Deploying wind power to a larger extent is one solution to reduce negative environmental impacts of electric power supply. However, various challenges are connected with increasing wind power penetration levels. From the perspective of transmission system operators, this includes balancing of varying as well as - to some extent - uncertain generation levels. From the perspective of power generating companies, changes in the generation mix will affect the market's merit order and, hence, their profits. This thesis focuses on provision and use of flexibility in the Nordic electricity market. First, this thesis studies wind power variations and accuracy of wind power forecasts in Sweden using statistical methods. Even though today’s wind penetration levels are still low in Sweden, power systems and electricity markets have to cope with these characteristics of variations and forecast errors to a larger extent in future. Second, it investigates to which extent an increased exchange and use of flexibility that is available in the intraday time-frame could efficiently facilitate system balancing and whether this would also be profitable from the power generating companies' perspective. Here, a simulation model is developed that reflects important aspects of production planning and trading decisions in the intraday time-frame. In a first case study, it is shown that the benefits of internal rescheduling strongly depend on the costs to adjust production plans in the intraday time-frame as compared to real-time. In a second case study, it becomes evident that trading flexibility in the intraday time-frame can reduce the need for system balancing more efficiently than internal rescheduling within each balance responsible party. Motivated by the positive gains of intraday trading and the challenge of appropriately modelling continuous intraday markets, trading activity and price development on Elbas is investigated. The results provide insights into trading behaviour on a continuous intraday market and show that trading is not always in accordance to the power system's physical situation. To the extent to which better information and adaptations in the market design could improve the market participants' base for trading decisions, policy recommendations and further research questions areas suggested. / Att använda vindkraft i en större utsträckning är en möjlighet att minska elproduktionens negativa miljöpåverkan. Det finns dock också olika utmaningar med stora mängder vindkraft. Från ett systemperspektiv gäller det till exempel att hålla balansen mellan tillförsel och konsumtion av el. Från elproducenternas perspektiv bör vindkraftens påverkan på elmarknaden nämnas eftersom det påverka aktörernas vinster. Avhandlingen titta närmare in i hur man kan få tillgång till mer flexibilitet på produktionssidan. Avhandlingen består av tre delar. För det första undersöks variationer och prognosfel av vindkraft i Sverige med hjälp av statistiska metoder. Även om andel vindkraft hittills är låg i Sverige, behöver elsystemet och elmarknader i framtiden hantera samma egenskaper av själva variationer och prognosfel som idag men i en större utsträckning. För det andra undersöks hur den flexibiliteten som finns i tidshorisonten några timmar innan leveranstimmen kan utnyttjas för att integrera vindkraften på ett sätt som är både fördelaktigt från systemets och från aktörernas perspektiv. Undersökningen sker med hjälp av en simuleringsmodell som omfattar viktiga delar i produktionsplanering och intradayhandel. I en fallstudie uppvisas att vinster av intern omplanering är i högsta grad beroende på kostnadsskillnaden mellan omplanering några timmar innan leveranstimmen och anpassning av körscheman under själva leveranstimmen. Resultat av ytterligare en fallstudie uppvisar att det är betydligt billigare och mer effektivt att använda intradayhandel istället för intern omplanering för att utnyttja den befintliga flexibiliteten och för att reducera obalanser som systemoperatörer annars behöver ta hand om under leveranstimmen. Detta är en anledning till att undersöka handelsmönster på Elbas som är en intradaymarknad med kontinuerlig handel. En annan anledning till den här tredje delen är utmaningarna i att modellera kontinuerlig intradayhandel. Studien beskriver handelsaktiviteten på Elbas och hur priserna utvecklas under handelstiden. Ett resultat är att handeln inte alltid återspeglar den fysiska situationen i elsystemet. I den utsträckningen som ett snabbare informationsflöde och förändringar i marknadsdesignen kunde förbättrar aktörernas underlag för intradayhandel, föreslås förbättringar och öppna forskningsfrågor. / <p>QC 20150911</p> / Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet

Le développement des énergies renouvelables éolienne et solaire implique de repenser les modèles à long terme du système énergétique. En effet, les impacts à court et long terme des productions intermittentes éolienne et solaire sur le système électrique entraînent un besoin de flexibilité : centrales de production très réactives, gestion de la demande,amélioration du réseau électrique ou stockage d’électricité. Le premier apport majeur à l’état de l’art est l’ajout du stockage d’électricité et du réseau électrique européen dans le modèle POLES (Prospective Outlook on Long-term Energy Systems). Un nouveau mécanisme d’investissement a été développé, mieux adapté aux enjeux des renouvelables ; il inclut plusieurs valeurs économiques du stockage. D’autre part, une nouvelle typologie applicable à la fois aux modèles de prospective énergétique et aux outils détaillés du secteur électrique,a montré l’intérêt de rassembler ces deux approches. Ainsi, la deuxième contribution principale est le couplage annuel de POLES à un modèle d’opération du système électrique,EUCAD (European Unit Commitment And Dispatch), qui optimise l’allocation technico économique des centrales européennes de production et de stockage. Les échanges bidirectionnels d’informations permettent de bénéficier à la fois de la cohérence à long terme des scénarios économiques de POLES et du détail technique d’EUCAD. Un scénario conservateur prévoit un développement rapide des options de flexibilité les moins chères :interconnexions, stockage hydraulique et gestion de la demande – que ce soit par des effacements de consommation ou par l’optimisation de la charge et décharge des batteries de véhicules électriques. Les batteries stationnaires, plus chères, sont développées en seconde partie de siècle. Leur développement pourrait être accéléré par une réduction des coûts fixes du stockage plus efficace qu’une amélioration du rendement. Les liens explicites entre renouvelables intermittents et stockage d’électricité ressortent aussi des résultats. / The current development of wind and solar power sources calls for an improvement of longtermenergy models. Indeed, high shares of variable wind and solar productions have shortandlong-term impacts on the power system, requiring the development of flexibility options:fast-reacting power plants, demand response, grid enhancement or electricity storage. Ourfirst main contribution is the modelling of electricity storage and grid expansion in the POLESmodel (Prospective Outlook on Long-term Energy Systems). We set up new investmentmechanisms, where storage development is based on several combined economic values.After categorising the long-term energy models and the power sector modelling tools in acommon typology, we showed the need for a better integration of both approaches.Therefore, the second major contribution of our work is the yearly coupling of POLES to ashort-term optimisation of the power sector operation, with the European Unit CommitmentAnd Dispatch model (EUCAD). The two-way data exchange allows the long-term coherentscenarios of POLES to be directly backed by the short-term technical detail of EUCAD. Ourresults forecast a strong and rather quick development of the cheapest flexibility options: gridinterconnections, pumped hydro storage and demand response programs, including electricvehicle charging optimisation and vehicle-to-grid storage. The more expensive batterystorage presumably finds enough system value in the second half of the century. A sensitivityanalysis shows that improving the fixed costs of batteries impacts more the investments thanimproving their efficiency. We also show the explicit dependency between storage andvariable renewable energy sources.

The energy system is undergoing a transformation on a never before witnessed scale. The changes are driven by global market forces and technological advancements, improving on a seemingly exponential scale. This in turn has led to the price of both renewables and the accompanying technology decrease over time, making the transition into renewables more economically viable. The drawback of variable renewable energy is that it is variable and dependent on the surrounding environment. Therefore, storing the energy during hours of production, to be used at a later stage when energy demand is higher is becoming ever more important and an attractive option. The purpose of this degree project is to, from a set of performance indicators, evaluate three different energy storage technologies and their respective impact on a distribution grid. The examined storage technologies are: Batteries, Capacitators and a H2 Fuel cell. A literature study was performed in order to find out how grid performance is evaluated, and how the different storage technologies operate. The obtained literature comes from scientific reports, and papers, found by utilizing Mälardalens University library-database. A model representing a Swedish grid with a connection point to the distribution side was created. The model is taken from previous credited work, and customized to fit the operational parameters of a Swedish grid. It was decided that the key indicators for evaluating the state of a grid was to look at the: voltage- and frequency variations, load factor, capacity factor and the overall system efficiency. The simulation is a discrete time simulation that utilizes parameters indicative of one full day of data. The results showed that, from a technological standpoint, the supercapacitor performed better in more categories than the Li-ion battery and H2 fuel cell. However, the Li-ion battery reduced the peaks of the frequency measurements which is a key metric when deciding on grid health. Also, there is the added benefit of the battery and fuel cell of having a longer operational time before the state of charge is depleted. This increases the flexibility of the technology and could therefore be more beneficial in other applications where power supply is more scarce.

This report explores the impacts of variable renewable energy (VRE) on power trading in the European wholesale electricity market. The intricate operation of a typical power exchange in Europe is accompanied by an equally complex balancing system. The increasing amount of VRE in the power system, such as wind and solar power, has far-reaching impacts for power traders in both this electricity market and the corresponding balancing system. As a result, the electricity market is evolving in unprecedented ways and new participants are entering the playing field to capitalize on the changing dynamics caused by VRE generators. One novel participant, the virtual power plant (VPP), possesses an advantage over other market participants by aggregating VRE generators with controllable renewable energy generators, like biogas and hydro plants, into one entity. This allows the VPP to both gain access to live VRE production data that larger plants don’t have, which it then utilizes to remotely dispatch various subpools of assets, and to provide balancing services to the grid. Subsequently, VPPs are able to trade VRE and other renewable electricity superiorly on the same spot markets and balancing systems as large central power plants and industrial consumers. The report asserts that VPP traders can earn profits through means of innovative trading strategies that exploit predictable market impacts caused by VRE power through a robust understanding of the electricity market and their unique access to data. / Denna rapport undersöker effekterna av variabel förnybar energi (VRE) på krafthandeln på den europeiska elhandelsmarknaden för stora aktörer. Den komplicerade driften av ett typiskt kraftutbyte i Europa åtföljs av ett lika komplicerat balanseringssystem. Den ökande mängden VRE i kraftsystemet, såsom vind- och solkraft, har långtgående effekter för krafthandlare på både denna elmarknad och motsvarande balanseringssystem. Som ett resultat utvecklas elmarknaden på enastående sätt och nya deltagare kommer in på spelplanen för att dra nytta av den förändrade dynamiken som orsakas av VRE-generatorer. En ny spelare, det virtuella kraftverket (VPP), har en fördel jämfört med andra marknadsaktörer genom att samla VRE-generatorer med styrbara förnybara energiproducenter, som biogas och vattenkraftverk, till en enhet. Detta gör att VPP både kan få tillgång till live VRE-produktionsdata som större anläggningar inte har, som den sedan använder för att distribuera olika underpooler av tillgångar och för att tillhandahålla balanstjänster till nätet. Därefter kan VPP: er handla med VRE och annan förnybar el på ett överlägset sätt på samma spotmarknader och balanseringssystem som stora centrala kraftverk och industrikonsumenter. Rapporten visar att VPP-handlare kan göra vinster genom innovativa handelsstrategier som utnyttjar förutsägbara marknadseffekter orsakade av VRE-kraft genom en detaljerad förståelse för elmarknaden och unik tillgång till data för produktionen av förnybar energi / <p>QC 20201118</p>

In this report, the effect that a higher penetration ofrenewable energy sources has on electric power grid stability isevaluated. The report also compares different methods of stabilizingan unstable grid. The model used is a two-area four-machinesystem and the main objective is to stabilize the synchronousgenerators such that they revert back to synchronism afterbeing subjugated to a small signal disturbance. The stabilizationmethods consists of supplementary Power System Stabilizers(PSSs) complementing the exciter systems of the synchronousmachines, as well as two types of converter-based controllers inthe renewable energy source: Grid-Following (GFL) convertersand Grid-Forming (GFM) converters. The results show thata system with renewable energy sources is more sensitive todisturbances and has a larger rotor angle deviation from a steadystate when using only GFLs compared to the conventional gridwithout PSSs. It is also found that a conventional grid requiressupplementary PSSs to be stable. This is also the case for asystem with renewable energy controlled by GFL. The systemwith GFM controllers does however not need supplementary PSSto be stable. This leads to the conclusion that GFM is morepreferable than GFL to control a grid with a higher penetrationof renewable energy. / I denna rapport utvärderas hur en högre andel förnybara energikällor påverkar stabiliteten i elnät, och jämför också olika metoder för att stabilisera ett instabilt nät. Modellen som används var ett två-områdes-fyrmaskinsystem och huvudsyftet är att stabilisera synkrongeneratorerna så att de återgår till synkronism efter att ha utsatts för en liten småsignalsstörning. Stabiliseringsmetoderna består av kompletterande Power System Stabilizers (PSS:er) som kompletterade exciteringssystemen i synkronmaskinerna, samt två typer av omvandlarbaserade styrenheter i den förnybara energikällan: Grid-Following (GFL)-omvandlare och Grid-Forming (GFM)omvandlare. Resultaten visar att ett system med förnybara energikällor är mer känsligt för störningar och har en större rotorvinkelavvikelse från ett stationärt tillstånd när GFL-kontroller används jämfört med det konventionella nätet utan PSS:er. Det visar sig också att ett konventionellt nät kräver kompletterande PSS:er för att vara stabilt. Detta är också fallet för ett system med förnybar energi som enbart kontrolleras av GFL-omvandlare. Systemet med GFM-omvandlare behöver dock inte kompletterande PSS för att vara stabilt. Detta leder till slutsatsen att GFM är mer att föredra än GFL för att kontrollera ett nät med högre andel förnybar energi. / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm

Syftet med studien var att undersöka samvariationen och korrelationen mellan de variabla förnybara energikällorna sol-, vind- och vattenkraft i fyra olika begränsade områden i Sverige. Studien ämnade att identifiera mönster mellan energislagen för att undersöka huruvida ett elkraftsystem enbart baserat på förnybara energikällor i Sverige är möjligt. Initialt genomfördes en litteraturstudie i syfte att ge kvalitativt underlag för det komplexa ämnet som undersöktes. Analysen och den kvantitativa delen av studien grundades på historiska klimatologiska data. Arbetet genomfördes i sin tur med hjälp av mjukvaran Matlab, där data hanterades och bearbetades. Parametrar och variabler som diskuterades och identifierades var framförallt effektspektrum, korskovarians och korrelation. Tidigare forskning tyder på att både positiv och negativ korrelation mellan olika variabla energislag förekommer beroende på vilka geografiska förutsättningar och vilket tidsspann som undersökts. Denna studie fann att negativ korrelation mellan sol- och vindkraft återkom för samtliga platser som studerades, medan sol- och vattenkraft istället korrelerade positivt. För vatten- och vindkraft var resultaten inte lika entydiga utan olika resultat erhölls beroende på tidsintervallet. / The purpose of the study was to examine the co-variation and correlation among the variable renewable energy sources solar, wind and hydropower in four different confined regions in Sweden. The study aimed to identify patterns among the energy sources to investigate whether a power system based on renewable energy sources in Sweden is achievable. Initially, a literature review was conducted to provide qualitative background for the complex subject investigated. The analysis and quantitative aspect of the report were based on historical climatological data. The work was carried out using Matlab software, where data was handled and processed. Parameters and variables discussed and identified primarily included power spectrum, cross-covariance, and correlation. Previous research suggests both positive and negative correlations among different variable energy sources occur depending on the geographic conditions and time span studied. This study found that negative correlation between solar and wind power recurred for all sites examined, while solar and hydropower instead showed a positive correlation. For hydropower and wind power, the results were not as consistent, with different outcomes depending on the time interval analyzed.

As manufacturing is creating welfare and prosperity, it is important for humankind. Nevertheless, manufacturing is causing the depletion of natural resources, environmental burdens affecting the health of animals, humans and eco-systems, and social conflicts. Thus, it is essential to implement sustainability into manufacturing. Paint shops are however known for being liable for a big part of the large energy consumptions within manufacturing. Therefore, it is necessary to investigate what cost-effective solutions can be implemented in paint shops in order to reduce the energy consumption in a sustainable manner. Hence, the aim of this study was to, from a manufacturing perspective identify possible cost-effective solutions for lowering energy consumption within paint shops. The aim was further divided into two research questions: • RQ1: What are the enablers for energy efficient paint shops? • RQ2: What are the challenges for energy efficient paint shops? The research approach used to answer the aim and research questions were a literature review and a case study. The literature review was performed to get a deeper understanding of the subject and was then complimented with the findings from the case study. The case study was performed at the paint shop of a global automotive manufacturing company in Sweden, which currently have a high energy consumption. The enablers identified were (1) implementation of solar photovoltaic, and an energy storage system, which enables an environmentally friendly way of generating energy on-site and store excess energy for later use. The energy storage system can also be used to save money by utilizing the fluctuating electricity market prices, charging the battery when the energy price is at its lowest. (2) Implementation of an UV-curing system and paint, which is an environmentally harmless method of curing paint. (3) Reducing or disabling the heating, ventilation and air conditioning system of a building when it is not a necessity. (4) Workers commitment and motivation towards sustainability, to ensure everyone’s participation. The challenges identified were (1) the expensiveness of sustainability, allocating and prioritizing it in budgets is challenging for a company since profitability is always a major concern that often overshadows sustainability. (2) The risk of modifying the processes within the paint shop, as the consequences are unexplored. (3) In its current state, the energy consumption of the paint shop is very high, it is hence difficult to provide the whole paint shop with solely solar photovoltaic. (4) An energy storage system requires space and freeing up that space is a challenge without reconstructing existing facilities. (5) With implementation of UV- curing, the paint used must be curable with UV-light. Additionally, complex three-dimensional shapes make it challenging to properly cure evenly with UV-curing. (6) It is not guaranteed whether it is possible to completely shut down heating, ventilation and air conditioning since industrial equipment in general is designed to always run. (7) Sustainability is not a focus and even if it is increasingly requested by society, the commitment of companies is experienced as low. It is challenging to motivate all the employees to work towards sustainability and find ways to always keep sustainability in mind and to prioritize it over other alternatives.

[pt] A natureza intermitente da geração eólica combinada com a conhecida volatilidade dos preços de eletricidade expõe as Empresas de Energia Eólica (WPCs) comprometidas com contratos de longo prazo aos chamados riscos de preço e quantidade. Vários instrumentos foram desenvolvidos nos últimos anos para mitigar essa exposição ao risco. No entanto, a maioria deles foi construído para lidar apenas com uma das partes, ou seja, a incerteza de preço ou geração. Para enfrentar essa questão, neste trabalho, propomos um instrumento derivativo customizado para as WPCs, aproveitando os princípios de opções e índices renováveis. A eficácia e atratividade do instrumento proposto, denominado Opção Eólica (WInd-Op), são avaliadas com dados reais do setor brasileiro por meio de um modelo de equilíbrio geral. Mostramos que as Empresas de Energia Solar (SPCs) podem ser candidatas relevantes para respaldar esses derivativos. Além disso, quando comparado com as opções tradicionais de compra e venda, usadas como referência, os resultados indicam que o equilíbrio obtido com o novo derivativo apresenta um volume total de negociação significativamente maior, preços de prêmio mais baixos e maior bem-estar geral. / [en] The intermittent nature of wind generation combined with the wellknown volatility of electricity spot prices expose Wind Power Companies (WPCs) committed to long-term forward contracts to the so-called price-andquantity risk. Several instruments were designed in the past years to mitigate this risk exposure. However, most of them were mainly constructed to cope with only one of its parts, i.e., price or generation uncertainty. To tackle this issue, in this work, we propose a tailored derivative instrument for WPCs leveraging the principles of options and renewable indexes. The effectiveness and attractiveness of the proposed instrument, referred to as the Wind-Indexed Option (WInd-Op), are evaluated with real data from the Brazilian sector through a general equilibrium setup. We show that Solar Power Companies (SPCs) can be relevant candidates to back these derivatives. Additionally, when compared to the traditional put-and-call options as a benchmark, the results indicate that the equilibrium obtained with the new derivative exhibits a significantly higher total traded volume, lower premium prices, and greater overall welfare.

Variable renewable energy sources typically connect to the power grid through power electronic interfaces. Increased use of such sources can cause issues for conventional distance protection. The purpose of distance protection is to detect transmission line faults and trip circuit breakers accordingly in order to maintain power system stability and power quality, and to ensure the safety of equipment and humans. Conventional distance protection solutions work satisfactorily in grids dominated by synchronous generators, but it has been recognized in industry and academia that new solutions may be needed in power grids dominated by power electronics interfaced generation due to the non-linear system impacts introduced by such sources. It was the aim of this thesis project to investigate the performance of alternative solutions used toward this end, specifically time domain distance protection solutions which are immune to the dynamics of power electronics interfaced sources. Short-circuit simulations for different fault scenarios have been performed in PSCAD, utilising models with a wind farm connected via a single overhead transmission line to a grid represented by a voltage source and impedance. The PSCAD line voltages and currents were processed in Matlab where both a more conventional phasor-based algorithm and a time domain differential equation based algorithm were implemented and simulated. A tripping logic based on detecting stable fault distance estimates within the primary protection zone was used. The implemented algorithms were compared for 96 scenarios in their ability to identify the faults and fault types, estimate the fault distances, and in their tripping speed. The results show an overall better performance for the differential equation algorithm compared to the conventional phasor-based algorithm, with more successful trips, faster tripping speed and superior distance estimate convergence on the correct fault distance. Some limitations have also been identified for the differential equation algorithm such as a fault impedance trajectory in the impedance plane which can lead to incorrect trips during external faults when using conventional tripping logic. It is suggested that more research be done regarding the differential equation algorithm with the next step being further algorithm development and testing when using fault impedance estimates and a tripping zone in the impedance plane. / Variabla förnybara energikällor använder vanligtvis kraftelektronik som ett gränssnitt för kopplingen till kraftnätet och ökningen av sådana källor kan skapa problem för konventionella distansskydd. Distansskydds syfte är att detektera jord- och fasfel på kraftledningar samt att skicka utlösningssignaler till strömbrytare för att isolera felet, vilket behövs för att upprätthålla kraftnätets stabilitet, effektkvalitet samt för att säkerställa säkerhet för komponenter och människor. Konventionella distansskydd fungerar bra i kraftnät dominerade av synkrongeneratorer men det har uppmärksammats av industrin samt den akademiska världen att nya lösningar kan behövas i kraftnät som är dominerade av energikällor med kraftelektronik-gränssnitt på grund av dess olinjära dynamik. Syftet med detta examensarbete är att undersöka prestandan av alternativa algoritmer för distansskydd som kan användas mot detta ändamål, specifikt tidsdomän algoritmer som är immuna mot dynamiken introducerad av kraftelektroniken. Kortslutningssimuleringar för olika scenarion har simulerats i PSCAD modeller med en vindkraftpark kopplad i änden på kraftledningen, där spänningarna och strömmarna sparas för vidare analys. Resultaten från PSCAD simuleringar bearbetades i Matlab där både en konventionell algoritm baserad på fasvektorer samt en tidsdomän algoritm baserad på differentialekvationer har implementerats och simulerats. Den implementerade utlösningslogiken baserades på att detektera stabila estimeringar för avståendet mellan skyddsreläet och felet på kraftledningen, där utlösningssignaler skickas för stabila estimeringar detekterade inom den primära skyddszonen för reläet. De implementerade algoritmerna jämfördes i 96 olika scenarion för deras förmåga att: identifiera fel och feltypen, estimera avståndet mellan skyddsreläet och felet samt för deras utlösningstider. Resultaten visar en i överlag bättre prestanda för differentialekvations-algoritmen jämfört med den konventionella fasvektor-baserade algoritmen med fler lyckade strömbrytarutlösningar, snabbare utlösningstider samt bättre konvergens och mer korrekt lokalisering för avståndsestimeringen mellan skyddsreläet och felet. Vissa limitationer har även identifierats för differentialekvations-algoritmen, exempelvis en felimpedans-kurva i impedansplanet vilket kan leda till inkorrekta utlösningar för externa fel om ett konventionellt impedansområden används för utlösningslogiken. Det föreslås att mer forskning bör utföras kring differentialekvations-algoritmen med nästa steg att vidare utveckla algoritmen samt utföra tester vid användande av felimpedansestimeringar och en utlösningslogik baserad på impedansområden.

The main focus of this thesis is on the power electronic converter system challenges associated with the grid integration of variable-renewable-energy (VRE) sources like wave, marine current, tidal, wind, solar etc. Wave energy conversion with grid integration is used as the key reference, considering its high energy potential to support the future clean energy requirements and due the availability of a test facility at Uppsala University. The emphasis is on the DC-link power conditioning and grid coupling of direct driven wave energy converters (DDWECs). The DDWEC reflects the random nature of its input energy to its output voltage wave shape. Thereby, it demands for intelligent power conversion techniques to facilitate the grid connection. One option is to improve and adapt an already existing, simple and reliable multilevel power converter technology, using smart control strategies. The proposed WECs to grid interconnection system consists of uncontrolled three-phase rectifiers, three-level boost converter(TLBC) or three-level buck-boost converter (TLBBC) and a three-level neutral point clamped (TLNPC) inverter. A new method for pulse delay control for the active balancing of DC-link capacitor voltages by using TLBC/TLBBC is presented. Duty-ratio and pulse delay control methods are combined for obtaining better voltage regulation at the DC-link and for achieving higher controllability range. The classic voltage balancing problem of the NPC inverter input, is solved efficiently using the above technique. A synchronous current compensator is used for the NPC inverter based grid coupling. Various results from both simulation and hardware testing show that the required power conditioning and power flow control can be obtained from the proposed multilevel multistage converter system. The entire control strategies are implemented in Xilinx Virtex 5 FPGA, inside National Instruments’ CompactRIO system using LabVIEW. A contour based dead-time harmonic analysis method for TLNPC and the possibilities of having various interconnection strategies of WEC-rectifier units to complement the power converter efforts for stabilizing the DC-link, are also presented. An advanced future AC2AC direct power converter system based on Modular multilevel converter (MMC) structure developed at Siemens AG is presented briefly to demonstrate the future trends in this area.