[pt] O planejamento da expansão da transmissão (PET) visa identificar novos reforços para a rede, permitindo uma conexão tecnicamente adequada entre demanda e geração de energia elétrica, ambas previstas para um determinado horizonte de planejamento. Um bom plano de expansão deve garantir o equilíbrio entre os custos de investimento e operação, mantendo um nível satisfatório de segurança no fornecimento de energia elétrica. Entretanto, a identificação de bons planos de expansão para o PET tem se tornado uma tarefa cada vez mais difícil. Isso se deve, principalmente, às características e dimensões dos sistemas atuais, a não linearidade e natureza combinatória do problema de otimização e às incertezas presentes nos dados. Os erros de previsão, a indisponibilidade de equipamentos e a disponibilidade dos recursos naturais são parâmetros que variam de forma aleatória e inserem um alto grau de incerteza nos sistemas elétricos, o qual aumenta proporcionalmente com o horizonte de planejamento. Uma das incertezas mais relevantes a ser gerenciada nas próximas décadas será a capacidade de geração oriunda de fontes renováveis, em particular as eólicas, devido à sua grande variabilidade. A utilização de dispositivos de armazenamento permitirá melhor aproveitamento dessas fontes e, portanto, torna-se necessário o desenvolvimento de ferramentas computacionais capazes de considerar tais dispositivos no problema PET. Esta dissertação apresenta uma nova metodologia de apoio ao problema PET inserindo armazenadores de energia elétrica para aumentar o aproveitamento de fontes renováveis no sistema. Isso, respeitando as restrições de segurança da rede, acompanhando à curva de demanda e levando em consideração as variáveis operativas destes dispositivos. A possibilidade de incluir sistemas de armazenamento de energia elétrica é avaliada através de uma análise custo-benefício. A metodologia proposta é aplicada a um sistema teste, submetido a diversas condições operativas, e os resultados obtidos são amplamente discutidos. / [en] The transmission expansion planning (TEP) aims at identifying new reinforcements for the network, allowing a technically adequate connection between demand and generation of electric energy, both foreseen for a given planning horizon. A good expansion plan must ensure a balance between investment and operating costs, while maintaining a satisfactory level of security of the electric energy supply. However, identifying good expansion plans for TEP has become an increasingly difficult task. This is mainly due to the characteristics and dimensions of the current systems, the nonlinearity and combinatorial nature of the optimization problem, and the uncertainties present in the data. Forecasting errors, equipment unavailability, and the availability of natural resources are parameters that vary in a random way and insert a high degree of uncertainty in the electrical system, which proportionally increases with the planning horizon. One of the most relevant uncertainties to be managed in the upcoming decades will be the generation capacity from renewable sources, particularly wind power, due to its great variability. Storage devices will allow better use of these sources and, therefore, it becomes necessary to develop computational tools capable of considering such devices in the TEP problem. This dissertation presents a new methodology to support the TEP problem by inserting electric energy storage to increase the use of renewable energy in the system, while respecting the security restrictions of the network, following the demand curve and taking into account the operational variables of these devices. The possibility of including electric energy storage systems is evaluated through a costbenefit analysis. The proposed methodology is applied to a test system, subject to various operating conditions, and the obtained results are widely discussed.

This thesis explores what Karlstad Airport needs to go 100% green. Photovoltaics are assumed to be installed at the facility and a Hydrogen Energy Storage System and Battery Energy Storage System will be evaluated to reduce peaks during charging of the planes. Different power peak limits are explored as well as different sized Energy Storage Systems and later evaluated economically. A method to find the cheapest possible system is created with some assumptions and is then used to evaluate throughout the whole dataset. In the end any of the different sized Energy Storage Systems reduces the profitability when considering each systems expected lifecycle.

An increased amount of intermittent electricity production, more electric vehicles (EV), and an overall electrification of society may all cause a higher variability between the balance of supply and demand on the electric grid. Battery storage has been identified as a solution to the emerging problem asit can be charged during hours of low power demand and then discharged to help meet the power demand during peak loads. This master thesis investigates how characteristics from yearly power demand data can be defined so that a battery energy storage system (BESS) can be dimensioned for it and which parameters are important when dimensioning a BESS. The investment cost of the dimensioned BESS is investigated and calculated, and there is as well a general discussion of potentials, drivers, and barriers for a grid owner to implement a BESS. The master thesis includes a literature study and a case study performed together with Tekniska verken and its subsidiary company Tekniska verken Nät where three cases of varying sizes were investigated:• An EV charging station, with a peak power demand of up to 1 MW.• A distribution station, with an original peak power demand of close to 3 MW.• Purchased power from the regional grid, with a peak power demand of almost 152 MW. By dimensioning a BESS from a year-long data curve of the hourly power demand, a power limit was set. The highest peak power value over the power limit, the longest peak duration, and the highest energy peak were then identified to establish the curve characteristics. A battery storage was investigated to see if it could be used to meet the demand occurring when implementing a power limit to the yearly power demand curve. Batteries store electrical energy in the form of electrochemical energy and then transforms the energy back into electrical energy when needed and does so with varying efficiency according to the type of chemistry that is used in the battery. The so-called lithium ion (li-ion) battery is mostly used today and utilizes lithium in the shape of ions along with a metallic cathode and a carbon anode. The cathode and anode can vary in a li-ion battery chemistry, which varies its characteristics and means that there are multiple types of li-ion battery chemistry types. The specific li-ion battery chemistry lithium iron phosphate (LFP), was established as the most applicable battery due to its high energy density, easy to attain materials, general safety, maturity, and amount of discharge cycles it can handle throughout its lifetime. A BESS could be modelled from the LFP limitations and data curve for each case. The results showed that a short-duration variability of a power demand was a success factor for the implementation of a BESS. It allows the BESS to recharge often and the minimum required energy capacity could be lower and more optimal. An investment cost insecurity was established from literature when comparing estimates, as it could vary depending on the published date, used battery chemistry, taxes, and subsidies in the origin country of the literature. Therefore an estimate given by the Swedish transmission system operator (TSO), Svenska Kraftnät of 5-6 MSEK/MWh from a report published in late 2022 was deemed most relevant. An investment cost for each scenario in every case could be calculated and additional economical benefits relevant in the cases such as comparing to the cost of conventional grid reinforcement or economical gains from a lowered grid subscription were investigated. However, an overall conclusion that the investment cost of a BESS was too expensive to be deemed feasible and that there were no overwhelming economical gains from reducing the peak loads was made. A final generalization and discussion of drivers and barriers concluded that the applicability of a BESS can be identified by the defining characteristics of a demand curve. Moreover, it was found that the BESS investment cost was too high when only applying it for grid reinforcement methods. Although, a BESS can have additional benefits to the grid stability. The grid owner cannot however, own a BESS and use it on the frequency service market which otherwise would potentially make it economically feasible to strengthen the grid. The ultimate goal of the project is to help create a broader understanding of battery storage as part of the electrical network, where and when it can be applicable, and how one could go about investigating its use. / En ökad mängd variabel elproduktion, fler elbilar och en elektrifiering av samhället i helhet. Detta kommer skapa en högre variabilitet och därmed större obalans mellan tillförsel och efterfrågan på elnätet. Batterilagring har identifierats som en potentiell lösning till det ökade problemet då det kan laddas vid ett lågt effektbehov och urladdas vid ett högt effektbehov. Genom detta examensarbete kommer det undersökas hur karaktäristik från årliga effektkurvor kan definieras. Det görs i syfte av att dimensionera ett batterilagringssystem utefter datan. Därefter undersöks även vilka parametrar som är viktiga vid dimensioneringen av ett batterilagringssystem. Utefter de dimensionerade batterilagringssystemen tas även en investeringskostnad fram. En diskussion framförs även utifrån den generella potentialen, drivkrafter och barriärer som finns vid implementering av ett batterilagringssystem från perspektivet av en nätägare. Examensarbete består av en litteraturstudie och en fallstudie som genomförs i samarbete med Tekniska verken i Linköping AB och Tekniska verken Nät, där tre fall av varierande storlek undersöks:• En elbilsladdningstation, med ett toppeffektbehov på upp till 1 MW.• En fördelningsstation, med ett ursprungligt toppeffektbehov på nästan 3 MW.• Köpt effekt från det regionala nätet, där toppeffektbehovet uppgår till nästan 152 MW. Vid dimensionering av ett batterilagringssytem från den årliga effektkurvan måste en effektbegränsning sättas. Därefter kan den överstigande effektopplasten, den längsta tiden effektbegränsningen överstigs och den högsta överstigande energin tas fram, för att etablera kurvans karaktäristik. En undersökning gjordes om ett batterilager kunde användas för att möta effektbehovet då en effektbegränsning införs till den årliga effektkurvan. Batterier lagrar elektrisk energi i formen av elektrokemisk energi för att sedan transformera tillbaka det till elektrisk energi då det finns ett behov. Effektiviteten av transformeringen varierar beroende på den kemiska blandningen som batteriet är uppbyggt av. Det så kallade litiumjonbatteriet är det mest använda idag och nyttjar litium i formen av joner tillsammans med en metallisk katod och en anod av kol. Katod och anod kan variera vilket medför en förändrad karaktäristik och betyder alltså att det finns olika sorters litiumjonbatterier. Den specifika litiumjärnfosfat (LFP) blandningen ansågs mest användbar i elnätsapplikationer. Detta på grund av sin höga energidensitet, lättillgängliga material, generella säkerhet, teknikens mognad och mängden urladdningscyklar den kan hantera. Ett batterilagringssytem kunde då modellerades utefter LFP-batterikemin i kombination med den årliga effektkurvan för varje fall. Resultatet därifrån visade att en korttidsvariabilietet av effektbehovet var en framgångsfaktor vid implementeringen av ett batterilagringssystem. Detta då det tillåter för ett batterilagringsystem att återladdas oftare och en lägre minimal energikapacitet kan dimensioneras vilket gör den mer optimal. Vid undersökning av investeringskostnaden upptäcktes en svaghet i litteraturen vid jämförandet av kostnadsuppskattningar. Uppskattningen kunde variera beroende på publiceringsdatum, val av batterikemi, landets skatter och bidrag. Därav valdes en kostnadsuppskattning från den svenska stamnätsägaren, Svenska Kraftnät på 5–6 MSEK/MWh utifrån en rapport publicerat sent i 2022 som mest relevant. Utifrån kostnadsuppskattningen kunde en beräkning av investeringskostnad och ytterligare ekonomiska gynnsamheter relevanta för varje fall undersökas (såsom en jämförelse mot konventionell nätförstärkning eller sänkt abonnemangskostnad). Den generella slutsatsen som drogs var däremot att investeringskostnaden för ett batterilagringssystem var för dyrt för att vara ekonomiskt genomförbart. Det var dessutom inga betydande ekonomiska gynnsamheter som kunde ändra på det då batterilagringssystemet endast användes till att sänka toppeffektlaster. En avslutande generalisering och diskussion av drivkrafter och barriärer framgav att applicerbarheten av ett batterilagringsystem kunde definieras utifrån den identifierade karaktäristiken av den årliga effektkurvan. Dessutom framkom det att investeringskostnaden i varje fall var för hög då batterilagringssystemet endast nyttjades som nätförstärkning. Hursomhelst kan ett batterilagringssystem bidra till ytterligare fördelar i elnätets stabilitet. Elnätsägaren kan inte äga ett batterilagringssystem och använda det på effektreservmarknaden som annars kunde bidra till batterilagringssystemets ekonomiska genomförbarhet. Det slutliga målet av arbetet har varit att ge en bredare förståelse för batterilagring som en del av elnätet. Detta genom att ta reda på när och var det är applicerbart och hur man kan utvärdera dess användning.

[pt] No Brasil, existem muitos projetos em sistemas fotovoltaicos, e a projeção para os próximos anos é de crescimento devido incentivos governamentais e os elevados preços das tarifas de energia. Associado a isso, o mercado de armazenamento de energia com baterias de íons de lítio tem se mostrado promissor devido a uma considerável queda nos preços dessas baterias nos últimos anos. Isso pode representar uma oportunidade para o mercado de sistemas fotovoltaicos quando os incentivos acabarem. Este trabalho propõe um modelo PLIM (Programação Linear Inteira Mista) estocástico para dimensionar um sistema fotovoltaico integrado com armazenamento de energia em baterias para grandes consumidores de energia, usando cenários de geração e consumo, podendo considerar diferentes modalidades tarifárias. As variáveis de decisão são o número de painéis, inversores, baterias, a operação diária do sistema de armazenamento e a demanda contratada do consumidor. A função objetivo busca minimizar o custo de investimento no sistema fotovoltaico, baterias e fatura de energia. A abordagem proposta será analisada sob diferentes premissas, uma com incentivos governamentais sobre a anergia injetada na rede e outra na qual a injeção de energia na rede não é permitida, a fim de avaliar a importância das baterias para manter a atratividade econômica do sistema fotovoltaico. Os resultados indicaram que o efeito sinérgico do sistema fotovoltaico com baterias potencializa a arbitragem, que está relacionada com a diferença entre as tarifas de energia de ponta e fora ponta. Isso ocorre principalmente com operação zero exportação porque somente assim o consumidor é livre para escolher a capacidade do seu sistema fotovoltaico, que hoje é limitado no Brasil quando o sistema é conectado na rede de distribuição. / [en] In Brazil, there are many projects in photovoltaic systems, and the projection for the coming years is positive due to the government incentives and the expensive energy tariffs. Associated with this, the Lithium-ion battery storage systems market has been promising due to a significant drop in battery prices in the last few years. This may represent an opportunity for the photovoltaic system market when the incentives run-out. This work proposes a stochastic mixed integer linear programming (MILP) model to design a photovoltaic system integrated with battery energy storage for big electricity consumers, using generation and consumption scenarios, being able to consider different Time-of-Use tariffs. The decision variables are the number of panels, inverters and batteries, its daily operation and the power demand contracted. The objective function aims to minimize the cost of investment, in the photovoltaic system, batteries and electricity bill. The proposed approach will be analyzed under different assumptions, one with the government incentive about injected surplus and another in which the injection into the network is not possible, in order to assess the importance of a storage system to keep the economic attraction of the photovoltaic system. Results indicated that the synergic effect of the photovoltaic system and battery potentialize the arbitrage, which is related to the difference between peak and off-peak energy tariff. This occurs, mainly with Zero Export operation because only this way the consumer is free to choose the capacity of the photovoltaic system, which is limited in Brazil when the system is allowed to inject energy into the network.

Energy from solar photovoltaic (PV) are generated as direct current (DC) and almost all of today’s electrical loads in residential buildings, household appliances and HVAC system (Heating Ventilation and Air-conditioning) are operated on DC. For a conventional alternating current (AC) distribution system this requires the need for multiple conversion steps before the final user-stage. By switching the distribution system to DC, conversion steps between AC to DC can be avoided and, in that way, losses are reduced. Including a battery storage–the system’s losses can be reduced further and the generated PV energy is even better utilised. This thesis investigates and quantifies the energy savings when using a direct current distribution topology in a residential building together with distributed energy generation from solar photovoltaic and a battery storage. Measured load and PV generation data for a single-family house situated in Borås, Sweden is used as a case study for the analysis. Detailed and dynamic models–based on laboratory measurements of the power electronic converters and the battery–are also used to more accurately reflect the system’s dynamic performance. In this study a dynamic representation of the battery’s losses is presented which is based on laboratory measurements of the resistance and current dependency for a single lithium-ion cell based on Lithium iron phosphate (LFP). A comparative study is made with two others, commonly used, loss representations and evaluated with regards to the complete system’s performance, using the PV and load data from the single-family house. Results show that a detailed battery representation is important for a correct loss prediction when modelling the interaction between loads, PV and the battery. Four DC system topologies are also modelled and compared to an equivalent AC topology using the experimental findings from the power electronic converters and the battery measurements. Results from the quasi-dynamic modelling show that the annual energy savings potential from the suggested DC topologies ranges between 1.9–5.6%. The DC topologies also increase the PV utilisation by up to 10 percentage points, by reducing the associated losses from the inverter and the battery conversion. Results also show that the grid-tied converter is the main loss contributor and when a constant grid-tied efficiency is used, the energy savings are overestimated.