Electric power has become a basic necessity of human life. The major share of electric power comes from fossil fuel which results in global warming and pollution. A share of generated power comes from nuclear power which is equally dangerous. Big hydro projects take away lots of fertile land. The continuous usage of fossil fuel also poses a threat of petroleum and coal getting over in the near future. The only way out of this energy scarcity is to depend more and more on renewable sources like solar, wind and micro-hydro. At present, instead of having preference over any particular source of renewable energy, effort should be made to extract power from every possible energy source available in whatever form it is and use it in an optimal way. Like any renewable energy sources, the wind power contains large potential for harnessing energy that has been well understood hundreds of years ago. The importance of wind power generation has come to focus recently both at installation and research level and lot of activities are being carried out for efficient use of wind energy. There are different types of wind turbine designs available in the literature. But the most commercially used model is the two or three blade horizontal axis propeller type wind turbine. Research has shown that variable speed operation of this type of turbine is advantageous over fixed speed operation in terms of total energy synthesis. The most commonly used machines for wind power conversion are synchronous machine, squirrel cage induction machine and slip ring induction machine (SRIM). Variable speed operation using synchronous machine or squirrel cage induction machine requires large ratings of the power converters. However, SRIM based variable speed wind generator is advantageous over other schemes due to its inherent advantages like lower power rating for the converters, higher energy capture and the flexibility of sharing reactive power between the stator and the rotor. SRIM is used for both grid connected and stand alone applications and have been reported in the literature. The grid connected applications have received major attention in the literature whereas there are only a very few instances of its stand alone counterparts. There are many places both within and outside India where utility grid has not yet reached or the available grid is very weak. Moreover, in many of the places, the transmission line is so long that the losses in the system are extremely high. Isolated wind power generation can be of great advantage in such places where the available wind power is harnessed and utilized locally. This has been the motivation to go for proposing an isolated wind power generation scheme in this thesis. The proposed scheme is designed to supply power to the load even when very low or no wind power is available. Therefore, a battery bank is also a part of the system. The power converter assembly of the proposed scheme has three major components. One is the rotor side converter which is connected to the rotor terminals of the SRIM. The second one is the stator side converter with output LC filter which is connected to the stator side. These two converters share a common DC link which is interfaced to the battery bank through a multi phase bi-directional fly-back DC-DC converter. Fig. 1. Overall block diagram of the proposed stand alone wind power generator Functionally, this thesis proposes a system as shown in Fig. 1, which has primarily two components with multiple energy ports viz. (i) the SRIM is one triple energy port component and (ii) the proposed power conditioner is another triple energy port component. The SRIM device consists of (i) a mechanical energy port that is interfaced with the windmill shaft (ii) an AC port through the stator windings that is interfaced with the micro-grid/load and (iii) a third port which is also an AC port through the rotor windings of the SRIM that interfaces with an AC port of the proposed power conditioner. The proposed power conditioner is another triple energy port device which consists of (i) a DC energy port that interfaces with a battery/accumulator, (ii) an AC port that interfaces with the rotor windings of the SRIM and (iii) another AC port that generates the micro-grid that is connected to the load and the stator port of the SRIM. The proposed power conditioner provides the frame work for managing the energy flow from the mechanical port of the SRIM to the rotor and accumulator as well as from the mechanical port to the stator/load and accumulator. Further, energy interaction can also take place between the stator and the rotor externally through the power conditioner. The power interfaces on all three energy ports of the proposed power conditioner poses several challenges that have been discussed in this thesis. This thesis focuses on developing schemes to solve these challenges as explained below. Speed sensorless control is a natural choice for slip ring induction machine because of the flexibility of sensing both stator and rotor currents. There are different methods proposed in the literature which deal with the speed sensorless control of slip ring induction machine. However, the elimination of the measurement noise in the flux position estimation is not sufficiently addressed. It is important to address this issue as this would lead to deterioration in rotor side control of SRIM if the measurement noise is not eliminated. Primarily, the schemes which use algebraic relation between the estimated rotor current in stator reference frame and the sensed rotor current, are prone to measurement noise. On the other hand, the schemes, which use rotor back-emf integration, are affected by DC drift problems, though they are not much affected by measurement noise. The proposed stator flux position estimation scheme incorporates the benefits obtained from both the above schemes while eliminating the disadvantages inherent to them. The rotor flux position is estimated by integrating the rotor back-electromotive force. The stator flux is then obtained from the rotor flux estimate. This integration mechanism leads to several problems like dc drift and lack of error decaying mechanism. This estimation scheme solves the above problems including reduction in the propagation of noise in the sensed current to the estimated rotor side unit vectors. On the implementation front, this scheme also eliminates the need for differentiating the unit vectors for estimating slip frequency. This makes the proposed flux estimator very robust. The proposed scheme is simulated and experimentally verified. There is an internal DC bus within the proposed power conditioner that manages the energy flow through the three energy ports. The internal DC bus is interfaced to an external accumulator or battery through a power interface called the multi phase bi-directional dc-dc converter. It is generally advantageous to have the motor rated for higher voltages in order to achieve better efficiencies for a given power rating as compared to low voltage motors. This implies higher DC bus voltage. On the other hand, it is advantageous to have the battery bank rated for low voltage in order to improve the volumetric efficiency which is better at lower battery bank voltages. Both these are contradictory requirements. The above problem is solved in this thesis by proposing a multi power port topology using a bidirectional fly-back converter that is capable of handling multiple power sources and still maintain simplicity and features like high gain, wide load variations and lower output current ripple. As a spin-off, the scheme can handle parallel energy transfer from even a eutectic combination of batteries without any additional control circuitry for parallel operation. Further, the scheme also incorporates a novel transformer winding technique which significantly reduces the leakage inductance of the coupled inductor. The proposed multi-port bidirectional converter is analyzed by including non-idealities like leakage inductance. The DC bus voltage regulation requirement is not very stringent because it is not directly fed to any load. Therefore, hysteresis voltage regulation with small proportional correction is used for DC bus voltage control. The proposed converter is built and experimentally verified in the proposed system as well as in a hybrid-electric vehicle prototype. The third port of the proposed power conditioner interfaces with the stator of the SRIM and the load. The stator/load needs to be connected to a stiff micro-grid. The control requirement of the micro-grid is very stringent because, even for a sudden variation in the wind speed or the load, the grid voltage magnitude and frequency should not change. The dynamic response of the grid voltage controller has to be very fast. Moreover, the grid voltage must be balanced in presence of unbalanced loading. This thesis proposes a converter called the stator side converter along with three phase L-C filter at its output to form the micro-grid. A generalized control scheme is proposed wherein the negative sequence components and the harmonics can be eliminated at the micro-grid by means of feed-forward compensators included in the fundamental positive synchronous reference frame alone. The theoretical foundation for this scheme is developed and discussed in the thesis. In isolated locations linear loads constitute a significant percentage of the total load. Therefore, on the implementation front, only the compensation of fundamental negative sequence is demonstrated. One more necessity for compensating the fundamental negative sequence is that, the SRIM offers only leakage impedance to the fundamental negative sequence components resulting in high fundamental negative sequence current even for a small fundamental negative sequence voltage present at the micro-grid. The proposed scheme ensures balanced three phase currents at the SRIM windings and the full unbalanced current is provided from the stator side converter. This scheme is validated both by simulation and experimentation. The proposed power conditioner is integrated and used in the implementation of the entire wind power generation scheme that is proposed in the thesis. The maximum power point tracking of the wind power unit is also incorporated in the proposed system. The simulation and experimental results are also presented. Finally, the engineering issues involved in the implementation of the proposed scheme are discussed in detail highlighting the hardware configuration and the equipments used. The wind turbine is emulated using a chopper controlled DC motor. The shaft torque of the DC motor is controlled to give the Cp−λ characteristic of a typical windmill. The control issues of the DC machine to behave as a wind turbine are also explained. Finally the thesis is concluded by a statement of potentials and possibilities for future work in this research area.

A new Markov chain based energy storage model to evaluate the power supply availability of microgrids with renewable energy generation for critical loads is proposed. Since critical loads require above-average availability to ensure reliable operation during extreme events, e.g., natural disasters, using renewable energy generation has been considered to diversify sources. However, the low availability and high variability of renewable energy sources bring a challenge in achieving the required availability for critical loads. Hence, adding energy storage systems to renewable energy generation becomes vital for ensuring the generation of enough power during natural disasters. Although adding energy storage systems would instantaneously increase power supply availability, there is another critical aspect that should be carefully considered; energy storage sizing to meet certain availability must be taken into account in order to avoid oversizing or undersizing capacity, which are two undesirable conditions leading to inadequate availability or increased system cost, respectively. This dissertation proposes to develop a power supply availability framework for renewable energy generation in a given location and to suggest the optimal size of energy storage for the required availability to power critical loads. In particular, a new Markov chain based energy storage model is presented in order to model energy states in energy storage system, which provides an understanding of the nature of charge and discharge rates for energy storage that affect the system's power output. Practical applications of the model are exemplified using electrical vehicles with photovoltaic roofs. Moreover, the minimal cut sets method is used to analyze the effects of microgrid architectures on availability characteristics of the microgrid power supply in the presence of renewable energy sources and energy storage. In addition, design considerations for energy storage power electronics interfaces and a comparison of various energy storage methods are also presented. / text

Atualmente, a geração eólica é a forma de geração de energia elétrica de maior crescimento no mundo. Não obstante, dependendo da forma em que é gerenciado este tipo de geração, pode causar impactos significativos no sistema de energia elétrica. Este trabalho estuda o comportamento da geração eólica nos sistemas de potência do ponto de vista dos aerogeradores e dos parques eólicos. É realizada uma modelagem dos principais componentes dos sistemas de geração eólica, particularmente dos aerogeradores de velocidade variável equipados com geradores de indução de dupla alimentação, com o intuito de aplicar estratégias de controle para a operação dos mesmos e estudar as suas características de funcionamento. São propostos métodos para a regulação da potência ativa gerada por estes aerogeradores e para a regulação da potência ativa gerada por parques eólicos compostos por vários aerogeradores de velocidade variável, com o objetivo de permitir um maior índice de penetração da geração eólica nos sistemas de energia elétrica. Usando a modelagem elaborada, são efetuadas rigorosas simulações computacionais do comportamento destas instalações eólicas funcionando com os métodos de regulação propostos. Os resultados obtidos nestas simulações mostram que o impacto da geração eólica pode ser consideravelmente diminuído, logrando atribuições semelhantes aos produtores de energia convencionais. Observa-se que estes métodos permitiriam flexibilizar a operação dos sistemas de geração eólica, possibilitando gerenciamentos mais adequados aos novos requerimentos exigidos pelos operadores dos sistemas de energia. / Nowadays, the wind power generation is the fastest growing electric power source in the world. Nevertheless, depending on the management of this kind of generation, it may cause significant impact in the power system. In this work, a modeling of the main components of wind power generation was performed, particularly of variable speed wind turbines with doubly fed induction generators, aiming to apply control strategies for its operation and to study its functional characteristics. Methods to regulate the active power generated by variable speed wind turbines, and to regulate the active power of wind farms composed of several of this turbines, are proposed with the objective to allow an increase in the level of penetration of wind generation in the power systems. Using the elaborated modeling, rigorous computational simulations of operation of these types of power stations, operating with the proposed methods, were accomplished. The obtained results in these simulations shows that it is possible to considerably minimize the wind power generation impacts, obtaining attributions similarly to conventional energy producers. It is observed that the proposed methods allows an operational flexibility of wind power generation, enabling a better management according to the new requirement of the power system operators.

Atualmente, a geração eólica é a forma de geração de energia elétrica de maior crescimento no mundo. Não obstante, dependendo da forma em que é gerenciado este tipo de geração, pode causar impactos significativos no sistema de energia elétrica. Este trabalho estuda o comportamento da geração eólica nos sistemas de potência do ponto de vista dos aerogeradores e dos parques eólicos. É realizada uma modelagem dos principais componentes dos sistemas de geração eólica, particularmente dos aerogeradores de velocidade variável equipados com geradores de indução de dupla alimentação, com o intuito de aplicar estratégias de controle para a operação dos mesmos e estudar as suas características de funcionamento. São propostos métodos para a regulação da potência ativa gerada por estes aerogeradores e para a regulação da potência ativa gerada por parques eólicos compostos por vários aerogeradores de velocidade variável, com o objetivo de permitir um maior índice de penetração da geração eólica nos sistemas de energia elétrica. Usando a modelagem elaborada, são efetuadas rigorosas simulações computacionais do comportamento destas instalações eólicas funcionando com os métodos de regulação propostos. Os resultados obtidos nestas simulações mostram que o impacto da geração eólica pode ser consideravelmente diminuído, logrando atribuições semelhantes aos produtores de energia convencionais. Observa-se que estes métodos permitiriam flexibilizar a operação dos sistemas de geração eólica, possibilitando gerenciamentos mais adequados aos novos requerimentos exigidos pelos operadores dos sistemas de energia. / Nowadays, the wind power generation is the fastest growing electric power source in the world. Nevertheless, depending on the management of this kind of generation, it may cause significant impact in the power system. In this work, a modeling of the main components of wind power generation was performed, particularly of variable speed wind turbines with doubly fed induction generators, aiming to apply control strategies for its operation and to study its functional characteristics. Methods to regulate the active power generated by variable speed wind turbines, and to regulate the active power of wind farms composed of several of this turbines, are proposed with the objective to allow an increase in the level of penetration of wind generation in the power systems. Using the elaborated modeling, rigorous computational simulations of operation of these types of power stations, operating with the proposed methods, were accomplished. The obtained results in these simulations shows that it is possible to considerably minimize the wind power generation impacts, obtaining attributions similarly to conventional energy producers. It is observed that the proposed methods allows an operational flexibility of wind power generation, enabling a better management according to the new requirement of the power system operators.

Atualmente, a geração eólica é a forma de geração de energia elétrica de maior crescimento no mundo. Não obstante, dependendo da forma em que é gerenciado este tipo de geração, pode causar impactos significativos no sistema de energia elétrica. Este trabalho estuda o comportamento da geração eólica nos sistemas de potência do ponto de vista dos aerogeradores e dos parques eólicos. É realizada uma modelagem dos principais componentes dos sistemas de geração eólica, particularmente dos aerogeradores de velocidade variável equipados com geradores de indução de dupla alimentação, com o intuito de aplicar estratégias de controle para a operação dos mesmos e estudar as suas características de funcionamento. São propostos métodos para a regulação da potência ativa gerada por estes aerogeradores e para a regulação da potência ativa gerada por parques eólicos compostos por vários aerogeradores de velocidade variável, com o objetivo de permitir um maior índice de penetração da geração eólica nos sistemas de energia elétrica. Usando a modelagem elaborada, são efetuadas rigorosas simulações computacionais do comportamento destas instalações eólicas funcionando com os métodos de regulação propostos. Os resultados obtidos nestas simulações mostram que o impacto da geração eólica pode ser consideravelmente diminuído, logrando atribuições semelhantes aos produtores de energia convencionais. Observa-se que estes métodos permitiriam flexibilizar a operação dos sistemas de geração eólica, possibilitando gerenciamentos mais adequados aos novos requerimentos exigidos pelos operadores dos sistemas de energia. / Nowadays, the wind power generation is the fastest growing electric power source in the world. Nevertheless, depending on the management of this kind of generation, it may cause significant impact in the power system. In this work, a modeling of the main components of wind power generation was performed, particularly of variable speed wind turbines with doubly fed induction generators, aiming to apply control strategies for its operation and to study its functional characteristics. Methods to regulate the active power generated by variable speed wind turbines, and to regulate the active power of wind farms composed of several of this turbines, are proposed with the objective to allow an increase in the level of penetration of wind generation in the power systems. Using the elaborated modeling, rigorous computational simulations of operation of these types of power stations, operating with the proposed methods, were accomplished. The obtained results in these simulations shows that it is possible to considerably minimize the wind power generation impacts, obtaining attributions similarly to conventional energy producers. It is observed that the proposed methods allows an operational flexibility of wind power generation, enabling a better management according to the new requirement of the power system operators.

Orientador: Dr. Alfeu J. Sguarezi Filho / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2015. / Neste trabalho apresenta-se uma configuração do sistema de armazenamento de energia com baterias aplicado a sistemas de geração de energia eólica empregando conversores de fonte Z conectados à rede elétrica. Os geradores de indução gaiola de esquilo, são frequentemente utilizados nos sistemas de geração de energia eólica, por sua robustez, simplicidade, peso menor e custo baixo. Este é conectado diretamente ao conversor de potência bidirecional back to back, pode fornecer potências ativa e reativa à rede elétrica. Além disso, é estudado o conversor de fonte Z aplicado nesta topologia. No entanto, a implantação de sistemas de armazenamento de energia com baterias nos sistemas de geração de energia eólica na atualidade é muito importante, devido à possibilidade de oscilações da tensão e corrente na rede elétrica, portanto, estes podem ajudar à estabilização das tensões, correntes e a frequência na rede elétrica. Este sistema é conectado ao conversor back to back por meio de um conversor elevador-abaixador de corrente contínua. Para controlar a velocidade no eixo do rotor no gerador de indução, a estratégia é baseada no controle direto de torque. Enquanto, para o conversor do lado da rede é empregada a técnica de controle orientado pela tensão. Para o banco de baterias é utilizado o controle da tensão no barramento de corrente contínua e do fluxo na corrente da bateria, utilizando controladores do tipo PI. Com os novos desenvolvimentos tecnológicos nas chaves de potência, são apresentadas topologias de conversores CC-CA como o conversor de fonte Z, este tipo de conversor corrige algumas limitações do conversor back to back, com as características de elevador/abaixador de tensão, sem o uso de dispositivos de comutação, são permitidos os curto-circuitos na chaves, empregando novas técnicas de modulação, e reduz a quantidade harmônica injetada na rede elétrica. Os estudos foram realizados por meio de técnicas de simulação computacional usando modelos matemáticos do sistema estudado para a validação das estratégias de controle empregadas em diferentes condições de operação. Para as simulações empregou-se a ferramenta computacional SimPowerSystems R do Matlab/Simulink R . / This paper presents a battery energy storage system applied to wind power generation based on Z-source inverter connected to the power grid. The squirrel cage induction generators, often used in wind power generation systems, for its robustness, simplicity, lower weight and low cost. This is connected directly to the bidirectional power converter back to back, therefore, and provides active and reactive powers to grid. In addition, it is studied the Z-source inverter applied in this topology. However, the implementation of battery energy storage systems in wind power generation systems, currently is very important, due to possibility of the voltage and current fluctuations in the power grid, so these may to stabilisation of current, voltage and frequency on the grid. This system is connected to back to back converter through a DC-DC converter (buck-boost). For the rotor speed control on induction generator, the strategy is based on direct torque control. While, for the grid side converter is employed the technique of voltage oriented control. For the battery bank voltage control is used on DC-link voltage and battery current flow, through PI type controllers. With the new technological developments in the keys of power, DC converters topologies are presented as the Z-source inverter, this type converter fixes some limitations of the converter back to back, with the characteristics of buck-boost voltage, without the use of switching devices, allowed short-circuits on converter, using new modulation techniques, and reduces the amount injected harmonic to power grid. The studies were performed by means of computer simulation techniques using mathematical models of studied system to validate the control strategies employed in different operating conditions. For the simulations was used the computational tool SimPowerSystems R do Matlab/Simulink R .

Made available in DSpace on 2014-12-17T14:56:15Z (GMT). No. of bitstreams: 1 DanielWH_DISSERT.pdf: 3818359 bytes, checksum: ac34198b688307ffda10243b5ad47c74 (MD5) Previous issue date: 2013-09-13 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In the last decade, the renewable energy sources have present a major propulsion in the world due to several factors: political, environmental, financial and others. Within this context, we have in particular the energy obtained through wind, wind energy - that has highlighted with rapid growth in recent years, including in Brazil, mostly in the Northeast, due to it s benefit-cost between the clean energies. In this context, we propose to compare the variable structure adaptive pole placement control (VS-APPC) with a traditional control technique proportional integral controller (PI), applied to set the control of machine side in a conversion system using a wind generator based on Double-Fed Induction Generator (DFIG). Robustness and performance tests were carried out to the uncertainties of the internal parameters of the machine and variations of speed reference. / As fontes de energia renov?veis t?m, na ?ltima d?cada, ganho uma grande propuls?o em todo o mundo devido aos mais diversos fatores: pol?ticos, ambientais, financeiros, entre outros. Dentro deste universo, temos, em especial, a energia obtida atrav?s do vento, energia e?lica - que tem se destacado com um crescimento vertiginoso nos ?ltimos anos, inclusive no Brasil, principalmente na regi?o Nordeste, devido ao seu custo-benef?cio entre as energias "limpas". Neste cen?rio, prop?e-se a compara??o do controlador por posicionamento de polos e estrutura vari?vel (VS-APPC) com o controlador proporcional integral (PI) aplicados em um sistema de convers?o de energia e?lica que utiliza um gerador de indu??o duplamente alimentado (Double-Fed Induction Generator- DFIG). Testes de robustez e desempenho foram realizados com incertezas nos par?metros da m?quina e varia??es de refer?ncia de velocidade

Attempts to reduce greenhouse gas emissions are promising with the recent dramatic increase of installed renewable energy sources (RES) capacity. Integration of large intermittent renewable resources affects smart grid systems in several significant ways, such as transient and voltage stability, existing protection scheme, and power leveling and energy balancing. To protect the grid from threats related to these issues, utilities impose rigorous technical requirements, more importantly, focusing on fault ride through requirements and active/reactive power responses following disturbances. This dissertation is aimed at developing and verifying the advanced and algorithmic methods for specification of protection schemes, reactive power capability and power control requirements for interconnection of the RESs to the smart grid systems. The first findings of this dissertation verified that the integration of large RESs become more promising from the energy-saving, and downsizing perspective by introducing a resistive superconducting fault current limiter (SFCL) as a self-healing equipment. The proposed SFCL decreased the activation of the conventional control scheme for the wind power plant (WPP), such as dc braking chopper and fast pitch angle control systems, thereby increased the reliability of the system. A static synchronous compensator (STATCOM) has been proposed to assist with the uninterrupted operation of the doubly-fed induction generators (DFIGs)-based WTs during grid disturbances. The key motivation of this study was to design a new computational intelligence technique based on a multi-objective optimization problem (MOP), for the online coordinated reactive power control between the DFIG and the STATCOM in order to improve the low voltage ride-through (LVRT) capability of the WT during the fault, and to smooth low-frequency oscillations of the active power during the recovery. Furthermore, the application of a three-phase single-stage module-integrated converter (MIC) incorporated into a grid-tied photovoltaic (PV) system was investigated in this dissertation. A new current control scheme based on multivariable PI controller, with a faster dynamic and superior axis decoupling capability compared with the conventional PI control method, was developed and experimentally evaluated for three-phase PV MIC system. Finally, a study was conducted based on the framework of stochastic game theory to enable a power system to dynamically survive concurrent severe multi-failure events, before such failures turn into a full blown cascading failure. This effort provides reliable strategies in the form of insightful guidelines on how to deploy limited budgets for protecting critical components of the smart grid systems.

The selection of the bulk power transmission technology in offshore wind farms is strongly related to the wind farm size and its distance to shore. Several alternatives can be evaluated depending on the rated power of the offshore wind farm, the transmission losses and the investment cost for constructing the transmission system. However, when is necessary to connect larger and more distant offshore wind farms; the best technological solution tends to the transmission system based on highvoltage and direct-current with line commutated converters (LCC-HVdc). This dissertation proposes the use of diode-based rectifers as a technical alternative to replace the thyristor-based rectifers in an LCC-HVdc link with unidirectional power flow. This alternative shows advantages with regard to lower conduction losses, lower installation costs and higher reliability. Nonetheless, as a counterpart the offshore ac-grid control performed by the thyristor-based HVdc rectifer is no longer available. This lack of control is compensated by using new control strategies over an offshore wind farm composed by wind turbines with permanent-magnet generators and fully-rated converters. The control strategies have been based mainly on the ability of the wind turbine grid-side converter to perform the control of the offshore ac-grid voltage and frequency. The performance has been evaluated by using PSCAD. Wherein, the most common grid disturbances have been used to demonstrate the fault-ride-through capability as well as the adequate steady state and transient response. / Rodríguez D'derlée, JJ. (2013). Control strategies for offshore wind farms based on PMSG wind turbines and HVdc connection with uncontrolled rectifier [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34510 / TESIS

Variable renewable energy (VRE) is becoming more present in the energy mix as society aims to shift power production from fossil fuels. Solar and wind power are VRE sources, which can result in fluctuations in the input to the network, creating supply uncertainty. The Swedish Transmission system operator (TSO), Svenska kraftnät (Svk), is obliged to ensure stability in the network, which must be considered when approving applications for subscriptions of connections to the transmission network. In the stability investigations performed before approving applications, Svk assumes that solar and wind power produces at their maximum capacity at their connection point before approving applications, to ensure safe and stable power system operation under any weather conditions. However, this might be an over-conservative assumption as the share of VRE sources increases. This is because there is an anti-correlation between wind and solar power, which results in a few colliding hours when both produce at full capacity. This study investigates the correlation between solar and wind power, evaluates the probability of high wind and solar power production coinciding at different percentages of their capacity, and analyses the potential for aggregating them in the studies performed to approve connections to the transmission network. The research method applied was an inductive approach, where a statistical analysis using Pearson's correlation and conditional probability was conducted based on reanalysed data collected from ERA5 and STRÅNG databases. The analysis showed a weak complementary correlation coefficient for all time periods, and the probability of very high production coinciding is small. If it occurs, it is more likely to happen during the first part of the year. The results show a spatial correlation in the probability. By implementing integration strategies, the conclusion is that there is a controllable risk when increasing the capacity. Even if there is a risk, it can be worth taking as more VRE sources can be connected to the transmission network. / Förnybar energi har blivit mer närvarande i dagens energimix när samhället strävar efter att förändra kraftproduktionen från fossilt till förnybara källor. Sol- och vindkraft är varierande förnybara energikällor vilket skapar fluktationer i inmatning till nätet samt ökad osäkerhet kring mängden tillgänglig produktion. Systemoperatören (TSO), Svenska kraftnät (Svk) är skyldig att säkerhetställa stabilitet i nätet, vilket måste beaktas vid ansökningar om anslutningar till transmissionsnätet. Denna studie undersöker därför korrelationen mellan sol- och vindkraft, samt utvärderar sannolikheten att hög sol- och vindkrafts produktion sammanfaller samtidigt. Forskningsmetoden som tillämpades var en induktiv metod, där en statistisk analys med Pearsons korrelationskoefficient såväl som sannolikheten mellan att deras produktion sammanföll samtidigt utfördes, baserat på återskapad väderdata insamlad från ERA5 och STRÅNG. Analysen visade svag komplementär korrelationskoefficient för alla tidsperioder och sannolikheten för att mycket hög produktion sammanfaller var liten. De tillfällen som produktionen sammanföll inträffade majoriteten under början av året. Genom implementering av de tillvalda strategierna är slutsatsen att det finns en kontrollerbar risk när man ökar den tillåtna anslutna kapaciteten sol- och vindkraft i transmissionsnätet. Det finns också en antikorrelation mellan sol- och vindkrafs produktion vilket resulterade i endast ett fåtal sammanfallande timmar när båda producerar på maximal kapacitet.