Amongst all renewable technologies, Photovoltaic (PV) energy is considered as the future of sustainable energy generation in many countries. PV systems in the generation section are increasing rapidly and this growth is expected to be continuous. On one hand, there is an increase on the number of new developmental PV components and devices. On the other hand, the real peak power of the installed PV plants is one of the important parameters for the energy-harvesting point of view. To find the maximum power point (MPP), many testing systems and maximum power point tracking (MPPT) algorithms have been developed. The testing system is used for system development as well as validating the quality of the PV products and MPPT algorithms in working conditions. In fact, many MPPT algorithms have been proposed. However, a rigorous method to compare their performances is still missing. The typical problem related to the evaluation of the number of PV system performances and MPPT algorithm comparison is the guarantee of the repeatability of the testing conditions (e.g. temperature and radiation). Just few works compare different algorithms or different PV panels at the same environmental conditions based on simulations only, without experimental evaluation. The challenges stem from the difficulties to duplicate the environmental conditions during the experimental evaluation. Very high costs and dimensions issues limit the use of artificial sun. It is very well known that the definition of current-voltage (I–V) and power-voltage (P–V) in different environmental conditions can characterize a solar cell, module or array; however, the knowledge of these curves is not sufficient to estimate the actual generated power of the panels in working condition. In fact, it is also necessary to recognize the employed MPPT algorithm. Therefore, an experimental testing system is necessary to have the capability of reproducibility in environmental conditions for comparing a number of algorithms and characterizing them by the ease of use. In this dissertation, a testing system for PV applications has been developed, characterized and designed according to some constraints. Flexibility and ease of use, low cost, capability to evaluate the characteristic curves of more than one PV panel simultaneously (same environmental conditions), capability of algorithms simulation, and capability of tracking MPP on the base of different MPPT algorithms are considered. Experimental test are carried out to validate the performance of the developed architecture of the PV testing systems. In addition, different MPPT algorithms have been compared in the same environmental conditions, testing steady state, dynamic and real-time behaviour.
|Type||PhD thesis, Politecnico di Milano|
|Publication status||Published - 20 Dec 2016|