Det här examensarbetet inriktar sig på att med ett simuleringsprogram försöka utröna om det skulle gå att använda feedback control av löphju-let på en kaplanturbin för att reglera frekvensen ut på elnätet. Detta görs idag med hjälp av att öka eller minska magnetiseringen av generatorn. Det blir också en jämförelse för att se om det blir någon skillnad på resultatet mellan PID/PI. Resultatet mellan PID och PI är väldigt snar-lika och på frågan om det skulle gå att frekvens styra med löphjulet är svaret antagligen, det beror på hur mycket turbinens svängmassa på-verkar varvtalsändringen. Det skulle däremot ge ökat underhåll och större förslitning på lager och packningar. / This degree project focuses on using a simulation program to try to find out if it would be possible to use feedback control of the impeller on a Kaplan turbine to regulate the frequency on the power grid. This is done today by increasing or decreasing the magnetization of the genera-tor. There will also be a comparison to see if there is any difference in the result between PID/PI. The result between PID and PI is very close, and to the question of whether it would be possible to control the fre-quency with the impeller, the answer is probably, it depends on how much the turbine's swing mass affects the speed change. However, this would result in increased maintenance and greater wear and tear on bearings and seals.

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.

Renewable energy resources are projected to claim a larger part of the Swedish power mix in coming years. This could potentially increase frequency fluctuations in the power grid due to the intermittency of renewable power generating resources. These fluctuations can in turn cause issues in the power grid if left unchecked. In order to resolve these issues, countermeasures are employed. One such countermeasure is for private actors to regulate power; in exchange they are financially compensated through reserve markets. The reserve market studied in this thesis is called Frequency Containment Reserve – Normal (FCR-N). Currently hydroelectric power provides almost all regulated power within this market. As the need for power regulation is expected to increase in the coming years, there exists a need to study other technologies capable of power regulation. This thesis focuses on one such technology called, virtual power plants. While virtual power plants are operating in other parts of the world, there were no virtual power plants operating in Sweden. As a result, the nature of an optimized virtual power plant and the economic benefits of optimization had not been previously investigated. To answer such questions, this thesis modelled and optimized the revenue of a virtual power plant. The examined virtual power plant consisted of cooling chillers, lighting, ventilation fans and a battery energy storage system. Where varying their total power demand allowed for them to provide power regulation. With the virtual power plant market in Sweden being in its infancy, this thesis serves as a first look into how an optimized virtual power plant using these components could function. To put the economic results of the optimization into context, a comparative model was constructed. The comparative model was based on a semi-static linear model. This is what the thesis’s industry partner Siemens currently uses. For the simulated scenarios, the optimized model generated at least 85% higher net revenues than the semi-static linear model. The increase in revenue holds potential to increase the uptake of virtual power plants on the Swedish market, thus increasing stability in the power grid and easing the transition to renewable energy. / Då förnyelsebara energiresurser antas omfatta en större roll av den svenska elproduktionen inom kommande år, så kan detta leda till att frekvensfluktueringar i elnätet ökar. Detta sker på grund av att den oregelbundna elproduktionen från förnyelsebara energiresurser inte matchas med konsumtion. Om dessa fluktueringar inte hanteras kan det i sin tur leda till skadliga störningar inom elnätet. För att motverka detta och således stabilisera elnätet används diverse lösningar. Ett sätt att åstadkomma ökad stabilisering i elnätet är att låta privata aktörer kraftreglera. De privata aktörerna som står för kraftregleringen gör detta i utbyte mot ekonomisk kompensation, genom att delta i reservmarknader. Den reservmarknad som studerades inom detta examensarbete kallas Frequency Containment Reserve – Normal (FCR-N). I nuläget står vattenkraft för nästan all reglerad kraft inom den här marknaden. Men då behovet av kraftreglering antas öka inom kommande år så behövs nya teknologier studeras som kan bistå med kraftregleringen. Den studerade teknologin inom detta examensarbete var ett virtuellt kraftverk. Då inga virtuella kraftverk var i bruk i Sverige då denna uppsats skrevs fanns det osäkerheter kring hur man optimalt styr ett virtuellt kraftverk och de ekonomiska fördelarna som detta skulle kunna leda till. Detta examensarbete modellerade och optimerade ett virtuellt kraftverk ur ett vinstperspektiv. Det virtuella kraftverket var uppbyggt utav kylmaskiner, ljus, ventilationsfläktar och ett batterisystem. Deras kraftkonsumtion styrdes på ett sådant sätt som lätt de bidra till kraftreglering på reservmarknaden. För att kunna analysera de ekonomiska resultaten från det optimerade virtuella kraftverket, så byggdes en jämförelsemodell. Denna jämförelsemodell är baserad på en semistatisk linjär modell, vilket är det som examensarbetets industripartner Siemens använder. Den ekonomiska jämförelsens resultat påvisade att inkomsten från den optimerade modellen var minst 85% högre än den semistatiskt linjära modellen, inom de studerade scenarierna. Denna inkomstökning skulle potentiellt kunna öka användningen av virtuella kraftverk på den svenska reservmarknaden vilket i sin tur skulle medföra högre stabilitet på elnätet. Genom att öka stabiliteten på elnätet kan således förnyelsebara energiresurser i sin tur lättare implementeras.

There is a trend in Sweden towards increasing the electricity production from renewable energy sources in the electric grid. The increased share of renewables could be seen as essential for Sweden to be able to meet the obligated climate goals. Integration of renewables will enable Sweden to be a progressive part in reducing greenhouse gases and decreasing the global warming. However, one issue with renewable energy sources is the inverter governed production. This, together with the decommission of larger synchronous generators, results in decreasing the inertia and increasing the instability inthe grid.  This thesis is dedicated to elaborating on frequency stability issues and investigating how Variable Speed Wind Turbines (VSWT) could contribute towards stabilized operation when included in frequency support services.  The study is generated through an extensive research process where focus areas are identified. Questions are purposed and then discussed through interviews with experienced people in the field. Estimated power production series from a wind turbine park (WTP) are applied in a constructed model to study the possibilities appearing when  including VSWTs in frequency support services. The income generated from including VSWTs in different regulation power market services is with the model compared against solely procuring the production capacity on the day ahead market. The studied frequency support services are then compared altogether to generate favorable solutions. The study examines both economic as well as technical features of the inclusion of VSWTs in frequency support services.  Results found in the study were that inclusion of wind turbines for power regulation purposes could be seen as increasingly manageable and needed in the electric grid. The maturity of technical solutions alongwith a transition in the regulation power market could be observed as leading factors. The diversification of regulation abilities and the increasing economic incentives in the regulation power market was also found to be important reasons for including wind turbines in the regulation power market. In the study, it was also found thataggregating the power production from several VSWT could increase the ability to deliver the studied services.  It was concluded that inclusion of VSWT in the frequency containment reserve during disturbed operation for down-regulation purposes as well as the fast frequency reserve was the most promising frequency support products for the inclusion of wind turbines. When including battery energy storages and to a larger part managing the durability demands for the services then the frequency contain reserve for normal operation and the frequency containment reserve for disturbed operation for upregulation purposes could be observed as preferable alternatives. Regulation abilities were concluded as achievable with the use of pitch and torque regulation techniques available in the variable speed wind turbine.

Integrating more renewable energy sources into the grid has caused increased instability due to the intermittency of renewable energy sources. Hence, the need for grid balancing strategies such as frequency regulation has intensified. Areim, a Nordic real estate investment company, through this thesis, aims to have an assessment conducted to estimate the environmental benefits or consequences of using their specific battery system as a participant in the Swedish frequency regulation market, using the lifecycle assessment framework. The study only considered the cradle-to-gate lifecycle scope, excluding the product disposal stage, and the impact categories used align with the Environmental Footprint assessment methodology. The functional unit is in per kilo-watthour delivered, and the batteries are expected to deliver 933 kWh of electric energy over the estimated lifetime of 15 years. The normalized carbon emissions caused by delivering 1 kWh of energy for frequency regulation using the status quo prequalified technologies primarily comprised of hydropower, combined heat and power, and battery energy storage produce 4.75 kgCO2eq. Introducing Areim's specific battery system 200 kW bid into the prequalified technologies mix by substitution produces 0.075 kgCO2eq fewer carbon emissions per kWh delivered. The sensitivity analysis further supports that Areim will yield added carbon emission savings by increasing its available prequalified re-source capacity in the market. The findings of this thesis can be used to support Areim and other companies interested in grid support services such as frequency regulation to decide whether it is beneficial to use their specific battery systems for such services from an environmental effect perspective.

The main purpose of this thesis was to develop and evaluate Key Performance Indicators (KPIs) and battery usage associated with Lithium-ion Battery Energy Storage Systems (LiBESS) used as Frequency Containment Reserve (FCR). The investigation was based on three of Vattenfall´s LiBESS projects that use the same lithium-ion battery technology but vary in system rating and configuration. It was found that two of the most important KPIs are response time and energy efficiency. The response time describes how fast the system can respond to changes in grid frequency. Additionally, the energy efficiency describes how effectively the system can provide energy storage during service and it can be parametrized into the efficiency of the battery, converter and transformer. The results show that all the considered LiBESS can fulfill the response time requirements of 30 seconds for FCR provision. In the future stricter requirements for the response time in grid stabilization services will most likely be required. Nevertheless, the results showed that a well configured LiBESS can provide response times on the millisecond scale. The energy efficiency evaluation showed that the system energy efficiency decreased from 89% to 85% when the power increased from 50% to 100% of rated power. At 75% of rated power it was found that the converter had the lowest efficiency (92%) based on the analysis of the efficiency of all the system components. It was also found that the power consumed by auxiliary loads was nearly constant for the examined power rates and that it significantly reduced the energy efficiency. Lastly, the battery usage analysis showed that the battery often idles or operates at low power rates if the frequency dead-band of ±10 mHz is applied around the nominal value of 50 Hz. Moreover, the battery usage can be characterized by an average State of Charge of 50% and a maximum Depth of Discharge of 30% during both charge and discharge of the batteries.