Resumen de Comparación de estrategias de control para sistemas MPPT: optimización de la potencia entregada a la carga vs optimización de la potencia extraída del generador fotovoltaico

Juan Adelaido Ríos Gutiérrez, Juan Manuel Enrique, Antonio Javier Barragán Piña, José Manuel Andújar Márquez

• español

  Los sistemas de seguimiento del punto de máxima potencia (MPPT) tratan de maximizar el rendimiento de una instalación fotovoltaica mediante el ajuste dinámico del ciclo de trabajo (δ) del convertidor CC/CC empleado para conectar el generador con la carga. Tradicionalmente, el algoritmo de control empleado para la definición del ciclo de trabajo determina el valor de este parámetro con objeto de maximizar la potencia generada por el generador fotovoltaico. Estas técnicas no tienen en cuenta el carácter no ideal del convertidor CC/CC, cuyo rendimiento real depende también del ciclo de trabajo (δ) con el que opera. Considerando las características del convertidor CC/CC no puede afirmarse, a priori, que el método que optimiza la generación de potencia del generador fotovoltaico maximiza también la entrega de potencia en la carga, objetivo final de un sistema MPPT. Este trabajo adapta el ampliamente extendido algoritmo "Perturbación/Observación, P&O" para optimizar la entrega de potencia en la carga, midiendo las variables que determinan el comportamiento del algoritmo a la salida del convertidor CC/CC, y compara el rendimiento obtenido con el que se obtiene con el planteamiento clásico de optimización de la potencia entregada por el generador fotovoltaico, en el que la medida de las variables que determinan el funcionamiento del algoritmo se realizan en la entrada del convertidor CC/CC. Se ha analizado un sistema fotovoltaico que emplea un convertidor boost para conectar el generador fotovoltaico (PVG) con la carga, el cual ha sido sometido a condiciones atmosféricas variables, en cuanto a radiación y temperatura, y a distintos requerimientos de consumo de carga, obteniendo los rendimientos ofrecidos por el sistema para las dos filosofías de control. Estos resultados se discuten para determinar si hay una pérdida significativa de rendimiento en el planteamiento clásico frente a la nueva propuesta y la conveniencia de desarrollar sistemas que optimicen la potencia útil, esto es, la entregada a la carga

• English

  The maximum power point tracking systems (MPPT) try to maximize the performance of a photovoltaic installation by dynamically adjusting the duty cycle (δ) of the DC/DC converter used to connect the generator to the load. Traditionally, the control algorithm used to define the duty cycle determines the value of this parameter in order to maximize the power generated by the photovoltaic generator. These techniques do not take into account the non-ideal character of the DC/DC converter, whose real efficiency also depends on the duty cycle with which it operates. Considering the characteristics of the DC/DC converter can not be said, a priori, that the method that optimizes the power generation of the photovoltaic generator also maximizes the power delivery in the load, the final objective of an MPPT system. This work adapts the well-known algorithm "Perturbation / Observation, P&O" to optimize the delivery of power in the load, measuring the variables that deterThe maximum power point tracking systems (MPPT) try to maximize the performance of a photovoltaic installation by dynamically adjusting the duty cycle (δ) of the DC/DC converter used to connect the generator to the load. Traditionally, the control algorithm used to define the duty cycle determines the value of this parameter in order to maximize the power generated by the photovoltaic generator. These techniques do not take into account the non-ideal character of the DC/DC converter, whose real efficiency also depends on the duty cycle with which it operates. Considering the characteristics of the DC/DC converter can not be said, a priori, that the method that optimizes the power generation of the photovoltaic generator also maximizes the power delivery in the load, the final objective of an MPPT system. This work adapts the well-known algorithm "Perturbation / Observation, P&O" to optimize the delivery of power in the load, measuring the variables that determine the behavior of the algorithm at the output of the DC / DC converter, and compares its performance with the performance that it is obtained with the classical approach of optimizing the power delivered by the photovoltaic generator, in which the measurement of the variables that determine the operation of the algorithm are made at the input of the DC / DC converter. A photovoltaic system that uses a boost converter to connect the photovoltaic generator with the load has been analyzed, which has been subjected to variable atmospheric conditions, in terms of radiation and temperature, and to different load consumption requirements, obtaining the performances offered by the system for the two control philosophies. These results are discussed to determine if there is a significant loss of performance in the classical approach with respect to the new proposal and the convenience of developing systems that optimize the useful power, that is, the power delivered to the loadmine the behavior of the algorithm at the output of the DC / DC converter, and compares its performance with the performance that it is obtained with the classical approach of optimizing the power delivered by the photovoltaic generator, in which the measurement of the variables that determine the operation of the algorithm are made at the input of the DC / DC converter. A photovoltaic system that uses a boost converter to connect the photovoltaic generator with the load has been analyzed, which has been subjected to variable atmospheric conditions, in terms of radiation and temperature, and to different load consumption requirements, obtaining the performances offered by the system for the two control philosophies. These results are discussed to determine if there is a significant loss of performance in the classical approach with respect to the new proposal and the convenience of developing systems that optimize the useful power, that is, the power delivered to the load