Maximum Wind Power Tracking of Doubly Fed Wind Turbine System Based on Adaptive Gain Second-Order Sliding Mode

This paper proposes an adaptive gain second-order sliding mode control strategy to track optimal electromagnetic torque and regulate reactive power of doubly fed wind turbine system. Firstly, wind turbine aerodynamic characteristics and doubly fed induction generator (DFIG) modeling are presented. Then, electromagnetic torque error and reactive power error are chosen as sliding variables, and fixed gain super-twisting sliding mode control scheme is designed. Considering that uncertainty upper bound is unknown and is hard to be estimated in actual doubly fed wind turbine system, a gain scheduled law is proposed to compel control parameters variation according to uncertainty upper bound real-time. Adaptive gain second-order sliding mode rotor voltage control method is constructed in detail and finite time stability of doubly fed wind turbine control system is strictly proved. The superiority and robustness of the proposed control scheme are finally evaluated on a 1.5 MW DFIG wind turbine system

Wind Power Frequency Control in Doubly FED Induction Generator Using CFMPC-FOPID Controller Scheme

Because the majority of wind turbines operate in maximum output power tracking mode, power system frequency cannot be supported. However, if the penetration rate of wind power increases, the system inertia related to frequency modulation may decrease. In addition, frequency stability will be severely affected in the event of significant disturbances to the system load. Due to the high penetration of wind power in isolated power systems, this study suggests a coordinated frequency management approach for emergency frequency regulation. In order to prevent the phenomenon of load frequency control in doubly fed induction generators (DFIGs), a unique efficient control scheme is developed. The Cascaded Fractional Model Predictive Controller coupled with Fractional-Order PID controller (CFMPC-FOPID) is developed to provide the DFIG system with an efficient reaction to changes in load and system parameters. The proposed controller must have a robust tendency to respond quickly in terms of minimum settling time, undershoot, and overshoot. Nonlinear feedback controllers are designed using frequency deviations and power imbalances to achieve the reserve power distribution between generators and DFIGs in a variety of wind speed conditions. It makes upgrading quick and easy. In Matlab/Simulink, a simulation model is built to test the viability of the suggested approach

A dual-statorwinding induction generator based wind-turbine controlled via super-twisting sliding mode

The dual-stator winding induction generator (DWIG) is a promising electrical machine for wind energy conversion systems, especially in the low/mid power range. Based on previous successful results utilising feed forward control, in this article, a super-twisting (ST) sliding mode improved control set-up is developed to maximise power extraction during low wind regimes. To accomplish this objective, via constant volts/hertz implementation, a ST controller was designed to command the DWIG control winding, such that the tip-speed ratio is robustly maintained at its optimal value. The proposed super-twisting control set-up was experimentally assessed to analyse its performance and to verify its efficiency in an actual generation test bench. The results showed a fast convergence to maximum power operation, avoiding chattering and offsets due to model uncertainties.Fil: Talpone, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; Argentina. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Puleston, Pablo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Cendoya, Marcelo Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Barrado Rodrigo, José Antonio. Universitat Rovira I Virgili; Españ

New contributions to frequency control based on virtual synchronous generators: application to power systems with high renewable energy sources integration

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. Tradicionalmente, servicios como la regulación y mantenimiento de la frecuencia de los sistemas eléctricos, cobertura de la demanda eléctrica o la existencia de las reservas rodantes (spinning reserves) han sido suministrados y asegurados por las fuentes de generación de energía eléctrica tradicionales. Sin embargo, los sistemas eléctricos han sufrido una serie de cambios en los últimos años que están afectando de manera directa al propio funcionamiento de los mismos. Por un lado, el aumento constante del consumo de energía y de la intensidad del propio uso energético, unido al aumento de las restricciones legislativas medioambientales, y por otro el concepto de la energía eléctrica como un producto comercial junto con la liberalización de los mercados energéticos, hacen que se tambaleen algunas de las premisas hasta ahora asumidas. En este sentido, y en un entorno de promoción de recursos renovables, hace que los servicios hasta ahora proporcionados sólo por la generación clásica deben también ser compartidos por todos los puntos de generación. No obstante, la alta penetración de este tipo de fuentes renovables en el sector eléctrico acarrea una seria de cuestiones derivadas de sus características y peculiaridades que es necesario abordar antes de proceder de manera masiva a su integración y, por tanto, a la independencia de la generación convencional. Adicionalmente, y debido a la naturaleza variable de la generación renovable (principalmente el viento y el sol) recobra mayor importancia el asegurar por parte de los organismos reguladores una reserva energética que permita actuar de manera eficiente y fiel en casos de desequilibrio de potencias. En este nuevo escenario, en el que el director de tesis ha trabajado a lo largo de la última década, se hace necesario contar con el desarrollo y adaptación de nuevas herramientas y soluciones que faciliten la integración de fuentes renovables sin que ello suponga una merma en las capacidades del sistema eléctrico en términos de estabilidad y de respuesta ante contingencias. Así pues, el objetivo principal de esta tesis consiste en el estudio, implementación y evaluación de sistemas eléctricos con alta penetración de recurso eólico y fotovoltaico con el fin de evaluar posibles soluciones para emular inercias virtuales y respuestas similares a las que se obtendrían con generación clásica, integrando así de manera efectiva el recurso renovable al control de la frecuencia del sistema eléctrico. En este escenario, resultaría crucial poder aliviar en parte las necesidades de almacenamiento de energía a los puntos de generación mediante la implementación de estrategias alternativas de control de respuesta ante excursiones de frecuencia en las unidades renovables, aportando éstas el apoyo necesario para mantener la frecuencia de red dentro de los límites establecidos. Por tanto, la solución aquí estudiada favorecería la integración masiva de recursos renovables, dentro de un escenario de estabilidad del sistema eléctrico apoyado por estas instalaciones, y donde la eliminación paulatina de elementos rotativos directamente conectados a la red debe sustituirse y/o emularse de manera que el sistema eléctrico ofrezca la misma fiabilidad que se percibe ante la presencia de generación convencional. Sólo así se conseguirá fomentar de manera argumentada las posibilidades tangibles de integración a gran escala de recursos renovables, adelantándonos a las necesidades que surgirán de manera inevitable como consecuencia de la disminución inicial de inercia del sistema (entendida de una manera clásica como elementos rotativos directamente conectados a red) y como consecuencia de la entrada de fuentes que poseen una variabilidad en sus niveles de generación. Destacar igualmente la importancia cada vez mayor del control de la frecuencia del sistema eléctrico, debido a la sensibilidad y dependencia que poseen de este parámetro la mayoría de las cargas y equipos con algún tipo de etapa de electrónica de potencia.[ENG] This doctoral dissertation has been presented in the form of thesis by publication. Over the last decades, most countries have been suffering an electrical energy transition, changing from a model based on non-renewable sources (mainly based on fossil fuels), to a new framework characterised by the integration of renewable energy resources (RES). These important changes have been mainly supported by the development of power electronics, environmental protection policies, and the need to reduce energy dependence on third countries. Moreover, the electrical sector stands out because of the diversity and heterogeneity of sources that can generate electricity. As a result, the current electrical scenario includes a high interest in the integration of variable renewable energy sources (vRES) shifting towards a new generation mix. In fact, these vRES (mainly photovoltaic and wind power installations) already play a relevant role, as some European countries have experienced generation levels over 50% during some time-periods of last years. As aforementioned, the two most mature renewable resources integrated into power systems are solar photovoltaic (PV) and wind power (especially variable speed wind turbines, VSWTs). Together with the integration of these two sources, and in contrast to traditional grids based on conventional power plants (i.e., hydro-power, thermal, and nuclear power plants), several important issues have emerged, needing to be analysed, assessed, and resolved.Los artículos que constituyen la tesis son los siguientes: 1. Fernández-Guillamón, Ana & Gómez-Lázaro, Emilio & Muljadi, Eduard & Molina-García, Ángel, 2019. "Power systems with high renewable energy sources: A review of inertia and frequency control strategies over time," Renewable and Sustainable Energy Reviews, Elsevier, vol. 115(C). 2. Ana Fernández-Guillamón & Jorge Villena-Lapaz & Antonio Vigueras-Rodríguez & Tania García-Sánchez & Ángel Molina-García, 2018. "An Adaptive Frequency Strategy for Variable Speed Wind Turbines: Application to High Wind Integration Into Power Systems,"Energies, MDPI, Open Access Journal, vol. 11(6), pages 1-21, June. 3. Fernández-Guillamón, A.; Vigueras-Rodríguez, A.; Gómez-Lázaro, E.; Molina-García, Á. Fast Power Reserve Emulation Strategy for VSWT Supporting Frequency Control in Multi-Area Power Systems. Energies 2018, 11, 2775. https://doi.org/10.3390/en11102775. 4. Fernández-Guillamón, Ana & Sarasúa, José & Chazarra, Manuel & Vigueras-Rodríguez, Antonio & Fernández-Muñoz, Daniel & Molina-Garcia, Ángel. (2020). Frequency control analysis based on unit commitment schemes with high wind power integration: A Spanish isolated power system case study. International Journal of Electrical Power & Energy Systems. 121. 106044. 10.1016/j.ijepes.2020.106044. 5. Fernández‐Guillamón, A., Vigueras‐Rodríguez, A. and Molina‐García, Á. (2019), Analysis of power system inertia estimation in high wind power plant integration scenarios. IET Renewable Power Generation, 13: 2807-2816. https://doi.org/10.1049/iet-rpg.2019.0220. 6. Fernández Guillamón, Ana; Martínez de Lucas, Guillermo; Molina García, Ángel y Sarasúa Moreno, José Ignacio (2020). An Adaptive Control Scheme for Variable Speed Wind Turbines Providing Frequency Regulation in Isolated Power Systems with Thermal Generation."Energies", v. 13 (n. 13); p. 3369. ISSN 1996-1073. https://doi.org/10.3390/en13133369. 7. Fernández-Guillamón, A.; Martínez-Lucas, G.; Molina-García, Á.; Sarasua, J.-I. Hybrid Wind–PV Frequency Control Strategy under Variable Weather Conditions in Isolated Power Systems. Sustainability 2020, 12, 7750. https://doi.org/10.3390/su12187750. 8. Fernández-Guillamón, Ana & Gomez-Lazaro, Emilio & Molina-Garcia, Ángel. (2020). Extensive frequency response and inertia analysis under high renewable energy source integration scenarios: application to the European interconnected power system.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma de Doctorado en Energías Renovables y Eficiencia Energétic

Development of a robust nonlinear pitch angle controller for a redesigned 5MW wind turbine blade tip

Power in wind turbines are traditionally controlled by varying the pitch angle at high wind speeds in region 3 of the wind turbine operation. The pitch angles controllers are normally driven by electrical or hydraulic actuators. The motivation of this research is to design and implement a pitch angle control strategy at the outer section of the blade via a separated pitch control at blade tip (SePCaT). A pneumatic actuator is implemented to drive the pitch angle control mechanism by incorporating pneumatic actuated muscles (PAM) due to its high power/mass ratio, high specific work, and good contraction ratio while maintaining low weight at the tip of the blade. A sliding mode controller (SMC) is modeled and implemented on a redesigned 5MW wind turbine numerically. The hypothesis is that the SePCaT control strategy is effective and satisfactory pitch angle trajectory tracking is achievable. The method is adopted, the system is modeled, and the response was observed by subjecting the model dynamics to desired pitch angle trajectories. Initially comparative controller response with respect to desired trajectory revealed satisfactory pitch angle tracking but further investigation revealed chattering characteristics which was minimized by incorporating a saturation function. SePCaT offers an effective pitch angle control strategy which is smaller, lighter, reliable and efficient

A Dual-Stator Winding Induction Generator Based Wind-Turbine Controlled via Super-Twisting Sliding Mode

The dual-stator winding induction generator (DWIG) is a promising electrical machine for wind energy conversion systems, especially in the low/mid power range. Based on previous successful results utilising feed forward control, in this article, a super-twisting (ST) sliding mode improved control set-up is developed to maximise power extraction during low wind regimes. To accomplish this objective, via constant volts/hertz implementation, a ST controller was designed to command the DWIG control winding, such that the tip-speed ratio is robustly maintained at its optimal value. The proposed super-twisting control set-up was experimentally assessed to analyse its performance and to verify its efficiency in an actual generation test bench. The results showed a fast convergence to maximum power operation, avoiding chattering and offsets due to model uncertainties.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Control and Optimization of Variable-Speed Wind Turbines and Large-Scale Wind Farms

Motivated by the vast potential of wind power as a renewable energy source and the reliability issues arising from its integration into a power system, this dissertation designs and analyzes a novel, diverse collection of controllers, which significantly enhance the capability and performance of variable-speed wind turbines and large-scale wind farms.In the dissertation, we consider a number of key problems and pressing issues in the area and develop, for each of them, a solution based on systems and control theory as well as optimization methods. More specifically, we first devise a nonlinear controller using feedback linearization and a gradient-based approach, which enables wind turbines with doubly fed induction generators to jointly control their active and reactive powers in both the maximum power tracking and power regulation modes. We also extend the controller by incorporating bias estimation and exploiting timescale separation, so that it can cope with turbines with uncertainties, and evaluate our controller via simulations with realistic wind profiles, demonstrating its effectiveness.Building upon single turbine controllers by other researchers and by us, we next turn to the emerging problem of wind farm power control, in which there is a lack of models that appropriately simplify the complex overall wind farm dynamics. To fill this void, we use system identification approaches to construct a structurally simple, approximate wind turbine control system (WTCS) model, which attempts to mimic the complex active and reactive power dynamics of generic analytical and empirical WTCS models. Through extensive validation, we show that the approximate model is accurate and versatile, capable of closely imitating several WTCS models from the literature and from real data.Based on the approximate model, we subsequently develop a centralized wind farm controller, which makes the wind farm power output accurately and smoothly track a desired reference from the power grid operator. The wind farm controller is made up of a model predictive controller on the outer loop, which uses various forecasts and feedbacks to iteratively plan the desired power trajectories for optimal tracking, and an adaptive controller on the inner loop, which uses estimated wind speed characteristics to adaptively tune the controller gains for optimal smoothness. We also carry out a series of simulations, which illustrate the salient features of our wind farm controller.Finally, we study how a wind turbine equipped with a maximum power tracking controller and a proportional inertia response controller may affect the power system frequency from a control standpoint, including the resulting system equilibria, pole-zero locations, and stability properties