Control and optimization strategies to maximize the energy generated by photovoltaic sources

This thesis presents control and optimization techniques to improve the energy generated by Photovoltaic (PV) power systems. The first part of this work presents an analysis of the Perturb and Observe MPPT algorithm, providing integral procedures to design the perturbation period and amplitude size parameters. The first method presented is aimed at design the amplitude size from a maximum PV power losses restriction, while the perturbation period is designed to track a dynamic irradiance profile with the correct three-point behavior to guarantee the system stability. Subsequently, a second method to precisely design the perturbation period of a Perturb and Observe MPPT algorithm is also proposed. Such a procedure is designed to calculate the perturbation period in agreement with the settling time of the PV voltage for any condition of the damping ratio. Similarly, this thesis proposes an optimization strategy to maximize the energy generated by the PV system through a non-linear control of the DC/DC converter. Such an optimization process is carried out using the Sliding Mode Control (SMC) theory to drive the PV voltage to follow an external reference provided by an MPPT algorithm avoiding the linearization of the PV system model, which is a classical solution used in the literature, to ensure the same performance in all the PV operation range. The first control structure proposed in this thesis is aimed to design an integral procedure to ensure a stable sliding regime in all the desired operation range of the system. This design procedure exhibits advantages in comparison with existing solutions that rely in the linearization of inner current loop dynamics. The second design method provides a single solution that involves both the MPPT algorithm and DC/DC converter controller. This integral design of both control systems allows to optimize the parameters values of both controllers. The SMC-based solutions are mathematically analyzed to mitigate the perturbations caused by the irradiance changes and oscillations in the load connected to the DC/DC converter, e.g. a grid-connected inverter. Finally, this thesis also analyses the negative effects caused by the mismatching phenomena at the PV array, mainly the power drop. Hence, an optimization process for the modules connections is proposed in order to mitigate the mismatching effects. That process is based on reconfiguration algorithms that change the electrical connection between the modules to maximize the PV array power. Those techniques are compared with the classical exhaustive search approach, demonstrating the advantages of the new solution by means of circuital simulations

• Autores: González Montoya, Daniel
• Tipo de recurso: Doctoral thesis
• Fecha de publicación: 2017
• Institución: Universidad Nacional de Colombia
• Repositorio: Universidad Nacional de Colombia
• Idioma: spa
• OAI Identifier: oai:repositorio.unal.edu.co:unal/59434
• Acceso en línea: https://repositorio.unal.edu.co/handle/unal/59434; http://bdigital.unal.edu.co/56931/
• Palabra clave: 62 Ingeniería y operaciones afines / Engineering; Photovoltaic systems; Grid connection; Maximum power point tracking; Sliding mode control; Genetic algorithms; Sistemas fotovoltaicos; Conexión a la red; Seguimiento del punto de Máxima potencia; Control por modos deslizantes; Algoritmos genéticos
• Rights: openAccess
• License: Atribución-NoComercial 4.0 Internacional