Photovoltaic (PV) industry is growing exponentially and the availability of specialized equipment for the laboratory tests is becoming crucial especially for manufacturers and laboratories working in the field of power electronics related to PV plants. All people concerned with renewable sources applications experience the need of laboratory equipment to carry out measurements and tests. In particular, in the field of PV generators, the difficulties are tied to the use of an actual outdoor plant for performing tests involving the PV source as well as various kinds of loads, such as resistive loads, DC motors, storage batteries and inverter-connected loads with their maximum power point trackers (MPPT). A real PV plant needs a wide outer surface and high costs. Moreover, its produced energy is strongly dependent on uncontrollable weather conditions. Finally, the necessary investment to set up an experimental plant for testing purpose can be made more severe by the continuous evolution of the involved technologies. Therefore, an alternative solution to the use of an actual outdoor plant has to be taken into consideration. The alternative is the set up of a PV emulator, i.e., a suitable laboratory equipment in which voltage and current are the same as in a real source. Such an experimental facility allows measurements and tests to be carried out, without the constraints of the environmental conditions and, above all, more cheaply, since the use of an actual PV array is avoided. Considering that the trend in PV industry moves toward more efficient PV plants, the set up of effective and reliable PV emulators is becoming more and more a challenging issue. The emulation of a PV generator is performed by two main tasks: the first one is the knowledge of the electrical characteristics of the generator, the latter consists in their realization by a power amplifier. On the score of such considerations, this book provides an extensive introduction to the modelling of PV generators and to their emulation by means of power electronic converters. The authors, have firstly focused on the definition of accurate PV source models, including the parameter extraction techniques, as well. Then, they have devised a system to reproduce the behaviour of a PV source, by using the characteristic voltage-current curves, obtained by the modelling, as a reference to suitably control a switching DC/DC converter. The book collects the results of many years of research and development of the authors at the CNR (National Research Council) - ISSIA (Institute of Intelligent System for Automation), Renewable Sources Laboratory (RES). The primary aim of the book is to guide the reader to design and set up a PV emulator based on controlled power converters, starting from an appropriate modelling of the PV source. The reader is thus allowed to manage a virtual plant in which the dependence of the PV source electrical behaviour on weather conditions, partial shadow and dynamics is accounted for. On the other hand, the book gives an in-depth tool and an extensive reference in modelling PV generators and the more common topologies of DC/DC converters. It is worth considering that the overall emulation concept, adopted in this book with reference to PV sources, is general; therefore, it can be easily extended to the other kind of electrical sources, such as fuel cells, batteries or wind turbines with permanent magnet motor.
Photovoltaic Sources: modelling and emulation. Chapter 5: Photovoltaic source dynamic modeling issues
Massimiliano Luna
2013
Abstract
Photovoltaic (PV) industry is growing exponentially and the availability of specialized equipment for the laboratory tests is becoming crucial especially for manufacturers and laboratories working in the field of power electronics related to PV plants. All people concerned with renewable sources applications experience the need of laboratory equipment to carry out measurements and tests. In particular, in the field of PV generators, the difficulties are tied to the use of an actual outdoor plant for performing tests involving the PV source as well as various kinds of loads, such as resistive loads, DC motors, storage batteries and inverter-connected loads with their maximum power point trackers (MPPT). A real PV plant needs a wide outer surface and high costs. Moreover, its produced energy is strongly dependent on uncontrollable weather conditions. Finally, the necessary investment to set up an experimental plant for testing purpose can be made more severe by the continuous evolution of the involved technologies. Therefore, an alternative solution to the use of an actual outdoor plant has to be taken into consideration. The alternative is the set up of a PV emulator, i.e., a suitable laboratory equipment in which voltage and current are the same as in a real source. Such an experimental facility allows measurements and tests to be carried out, without the constraints of the environmental conditions and, above all, more cheaply, since the use of an actual PV array is avoided. Considering that the trend in PV industry moves toward more efficient PV plants, the set up of effective and reliable PV emulators is becoming more and more a challenging issue. The emulation of a PV generator is performed by two main tasks: the first one is the knowledge of the electrical characteristics of the generator, the latter consists in their realization by a power amplifier. On the score of such considerations, this book provides an extensive introduction to the modelling of PV generators and to their emulation by means of power electronic converters. The authors, have firstly focused on the definition of accurate PV source models, including the parameter extraction techniques, as well. Then, they have devised a system to reproduce the behaviour of a PV source, by using the characteristic voltage-current curves, obtained by the modelling, as a reference to suitably control a switching DC/DC converter. The book collects the results of many years of research and development of the authors at the CNR (National Research Council) - ISSIA (Institute of Intelligent System for Automation), Renewable Sources Laboratory (RES). The primary aim of the book is to guide the reader to design and set up a PV emulator based on controlled power converters, starting from an appropriate modelling of the PV source. The reader is thus allowed to manage a virtual plant in which the dependence of the PV source electrical behaviour on weather conditions, partial shadow and dynamics is accounted for. On the other hand, the book gives an in-depth tool and an extensive reference in modelling PV generators and the more common topologies of DC/DC converters. It is worth considering that the overall emulation concept, adopted in this book with reference to PV sources, is general; therefore, it can be easily extended to the other kind of electrical sources, such as fuel cells, batteries or wind turbines with permanent magnet motor.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
