Sediment-related issues in reservoirs can often pose significant challenges to their operational effectiveness, sustainability, and environmental impact. Sustainable sediment management can help resolve these issues and extend the lifespan of dams. The reservoir in Andakílsá river in west Iceland is one out of many reservoirs that has experienced sediment-related problems, and in this study, it was evaluated whether a particular sediment management solution called SediCon Sluicer could be a suitable solution for the site. More specifically, evaluate whether the river transport capacity is sufficient to transport the sediments released from the SediCon Sluicer outlet pipe, so they don’t settle and form thick deposit layers in the river bottom. A hydraulic model of the river was set up in a two-dimensional HEC-RAS model (version 6.3.1) and the Manning’s roughness coefficient in the channel calibrated using water level data. The Manning’s value 0.025 was found to best describe the channel roughness. A HEC-RAS 2D Sediment Transport model was then used to simulate different amount of sediments being released into the river for different flow scenarios. A flood event with 95% confidence level to occur once a year was found to have a peak flow of 50 m3/s and have a duration of around 18 hours. However, the average peak flow from the biggest flood events during a 14-year period was found to be 118 m3/s, and that type of flood events can have a duration up to 70 hours. The results from the sediment simulation scenarios showed that for flood events with long duration and high discharge, the yearly accumulated sediments could most likely all be flushed once a year without too much deposit in the river. A shorter flood event, that is almost certain to occur once a year, is not likely to be able to flush out all the yearly accumulated sediments all at once. Perhaps the SediCon sluicer could be operated several times a year, but a more detailed flow frequency analysis must reveal what smaller floods can be expected yearly. This solution could be a suitable option for the river, but more research and analysis need to be performed for a better certainty on the optimal operational range. / Sedimentrelaterade problem i reservoarer kan ofta utgöra betydande utmaningar för vattensystemets effektivitet, hållbarhet och miljöpåverkan. Hållbar sedimenthantering kan hjälpa till att lösa dessa problem och förlänga dammarnas livslängd. Reservoaren i Andakílsá-floden på västra Island är en av många reservoarer som har upplevt sedimentrelaterade problem, och i denna studie utvärderades om en specifik sedimenthanteringslösning kallad SediCon Sluicer kunde vara en lämplig lösning för platsen. Mer specifikt, utvärdera om flodens transportkapacitet på nedströmssidan om reservoaren är tillräcklig för att transportera sedimenten som frigörs från SediCon Sluicers utloppsrör, så att de inte sätter sig och bildar tjocka avlagringslager i flod-botten. En modell över hydraulik och sedimenttransport i floden sattes upp i en tvådimensionell HEC-RAS-modell (version 6.3.1) och Mannings friktionskoefficient i kanalen kalibrerades med hjälp av vattennivådata. Manning-värdet 0,025 visade sig bäst beskriva kanalens grovhet. En HEC-RAS 2D Sediment Transport-modell användes sedan för att simulera olika mängder sediment som släpps ut i floden för olika flödesscenarier. Resultaten från sedimentsimuleringen visade att om sediment släpptes ut en gång om året så krävs en tillräckligt varaktigt högflödesscenario för att få acceptabel transport, medan sedimenten kan avsättas i floden vid kortare händelser. SediCon Sluicer kanske skulle kunna köras flera gånger per år, men en mer detaljerad flödesfrekvensanalys måste i så fall visa vilka sekvenser av mindre översvämningar som kan förväntas årligen. Denna lösning skulle kunna vara ett lämpligt alternativ för floden, men mer forskning och analys behöver göras för att få en bättre säkerhet om det optimala driftområdet.

Daily demands for electrical power are met through sub-daily release of turbined water in the form of hydropeaking. Hydropeaking’s changes to stream flow are listed as a threat to biodiversity in river ecosystems as it causes rapid habitat alteration such as increased depth and velocity, affecting the species living downstream. The brown trout and landlocked salmon populations in Gullspång River, Sweden, are threatened and subjects to the hydropeaking regime. This study investigated the effects of hydropeaking in summertime (summer peaks) in Gullspång River on growth and survival of age 0 (fry) and age 1 (parr) brown trout and Atlantic salmon. The study used an individual-based model (inSTREAM 7.2-SD) to predict how different peak scenarios would affect the different species and age groups. A previous study’s parameters and model calibration for the study area were used, and I manipulated the flow time-series to create new flow time-series including three single peaking scenarios on different dates during summer, one multiple summer peak scenario as well as a no-peak (steady flow) scenario. The analysis focused on qualitative patterns in how the populations responded to the various flow scenarios. Age 0 salmon’s growth and survival were negatively affected by all peaking scenarios in comparison to the steady flow scenario, with the combined peaking scenario having the worst effect. Age 0 trout survival was either unaffected by single peaking (Scenario 1 & 2) or negatively affected (Scenario 3) and was also worst affected by the combined peaks compared to steady flow. Age 1 survival of both species was positively affected by the combined peaking but either unaffected (Scenario 1 & 2) or negatively (Scenario 3) affected by single peaks compared to the steady flow scenario. Age 1 growth followed a similar trend with highest growth rate in the combined peaks scenario and the lowest in the steady flow for both species. Results of the study may contribute to river management decisions regarding choice of peaking period depending on management goals regarding target species and life cycle stage. / Dagliga efterfrågan av elektricitet tillgodoses genom daglig korttidsreglering avvattenkraftverk där vatten flödar genom turbinerna. Korttidsreglering är listat somett av de större hoten mot den biologiska mångfalden i floders ekosystem då det ledertill snabba habitatförändringar som ökat djup och flödeshastighet, vilket påverkararterna som lever nedströms. Gullspångsälvens bestånd av öring och lax är hotadeoch utsätts för korttidsreglering som nyttjas i älven. Den här studien undersöktekorttidsregleringens påverkan under sommartid (sommartoppar) i Gullspångsälvenpå tillväxt och överlevnad hos ålder 0 (yngel) och ålder 1 (parr) öring och atlantlax.Studien använde en individbaserad modell (inSTREAM 7.2-SD) för att förutspå hurscenarion med olika toppar påverkar de olika arterna samt åldersgrupperna. Entidigare studies parametrar och kalibrering av modellen för studieområdet användesoch jag ändrade flödestidsserierna för att skapa nya flödestidsserier vilket1inkluderade tre enstaka sommartoppar vid olika datum under sommaren, ettkombinerat sommartoppscenario samt ett scenario utan topp (stadigt flöde).Analysen fokuserade på kvalitativa mönster bland populationernas respons till deolika flödestoppscenarion. 0-laxens tillväxt och överlevnad var negativt påverkad avalla flödestoppscenarion i jämförelse med det stadiga flödesscenariot, där detkombinerade flödesscenariot resulterade i en värsta påverkan. 0-öringens överlevnadvar antingen opåverkad (Scenario 1 & 2) eller negativt påverkad (Scenario 3) avenstaka flödestoppar samt också värst påverkad av det kombinerade flödesscenariot ijämförelse med det stadiga flödet. Överlevnaden hos ålder 1 av båda arter blevpositivt påverkad av det kombinerade flödescenariot men var antingen opåverkad(Scenario 1 & 2) eller negativt påverkad (Scenario 3) av de enstaka flödestopparnajämfört med det stadiga flödet. Tillväxten hos ålder 1 av båda arter följde ett liknandemönster där störst tillväxt uppmättes i det kombinerade scenariot och den lägstatillväxten i det stadiga flödesscenariot. Studiens resultat kan bidra tillförvaltningsbeslut gällande älvar när det kommer till utformningen av flödestoppar,beroende på vilka förvaltningsmål som finns för arter och dess livscykelstadium.

Gegenstand dieser Dissertation ist die Entwicklung von zwei Bewertungsinstrumenten zum Abschätzen von anthropogenen Störungen auf Fische: Das erste ist eine Sensitivitätsklassifizierung, die die Resistenz und das Erholungspotenzial einer Art gegen einen Stressor widerspiegelt. Das Prinzip basiert auf der Kombination & Aggregation von Life History Traits, die für die Resilienz der Art entscheidend sind wie z. B. maximale Größe oder Reproduktionswerte, aber auch der Migrationstyp. Diese Traits wurden einzeln je nach Typ und artspezifischer Ausprägung Perzentilgruppen zugeordnet und diese dann zu einem übergeordneten Sensitivitätswert aggregiert, der für 168 Arten bestimmt werden konnte. Von Arten mit einem hohen Wert ist eine höhere Resistenz gegenüber einem Stressor zu erwarten, ein niedriger Wert hingegen deutet auf eine geringe Resistenz aber hohes Erholungspotenzial nach Aufhebung des Stressors. Der Sensitivitätswert kann für die Bewertung menschlicher Einflüsse auf einzelne Arten, aber auch Artgemeinschaften und in einer Vielzahl von Szenarien genutzt werden wie z. B. Risikobewertungen und Umweltverträglichkeitsprüfungen, aber auch in Schutz- und Revitalisierungsbemühungen Anwendung finden. Das zweite Bewertungssystem, auf der in dieser Arbeit ein starker Fokus gelegt wird, ist der Europäische Fischgefährdungsindex EFHI, ein Evaluationswerkzeug für Wasserkraftrisiken für Fische. Dieser nutzt konzeptionelle, empirische und modellierte Daten zu den individuellen Risiken einzelner Kraftwerksbausteine und verschneidet sie mit der artspezifischen Empfindlichkeit betroffener Fische. Der Sensitivitätswert ist einer der Hauptfaktoren, die diese Empfindlichkeit bestimmen und wird um weitere Informationen wie der Körperform oder Schwimmblasenanatomie ergänzt. Der EFHI bewertet kontextabhängig einen artenspezifischen Risikowert, der dann zu einem Endergebnis zwischen 0 (kein Risiko) und 1 (höchstes Risiko) zusammengefasst wird. Der EFHI ist in ganz Europa anwendbar. / Content of this thesis is the development of two tools to assess anthropogenic impacts on fishes. The first is a score that classifies a species’ sensitivity to anthropogenic stress that would elevate the mortality of individuals in a population. It is based on the species-specific, unique suite of life history traits that mediate a species’ resilience e.g., maximum adult size, maturation metrics and fecundity, but also the migration type of species i.e., diadromous, potamodromous and resident. Traits on a continuous scale were grouped using percentiles, binary variables like migration type were treated nominally, and aggregated into a single score ranging from 1.58 to 4.42 for 168 species. Species with a high score are expected to resist a stressor for a longer time or resist a stressor of higher magnitude, respectively, whereas a lower score reflects a low individual resistance to a stressor but a rapid recovery. This score can be used for risk and impact evaluations of anthropogenic activities, but also to track restoration or conservation efforts. The second assessment system on which a particular focus is laid in this thesis is the European Fish Hazard Index EFHI, an assessment tool for hydropower risks for fishes. In the EFHI, the sensitivity score described above is one of the main factors determining specific susceptibility, along with body shape, swim bladder anatomy and conservation concern. The tool evaluates hazards related to the four hydropower components i) overall flow alterations, ii) entrainment and turbine mortality, iii) upstream fish passage and iv) downstream fish passage and calculates species- and components specific hazard scores that are ultimately aggregated into the final EFHI score ranging from 0 (no risk) to 1 (highest risk). It can be used across the bio-geographic range of all 168 species for which a sensitivity score could be calculated.

This study aims to estimate the level of satisfaction about resettlement arrangements for local people who have been affected by A Luoi hydroelectric construction project in the Thua Thien Hue province. This research used the Likert scale method to assess the satisfaction level of 98 households living in two of the resettlement sites. Results illustrate that there is variations in the level of satisfaction of local people in the two resettlement sites, Hong Thuong and Hong Ha. In the resettlement area (RA) of the Hong Thuong Commune, people are dissatisfied with the location arrangement. There is a lack of quality in the houses built, been damaged, cracked and degraded, since the construction design is not appropriate for the customs and practices of local people, with a satisfaction rating of 1.07. Meanwhile, at the resettlement site of the Hong Ha commune, people felt satisfied with the arrangement site of the RA and allocated residential land area with the satisfaction rating of 4.19. Our results will help the government, as well as the project owners, to understand the points of dissatisfaction of local people in order to have accordant solutions, ensuring the stable life for local people in those settlement areas. / Nghiên cứu này nhằm mục đích đánh giá được mức độ hài lòng của người dân về việc bố trí tái định cư (TĐC) cho người dân bị ảnh hưởng bởi dự án xây dựng thuỷ điện A Lưới, tỉnh Thừa Thiên Huế. Nghiên cứu đã sử dụng phương pháp thang đo Likert để đánh giá mức độ hài lòng của 98 hộ dân sống tại hai khu tái định cư Hồng Thượng và Hồng Hạ. Kết quả nghiên cứu đã cho thấy có sự khác nhau về mức độ hài lòng của người dân tại hai khu TĐC. Tại khu TĐC Hồng Thượng người dân thấy không hài lòng về địa điểm bố trí TĐC, nhà ở được xây dựng thiếu chất lượng đã bị hư hỏng, nứt nẻ xuống cấp, thiết kế xây dựng không phù hợp với phong tục, tập quán của người dân địa phương, với chỉ số đánh giá hài lòng là 1,07. Trong khi đó, tại khu TĐC xã Hồng Hạ người dân lại thấy hài lòng về điểm bố trí TĐC và diện tích đất ở được cấp, với chỉ số đánh giá hài lòng là 4,19. Kết quả nghiên cứu của đề tài sẽ giúp cho chính quyền cũng như chủ đầu tư dự án nắm rõ những điểm không hài lòng của người dân để có hướng giải quyết phù hợp nhằm đảm bảo cuộc sống ổn định cho người dân tại nơi tái định cư.

The increasing penetration of variable renewable energy sources in the Nordic Power System is causing frequency quality degradation and has increased the importance of primary frequency control provided by hydropower plants. Hydropower is the world’s largest renewable energy source. Its reliability, controllability and dispatchability along with its large storage volume makes it the most important source for providing frequency regulation in the Nordic Power System. Many hydropower plants offering regulating power have Kaplan turbines which have complex mechanical systems. Furthermore, the frequent and fast mechanical movements of the Kaplan turbines, providing frequency regulation causes the problem of wear and tear in the guide vanes and runner blades of the turbines. Kaplan turbines are suitable for stable operation.   To mitigate this problem, a solution of hybrid hydropower plants combined with  battery energy storage systems is investigated in this thesis, where batteries can take care of fast frequency deviations, allowing for a more stable operation of the turbines. The analysis is based on the FCR-N service offered by hydropower plants, because FCR-N is identified as one of the services that requires very fast changes in the output power of the hydropower plant. Modelling and simulation, data analysis and on-site measurement are adopted as main study methods in this thesis.  The simulation models of a hydropower plant and a hybrid hydropower plant are developed for the analysis. The simulation model of the hydropower plant is validated using data from a typical Swedish hydropower plant. Quantification of wear and tear is the main focus of the study. The performance of the hydropower plant and hybrid hydropower plant are compared in terms of wear and tear of turbines, speed of the response of plants to frequency deviations and number of directional changes during the mechanical movements of the turbine. Finally, it is concluded that, addition of batteries with hydropower plants will reduce wear and tear of the turbines as well as improve the frequency quality in the Nordic Power System.

In the past century, hydropower development in Sweden has been facilitated by the lack of appropriate environmental legislation. This exploitation has resulted in the current poor ecological status of most Swedish water bodies affected by hydropower, and in the need for new policies that reflect the 2000 European Water Framework Directive. Thus, the Swedish Agency for Marine and Water management (SwAM), the Swedish Energy Agency (SEA) and Svenska Kraftnät have elaborated a new national plan for the revision of almost all hydropower licenses in the next 20 years, and Vattenkraftens Miljöfond has carried out a pilot project on Ljungan river, to test different working methods for regional collaboration, and to find effective solutions for achieving the greatest possible benefit for the aquatic environment, while ensuring an efficient national hydropower supply. This thesis focuses on the fish habitat rehabilitation of a portion of Ljungan river highly affected by hydropower practices. By combining a 1D/2D hydraulic model, calibrated and validated, with a habitat model that defines the hydraulic preferences of the target fish species, it was possible to run different simulations and to quantify the optimal habitat obtainable in each scenario, following the PHABSIM methodology. The outputs of this analysis were produced in the form of Composite Suitability Index (CSI) maps and Weighted Usable Area (WUA)­discharge curves. The former resulted to be a very useful tool for analyzing the spatial distribution of suitable habitats for certain ecological processes, and for planning in­stream habitat improvement measures, while the latter have been efficiently used to identify and quantify the maximum habitat improvement achievable with the different mitigation scenarios. This approach helped to firstly assess the habitat improvement that would result from removing the weirs located along the river, leading to the conclusion that the removal would be effective only if combined with other morphological changes of the river channel. Additionally, the coupled eco­hydraulic model has been useful for the design of ecological flow scenarios able to achieve different levels of habitat improvement, including scenarios aimed at minimizing energy production losses. The use of the PHABSIM methodology resulted to be very suitable for the scale and scope of the project. However, it also required to limit the iii ecological drivers considered in the analysis and to make some simplistic assumptions about target species behavior, which must always be underlined and acknowledged when using the results in decision­making processes. / Under det senaste århundradet har vattenkraftsutbyggnaden i Sverige underlättats av bristen på lämplig miljölagstiftning. Detta utnyttjande har lett till att de flesta svenska vattenförekomster har en dålig ekologisk status och att det behövs en ny politik som återspeglar det europeiska ramdirektivet för vatten från 2000. Således har Havs­ och vattenmyndigheten, Energimyndigheten och Svenska Kraftnät utarbetat en ny nationell plan för översyn av nästan alla vattenkraftslicenser under de kommande 20 åren, och Vattenkraftens Miljöfond har genomfört ett pilotprojekt i Ljungan älv för att testa olika arbetsmetoder för regionalt samarbete och hitta effektiva lösningar för att uppnå största möjliga nytta för vattenmiljön samtidigt som man säkerställer en effektiv nationell vattenkraftförsörjning. Denna avhandling fokuserar på återställandet av fiskhabitatet i en del av Ljungan älven som är starkt påverkad av vattenkraftsutövning. Genom att kombinera en 1D/2D hydraulisk modell, kalibrerad och validerad, med en habitatmodell som definierar målfiskarternas hydrauliska preferenser var det möjligt att göra olika simuleringar och kvantifiera den optimala livsmiljö som kan erhållas i varje scenario, enligt PHABSIM­metodiken. Detta tillvägagångssätt har använts för att först och främst bedöma den förbättring av livsmiljön som skulle bli resultatet av att ta bort de dammar som finns längs älvsträckan, vilket ledde till slutsatsen att avlägsnandet skulle vara effektivt endast om det kombineras med andra morfologiska förändringar av flodfåran. Dessutom har den kopplade ekohydrauliska modellen varit användbar för att utform ekologiska flödesscenarier som kan uppnå olika nivåer av habitatförbättring, inklusive scenarier som syftar till att minimera förlusterna i energiproduktionen.

Atlantic salmon (Salmo salar) are found in a range of locations along Sweden's coastline, but Sweden's largest lake, Vänern, also harbors a population of salmon; the rare freshwater migratory form. The majority of the salmon in Lake Vänern migrate upstream in River Klarälven in order to spawn, where they are assisted by humans through the "trap and transport" method to get past Klarälven's eight hydropower dams, which otherwise constitute definite obstacles to upstream migration. When the salmon later migrate downstream to Lake Vänern they receive no assistance and experience a high mortality rate as they are partially forced to swim through the turbines. The wild salmon population today includes over 1000 spawners annually, an increase from <200 in the 196os, but far below historic records of over 10,000 spawners.  This report therefore aimed to investigate the population growth rate and extinction risk for the salmon in Klarälven, both in the current situation and with passages installed past the hydropower plants, and in doing so answer the questions 1) How large is the population growth rate and risk of extinction for today’s population of salmon in Klarälven over the course of 100 years? and 2) How would passage solutions past the hydropower plants in Klarälven affect the population growth rate and risk of extinction for today’s population of salmon in Klarälven over the course of 100 years? These questions were answered by running a population viability analysis in the program Extinction Vortex, which allows the programming of model populations and the manipulation of parameters to test different scenarios. The scenarios that were tested were 1) Scenario 1: Today's method with trap and transport and total lack of passages, 2) Scenario 2: Trap and transport continues, and downstream passages are installed past all eight power plants, and 3) Scenario 3: Upstream and downstream passages are installed past all eight power plants and trap and transport ceases. The results of the vulnerability analysis did not show any risk of extinction for the next 100 years, but a long-term negative trend for the salmon in Klarälven using today's method was seen. However, the development became significantly more positive for the salmon in Klarälven when the installation of downstream passages was simulated, but after that not significantly more positive when the installation of upstream passages was simulated as well. This result provided answers to the research questions and based on them it could be concluded that even though the salmon in Klarälven are not under any acute threat at the moment, and that there may be other fish populations in other regulated streams and rivers that would benefit more from environmental adaptation, measures need to be taken also in Klarälven, to ensure the long-term conservation of the unique freshwater migrating salmon that inhabit the area. / Laxen (Salmo salar) förekommer på flera håll längst Sveriges havskuster, men även Sveriges största insjö Vänern hyser en population av lax; den sällsynta sötvattensvandrande formen. Majoriteten av Vänerlaxarna migrerar upp för att leka i Klarälven, där de assisteras av människan genom metoden ”trap and transport” som tar dem förbi Klarälvens åtta vattenkraftverk vilka annars utgör definitiva vandringshinder. När laxen sedan ska ta sig tillbaka ner till Vänern får de ingen assistans, i stället tvingas de delvis simma genom turbinerna med stor dödlighet som följd. Laxpopulationen idag består av över 1000 lekande fiskar varje år, en ökning från <200 individer på 1960-talet, men långt under historiska siffror på över 10 000 lekande laxar. Detta arbete syftade därför till att undersöka populationsutvecklingen och utdöenderisken för Klarälvslaxen, såväl i nuläget som vid en installation av passager förbi kraftverken, och genom detta besvara frågeställningarna 1) Hur stor är populationsutvecklingen och utdöenderisken för dagens population av Klarälvslax över kommande 100 år? och 2) Hur skulle passagelösningar förbi vattenkraftverken i Klarälven påverka populationsutvecklingen och utdöenderisken för dagens population av Klarälvslax över kommande 100 år? Dessa frågeställningar besvarades med hjälp av en sårbarhetsanalys i programmet Extinction Vortex, som tillåter uppbyggandet av modellpopulationer och manipulation av parametrar för att testa olika scenarier. Scenarierna som testades var 1) Scenario 1: Dagens metod med trap and transport och total avsaknad av passager, 2) Scenario 2: Trap and transport fortsätter samt nedströmspassager installeras förbi alla åtta kraftverk, och 3) Scenario 3: Upp- och nedströmspassager installeras förbi alla åtta kraftverk och trap and transport upphör. Resultatet av sårbarhetsanalysen visade inte på någon utdöenderisk kommande 100 år, men en negativ trend för Klarälvslaxens långsiktiga populationsutveckling med dagens metod. Utvecklingen blev dock signifikant mer positiv för Klarälvslaxen vid den simulerade installationen av nedströmspassager, och ännu något stabilare när även uppströmspassager installerades. Detta resultat gav svar på frågeställningarna, och utifrån detta kunde slutsatsen dras att trots att Klarälvslaxen inte befinner sig under något akut hot för närvarande, och att det kan finnas andra fiskpopulationer i andra vattendrag som är i mer akut behov av miljöanpassning, så behöver åtgärder komma på plats även i Klarälven, för att säkerställa det långsiktiga bevarandet av den unika sötvattensvandrande Klarälvslaxen.

I Sverige finns cirka 2000 vattenkraftverk men endast 10 procent har någon form av omlöp eller annan lösning (Risinger, 2012). Nya, strängare regler håller nu på att införas. Sedan 2014 finns en gemensam strategi från Energimyndigheten och Havs- och vattenmyndigheten för åtgärder i svensk vattenkraft (Risinger, 2014). En godkänd fiskväg är ett av kraven.Särskilt den småskaliga vattenkraften (energitillförsel under 10 MWh enligt Risinger (2012)) drabbas. Deras intäkter står många gånger i proportion till energiproduktionen och därmed saknas ofta de ekonomiska förutsättningarna för en fiskväg. Vidare kommer en del av vattnet, och därmed potentiella inkomster, att gå förlorade. Den här undersökningen syftar till att utröna vad ett omlöp får för konsekvenser i form av effektförluster. Det är naturligtvis omöjligt att komma fram till ett universellt svar. Istället mäts förlusterna hos ett specifikt mindre verk som redan har ett omlöp: Åby vattenkraftverk som ägs och drivs av Växjö kommun. Metoden som används är traversering i kombination med hydroskopisk flygel. Sedan tidigare finns beräknade värden från kommunen för flödet i omlöpet. Dessa jämförs med undersökningens uppmätta värden. Undersökningen visar att vid normalt vattenstånd (165,13 MÖH) flödar 167 ± 10 l/s vatten genom omlöpet. Detta är ett 70 l/s större flöde i jämförelse med kommunens beräknade värde. Förklaringar till den skillnaden ges av mätfel då djupet mättes och att inloppet hade byggts om mellan kommunens beräkningar och utförda mätningar. Även den formel som användes då de beräknade värdena togs fram föreslås som en tänkbar felkälla. 167 ± 10 l/s innebär ett bortfall om 4,2 ± 0,3 kW potentiell effekt. / There are around 2000 hydropower plants in Sweden, but only 10 percent of them has a bio channel, fishway or equivalent solution (Risinger 2012). New, more strict rules are now about to be introduced. Since 2014 there is a mutual strategy from the two Swedish authorities ”Energimyndigheten” and ”Havs- och vattenmyndigheten”, which demands multiple actions from Swedish hydropower. (Risinger, 2014). An approved fishway is one of these.The small-scale hydropower plants (plants who produce less than 10 MWh according to Risinger (2012)) are especially affected from this. Their income is proportional to their production and therefore they’ll usually lack the economical ability to build a fishway. Furthermore, a part of the streaming water (which otherwise would equal income) will get lost. This study aims to decide the loss of effect a fishway causes. Of course, it is impossible to derive a universal answer. Instead the losses are measured at a specific smaller plant that already has a fishway: Åby hydropower plant that is owned and operated by Växjö municipality. Method being used is traversing in combination with a turbine flow meter. There are already calculated flows made by the municipality. These values will be compared with the measured values. The study shows that at a normal water level (165,13 m.a.sl) 167 ± 10 l/s of water is streaming through the fishway. This is a 70 l/s bigger flow in comparison with the municipality’s calculations. An explanation to this difference is given by measurement errors when the depth was measured, that the intake had been modified between when the calculations was being made and when the study’s measurements took place. Also, the formula being used for the calculated values is proposed as a possible source of error. 167 ± 10 l/s will result in a loss of 4,2 ± 0,3 kW potential effect.

This master thesis examines technical requirements for small hydro power plants (HPP) to operate proximate parts of the power grid in island mode. The work examines how small hydropower can be modified and complemented with additional technologies to achieve sufficient frequency control capabilities. A case study was performed within the concession area of power grid operator Ålem Energy. One of the HPPs, located in Skälleryd, is owned by Ålem Energy and became the focal point of the study. Relevant parts of the concession area were surveyed for properties such as system inertia, electric load and available power. Furthermore, a model of Kaplan turbine 1 in Skälleryd HPP was created with the purpose of studying the benefits of bypassing regulation control from the wicket gates directly to the runner. The method was tested in an off-grid islanding test. Frequency control of the turbine was tested powering electric heaters and, using a new method, controlling a virtual power grid. Finally, a theory was developed to estimate the transient disturbance resilience (TDR) of a power grid. The theory was applied to the HPP in Skälleryd to suggest modifications for the plant to achieve sufficient islanding capabilities. The survey of the power system revealed a promising potential for the HPPs to operate in island mode, especially at later stages when the grid spans several HPPs for more system inertia. The available power from the HPPs was however strongly seasonal which imposes flexibility on a future plan of action for engaging the grid in island mode. The method of controlling the turbine power from the runner proved to have several difficulties. Firstly, the current hydraulics system was not able to freely control the runner as the hydrodynamic forces on the runner blades were too large. Secondly, the method was found to be unstable due to inherent amplification of speed deviations. Furthermore, the low inertia at Skälleryd is likely detrimental to the lone frequency control of the turbine. Therefore other methods for improving frequency control were suggested. The developed theory for TDR was used to create charts describing the TDR for various combinations of system inertia and regulation speed. By studying the proprieties of Skälleryd HPP in the charts the necessary modifications could be rationally chosen. A frequency regulating dummy load was found to be the simplest option. A control scheme was suggested with the dummy load performing primary frequency control and the turbines at Skälleryd performing secondary control, restoring the dummy load to its nominal state.

Hydropower is the most important power balancing resource in the Swedish electrical power system, regulating the power supply to match the load. Consequently, several hydropower plants have periods of stand-by operation where the power production is absent but where several devices within a plant are still active. Such a device is the step-up power transformer, which during stand-by operation still generates no-load energy losses. These losses can accumulate to a considerable amount of energy and costs during the long technical lifetime of the apparatus. One option to minimize these no-load energy losses is by turning the transformer off when its generating unit is in stand-by operation. However, when this transformer operational change has been explained to experts in the field, the most common response has been that a more frequent reenergizing of a transformer leads to higher risks for errors or transformer breakdowns. This study aimed to analytically investigate three effects from this operational change. First, the potential of fatigue failure for the windings due to the increased sequences of inrush current. Secondly, the thermal cycling as a consequence of change in present losses. Lastly, the energy and economic saving potentials for hydropower plants where this operational adjustment is applied. The study used both established as well as analytical tools explicitly created for this study. These were then applied on currently active transformers in different plant categories in Fortum’s hydropower fleet. The study primarily showed three things. Firstly, risk of fatigue failure due to the increased presence of inrush currents did not affect the transformer’s technical lifetime. Secondly, the thermal cycling changes were slightly larger with absent no-load losses during stand-by operation. The average temperature for the transformer decreased, which in general is seen as a positive indicator for a longer insulation lifetime and thus the transformer’s technical lifetime. Finally, the created frameworks showed the potential of saving energy and money for all plant categories, where the potential grew with the installed production capacity and the stand-by operation timeshare. Despite the simplifications made to describe the complex reality of a transformer operating in a hydropower plant, this thesis contributes to lay a foundation for future investigation of an easy adjustment to avoid unnecessary energy losses and costs for transformers in hydropower plants