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This paper presents the implementation of a generalized photovoltaic simulation model using MATLAB®/GUI interface. The model is developed using basic circuit equations of the Photovoltaic (PV) cells including the effects of solar radiation and temperature changes. These effects added in real time operation simultaneously. Since the PV module has nonlinear characteristics, it is necessary to model it for the design and simulation of maximum power point for such system applications. Photovoltaic system characteristic curves as current-voltage (I-V) and power-voltage (P-V) characteristics are drawn according to values change of the temperature and solar radiation which observed in MATLAB®/GUI interface. The simulation results showed that these factors and the corresponding PV model influence the maximum power obtained from PV modules under operating conditions. The simulation model also presented the design of the array and the batteries of the load connected to the photovoltaic system.

It is well known that the hot spot temperature represents the most critical parameter identifying the power rating of a transformer. This paper investigates the effect of the degradation of core magnetic properties on temperature variation of aged oil-cooled transformers. Within this work, 2D accurate assessment of time average flux density distribution in an oil insulated-cooled 25 MVA transformer has been computed using finite-element analysis taking into account ageing and stress-induced non-uniform core permeability values. Knowing the core material specific loss and winding details, local core and winding losses are converted into heat. Based upon the ambient temperature outside the transformer tank and thermal heat transfer related factors, the detailed thermal modeling and analysis have then been carried out to determine temperature distribution everywhere. Analytical details and simulation results demonstrating effects of core magnetic properties degradation on hot spot temperatures of the transformer’s components are given in the paper