Approximation of Experimental Data for Inverter Output Power and Research on the Distribution of the Load between Different Inverters of String Topology for Photovoltaic Power Plants

In this paper, the authors have done a processing of experimental data for the generated output power of two photovoltaic parks by means of different methods. An approximation of the data is done for the output power during a good day (with maximum solar radiation) by a Sum of Sinusoidal Functions, and during a bad day (small solar radiation) by a sum of Gaussian functions. The paper presents also a research on the distribution of the load between different inverters of a string topology on-grid photovoltaic system. It is done by means of MATLAB software computer approximation of experimental data from the monitoring of photovoltaic generators, in order to estimate and prolong the lifetime of the different inverters of the string topology of the system. Based on results of the research a schedule for exchange of the inverters is proposed, in order to optimize the lifetime of the entire system.