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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Examining Fear of Recurrence in Cancer Survivors

Dixon, Christina L 01 January 2019 (has links)
Improvements in the medical field have given many cancer patients and survivors better odds of long-term survival. As more patients become survivors, the demand for psychological treatment becomes greater. The most prevalent concern of survivors is getting help with a psychosocial condition known as fear of recurrence (FOR). Prior to this study, few researchers had explored how having a more aggressive cancer influences the development of FOR. The purpose of this quantitative study was to determine whether cancer stage and type (a measurement of severity) are predictive of FOR development in the high-risk cancer groups lung and bronchus and female breast. The theoretical framework guiding this research was based on Mishel's theory of uncertainty in illness, which states that uncertainties about illness recurrence can cause survivors to experience breakdown in their lives (whether psychological and/or physical). The fear of cancer recurrence inventory (FCRI) survey was administered to 97 lung and bronchus and female breast cancer survivors; the survivors were asked to rate their level of discomfort about the possibility of a cancer recurrence. Data were analyzed using multiple linear regression. The results indicated that cancer type and severity both impacted the development and severity of FOR in lung and bronchus and female breast cancer survivors. Furthermore, regardless of the cancer type, stage of cancer, age of the survivor, or years in remission, survivors reported clinical levels of FOR in all areas of concern. Practitioners can use the current findings to work towards developing better intervention and treatment programs that promote quality survivorship and reduce the risk and rate of FOR in high risk cancer populations.
12

An Integrated Study on Chicken Gut Microbiome Associated with Diets and Feed Utilization Using Microarray and Illumina Sequencing

Pan, Deng January 2014 (has links)
No description available.
13

Aggregated Demand-Side Energy Flexibility : Residential Assets Potential FCR-D Revenues and Energy Forecast Optimization

Eriksson, Erik January 2024 (has links)
Today, power grids are designed as a traditional large-scale centralized generation. However, as more renewable asynchronous resources are integrated, the share of rotating synchronous machines decreases. These asynchronous resources lack the inherent inertia from conventional generation, resulting in new challenges in power grid management. Without proper measures, the frequency might deviate significantly during system disruptions. During a frequency deviation, the power system operator activates power reserves to mitigate and maintain the balance. Currently, these reserves the vast majority of hydropower. New technologies for providing these reserves are needed with increasing intermittent power generation. One potential technical asset to reduce these challenges resides in demand-side energy flexibility. Demand-side energy flexibility for residential has mostly been large, but disregarded resources since small individual consumers lack the required capacity to provide ancillary services. This necessitates the need for aggregation as a possible solution.  This master thesis aims to investigate the economic potential for utilizing demand response, battery energy storage systems, and electric vehicle charging as a resource for frequency containment reserves to stabilize the power system. The thesis investigates the demand-flexibility for each asset based on residential behavior to determine the complete potential regarding requirements set by the system operator. The study also investigates how ABB AbilityTM OPTIMAX®, as an optimization tool, could optimize the model’s energy demand to generate increased energy cost savings.  The results of the investigation’s indicate great potential for all assets when aggregated, especially the aggregation of the battery energy storage system and the wastewater heat pump system. The study showed the tool ABB AbilityTM OPTIMAX®’s energy-saving potential, especially when integrating the model with photovoltaic generation with battery energy storage systems. Observations that led to further discussions included whether oversizing assets could be an option to increase demand flexibility and revenue. / Dagens elnät är konstruerat som en storskalig centraliserad production. Men,när integration av förnyelsebar och asynkrona prodcunter ökar, minskar andelenroterande synkrona generatorer. Dessa asynkrona system tillhandahåller dennaturliga trögheten som konventionella system med roterande massa. Dettamedför nya utmaningar för hantering och kontroll av elnätet. Utan tillräckligaåtgärder kan frekvensen avvika betynade vid ett systemfel. Vid händele av ettsystemfel aktiverar kraftsystemoperatören olika stödtjänster för att minimeraoch balansera frekvensen. I dagsläget står vattenkraften för den absolut störstaandelen av stödtjänster. Med en fortsatt ökande andel av förnyelsebara energislag,kommer det att krävas ytterligare teknologier. En möjligt teknisk lösning äratt utnyttja den redan befintliga förbrukningsflexibiliteten i bostadshus. Närman tidigare räknat på förbrukningsflexibiliteten i bostadshus har man oftabortsett från små och mindre laster då dessa enskilda laster ofta saknar denkapacitet som krävs för att bidra på balansmarknade, vilket kan lösas genomatt aggregera dessa mindre, individuella laster. Målet med detta examensarbeteär att undersöka den ekonomiska potentialen genom att utnyttja den befintligaoch outnyttjade förbrukningsflexibiliteten hos laster i ett bostadsområde genomatt som en resurs bidra med stödtjänster till elnätet . Dessa laster är ventilation,spillvattenvärmepump, belysning, elbilsladdning och batterilagring. För attbestämma den total tillgängliga kapaciteten undersöker även studien varje enskildtillgångs förbrukningsflexibilitet, vilket beror av boendes vanor, väderlek, mm.Slutligen undersöker även studien möjliga energikostnadsbesparingar med attanvända ABBs optimeringsprogram ABB Ability™ OPTIMAX®. Resultatenfrån stuiden visar på stora potentiella ekonomiska inkomster för alla tillgångar,speciellt för batteri system samt spillvattenvärmepumpen. Studien visade ävenpå goda energikostnadsbesparingar genom att använda ABB Ability™ OPTIMAX®,speciellt vid integrering av solcellsproduktion och batteri systemen. Observationersom ledde till ytterligare diskussioner var om överdimensionering av tillgångarkan vara ett alternativ för att öka förbrukningsflexibiliteten och de potentiellaintäkterna.3
14

Förbrukningsflexibilitetens potential och påverkan på kraftsystemet : Med fokus på automatisk frekvensreglering genom styrning av kylskåp / The potential of demand response and its impact on the power system : With focus on fridges as automatic frequency control reserves

Ly, Sandra, Thell, Linda January 2015 (has links)
Increased use of variable energy and integration of electricity markets in the European Union have led to new challenges when balancing supply and demand in the grid. Load management is a possible way to manage these challenges by adjusting electricity consumption in order to balance the power system. Household appliances can be used for this purpose, for example by providing automatic frequency control. The aim of this master thesis is to investigate the potential of load management from private households and to examine how the power system is affected by a more flexible electricity consumption. The thesis focuses on fridges as automatic frequency control reserves and the ability of fridges to balance the power system. Attributes such as capacity, activation time, persistence and the effect of load reconnection has been modelled in Simulink, Matlab. Complementary interviews with actors from the electricity industry have been done to summarize their insights on demand response. The results indicate that fridges can be used as a part of the automatic frequency controlled reserve FCR-N, based on assumptions made in this study. However, current requirements imposed on balancing resources are not fully met by the fridges. In order for household appliances to provide the needed flexibility, some requirements might need to be rephrased. The results also show that the capacity for providing balancing services differs for positive and negative imbalances, as consumption can be reduced with 30 MW and increased with 66 MW. When controlling the fridges by moving the reference temperature, there is a risk that the appliances will synchronize with each other, i.e. reconnect or disconnect at the same time, resulting in frequency oscillations. It is therefore important that load management is designed to avoid this kind of behavior.
15

Förbrukningsflexibilitetens potential och påverkan på kraftsystemet : Med fokus på automatisk frekvensreglering genom styrning av kylskåp / The potential of demand response and its impact on the power system, with focus on fridges as automatic frequency control reserves

Ly, Sandra, Thell, Linda January 2015 (has links)
Increased use of variable energy and integration of electricity markets in the European Union have led to new challenges when balancing supply and demand in the grid. Load management is a possible way to manage these challenges by adjusting electricity consumption in order to balance the power system. Household appliances can be used for this purpose, for example by providing automatic frequency control. The aim of this master thesis is to investigate the potential of load management from private households and to examine how the power system is affected by a more flexible electricity consumption. The thesis focuses on fridges as automatic frequency control reserves and the ability of fridges to balance the power system. Attributes such as capacity, activation time, persistence and the effect of load reconnection has been modelled in Simulink, Matlab. Complementary interviews with actors from the electricity industry have been done to summarize their insights on demand response. The results indicate that fridges can be used as a part of the automatic frequency controlled reserve FCR-N, based on assumptions made in this study. However, current requirements imposed on balancing resources are not fully met by the fridges. In order for household appliances to provide the needed flexibility, some requirements might need to be rephrased. The results also show that the capacity for providing balancing services differs for positive and negative imbalances, as consumption can be reduced with 30 MW and increased with 66 MW. When controlling the fridges by moving the reference temperature, there is a risk that the appliances will synchronize with each other, i.e. reconnect or disconnect at the same time, resulting in frequency oscillations. It is therefore important that load management is designed to avoid this kind of behavior.
16

Bridging the Knowledge Gap for New Market Entrants in the Swedish Electric Power System : Market development modeling for the FCR-D Up balancing market / Att överbygga kunskapsgapet för nya markandsaktörer i det svenska elkraftsystemet

Lindroos, Lukas, Odenlind, David January 2023 (has links)
The need for ancillary services is on the rise due to the increasing share of weather-dependent power sources in the electric power system. This master thesis focuses on the Swedish FCR-D Up market. It is a national balancing market for transmission system operator’s procurement of the ancillary service called FCR-D Up, that is the up-regulating frequency containment reserve in case of system disturbances. The FCR-D Up market is undergoing significant changes to adapt to the changing electric power system, which may affect the current market dominance of hydropower suppliers due to the emergence of new suppliers and regulatory changes by the Swedish transmission system operator. This master thesis establishes a conceptual qualitative market development system model for price formation on the FCR-D Up market. The research question addressed is: "What FCR-D Up market developments and regulatory market changes on the supply and demand side respectively are expected in Sweden in the upcoming years, 2024-2026, and how will they affect the market prices?" The research was based on the theoretical concepts of system modeling and price formation, using Soft Systems Methodology. Data was collected from various sources and analysed using CATWOE analysis, Casual Loop Diagram, as well as supply and demand curve model theory. It was concluded that price-influencing market development and regulatory changes are focused on the supply side of the market. These include the market entry of new suppliers, transition to marginal pricing, new technical requirements for market participation and increasing value stacking opportunities for FCR-D Up suppliers on Nord Pool’s electricity markets and the other balancing markets. / Behovet av stödtjänster ökar på grund av den ökande andelen väderberoende kraftkällor i elkraftsystemet. Denna masteruppsats fokuserar på den svenska FCR-D Upp-marknaden. Det är en nationell balansmarknad för transmissionsnätsoperatörens upphandling av den stödtjänst som kallas FCR-D Upp, som är den uppreglerande frekvenskontrollreserven vid störningar i systemet. FCR-D Uppmarknaden genomgår betydande förändringar för att anpassas till det föränderliga elkraftsystemet, vilket kan påverka den nuvarande marknadsdominansen av vattenkraftsleverantörer på grund av tillkomst av nya leverantörer och regulativa marknadsförändringar av transmissionsnätsoperatören. Denna masteruppsats etablerar en konceptuell kvalitativ systemmodell för marknadsutveckling avseende prisbildning på FCR-D Upp-marknaden. Forskningsfrågan är: "Vilken utveckling av FCR-D Upp-marknaden och vilka regulatoriska marknadsförändringar på utbuds- respektive efterfrågesidan förväntas i Sverige under de kommande åren, 2024-2026, och hur kommer de att påverka marknadspriset?". Arbetet baserades på teoretiska koncept kring systemmodellering och prisbildning, med fokus på Soft Systems Methodology. Data samlades in från olika källor och analyserades med hjälp av CATWOE-analys, Casual Loop Diagram samt modellteori för utbuds- och efterfrågekurvor. Slutsatsen var att prisinfluerande marknadsutvecklingar och regulatoriska marknadsförändringar är inriktade på marknadens utbudssida. Det handlar bland annat om nya leverantörers inträde på marknaden, övergången till marginalprissättning, nya tekniska krav för marknadsdeltagande och ökande möjligheter till värdestapling för FCR-D Upp leverantörerpå Nord Pools elmarknader och de andra balansmarknaderna.
17

Modelling and Dynamic Performance of Hydropower in Frequency Regulation : Modelling of Double Regulated Hydropower Turbines

Ormsson, Kristinn Arnar January 2021 (has links)
The frequency of the Nordic power system has been increasingly deviating outside the normal frequency band (50 ± 0.1 Hz) in the past two decades. In an effort to counteract this, the Nordic Transmission System Operators (TSOs) have proposed new and stricter requirements on the units participating in Frequency Containment Reserve (FCR) market. The implication of these new requirements is that all units participating in the FCR markets must be re-evaluated and early predictions state that double regulated (DR) hydropower turbines, such as Kaplan and Bulb types, will have problems meeting these new requirements. To limit the amount of work required to re-evaluate all DR turbines, which might ultimately show that the unit will not pass the requirements, it is highly beneficial for power producing companies to be able to simulate the turbine response accurately enough, without full-scale physical testing, to filter out the possible cases from the impossible ones. This thesis is aimed at finding a hydropower turbine model that could accurately predict the FCR prequalification outcome for a DR hydropower turbine in Simulink from only pre-existing testing and design data. Three hydropower turbine models, one single regulated (SR) and two DR, were tested and validated for FCR Normal operation (FCR-N). The validation was performed by comparing the model results to field test data attained from a full-scale FCR-N test performed on one of Fortum’s DR hydropower units. Furthermore, two of these models were simulated and tested with regard to the FCR Disturbance (FCR-D) requirements but not validated as no such data was available. The results showed that simulating DR turbines with SR models can give inaccurate results as the SR model could not capture the more complex dynamics of the DR turbine accurately enough. The SR model underestimated the active power response drastically while at the same time overestimating the dynamic stability. The DR turbine models managed to capture the dynamics better with the most prominent model, DR Model 2, giving less than 3 % overestimation of the FCR-N capacity and a correctly predicting that the unit would fail the dynamic stability for FCR-N. The thesis results further showed that when modelling DR turbines, the calculation of the net head is vital for accurate model response. Finally, both the SR and DR model agreed that the unit would likely not pass the FCR-D requirements and therefore confirm the early predictions that DR hydropower turbines, such as the one modelled in this thesis, may have problems passing the new FCR prequalification requirements. Ultimately this might impact electrical price or frequency quality negatively. / Frekvenskvaliteten i det nordiska kraftsystemet har stadigt avvikit alltmer från det normala frekvensbandet (50 ± 0,1 Hz) under de två senaste decennierna. I ett försöka att motverka denna trend har de nordiska kraftsystemoperatörerna (TSO) föreslagit nya och striktare krav på aggregat som deltar i frekvensreservsmarknaden (FCR). Dessa nya krav innebär att alla aggregat som redan deltar på FCR-marknaden måste omvärderas och de bedömningar som har gjorts antyder att dubbelreglerade (DR) vattenkraftturbiner, som kaplan- och bulbturbiner, kommer att ha svårt med att uppfylla dessa nya krav. För att begränsa mängden arbete som krävs för att omvärdera alla DR-turbiner, som i slutändan kan visa att aggregatet inte kommer att klara kraven, är det mycket för fördelaktigt för kraftföretag att kunna noggrant simulera turbinresponsen innan de fysiska testerna utförs, för att filtrera bort de omöjliga fallen från de möjliga. Detta examensarbetes syfte var att hitta en turbinmodell som med bra noggrannhet kan förutsäga FCR förkvalificeringsresultatet for en dubbelreglerad vattenkraftturbin, med hjälp av Simulink från endast befintliga driftdata och information om aggregatets konstruktion. Tre turbinmodeller, en enkelreglerade (SR) och två dubbelreglerade, testades och validerades för FCR Normal drift (FCR-N). Valideringen utfördes genom att jämföra modellresultaten med fälttestdata från ett fullskaligt FCR-N-test som utfördes på en av Fortums dubbelreglerade vattenkraftturbiner. Dessutom simulerades även två av dessa modeller och testades med avseende på frekvensreglering vid störd drift (FCR-D) men validerades inte på grund av avsaknad av fälttestdata. Resultaten visade att simulering av dubbelreglerade turbiner med enkelreglerade turbinmodeller kan vara problematisk eftersom enkelreglerade modellen inte kunde fånga dubbelregleringsturbinernas mer komplexa dynamik tillräckligt bra. Enkelreglerade modellerna tydligt underskattade den aktiva effektresponsen samtidigt som de överskattade den dynamiska stabiliteten. De dubbelreglerade turbinmodellerna fångade däremot dynamiken bättre, där den mest framstående modellen, DR model 2, gav mindre än 3 % överskattning av FCR-N-kapaciteten och en korrekt förutsägelse att enheten skulle misslyckas uppfylla den dynamiska stabiliteten för FCR-N. Resultaten visade vidare att beräkningen av nettofallhöjden är avgörande för korrekt modellrespons. Slutligen var både singel- och dubbelreglerade modellerna överens om att aggregatet sannolikt inte skulle klara FCR-D-kraven och bekräftar därmed de tidiga bedömningarna att dubbelreglerade aggregat, som den som modellerades i denna avhandling, kan ha svårt att klara de nya FCR kraven. I slutändan kan det påverka såväl elpris som frekvenskvalitet negativt.
18

Utvecklingen av marknadsvärdet för svenska ​​frekvenshållningsreserver 2024–2030 : En prognos för utvecklingen av marknadsvärdet för frekvenshållningsreserverna FCR-N, FCR-D upp och FCR-D ned på den svenska balansmarknaden mellan 2024 och 2030 / The Development of the Market Value of Swedish Frequency Containment Reserves 2024–2030 : A forecast for the development of the market value for the frequency containment reserves FCR-N, FCR-D up and FCR-D down in the Swedish balancing market between 2024 and 2030

Ludvig, Aldén, Gustav, Espefält, Gabriel, Gabro January 2024 (has links)
I takt med en ökad andel variabel förnybar elproduktion i Sveriges energimix blir elnätets flexibilitet allt viktigare för att upprätthålla en stabil elförsörjning. Detta arbete undersöker framtida prognoser för priser och volymer på de svenska frekvenshållningsreserverna FCR-N, FCR-D upp och FCR-D ned fram till år 2030. Prognoser för sådan utveckling är viktiga för elmarknadens aktörer och deras beslut att investera i flexibilitetsresurser. SARIMAX-modeller utvecklades baserade på historisk data och antaganden om framtida utvecklingar, vilka i sin tur grundades på en intervju med en branschexpert samt aktuella kartläggningar och rapporter. Resultaten visar på en markant nedåtgående pristrend. För FCR-N prognostiseras priserna sjunka med 367 % från 2024 till 2030, från 29 euro/MW till 5 euro/MW. FCR-D upp förväntas följa en liknande trend med ett prisfall på 325 %, från 20 euro/MW år 2024 till 4 euro/MW år 2030. Den kraftigaste prisnedgången prognostiseras för FCR-D ned, där priserna beräknas rasa med över 1900 % under samma period - från 61 euro/MW år 2024 till endast 3 euro/MW år 2030. Vad gäller volymer visar prognoserna på en relativt stabil utveckling kring upphandlingsplanerna, med en viss ökning för FCR-D ned på 44 % från 2024 till 2030. Den pågående etableringen av batterilager förutses ha stor påverkan genom att öka konkurrensen och pressa priserna nedåt. De låga prisnivåerna 2030 kan dock göra det utmanande att motivera investeringar enbart baserat på intäkter från FCR-marknader. Vidare diskuteras modellernas begränsningar samt behovet av framtida forskning kring batteriteknik, råvaruaspekter och avancerade simuleringsmodeller för att bättre förstå marknadsdynamiken. / As the share of variable renewable electricity production increases in Sweden's energy mix, the flexibility of the power grid becomes increasingly important to maintain a stable electricity supply. This study aims to forecast prices and volumes of the Swedish frequency containment reserves FCR-N, FCR-D up, and FCR-D down until 2030. Forecasts of such developments are important for electricity market participants and their decisions to invest in flexibility resources. SARIMAX models were developed based on historical data and assumptions about future developments, which in turn were based on an interview with an industry expert as well as current reports. The results indicate a significant downward price trend. For FCR-N, prices are forecasted to decrease by 367% from 2024 to 2030, dropping from 29 euros/MW to 5 euros/MW. FCR-D up is expected to follow a similar trend with a 325% price drop, from 20 euros/MW in 2024 to 4 euros/MW in 2030. The sharpest price decline is forecasted for FCR-D down, where prices are estimated to plummet by over 1900% during the same period - from 61 euros/MW in 2024 to only 3 euros/MW in 2030. Regarding volumes, the forecasts show a relatively stable development around the procurement plans, with a certain increase for FCR-D down by 44% from 2024 to 2030. The ongoing establishment of battery storage is expected to have a major impact by increasing competition and putting downward pressure on prices. However, the low price levels in 2030 may make it challenging to justify investments based solely on revenues from FCR markets. Furthermore, the limitations of the models are discussed, as well as the need for future research on battery technology, raw material aspects, and advanced simulation models to better understand market dynamics.
19

Comparison of fast frequency reserve strategies for Nordic grid frequency stability

Ismael, Alexander January 2020 (has links)
How long would modern society cope with a power outage, what would happen to vital systems that we today take for granted in modern society. The Nordic electricity grid is facing a major shift where electricity production from non-renewable sources are to be replaced increasingly by renewable sources. By increasing the penetration of wind and solar power the electric power system might be exposed to disturbances due to decreasing inertia as a result of the electricity transition. Currently the electric power system has different reserves to use to maintain frequency stability but there are other reserves that could help further in the fight for the balance between electricity production and consumption. This project examines whether the new reserve service, fast frequency reserve (FFR), can help the existing frequency containment reserve for disturbed (FCR-D) operation. Therefore, two experiments were conducted using the simulation tool ARISTO, addressing relevant issues involving frequency stability. Motivation for the hypothesis was to investigate if FFR could reduce the frequency transients and improve frequency variations by developing various setups and cases when inertia was retained and when the system inertia was reduced at different stages. The results of the experiments showed that the global minimum frequency, nadir, had increased for all test cases compared to the reference case when using FFR, this proved that the FFR in fact help reducing frequency transients. The results showed furthermore that when the FFR had a duration time of 30 seconds compared to only 5 seconds, the frequency variations could be improved for certain setups for experiment 2.
20

Variations in the primary control availability : An investigation of market conditions’ influence on the FCR-N product

Mann, Johan, Dahlin, Kasper January 2015 (has links)
The systematic implementation of intermittent energy production sources has made the energy system more volatile and unpredictable than ever before. This development increases the importance of balancing services, in particular the primary control. However, the current research that has been conducted on the primary regulation products is limited. Specifically, the factors that drive the variation in availability and price of the primary control are unknown and the procurement is in some aspects based on perception rather than quantitative analysis. This study has investigated which these factors are and their relative significance on the availability and price of the primary control product called Frequency Containment Reserve for Normal Operation – FCR-N. The study was conducted according to methods with both qualitative and quantitative aspects to cover the complex nature of the problem from different views. The study was done in collaboration with Fortum POT at their office to gain insight and support from a market actor. Given the research questions, the result from this study is threefold. Firstly, the factors that affect the FCR-N availability have been identified and other factors have been categorised as insignificant. Secondly, the factors’ relative significances are stated to show their dependency with the FCR-N product. Lastly, an outlier case study showed how extreme situations changes the conditions for the FCR-N procurement. It has been concluded that the FCR-N price for normal operation on the Nordic electricity market can be generalised successfully through the identified parameters. It is also shown that deviations from normal operations have the possibility to create deviations in the FCR-N availability, indicating that these hours of extreme values need additional analysis in order to fully understand the available capacity. However, the significance of the researched parameters will be an indication in analysis of both the normal case and during deviations as these are the most important measures for the FCR-N availability and price.

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