consisting of increased profitability for companies in an early transition to a more circular business. The most essential prerequisites to enable a more circular furniture industry is enabling cooperation between actors and joint efforts to change current trends. It is thus clear that a change in the furniture industry is required, which requires actors to dare to change towards a more circular business.

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This study takes advantage of wide area measurements to propose a centralized nonlinear controller that acts on power system stabilizers, to cooperatively increase the damping of problematic small signal oscillations all over the system. The structure based on decision trees results in a simple, efficient, and dependable methodology that imposes much less computational burden than other nonlinear design approaches, making it a promising candidate for actual implementation by utilities and system operators. Details are given to utilize existing stabilizers while causing minimum changes to the equipment, and warranting improvement or at least no detriment of current system behavior. This enables power system stabilizers to overcome their inherent limitation to act only on the basis of local measurements to damp a single target frequency. This study demonstrates the implications of this new input on mathematical models, and the control functionality that is made available by its incorporation to conventional stabilizers. In preparation of the case of study, a heuristic dynamic reduction methodology is introduced that preserves a physical equivalent model, and that can be interpreted by any commercial software package. The steps of this method are general, versatile, and of easy adaptation to any particular power system model, with the aggregated value of producing a physical model as final result, that makes the approach appealing for industry. The accuracy of the resulting reduced network has been demonstrated with the model of the Central American System. / Ph. D.

This thesis investigates time synchronization, which is crucial in various applications, such as power grid monitoring, communication systems, and in the fusion of information from different sensors. Global Navigation Satellite Systems (GNSS) are currently the state-of-the-art for time synchronization in distributed wireless sensor networks. However, due to GNSS being vulnerable to jamming, alternative methods are required to ensure robustness in critical systems. Preferably, a system would not be controlled by a single country or organization, e.g., GPS. Therefore, time synchronization methods utilizing commonly available signals, such as radio or television broadcasting, are of interest. Long Term Evolution (LTE), the fourth-generation (4G) cellular network, is widely accessible and the framework is internationally standardized. Consequently, the scope of the thesis is limited to LTE-based methods for time synchronization.  Based on the desired receiver-to-receiver characteristics, Scalable Wireless Network Synchronization (SWINS) and Reference Broadcast Synchronization (RBS) were selected to obtain time synchronization. RBS is an active synchronization method requiring communication within the sensor network, while the passive SWINS method solely relies on self-captured measurements. Time synchronization performance was evaluated using Matlab. Simulations show an increased accuracy for SWINS in synchronized LTE networks, while RBS is superior in unsynchronized cellular networks. Both LTE-based methods show performance comparable to the time synchronization accuracy guaranteed with publicly available GPS signals. A sensitivity analysis with varying disturbances shows that jointly estimating time offset and position is preferred to sole time offset estimation if the transceiver position uncertainty exceeds 50 meters.

Frequency monitoring network (FNET) is an Internet based GPS synchronized wide-area frequency monitoring network deployed at distribution level. At first part of this thesis, FNET structure and characteristics are introduced. After analysis and smoothing FDR signals, the algorithm of event trigger is present with Visual C++ DLL programming. Estimation of disturbance location method is discussed based on the time delay of arriving (TDOA) in the second part of this work. In this section, author shows the multiply method to calculate event time, which is important when deal with pre-disturbance frequency in TDOA part. Two event kinds are classified by the change of frequency and the linear relationship between change of frequency and imbalance of generation and load power is presented. Prove that Time Delay of Arrival (TDOA) is a good algorithm for estimation event location proved by real cases. At last, the interface of DLL module and the key word to import and export DLL variables and function is described. At last, PSS compensation optimization with a set of nonlinear differential algebraic equations (DAE) is introduced in detail. With combining the bifurcation theory of nonlinear system and the optimization theory, the optimal control of small-signal stability of power electric systems are solved. From the perspective of stability margin, global coordination of controller parameters is studied to ensure the stable operation of power grids. The main contents of this thesis include: ï¼ 1ï¼ Models of power systems and test power electric systems. Tht5e dynamic and static models of the elements of power systems, such as generatorbbs, AVRs, PSSs, loads and FACTS controllers are presented. Method of power system linearization modeling is introduced. Three test power systems, WSCC 9-bus system, 2-area system, New England 39-bus system, are used in thesis. ï¼ 2ï¼ Multi-objective optimizations based on bifurcation theory. The optimization models, damping control-Hopf bifurcation control, voltage control-damping control, are presented. Pareto combined with evolutionary strategy (ES) are used to solve multi-objective optimizations. Based on traditional PSS parameters optimizations, it can be formulated as a multi-objective problem, in which, two objectives should be taken into account. The minimum damping torque should be identified. / Master of Science

The deployment of large-scale photovoltaic (PV) systems is rising in the Swedish power system, both in quantity and in system size. However, the intermittent characteristics of the PV production raises questions concerning the stability in the electric power grid, and power output fluctuations from the PV systems can lead to voltage quality issues. Hence, the distribution system operator E.ON Energidistribution and the solar energy developer company Solkompaniet are interested in investigating potential challenges and possibilities related to the integration of large-scale PV systems in the electric power grid. This thesis studies fast voltage variations in the electric power grid due to output fluctuations from large-scale PV systems, and examines the possibility to mitigate the voltage variations by reactive power support strategies in the PV inverters. Four studies are carried out to investigate the prerequisites for establishing large-scale PV systems. Firstly, a worst-case study considering eight existing substations in the electric power grid as well as a new substation is carried out, to examine the impact of different parameters on the voltage variations. Parameters such as transformer operation mode, location of the point of connection, switching mode and load capacity are compared in the study. Further, time series calculations are done to investigate the voltage variations over one year, and a study with an oversized PV system is done to investigate the possibility for increasing the PV capacity without grid reinforcements. Lastly, a study is performed with reactive power compensation from the PV inverters to examine the possibility to maintain a stabilized voltage level at the point of connection. The studies are performed in E.ONs network model in the power system simulator software PSS/E, with data for the transmission grid, the regional grid, and parts of the distribution grid included. PV systems with a rated capacity from 32 MWp and upwards are connected to substations in the regional grid, where fast voltage variations on nominal voltage levels of 20/10 kV are studied and evaluated from the perspective of the power producer. From this thesis, it can be concluded that neither of the implemented studies results in voltage variations that violate E.ONs technical requirements on fast voltage variations in the point of connection. Further, the results from the worst-case study show the importance of analysing the specific system of interest when connecting PV systems, since the properties of the existing system have an impact on the voltage variations. The time series calculations show that the voltage variations over a time period of one year are highly influenced by the PV production and the load capacity in the substation, and the study with an oversized PV system shows the possibility for increasing the PV capacity without curtailing large amounts of active power. Finally, the study with reactive power compensation concludes that grid support strategies in the PV inverters may be a key solution for making optimal use of the existing electric power grid and enabling the continued expansion of large-scale PV systems in the Swedish power system. / Utbyggnaden av storskaliga solcellsanläggningar (PV) ökar i det svenska kraftsystemet, både i kvantitet och i systemstorlek. De intermittenta egenskaperna hos energiproduktionen väcker emellertid frågor angående stabiliteten i elnätet, och effektförändringar från anläggningarna kan leda till spänningskvalitetsproblem. Därför är distributionssystemoperatören E.ON Energidistribution och solenergiföretaget Solkompaniet intresserade av att undersöka potentiella utmaningar och möjligheter relaterade till integrationen av storskaliga solcellsanläggningar i elnätet. Detta examensarbete studerar snabba spänningsvariationer i elnätet till följd av effektförändringar från storskaliga solcellsanläggningar, och undersöker möjligheten att mildra spänningsvariationerna genom strategier för reaktiv effektreglering i växelriktare.  Fyra studier genomförs för att undersöka förutsättningarna för att etablera storskaliga solcellsanläggningar. För det första genomförs en värsta-fallstudie med beaktande av åtta befintliga stationer i elnätet samt en ny station, för att undersöka olika parametrars påverkan på spänningsvariationerna. Parametrar som transformatorns driftläge, plats för anslutningspunkten, omkopplingsläge och lastkapacitet jämförs i studien. Vidare görs tidsserieberäkningar för att undersöka spänningsvariationerna över ett år, och en studie med en överdimensionerad solcellsanläggning görs för att undersöka möjligheten att öka solcellskapaciteten utan elnäts- förstärkningar. Slutligen genomförs en studie med reaktiv effektkompensation från växelriktare för att undersöka möjligheten att upprätthålla en stabiliserad spänningsnivå i anslutningspunkten. Studierna utförs i E.ONs nätverksmodell i programvaran PSS/E för kraftsystemsimuleringar, med data för transmissionsnätet, regionnätet och delar av distributionsnätet inkluderat. Solcellsanläggningar med en nominell kapacitet från 32 MWp och uppåt ansluts till stationer i regionnätet, där snabba spänningsvariationer på nominella spänningsnivåer om 20/10 kV studeras och utvärderas ur kraftproducentens perspektiv. Från resultaten kan man dra slutsatsen att ingen av de genomförda studierna resulterar i spänningsvariationer som överskrider E.ONs tekniska krav på snabba spänningsvariationer i anslutningspunkten. Vidare visar resultaten från värsta-fallstudien vikten av att analysera det specifika systemet vid anslutning av solcellsanläggningar, eftersom egenskaperna hos det befintliga systemet har en inverkan på spänningsvarationerna. Tidsserieberäkningarna visar att spänningsvariationerna över en tidsperiod av ett år påverkas starkt av både energiproduktionen och lastkapaciteten i stationen, och studien med en överdimensionerad solcellsanläggning visar på möjligheten att öka den nominella kapaciteten utan att spilla stora mängder aktiv effekt. Slutligen ger studien med reaktiv effektkompensation slutsatser om att strategier i växelriktare kan vara en möjlig lösning för att utnyttja det befintliga elnät optimalt och möjliggöra en fortsatt expansion av storskaliga solcellsanläggningar i det svenska kraftsystemet.