Parque solar con conexión AC serie de unidades generadoras para maximizar la generación de potencia en condiciones de falla.
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Date
2024
Authors
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Journal ISSN
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Publisher
Universidad de Concepción
Abstract
La aplicación de energía fotovoltaica como forma de alimentación es cada día más utilizado en la industria al ser energía renovable y de naturaleza no contaminante. Su uso va en aumento principalmente por la reducción del valor de los equipos y de los costos de instalación que han experimentado estos últimos años. Al ser modelados como fuentes de corriente directa (DC), es necesario el uso de inversores para las cargas comunes como lo son cargas RL o la propia red eléctrica. Si se desea mejorar la calidad de señal, es posible aumentar la cantidad de inversores, reduciendo el contenido armónico y aumentando su resolución al existir más niveles de voltaje alcanzables. Existen varias topologías de inversor multinivel (MLI) en el mercado, una de las más usadas es el topología multinivel con celdas H conectadas en cascada (CHB). Una de sus ventajas es el costo menor en comparación a otras topologías, como también la flexibilidad para incrementar el número de niveles. Esto igual trae consigo contras, como que el modelado se vuelve mucho más complejo y que el sistema es más susceptible a fallas al haber mayor cantidad de elementos. Por esto, siempre se está en la búsqueda de optimizarlos en el ámbito de las fallas, ya que estas pueden degradar el comportamiento de motores o, incluso, producir el paro total del sistema. Uno de los mayores problemas al fallar una celda es la disminución de la potencia a la salida, junto a un desbalance de voltaje en la carga. Para suplir ese desbalance, la solución actual es eliminar las dos celdas restantes de esa pierna, produciendo otra disminución aún mayor de la potencia total. El presente trabajo muestra dos soluciones algorítmicas al problema de compensar la potencia perdida. Se basan en aumentar el número de paneles por celda necesarios inicialmente, para así, ante una falla, modificar la moduladora de una u otra manera, manteniendo la condición de operación. El primer algoritmo modifica la moduladora de la fase con falla en amplitud, mientras que el segundo modifica las moduladoras de fases sin fallas en amplitud y fase. El esquema propuesto se verifica mediante simulación en el software PLECS, utilizando distinto número de celdas para la comparación entre algoritmos, como también distinta cantidad de fallas. Los resultados muestran un menor número de paneles solares necesarios para suplir fallas en el algoritmo 2, llegando incluso a no necesitar más paneles que los mínimos requeridos para trabajar a condición normal de operación, como también un mejor aprovechamiento de los recursos cuando se aumenta el número de celdas por fase.
The application of photovoltaic energy as a form of power is increasingly used in industry as it is renewable energy and non-polluting in nature. Its use is increasing mainly due to the reduction in the value of the equipment and installation costs that have been experienced in recent years. As they are modeled as DC sources, it is necessary to use inverters for common loads such as RL loads or the power grid itself. If it is desired to improve the signal quality, it is possible to increase the number of inverters, reducing the harmonic content and increasing its resolution as there are more achievable voltage levels. There are several MLI topologies in the market, one of the most used is the CHB. One of its advantages is the lower cost compared to other topologies, as well as the flexibility to increase the number of levels. This also brings disadvantages, such as that the modeling becomes much more complex and the system is more susceptible to failures due to the greater number of elements. For this reason, we are always looking to optimize them in terms of failures, since these can degrade the behavior of motors or even cause the total shutdown of the system. One of the biggest problems when a cell fails is the decrease in power output, along with a voltage unbalance in the load. To make up for that imbalance, the current solution is to remove the two remaining cells from that leg, producing another even greater decrease in total power. The present work shows two algorithmic solutions to the problem of compensating for the lost power. They are based on increasing the number of panels per cell initially required, so that, in the event of a failure, the modulator can be modified in one way or another, maintaining the operating condition. The first algorithm modifies the phase modulator with amplitude fault, while the second modifies the phase modulators without amplitude and phase faults. The proposed scheme is verified by simulation in PLECS software, using different number of cells for comparison between algorithms, as well as different number of faults. The results show a lower number of solar panels needed to supply faults in algorithm 2, even not needing more panels than the minimum required to work at normal operating conditions, as well as a better use of resources when the number of cells per phase is increased.
The application of photovoltaic energy as a form of power is increasingly used in industry as it is renewable energy and non-polluting in nature. Its use is increasing mainly due to the reduction in the value of the equipment and installation costs that have been experienced in recent years. As they are modeled as DC sources, it is necessary to use inverters for common loads such as RL loads or the power grid itself. If it is desired to improve the signal quality, it is possible to increase the number of inverters, reducing the harmonic content and increasing its resolution as there are more achievable voltage levels. There are several MLI topologies in the market, one of the most used is the CHB. One of its advantages is the lower cost compared to other topologies, as well as the flexibility to increase the number of levels. This also brings disadvantages, such as that the modeling becomes much more complex and the system is more susceptible to failures due to the greater number of elements. For this reason, we are always looking to optimize them in terms of failures, since these can degrade the behavior of motors or even cause the total shutdown of the system. One of the biggest problems when a cell fails is the decrease in power output, along with a voltage unbalance in the load. To make up for that imbalance, the current solution is to remove the two remaining cells from that leg, producing another even greater decrease in total power. The present work shows two algorithmic solutions to the problem of compensating for the lost power. They are based on increasing the number of panels per cell initially required, so that, in the event of a failure, the modulator can be modified in one way or another, maintaining the operating condition. The first algorithm modifies the phase modulator with amplitude fault, while the second modifies the phase modulators without amplitude and phase faults. The proposed scheme is verified by simulation in PLECS software, using different number of cells for comparison between algorithms, as well as different number of faults. The results show a lower number of solar panels needed to supply faults in algorithm 2, even not needing more panels than the minimum required to work at normal operating conditions, as well as a better use of resources when the number of cells per phase is increased.
Description
Tesis presentada para optar al título profesional de Ingeniero Civil de Electrónico
Keywords
Energía solar, Corriente alterna, Sistemas fotovoltaicos