http://hdl.handle.net/10498/6764 2026-05-09T21:26:29Z 2026-05-09T21:26:29Z Alnawafah, Hamza http://hdl.handle.net/10498/33029 2024-07-25T09:21:46Z 2024-04-10T00:00:00Z

Modeling and integration of smart control strategies to improve large-scale pv system management and operation in a low inertia power grid Alnawafah, Hamza In the context of international endeavors to address climate change, there is a discernible transition occurring from the utilization of fossil fuels to the adoption of cleaner and sustainable sources of energy. The aforementioned transformation has resulted in a growing appeal and improved financial feasibility of renewable energy initiatives. These sources have a substantial impact on the reduction of CO2 emissions and the improvement of energy supply security. Nevertheless, the integration of renewable energy sources into transmission and distribution power networks also brings about a certain level of unpredictability and uncertainty. Effectively aligning real-time energy generation with customer demand faces complexity due to the need for affordable energy storage. Distributed generation helps mitigate transmission losses but introduces operational complexity. Growing electricity demand from electric transport and heating poses challenges for conventional power stations and infrastructure. Integrating renewable energy sources (RESs) offers substantial potential for reducing carbon emissions, combatting air pollution, addressing climate change, and improving overall quality of life. Traditional synchronous generators maintain power balance through kinetic energy, absent in RESs due to electromagnetic decoupling. RESs require specific control strategies for frequency regulation, given their intermittent nature and unique dynamics. Control complexities heighten when system inertia decreases due to the absence of synchronous generators connected to the grid. System inertia is pivotal for power system stability during sudden imbalances in active power. Thus, reducing system inertia is a significant concern for ensuring frequency stability. Integrating RESs also introduces technical hurdles, including heightened uncertainty, limited fault tolerance, increased fault currents, lower generation reserves, and compromised power quality. To address these challenges, advanced technologies, including control strategies, optimization, energy storage, and fault current limiters, have been developed. Employing these innovative methodologies is crucial for successful RES integration into power systems, while navigating inherent technological complexities. This thesis revolves around a pivotal moment in the energy landscape of a Middle Eastern country, driven by factors like increased energy demand, growing environmental awareness, and government support for renewables. Large-scale photovoltaic (PV) projects are now highly attractive, capable of generating hundreds of megawatts within a single grid area. However, integrating these projects into the power grid of this nation presents substantial challenges that this research seeks to address. To ensure a seamless and improved integration of large-scale PV systems, this study employs a multifaceted approach. It begins with the creation of a comprehensive computer model meticulously representing the power grid of this Middle Eastern country. Real-world data is then used to validate this model, enhancing our understanding of the grid's behavior and any disparities between the model and the actual system. Moreover, the research focuses on quantifying the system's inertia, a crucial parameter for grid stability and disturbance response, especially with the increasing presence of PV generation. By analyzing the system's dynamic response, this objective aims to identify the system's inertia level and its implications for PV integration, ensuring secure power grid operation. In addition, the study delves into the impacts of high PV penetration on the electricity grid of this nation, considering factors like variable output, intermittency, and integration challenges. It seeks to pinpoint issues related to energy balance and grid stability and proposes strategies for reliable and secure grid operation under high PV penetration scenarios. Enhancing grid stability further involves encouraging large-scale PV systems to actively participate in providing inertial response. Investigating various control strategies and operational techniques to achieve this goal aims to make the power system more robust and resilient. Lastly, the study identifies and implements control strategies to optimize PV system integration, including voltage regulation, power flow management, and frequency control. These strategies aim to improve integration, ensuring reliable operation and adherence to grid stability and power quality standards. The hypotheses guiding this thesis encompass a range of critical questions, including the optimization of PV systems for grid stability and the improvement of grid control algorithms to enhance PV system penetration. The evaluation of different PV system configurations and their impact on grid stability and power quality is also addressed. In summary, this research, grounded in empirical data and rigorous modeling, aims to comprehensively address these hypotheses. Ultimately, it seeks to provide valuable insights that support the successful integration of large-scale PV systems into Jordan's power grid, contributing to the nation's sustainable and resilient energy generation journey.

2024-04-10T00:00:00Z Hosseini, Ehsan http://hdl.handle.net/10498/31675 2024-04-10T09:22:47Z 2023-09-14T00:00:00Z

Intelligent control of hybrid power plants with wind turbines, pv solar systems, and energy storage systems Hosseini, Ehsan El concepto de sistemas de energía de múltiples fuentes, como por ejemplo en microrredes basadas en fuentes de energía renovable (RES), almacenamiento y conexión a la red, tiene como objetivo participar activamente en el equilibrio de la producción y el consumo de electricidad. Esta tesis estudia los desafíos de la integración de RES respaldados por sistemas de almacenamiento de energía (ESS) a la red principal en un sistema de energía de gran escala, además de considerar la eficiencia de ESS y los posibles problemas a largo plazo. Aerogeneradores (WT) y sistemas solares fotovoltaicos (PV) son fuentes de energía accesibles y dos de los sistemas de energía renovable de más rápido crecimiento que juegan un papel vital en las microrredes eléctricas. Esta creciente penetración de las energías renovables en la generación de energía implica una conexión precisa entre la red principal, las cargas potenciales y los recursos de energía. En este contexto, los convertidores electrónicos de potencia y las técnicas avanzadas de control son aspectos relevantes que han motivado a los investigadores a desarrollarlos. El convertidor es un componente crucial para la conexión de una fuente de energía a la red o a la carga local. En cuanto a la conexión a la red, la mayoría de los estudios se han centrado en los inversores para proponer nuevas topologías y estructuras de control. Los inversores basados en fuente de impedancia, también llamados inversor de fuente Z (ZSI), han captado el interés de los investigadores en los últimos años. Estos inversores pueden reducir o elevar la tensión, realizar la conversión en una sola etapa e integrar un ESS sin un convertidor adicional como característica principal. Muchas modificaciones estructurales se han desarrollado para mejorar su estructura. Uno de ellos es el cuasi-ZSI (qZSI), que tiene varias ventajas sobre la topología ZSI básica. Debido a las interesantes características que los hacen adecuados para aplicaciones con RES, el qZSI ha sido seleccionado en esta tesis para integrar plantas híbridas con energía eólica y PV a la red principal. En aplicaciones de sistemas de energía a gran escala, un solo inversor no puede satisfacer la potencia requerida; por lo tanto, se pueden necesitar varios inversores para construir un inversor multinivel de puente H en cascada (CHBMLI). El concepto ZS/qZS, integrado con inversores multinivel, hereda los méritos del CHBMLI con una mayor fiabilidad del inversor gracias a la inmunidad a los cortocircuitos. Cuando se aplica a sistemas de energía a escala de MW, qZS-CHBMLI se puede escalar fácilmente agregando más módulos en cascada. El sistema de gestión de energía (EMS) es otro tema importante que debe abordarse mediante el uso de un esquema de control adecuado. Un esquema de control apropiado debe generar las señales de control relevantes para extraer la potencia demandada de las fuentes de entrada de forma individual o simultánea mientras se mantiene la tensión o corriente de salida regulada. Desde una perspectiva amplia, el estudio del EMS para RES es importante para lograr una operación eficiente de los sistemas de generación de energía respaldados por ESS y la conversión de energía con cargas locales o red, y satisfacer los requisitos de calidad de la energía. Esta tesis propone EMS inteligentes innovadores para lograr el correcto funcionamiento de un EMS estructural basado en la eficiencia de ESS y problemas a largo plazo para plantas híbridas con WT, PV, ESS y qZS-CHBMLI. Se propone una función multivariable no lineal restringida para aumentar la eficiencia de los almacenamientos de energía de la batería (BES) utilizados en una planta híbrida y conectada a una red a través de qZS-CHBMLI. Se utilizan algoritmos inteligentes para resolver la función objetivo propuesta. La función Fmincon de MATLAB y el algoritmo de aprendizaje por refuerzo (RL), que aprovecha una función de recompensa no lineal, son los algoritmos de resolución usados para el problema de optimización propuesta. Además, un nuevo EMS basado en lógica difusa ha sido implementado. Este tema merece un mayor esfuerzo de investigación, ya que no hay estudios publicados que hayan abordado el estudio de BES-qZS-CHBMLI con plantas híbridas que integran WT y PV, combinando RL y nuevas estrategias de control basadas en la eficiencia de las BES. En cuanto a la topología del sistema, pocos estudios han abordado la dinámica de la microrred AC con plantas híbridas, BESS y un optimizador-EMS conectado a la red. En la mayoría de los estudios, se ha utilizado un convertidor CC/CC para implementar la estrategia MPPT para fuentes de energía PV y WT, y habitualmente se utilizó un inversor de fuente de tensión (VSI) para la conversión CC/CA. La topología propuesta aquí se basa en ES-qZS-CHBMLI, sin convertidor CC/CC adicional. Además, todos los estudios previos publicados han utilizado una configuración de planta basada en un BES-qZS-CHBMLI integrando los mismos sistemas PV y BES en cada módulo en serie e integrando sistemas PV o WT con diferente potencia nominal en cada módulo. Finalmente, la evaluación del funcionamiento de la red en términos de potencias activas y reactivas desde el punto de vista del operador de red no han sido considerado en estos estudios previos. Con respecto al EMS, los trabajos previos han implementado un EMS basado en distribuir la potencia entre los BES según su estado de carga (SOC), donde se ha pasado por alto la eficiencia de los BES porque el EMS se centró solo en los valores del SOC y la potencia demandada. Esta investigación ha desarrollado nuevas soluciones para mejorar el control y operación de las plantas eléctricas híbridas con sistemas WT, PV y EES mediante el uso de inversores más eficientes y estrategias de control basadas en algoritmos de control inteligente.

2023-09-14T00:00:00Z De Oliveira-Assis, Lais http://hdl.handle.net/10498/28885 2023-06-21T00:33:07Z 2022-01-01T00:00:00Z

New and improved solutions for the configuration, management and operation of large-scale photovoltaic power plants using hybrid energy storage system De Oliveira-Assis, Lais This thesis is presented in the context of multiple efforts being made by research groups in order to disseminate and evolve the technological knowledge in the renewable energy (RE) field. The motivation of this study is based on the main disadvantages of photovoltaic (PV) solar power generation compared to conventional energy sources, such as intermittency, non-dispatchability, and unreliability. From those drawbacks, the aim is to find creative solutions to mitigate these issues with a power plant combining PV and hybrid energy storage systems (HESS). In doing so, hybrid power plants represent a very interesting option for power generation and grid integration of PV systems, since they allow increased efficiency in the energy generation, as well as storing and supporting RE generation when needed.The storage systems are particularly important to deal with the intermittent nature of solar radiation. A wide variety of storage systems exists nowadays, all of them based on different operating principles and target applications. A thorough review of the literature has exposed that, depending on the application, a certain type of storage could be preferred above others. Besides, two or more different technologies working together can present complementary features. In this sense, the HESS can accomplish higher efficiencies and improved systems for grid connection. The objective is to develop new solutions to improve the configuration, management, and operation of PV plants with energy storage, designing the necessary control techniques and validating them through real-time simulations. In this context, this thesis presents a large-scale PV power plant with HESS, through a DC/DC impedance source converter (DC/DC-ZSC), and a new simplified model (SM) of the quasi Z-source inverter with battery energy storage (qZSI-BES) attached directly to the Z-network without an extra DC/DC converter. The HESS consists of battery arrays (BES) and ultracapacitors (UC). The newly designed SM is implemented, assessed, and validated experimentally in laboratory through a TYPHOON HIL system and a dSPACE MicroLabBox control board. Three different energy management strategies are implemented, using two of them advanced control techniques based on fuzzy logic. The control loops of the active, reactive, BES, and UC power have been conveniently deployed. The results obtained are coherent with the expected responses, observing an appropriate power balance and grid energy dispatch. This thesis aims for a relevant contribution in the development of low polluting energy sources that can fulfill the growing electricity demand. Following the global trends, and recognizing the importance of this knowledge for the scientific community and for society, this thesis will provide new solutions in the field of solar PV generation. In view of the fact that research has mainly focused on small-scale hybrid power plants so far, further studies are required regarding the configuration, design, control, energy management, operation, and problems associated with large PV power plants with hybrid storage.

2022-01-01T00:00:00Z Pereira Soares Ramos, Emanuel Philipe http://hdl.handle.net/10498/28884 2023-06-21T00:33:05Z 2022-01-01T00:00:00Z

Offshore hybrid power plants with wind energy, photovoltaic and energy storage Pereira Soares Ramos, Emanuel Philipe Large centralized conventional power plants, although robust and reliable, have numerous disadvantages. The use of distributed generation has increased to fulfill the growing energy demand, and to reduce the distance between generation and consumption. Consequently, hybrid energy systems that combine several renewable energy sources are flowering, mainly in grid-connected configurations. The presence of this distributed generation in the electric grid changes its control and operation significantly. Therefore, special attention should be paid to the study of hybrid systems composed of wind turbines (WTs) and photovoltaic solar panels, due to their intermittent and fluctuation characteristics. Currently, a means of improving the connection of such systems to the electricity grid is to combine different energy sources with energy storage systems. Due to the development of storage technologies, they can be used in numerous applications, such as frequency regulation, system stabilization, reduction of transmission losses, increased reliability, load regulation or support for grid services, among others.The hybrid power generation systems used to date are mostly small-scale, with a rated power of tens or hundreds of kW. Another relevant aspect is that most hybrid power systems are located onshore. Nevertheless, a considerable growth of large-scale offshore wind farms is noticeable currently in Europe, mainly due to advances in WTs and foundation structures, which have improved their economic conditions and contributed to the implementation of offshore plants. It is expected that the installed capacity will continue to increase, since the European Union aims at reaching about 100 GW of offshore wind capacity by 2030. In this thesis, a detailed study evidencing this growth has been carried out. The most significant characteristics of 57 plants installed in Europe with a rated power above 150 MW and fully commissioned until 2019, as well as 11 plants authorized or under construction, are studied in detail, drawing relevant conclusions from the data collected. The results show the trends on WT size and capacity, turbine model, distance to shore, water depth, investment cost, type of foundation, transmission technology, and voltage array systems among others. This thesis gathers the latest information about the topic, deducing future trends from the evaluation of offshore wind farms fully commissioned, authorized or under construction.Furthermore, this thesis evaluates the performance of a hybrid power plant consisting of a WT, a solar photovoltaic (PV) power plant, and an energy storage system that share the same grid connection point. This hybrid power plant has a rated power in the range of several MW. Typically, permanent magnet synchronous generator-based WTs present a two-stage power converter topology based on a DC/DC boost converter and voltage source inverter. In the thesis, this configuration is substituted by a quasi-Z-source inverter, which is an attractive solution for boosting and converting the voltage from DC to AC in a single stage. A switched dynamic model of the quasi-Z-source inverter (including the modelling of all switches and firing pulses) is not recommended for steady-state stability studies, long-term simulations, or large electric power systems. For such studies, two averaged dynamic models are proposed in this thesis. Both models present the same control system as the switched dynamic model, except for the generation of the firing pulses, which is not necessary in the averaged models. The two models proposed are evaluated and compared with the switched dynamic model. Both proposed averaged models can substitute the switched dynamic model with satisfactory accuracy in terms of time-domain response in steady-state stability studies. In addition, two voltage sources emulating the terminals of C1 and C2 are added to enable the integration of PV and BES, respectively. The grid-connected hybrid power plant under study consists of a 1.5 MW WT, a 402 kW PV generator connected to the capacitor C2, and a 532 kW lithium-ion battery connected to capacitor C1, making a total 2.44 MW for the rated power of the hybrid plant. Moreover, a load of 1.2 MVA shares a common connection point with the hybrid power plant.After choosing the most suitable configuration for the connection of the WT, the photovoltaic power plant, and the energy storage system; a second objective of the thesis is the development of control strategies for the energy sources and their converters. Different control strategies are implemented and evaluated to regulate active and reactive power, and voltage levels. Finally, a third objective is the design of a supervisory control system for the hybrid power plant. This system must be able to manage and coordinate the energy flow between the devices in the hybrid system. For this purpose, some of the variables considered by the supervisory control system are the generation set point established by the grid operator, the instantaneous production of WTs and the photovoltaic panels, and the state of charge of the battery. Different control strategies have been developed for a proper energy management, and an adequate regulation of the electric parameters of the hybrid plant internally and at the point of connection to grid. Using widely recognized models for the components of the hybrid power plant, it has been possible to represent the behaviour of the system and to evaluate the original designs of this thesis through simulation under different operating conditions (changes in wind speed, solar radiation, or electricity generation of the grid, etc.). The simulation results have shown the adequate performance of the hybrid power plant through the control strategies implemented, which coordinate the renewable energy sources, the battery and the load using impedance source converters.

2022-01-01T00:00:00Z