Photovoltaic systems representation for high frequency studies - part I: The power transformer modeling

Studies involving high frequency quantities require appropriate system modeling for accurate simulated results. Electromagnetic transients and electromagnetic compatibility are traditional fields where high frequency phenomena are present, thus demanding special models. Since power electronic devices represent a permanent source of electric disturbances, such as fast voltage transitions, many problems arise from their operation. In a photovoltaic system, which is the focus of the present paper, important phenomena of this nature take place, such as displacement currents flowing through different paths within the system, stepped voltage manifestation in equipment neutral point and high frequency earth return currents, among others. For their accurate reproduction, the whole photovoltaic installation must be appropriately represented in the simulations, allowing the problem investigation and the development of solutions. In this context, this work is dedicated to the power transformer high frequency modeling, firstly presenting an extensive survey on the topic and, latter, proposing a simple but effective model. Special attention was given to the model parameters determination, being a measuring methodology employed for this aim and an application example presented, for a real case.