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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.
61

Evaluation of key performance indices for frequency quality : A method for evaluating frequency stability in the Nordic power system

Larbi Engelbrektsson, Sophia January 2023 (has links)
The Nordic power system is in a changing phase, with more power electronic interfaced connections, and HVDC connections to other synchronous areas, which impacts the frequency quality. This is a challenge for the transmission system operator of Sweden, Svenska Kraftnät, who, with the other Nordic transmission system operators, is responsible for the physical balancing of the Nordic power system. To ensure that the grid can maintain stable operation when power imbalances or a disturbance occur, the frequency quality is important to evaluate. According to the current measurement of frequency quality, minutes outside of the standard frequency band, the frequency quality in the Nordic power system has been deteriorating. The current measurement does not capture what impact the frequency quality and needs to be redefined, with more precise measurements, for Svenska Kraftnät to be able to take necessary actions to ensure stability of the power system. Therefore, the purpose of this project is to determine which key performance indices, KPIs, can be used to develop the definition of frequency quality, and which system parameters are captured by the different KPIs. This project is executed with simulations in Matlab/Simulink to determine the impact five system parameters have on 15 different KPIs, and the results from the simulations are validated with historical data. The results indicate that all system parameters can be captured with KPIs, but after validation with historical data only two system parameters, which correlated with four KPIs, were deemed to be valid. The amount of FCR-N energy activated can be captured with the standard deviation of frequency, frequency area, and number of FCR-D activations. The kinetic energy can be captured by the standard deviation of RoCoF. The KPIs are recommended to be used to identify, and measure, the impact of new technical requirements for frequency control, and how the frequency stability is impacted by changes in the system. The conclusion is that four key performance indices are recommended to improve the definition of frequency quality, and further research is recommended to further define the concept of frequency quality. / För tillfället sker stora förändringar i det nordiska elsystemet. Fler produktionsanläggningar och industrier ansluts med kraftelektronik och fler HVDC-anslutningar byggs till andra synkronområden, vilket har stor inverkan på frekvenskvalitén. Detta leder till nya utmaningar för det svenska transmissionsnätets systemansvariga myndighet, Svenska Kraftnät, som gemensamt med sina nordiska motsvarigheter är ansvariga för den fysiska balanseringen i det nordiska synkronområdet. Det är viktigt att kontinuerligt följa upp frekvenskvalitén i transmissionsnätet så att stabil drift kan garanteras både vid mindre obalanser eller i händelse av större störningar. Det nuvarande nyckeltalet för uppföljning av frekvenskvalité, minuter utanför normalbandet, indikerar att frekvenskvalitén i det nordiska synkronområdet har blir sämre de senaste åren. Det nuvarande nyckeltalet indikerar inte vad som påverkar frekvenskvalitén och behöver omdefinieras med mer precisa nyckeltal för att Svenska Kraftnät ska kunna vidta nödvändiga åtgärder för att garantera en stabil drift av transmissionnätet. Syftet med examensarbetet är att definiera nya nyckeltal för att beskriva frekvenskvalité samt undersöka vilka systemparametrar som fångas av de olika nyckeltalen. I detta projekt har simuleringar utförts i Matlab/Simulink för att bestämma den inverkan fem olika systemparametrar har på 15 olika nyckeltal. Resultaten från simuleringar valideras med historisk data. Resultaten från simuleringen indikerar att de fem systemparametrarna kan fångas av olika kombinationer av de föreslagna nyckeltalen, men efter validering med historisk data bedöms enbart två systemparametrar fångas av totalt fyra nyckeltal. Systemparametern aktiverad FCR-N energi fångas av tre nyckeltal: frekvensens standardavvikelse, frekvensarea och antal FCR-D-aktiveringar. Systemparametern kinetisk energi fångas av ett nyckeltal: frekvensderivatans standardavvikelse. De fyra identifierade nyckeltalen kan användas för att identifiera och mäta hur frekvenskvalitén påverkas av nya tekniska krav, samt hur frekvensstabilitet påverkas av förändringar i systemet. Slutsatsen för detta projekt är att fyra nya nyckeltal rekommenderas för att utveckla definitionen av frekvenskvalité. Vidare arbete rekommenderas för att kunna utveckla begreppet vidare.
62

[en] ECONOMIC VALUE OF REACTIVE POWER DEVICES / [pt] MAPEAMENTO DO VALOR ECONÔMICO DOS EQUIPAMENTOS DE COMPENSAÇÃO DE POTÊNCIA REATIVA

IVO SERGIO BARAN 13 December 2002 (has links)
[pt] No novo modelo para o setor elétrico brasileiro a operação do sistema é de responsabilidade do Operador Independente do Sistema enquanto que a propriedade do equipamento e os gastos com a sua manutenção são de responsabilidade do agente prestador do serviço ancilar.Desta forma, o lucro do agente prestador do serviço ancilar de potência reativa será função do custo deste serviço uma vez que a sua remuneração é previamente definida pelo agente regulador. Dentro desta ótica os riscos operacionais dos equipamentos de compensação de potência reativa, se não forem convenientemente mitigados,poderão aumentar os gastos com a manutenção e o pagamento de multa pela indisponibilidade do equipamento.Riscos operacionais são situações de sistema que estão fora da responsabilidade do agente mas que poderão reduzir o seu faturamento.Esta dissertação descreve os riscos operacionais e faz algumas sugestões para proteger o agente da redução do seu faturamento. / [en] In the new brazilian deregulated electrical network, system operation is under Independent System Operator responsibility while the ancillary service agent is the owner of the reactive power equipment and, as a consequence, is responsible for its maintenance costs. In the new model, the profit of the agent is a function of the maintenance costs because his payment is previously defined by the authorities. The operational risks of the reactive power equipments, if not conveniently mitigated, may increase the maintenance frequency and may also result in the payment of a fee due to the equipment unavailability.Operational risks are events in the electrical transmission system that are not under the responsibility of the agent but may reduce his profits. This report describes these operational risks and makes some suggestions to protect the agent against the reduction in his profits.
63

Horský hotel / Mountain hotel

Kyceltová, Lucie January 2014 (has links)
The theme of this work is the building design, brand new mountain hotel with wellness services in Spindleruv Mlyn. The plot is located in a quiet part of town, near a wooded area and form a river Labe.V designed hotel is located three floors above ground level of the building is solved attic space. Roofed by a wooden roof false hip roof. Ground unsophisticated form a geometric shape, which layout is divided into sections. On the ground floor wellness facilities, a portion of the input dopňkovými with hotel services, floor is done mainly for accommodation, as well as the attic. Hotel is equipped with a slightly sloping plot in the construction of houses and other hotels. All living spaces are naturally ventilated and illuminated. The supporting structure consists Liapor system. The appearance of the hotel is in line with the surroundings.
64

The local potential of V2G : Estimation of the benefits of Vehicle to Grid in the energy community of Stenberg

Drommi, Cyprien January 2022 (has links)
In the countries willing to follow an energy transition towards decarbonization, a strong emphasis is put on electrification. Carbon-free power production tends to rely more on intermittent renewable energies, bringing many uncertainties on the electricity output to the grid. The transportation sector aims to reach a high penetration of electric vehicles (EVs) on the road to overcome its fossil fuels dependency, adding an important load to charge their batteries. The V2G technology intends to alleviate these new issues by allowing the fleet of EVs to act like a storage system for the grid. This concept was proven to be mature but requires more pilot projects to build a greater consensus. The energy community BRF Stenberg, under construction in Hudiksvall, is willing to integrate V2G in its energy system. In this paper a model of the energy system for the whole community is built. Different types of V2G application are simulated and compared to a baseline. The constraints are formulated as a quasi-linear optimisation, where the cost from electricity purchase is minimized. A direct DCDC connection between PV production and EV charging is investigated, as well as the impact on the degradation of the batteries. The results show that it is necessary to integrate frequency regulation services to build a profitable project. The DC connection does not bring a significant benefit to the system. The battery degradation is proven to be a critical parameter that must be accounted for in the design of the system. / I de länder som är villiga att följa en energiomställning mot en koldioxidfri utveckling läggs stor vikt vid elektrifiering. Kolfri elproduktion tenderar att vara mer beroende av intermittenta förnybara energikällor, vilket medför många osäkerhetsfaktorer i fråga om elproduktionen till elnätet. Transportsektorn strävar efter att uppnå en hög penetration av elfordon på vägarna för att övervinna sitt beroende av fossila bränslen, vilket ger en viktig belastning för att ladda deras batterier. V2G-tekniken syftar till att lindra dessa nya problem genom att låta fordonsflottan fungera som ett lagringssystem för nätet. Konceptet har visat sig vara moget men kräver fler pilotprojekt för att skapa ett större samförstånd. Energisamfälligheten BRF Stenberg, som håller på att byggas i Hudiksvall, är villigt att integrera V2G i sitt energisystem. I den här artikeln byggs en modell av energisystemet för hela Energisamfälligheten. Olika grader av V2G-tillämpning simuleras och jämförs med en baslinje. Begränsningarna formuleras som en kvasilinjär optimering, där kostnaden för elinköp minimeras. En direkt DC-DC-anslutning mellan solcellsproduktion och fordonsladdning undersöks, liksom effekten på batteriernas nedbrytning. Resultaten visar att det är nödvändigt att integrera frekvensregleringstjänster för att bygga ett lönsamt projekt. Likströmsförbindelsen ger inte någon betydande fördel för systemet. Batteridegraderingen visar sig vara en kritisk parameter som måste beaktas vid utformningen av systemet.

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