La industria del calzado en el Perú es un sector relevante en la economía por su participación y la generación de puestos de trabajo. Se considera como unas de las actividades minoristas más importantes del país. El mercado de calzados en el Perú se caracteriza por ser bastante competitivo, con colaboración de variadas marcas tanto nacionales como internacionales. Por otro lado, es un producto que ha dado espacio para la diferenciación y que cambia temporada tras temporada siguiendo las últimas tendencias de moda. La empresa es una fábrica de calzados el cual comercializa calzados a través de sus asesores de venta. Estos asesores presentan diversos problemas, entre ellos los más importantes: la información con la que cuenta de sus clientes, productos, pedidos, etc., es escaza o desactualizada; la entrega de pedidos se ha realiza a destiempo o con retrasos; el crédito de los clientes no está controlado; el pago de moras o cuotas no se realiza adecuadamente; en la venta por consignación, frecuentemente se cometen errores en la generación de cuotas. Antes la situación problemática existente se plantea el desarrollo de un sistema móvil con el objetivo de mejorar la productividad de los asesores de venta en sus actividades diarias, lograr un mejor manejo de la información en la empresa e incrementar la rentabilidad por medio de la venta de calzados. El desarrollo de la solución comprende las siguientes fases: modelado del negocio, modelado del sistema, arquitectura del software, construcción, calidad, pruebas de software y la gestión del proyecto. / The footwear industry in Peru is a relevant sector in the economy for its participation and the generation of jobs. It is considerate as one of the most important retail activities in the country. The footwear sector in Peru is characterized by being quite competitive with the collaboration of several national and international brands. In addition, it is a product that provides space for differentiation and that changes seasons continuously following the latest fashion trends. The company is a shoe factory that sells shoes through sales consultants. These consultants present various problems, some of the most important: the information of its customers, products, orders, etc., is scarce or out of date; the delivery of orders is done out of time or with delays; customer credit is not controlled; the payment of arrears or quota is not made properly; in consignment sales, mistakes are often made in the generation of quota. Given the problematic situation, it is proposed to develop a mobile system that aims to improve the productivity of sales consultants in their daily activities, achieve better management of information in the company and increase profitability through the sale of footwear. The development of the solution contains the phases:business modeling, system modeling, software architecture, building, software quality, testing and the project management. / Tesis

The diploma thesis aims to explain, demonstrate and verify the basic practical principles and methods of warehouse management system. This thesis could be used as an advanced guide for warehouse management system software. All this by using own knowledge and experience acquired by practical and purposeful activities done in co-operation with ORYX GROUP Ltd. which is one of the few companies in the Czech Republic developing similar systems.

In modern days electric power systems, the penetration of renewable resources and the introduction of free market principles have led to new challenges facing the power producers and regulators. Renewable production is intermittent which leads to fluctuations in the grid and requires more control for regulators, and the free market principle raises the challenge for power plant producers to operate their plants in the most profitable way given the fluctuating prices. Those problems are addressed in the literature as the Economic Dispatch, and they have been discussed from both regulator and producer view points. Combined Cycle Power plants have the privileges of being dispatchable very fast and with low cost which put them as a primary solution to power disturbance in grid, this fast dispatch-ability also allows them to exploit price changes very efficiently to maximize their profit, and this sheds the light on the importance of prices forecasting as an input for the profit optimization of power plants. In this project, an integrated solution is introduced to optimize the dispatch of combined cycle power plants that are bidding for electricity markets, the solution is composed of two models, the forecasting model and the optimization model. The forecasting model is flexible enough to forecast electricity and fuel prices for different markets and with different forecasting horizons. Machine learning algorithms were used to build and validate the model, and data from different countries were used to test the model. The optimization model incorporates the forecasting model outputs as inputs parameters, and uses other parameters and constraints from the operating conditions of the power plant as well as the market in which the plant is selling. The power plant in this mode is assumed to satisfy different demands, each of these demands have corresponding electricity price and cost of energy not served. The model decides which units to be dispatched at each time stamp to give out the maximum profit given all these constraints, it also decides whether to satisfy all the demands or not producing part of each of them.

<p>In the US, seven regional transmission organizations (RTOs) operate wholesale electricity markets within three largely independent transmission systems, the largest of which includes five RTO regions and many vertically integrated utilities.</p> <p>RTOs operate a day-ahead and a real-time market. In the day-ahead market, generation and demand-side resources are optimally scheduled based on bids and offers for the next day. Those schedules are adjusted according to actual operating conditions in the real-time market. Both markets involve a unit commitment calculation, a mixed integer program that determines which generators will be online, and an economic dispatch calculation, an optimization determines the output of each online generator for every interval and calculates locational marginal prices (LMPs).</p> <p>The use of LMPs for the management of congestion in RTO transmission systems has brought efficiency and transparency to the operation of electric power systems and provides price signals that highlight the need for investment in transmission and generation. Through this work, we aim to extend these efficiency and transparency gains to the coordination across RTOs. Existing market-based inter-regional coordination schemes are limited to incremental changes in real-time markets. </p> <p>We propose a multi-regional unit-commitment that enables coordination in the day-ahead timeframe by applying a distributed approach to approximate a system-wide optimal commitment and dispatch while allowing each region to largely maintain their own rules, model only internal transmission up to the boundary, and keep sensitive financial information confidential. A heuristic algorithm based on an extension of the alternating directions method of multipliers (ADMM) for the mixed integer program is applied to the unit commitment. </p> The proposed coordinated solution was simulated and compared to the ideal single-market scenario and to a representation of the current uncoordinated solution, achieving at least 58% of the maximum potential savings, which, in terms of the annual cost of electric generation in the US, could add up to nearly $7 billion per year. In addition to the coordinated day-ahead solution, we develop a distributed solution for financial transmission rights (FTR) auctions with minimal information sharing across RTOs that constitutes the first known work to provide a viable option for market participants to seamlessly hedge price variability exposure on cross-border transactions.

Sweden has experienced a significant increase in installed solar power capacity between 2010 and 2020, driven by decreasing installation costs, government subsidies and widespread public interest. However, Sweden's geographical distribution of electricity generation and consumption presents challenges for the national grid. Recent instability in the electricity supply due to the war in Ukraine has prompted increased interest in residential battery energy storage systems (BESS) as a means to enhance energy resilience and reduce electricity bills. The rapid growth of the European residential BESS market is expected to continue, driven by the need for flexibility and energy-shifting services in response to increasing renewable energy production. BESS can provide economic benefits to households with installed PV systems through peak shaving, allowing them to store excess electricity during periods of high production and use it during peak demand. This thesis investigates photovoltaic (PV) and BESS performance and profitability for Swedish households under various conditions. The study considers parameters such as system costs, energy prices, grid tariffs and dynamic battery management strategies to investigate the profitability of the systems. The research aims to provide guidelines for households to maximize the benefits of their PV and BESS installations and minimize their dependence on the grid. The effectiveness and practicality of the developed method are demonstrated through verification in two real-world installations. The study’s findings demonstrate that electricity prices, household consumption and roof orientation highly influence the profitability of PV systems. If future electricity prices align with present forecasts, installations on north-facing roofs will not be profitable under any circumstances investigated in this study. A distinct correlation is also discernible between larger loads and improved economic viability for PV and BESS installations, while a smaller battery capacity results in higher economic viability. This reveals that BESS profitability currently is limited due to high installation costs. However, the potential for future BESS profitability is shown if battery costs are reduced and more advanced battery dispatch strategies are developed. / Sverige har upplevt en betydande ökning av installerad solkraftskapacitet mellan åren 2010 och 2020, drivet av faktorer som minskande installationskostnader, statliga bidrag och ett brett folkligt intresse. Geografiska skillnader mellan elproduktion och konsumtion i Sverige innebär utmaningar för elnätet. Instabilitet i elförsörjningen till följd av kriget i Ukraina har ökat intresset för batterilagringssystem i bostäder som ett medel för hushåll att öka deras energiresiliens och minska elkostnaderna. Den snabba tillväxten på den europeiska marknaden för batterilagringssystem förväntas fortsätta, drivet av behovet av flexibilitet i elnätet och energiomställningstjänster till följd av ökad produktion av förnybar energi. Batterilagringssystem kan ge ekonomiska fördelar för hushåll med installerade PV-system genom utjämning av effekttoppar, vilket gör att överskottsenergi kan lagras under perioder av hög produktion och användas under toppbelastning. Denna rapport undersöker prestanda och lönsamhet för solcells- och batterisystem för svenska hushåll under olika förhållanden. Studien utforskar betydande parametrar såsom systemkostnader, energipriser, nättariffer och dynamiska batterihanteringsstrategier för att undersöka lönsamheten för systemen. Detta ämnar till att ge riktlinjer för hushåll att maximera fördelarna med solcells- och batteri-installationer och minimera dess beroende av elnätet. Effektiviteten och praktikaliteten av den utvecklade metoden demonstreras genom verifiering i två verkliga installationer. Resultaten visar atta elpriser, hushållsförbrukning och takorientering i hög grad påverkar lönsamheten hos solcellsanläggningar. Om framtida elpriser stämmer överens med nuvarande prognoser kommer installationer på tak mot norr inte att vara lönsamma under några omständigheter som undersökts i denna studie. En tydlig korrelation kan också urskiljas mellan större elkonsumtion och förbättrad ekonomisk lönsamhet för PV och batteri-installationer, medan en mindre batterikapacitet resulterar i högre ekonomisk lönsamhet. Detta visar att batteriers lönsamhet för närvarande är begränsad på grund av höga installationskostnader. Potentialen för framtida lönsamhet för batterier visas dock om batterikostnaderna sänks och mer avancerade batterihanteringsstrategier utvecklas.

Bakgrund: Årligen drabbas cirka 5000 personer i Sverige av ett hjärtstopp utanför sjukhus. Tidig start av hjärt- och lungräddning är en förutsättning för ökad överlevnad vid ett hjärtstopp, samtidigt visar forskning på att ambulansens framkörningstid har ökat. I väntan på ambulans har sms-livräddare implementerats för att påbörja livräddande åtgärder. I dagsläget finns få studier gjorda på sms-livräddares erfarenheter och insatser vid accepterat hjärtstoppslarm, för att synliggöra hinder och eventuella fysiska och psykiska påfrestningar som de kan möta. Vid ett hjärtstopp arbetar ambulanssjuksköterskan och sms-livräddare tillsammans i team, detta gör det viktigt för ambulanssjuksköterskan att ha en ökad förståelse för sms-livräddares erfarenheter.  Syfte: Studiens syfte var att beskriva sms-livräddares erfarenheter och insatser i samband med ett accepterat hjärtstoppslarm. Metod: En blandad metod enkätstudie med en explorativ sekventiell design användes. Materialet utgick från 1231 enkäter som samlats in av Heartrunner Sweden. Materialet analyserades i tre faser. Resultat: Resultatet visade på att sms-livräddare möttes av flera hinder som medförde att deras insatser försvårades eller uteblev. Resultatet resulterade i fyra kategorier: Erfarenheter av utlarmning, Hjärtstartare, Samverkan i team och emotionella reaktioner. Sms-livräddare upplevde många känslor i samband med larmet som visade på ett eventuellt behov av debriefing. Slutsats: Trots negativa erfarenheter var 99,9% av sms-livräddarna motiverade att fortsätta sina insatser i framtiden. Resultatet tyder på att sms-livräddare hade en viktig roll i samverkan med ambulans och räddningstjänst. Sms-livräddare kunde behöva mer bekräftelse för deras insatser och stöttning för eventuella känslor som kunde uppkomma vid larm om misstänkt hjärtstopp utanför sjukhus. / Background: Every year, approximately 5000 people in Sweden suffer an out-of-hospital cardiac arrest. Early start of cardiopulmonary resuscitation is a prerequisite for increased survival in a cardiac arrest, while research shows that ambulance arrival time has increased. While waiting for an ambulance, mobile-phone dispatch of laypersons has been implemented to initiate life-saving measures. At present, few studies have been conducted on the experiences and interventions of mobile-phone dispatch of laypersons in the event of an accepted cardiac arrest alarm, in order to highlight obstacles and any physical and psychological stresses that they may face. In a cardiac arrest, the ambulance nurse and mobile-phone dispatch of laypersons work together in teams, this makes it important for the ambulance nurse to have an increased understanding of mobile-phone dispatch of laypersons ' experiences. Aim: The aim of the study was to describe mobile-phone dispatch of laypersons experiences and interventions in connection with an accepted cardiac arrest alarm. Method: A mixed method survey study with an explorative sequential design was used. The material was based on 1231 questionnaires collected by Heartrunner Sweden. The material was analysed in three phases. Results: The results showed that mobile-phone dispatch of laypersons were faced with several obstacles that made their interventions difficult or absent. The study resulted in four categories: Experience in emergency response, defibrillators, teamwork and emotional reactions. Mobile-phone dispatch of laypersons experienced many emotions in connection with the alarm, indicating a possible need for debriefing. Conclusion: Despite negative experiences, 99.9% of mobile-phone dispatch of laypersons were motivated to continue their interventions in the future. The result suggests that mobile-phone dispatch of laypersons had an important role in collaboration with ambulance and rescue services. Mobile-phone dispatch of laypersons could benefit from more acknowledgement of their interventions and support for any emotions that may arise when a suspected cardiac arrest is reported outside a hospital.

The study carried out in this master thesis is part of a larger project led by Energynautics GmbH focusing on renewable energy development in the Caribbean. One of the Caribbean states, consisting of multiple islands, has set a target of 30 % of renewable energy in the power sector by 2030. The first objective of the thesis is to develop optimal generation capacity expansion plans for two different islands of this country, utilizing solar PV generation, which is the only available renewable energy resource. To achieve this objective, three main tasks are identified. The first is the development of an optimal generation capacity expansion plan for the next three years using the optimization tool HOMER Energy. At the beginning only diesel generation is present on the islands. For each study case year, the installed capacity of PV and BESS is optimized and enabling technologies such as curtailment (controllability of PV) and grid-forming inverters are deployed. The second task focuses on the development of a new dispatch strategy, improving on the black box dispatch algorithms built into HOMER. The dispatch strategy minimises the cost of electricity generation and is based on a rolling 48 hours forecasts of the load and PV. It is implemented in MATLAB and linked to HOMER via the built-in MATLAB interface. As HOMER is focused on generation expansion and dispatch and inherently neglects the grid, a grid study is required to assess the stability of the network. This study is the last task of the thesis and is limited to determined steady-state voltage and the asset loading on one of the studied islands through load flow simulations in DIgSILENT PowerFactory. It is shown that there are no major issues even at high PV shares, however, grid performance can be improved if the PV unit is equipped with reactive power capability to control the voltage. A study on the impact of the Q(U)- control and the PQ-capability of the PV and BESS inverters is performed. / Studien som genomförts i detta examensarbete är en del av ett större projekt vilket leds av Energynautics GmbH med fokus på utveckling av förnybar energi i Karibien. En av de Karibiska staterna, bestående av flera öar, har ett mål på 30 % förnybar energi i elkraftssektorn innan 2030. Första syftet med examensarbetet är att utveckla optimala utbyggnadsplaner för produktionskapaciteten för två olika öar i detta land, med användning av solcellsproduktion, vilket är den enda tillgängliga förnybara energikällan. Den första uppgiften är utvecklingen av en optimal utbyggnadsplan för produktionskapaciteten för de kommande tre åren med optimeringsverktyget HOMER Energy. Från början fanns det bara dieselgeneratorer på öarna. För varje studerat år optimeras den installerade kapaciteten av PV och BESS samt aktivering av möjliggörande teknologier som begränsning av PV-produktion och grid-forming växelriktare. Den andra uppgiften fokuserar på utvecklingen av en ny driftsstrategi, förbättring av den basala driftsalgoritm som är inbyggd i HOMER. Driftsstrategin minimerar kostnaden av elproduktionen och är baserad på en 48 timmars prognos av laster och PV. Den är implementerad i MATLAB och kopplad till HOMER via det inbyggda MATLABgränssnittet. Eftersom HOMER fokuserar på produktionsutbyggnad och drift och i praktiken försummar elnätet, krävs en studie av elnätet för att utvärdera stabiliteten av elnätet. Studien av denna sista uppgift i examensarbetet är begränsad till att bestämma spänningen vid jämnviktsläge och den utvärderade lasten på en av de studerade öarna genom belastningsfördelningsberäkning i DIgSILENT PowerFactory. Det visade sig att det inte fanns några stora problem även med stora andelar PV, men elnätets prestanda kan förbättras om PV-omriktarna är utrustade med reaktiv effektstyrning som kontrollerar spänningen. En studie avinverkan från Q(U)-styrning och PQ-kapacitet av PV- och BESS-växelriktare har utförts.

The integration of distributed energy sources and systems is of high relevance for the transition towards a more sustainable energy system. Taking into consideration the  amount of emissions produced by the heating sector, which account for at least half of the energy demand in buildings, district heating systems have the potential to play a key role in the transition, by enabling the integration of various energy sources and provide flexible energy services to the grid. The objective of this research is to evaluate the potential for flexible sector coupling between the electrical and heating sectors, utilizing thermal energy storage alongside various heat generation units, including heat pumps and a combined heat and power (CHP) unit. To examine this concept, we used a district heating facility located in Oskarshamn, Sweden, as our case study. At present, the production mix at this facility comprises various production units- that utilize mainly biomass as their fuel source, including wood pellets, wood chips, and occasionally, bio-oil. Extensive research was conducted to review the existing literature and gain a comprehensive understanding of the technologies and concepts associated with FSC. This thorough examination allowed for a comprehensive overview of the current state-of-the-art in FSC. As the main contributions of this work, two numerical models respectively for production and dispatch optimization were developed and simulated complementary, concerning the thermal and electrical system of the studied plant. A dispatch model was developed with the aim of analyzing the operating behaviour of the system, identifying the available energy sources and optimizing their hourly dispatch. Subsequently, utilizing the open-access tool for capacity and investment optimization (OSeMOSYS), various scenarios were examined to evaluate the potential of thermal energy storage (TES), where a water tank was found to be the most cost-effective solution, and heat pump integration in enhancing the plant performance and providing flexibility. The study was divided into two distinct time periods. The first period focused solely on hourly dispatch optimization until 2035. In the second period, the analysis extended to include investment optimization, followed by the subsequent dispatch optimization until 2050, hence, using both tools. To effectively compare and assess the different scenarios, several key performance indicators (KPIs) were chosen, including the levelized cost of energy (LCOE), capital expenditure (CAPEX), generation costs, and emissions. These scenarios were designed to account for variations in crucial variables such as electricity prices, the plant’s self-consumption potential, and the capital cost of storage. By considering the aforementioned factors, a comprehensive analysis was conducted to determine the optimal approach for maximizing performance and cost-effectiveness. It is important to mention that the electrical self-consumption within the plant was considered as one of the potential improvements. While the potential for electrical self-consumption was mainly studied on a shorter-term, the variability in the capital cost of the TES system was better considered on the long-term investment analysis. From the different simulations, the cases where self-consumption is included result in smaller operating costs, as producing electricity via the CHP unit of the plant is cheaper on average than the prices offered by the local distribution company. The obtained capacities for TES and the heat pump vary among the studied scenarios. Higher electricity prices favor investments in alternative fuel boilers like wood chips or wood pellets, while lower electricity prices result in increased TES capacities and higher heat pump production. The capital cost of storage also determines the capacity chosen for the storage water tank, sometimes investing a bit more to gain efficiency and reduce operational costs. Throughout the project, various sustainability aspects have been addressed. These encompass environmental responsibilities, with a focus on reducing CO2 emissions, enhancing social equity by implementing a more efficient heating system within the municipality, and assessing the economic viability of these initiatives. In conclusion, the study provides evidence and showcases the viability of implementing FSC in Oskarshamn’s power plant, as results from the different scenarios commonly show that FSC could bring down the total costs, as well as the amount of CO2 emissions on a long-term basis. Based on the findings, additional recommendations are proposed to optimize the plant’s performance and leverage the potential of this innovative approach. The proposed recommendations include increasing the time resolution in the model simulations to improve result accuracy and exploring different scenarios, which may involve considering various electricity or fuel price predictions, among other factors. / Integreringen av distribuerade energikällor och energisystem är av stor betydelse för övergången till ett mer hållbart energisystem. Med hänsyn till det utsläpp från värmesektorn, som står för minst hälften av energibehovet i byggnader, har fjärrvärmesystem potential att spela en nyckelroll i omställningen genom att möjliggöra integrering av olika energikällor och tillhandahålla flexibla energitjänster till nätet. Syftet med denna forskning är att utvärdera Potentialen för flexibel sektorkoppling (FSC) mellan el- och värmesektorerna, med hjälp av termisk energilagring tillsammans med olika värmeproduktionsenheter, inklusive värmepumpar och en kombinerad kraftvärmeproduktion (CHP). För att undersöka detta koncept, använde vi en fjärrvärmeanläggning i Oskarshamn, Sverige, som vår fallstudie. För tillfället består produktionsmixen vid denna anläggning av olika produktionsenheter som huvudsakligen använder biomassa som bränslekälla, inklusive träpellets, träflis och ibland bioolja. Omfattande forskning genomfördes för att granska den befintliga litteratur och få en heltäckande förståelse för de tekniker och koncept som är förknippade med FSC. Denna grundliga undersökning möjliggjorde en omfattande översikt av det aktuella kunskapsläget inom FSC. Som de viktigaste bidragen i detta arbete utvecklades och simulerades två numeriska modeller för produktions- respektive leveransoptimering, som berör det termiska och elektriska systemet i den studerade anläggningen. En fördelningsmodell utvecklades i syfte att analysera systemets driftsbeteende, identifiera tillgängliga energikällor och optimera deras fördelning per timme. Med hjälp av det verktyget med öppna tillgång (open-aceess) för kapacitets- och investeringsoptimering (OSeMOSYS) undersöktes därefter olika scenarier för att utvärdera potentialen för termisk energilagring (TES), där en vattentank visade sig vara den mest kostnadseffektiva lösningen, och integration av värmepumpar för att förbättra anläggningens prestanda och ge flexibilitet. Studien var uppdelad i två olika tidsperioder. Den första perioden fokuserade enbart på optimering av timfördelning fram till 2035. Under den andra perioden utvidgades analysen till att omfatta investeringsoptimering, följt av efterföljande optimering av driften fram till 2050, vilket innebär att båda verktygen användes. För att effektivt kunna jämföra och bedöma de olika scenarierna valdes flera viktiga nyckelprestandaindikatorer (KPI:er), inklusive den nivellerade energikostnaden (LCOE), kapitalinvesteringar (CAPEX), produktionskostnader och CO2 utsläpp. Dessa scenarier utformades för att ta hänsyn till variationer i viktiga variabler som elpriser, anläggningens självkonsumtionspotential och kapitalkostnaden för lagring. Med hänsyn till de ovan nämnda faktorerna genomfördes en omfattande analys för att fastställa den optimala metoden för att maximera prestanda och kostnadseffektivitet. Det är viktigt att nämna att den elektriska självförbrukningen inom anläggningen betraktades som en av de potentiella förbättringarna. Medan potentialen för elektrisk självförbrukning främst studerades på kortare sikt, beaktades variationen i kapitalkostnaden för TES-systemet bättre i den långsiktiga investeringsanalysen. De olika simuleringarna visar att de fall där självförbrukning ingår resulterar i lägre driftskostnader, eftersom elproduktionen via kraftvärmeverket i genomsnitt är billigare än de priser som erbjuds av det lokala distributionsbolaget. De erhållna kapaciteterna för TES och värmepumpen varierar mellan de studerade scenarierna. Högre elpriser gynnar investeringar i alternativa bränslepannor som flis eller träpellets, medan lägre elpriser resulterar i ökad TES-kapacitet och högre värmepumpsproduktion. Kapitalkostnaden för lagring avgör också vilken kapacitet som väljs för vattentanken (some en TES), ibland investerar man lite mer för att öka effektiviteten och minska driftskostnaderna. Under hela projektet har olika hållbarhetsaspekter beaktats. Dessa omfattar miljöansvar, med fokus på att minska CO2-utsläppen, öka den sociala rättvisan genom att införa ett mer effektivt värmesystem inom kommunen, och bedöma den ekonomiska bärkraften i dessa initiativ. Sammanfattningsvis visar studien att det är möjligt att implementera FSC i Oskarshamns kraftverk, eftersom resultaten från de olika scenarierna visar att FSC kan sänka de totala kostnaderna samt mängden CO2-utsläpp på lång sikt. Baserat på resultaten föreslås ytterligare rekommendationer för att optimera anläggningens prestanda och utnyttja potentialen i denna innovativa metod. De föreslagna rekommendationerna inkluderar att öka tidsupplösningen i modellsimuleringarna för att förbättra resultatens noggrannhet och utforska olika scenarier, vilket bland annat kan innebära att man överväger olika el- eller bränsleprisprognoser.

[pt] Um dos algoritmos mais eficientes para resolver problemas de planejamento de operações hidrotérmicas, que são modelos estocásticos multiestágio de larga escala, é o chamado algoritmo de programação dinâmica dupla estocástica (SDDP). O planejamento da operação dos sistemas de energia visa avaliar o valor dos recursos escassos (por exemplo, água) para alimentar os modelos de despacho de curto prazo usados na implementação real das decisões. Quando o modelo de planejamento se desvia significativamente da realidade da operação implementada, as políticas de decisão são consideradas inconsistentes no tempo. A literatura recente explorou diferentes fontes de inconsistência, como medidas de risco dinâmico inconsistentes no tempo, representação imprecisa do processo de informação e simplificações no modelo de planejamento de rede. Este trabalho aborda a inconsistência no tempo devido a simplificações na representação da rede no modelo de planejamento que estende a literatura existente. O objetivo deste trabalho é propor uma estrutura, composta por uma metodologia e um pacote computacional de código aberto, para testar o impacto operacional e econômico das simplificações da modelagem sobre o fluxo de energia da rede em sistemas de energia hidrotérmica. Entre as inúmeras formulações disponíveis no pacote, nos concentramos em avaliar o custo e o desempenho operacional das seguintes aproximações de modelos: o modelo de rede de transporte (NFA), atualmente em uso pelo operador de sistema brasileiro; o relaxamento de cone de segunda ordem (SOC); o relaxamento de programação semidefinida (SDP); a aproximação do fluxo de energia de corente continua (DC); e o DC com aproximação de fluxo de potência com perda de linha (DCLL). Todas as formulações mencionadas anteriormente são testadas como aproximações para o modelo de rede na fase de planejamento, onde é construída a função de custo futuro. Em seguida, avaliamos cada aproximação simulando a operação do sistema usando um modelo de implementação que minimiza o custo imediato sob as restrições de fluxo de energia AC e a respectiva função de custo futuro. A comparação é feita para dois sistemas, um composto por um ciclo e o outro aproximadamente radial. / [en] One of the most efficient algorithms for solving hydrothermal operation planning problems, which are large-scale multi-stage stochastic models, is the so-called stochastic dual dynamic programming (SDDP) algorithm. Operation planning of power systems aims to assess the value of the scarce resources (e.g. water) to feed short-term dispatch models used in the actual implementation of the decisions. When the planning model significantly deviates from the reality of the implemented operation, decision policies are said to be time-inconsistent. Recent literature has explored different sources of inconsistency such as time-inconsistent dynamic risk measures, inaccurate representation of the information process and simplifications in the network planning model. This work addresses the time-inconsistency due to simplifications in the network representation in the planning model extending the existing literature. The objective of this work is to propose a framework, comprised of a methodology and an open-source computational package, for testing the operative and economic impact of modeling simplifications over the network power-flow in hydrothermal power systems. Among the myriad of formulations available in the package, we focused on assessing the cost and operative performance of the following model approximations: the transportation network-flow model (NFA), currently in use by the Brazilian system operator; the second-order cone relaxation (SOC); the semidefinite programming relaxation (SDP); the DC power-flow approximation (DC); and the DC with line-loss power-flow approximation (DCLL). All the previously mentioned formulations are tested as approximations for the network model in the planning stage, where the cost-to-go function is built. Then, we evaluate each approximation by simulating the system s operation using an implementation model, which minimizes the immediate cost under AC power-flow constraints and the respective cost-to-go function. The comparison is made for two systems, one composed of a cycle and the other approximately radial.

[pt] Transmission switching já foi apresentado anteriormente como uma ferramenta capaz de prover benefícios significativos na operação de sistemas de potência, como redução de custos e aumento de confiabilidade. Dentro do contexto de mercados co-otimizados para energia e reservas, este trabalho endereça a co-otimização de transmission switching pós-contingência no planejamento da operação de sistemas elétricos. Os modelos propostos para programação diária e despacho econômico diferem de formulações existentes devido à consideração conjunta de três fatores complicadores. Primeiro, ações de transmission switching são consideradas nos estados pré e pós-contingência, portanto requerendo variáveis binárias pós-contingência. Adicionalmente, a programação de geradores e as ações de transmission switching são co-otimizadas. Além disso, a operação de geradores é caracterizada temporalmente em um contexto multi-período. Os modelos propostos são formulados como programas inteiros-mistos desafiadores para os quais os softwares comerciais comumente utilizados para modelos mais simples podem levar à intratabilidade até para instâncias de tamanho moderado. Como metodologia de solução, nós apresentamos uma versão aperfeiçoada de um algoritmo de geração de colunas e restrições aninhado, com a adição de restrições válidas para melhorar o desempenho computacional. Simulações numéricas demonstram o desempenho efetivo da abordagem proposta, assim como suas vantagens econômicas e operacionais sobre modelos existentes que desconsideram o transmission switching pós-contingência. / [en] Transmission switching has been previously shown to offer significant benefits to power system operation, such as cost savings and reliability enhancements. Within the context of co-optimized electricity markets for energy and reserves, this work addresses the co-optimization of post contingency transmission switching in power system operation planning. The proposed models for unit commitment and economic dispatch differ from existing formulations due to the joint consideration of three major complicating factors. First, transmission switching actions are considered both in the preand post-contingency states, thereby requiring binary post-contingency variables. Secondly, generation scheduling and transmission switching actions are co-optimized. In addition, the time coupled operation of generating units is precisely characterized. The proposed models are formulated as challenging mixed-integer programs for which the off-the-shelf software customarily used for simpler models may lead to intractability even for moderatelysized instances. As a solution methodology, we present enhanced versions of an exact nested column-and-constraint generation algorithm featuring the inclusion of valid constraints to improve the overall computational performance. Numerical simulations demonstrate the effective performance of the proposed approach as well as its economic and operational advantages over existing models disregarding post-contingency transmission switching.