Electrical Power Fluctuations in a Network of DC/AC inverters in a Large PV Plant: relationship between correlation, distance and time scale

摘要

This paper analyzes the correlation between the fluctuations of the electrical power generatedudby the ensemble of 70 DC/AC inverters from a 45.6 MW PV plant. The use of real electricaludpower time series from a large collection of photovoltaic inverters of a same plant is an impor-udtant contribution in the context of models built upon simplified assumptions to overcome theudabsence of such data.udThis data set is divided into three different fluctuation categories with a clustering proce-uddure which performs correctly with the clearness index and the wavelet variances. Afterwards,udthe time dependent correlation between the electrical power time series of the inverters is esti-udmated with the wavelet transform. The wavelet correlation depends on the distance betweenudthe inverters, the wavelet time scales and the daily fluctuation level. Correlation values for timeudscales below one minute are low without dependence on the daily fluctuation level. For timeudscales above 20 minutes, positive high correlation values are obtained, and the decay rate withudthe distance depends on the daily fluctuation level. At intermediate time scales the correlationuddepends strongly on the daily fluctuation level.udThe proposed methods have been implemented using free software. Source code is availableudas supplementary material.