Statistical characterisation of harmonic current emission for large photovoltaic plants

Abstract

SUMMARY Harmonic current emission of photovoltaic (PV) systems is a well-known problem. However, its quantitative characterisation, which requires the compilation and use of abundant statistical data, had never been satisfactorily dealt with. This paper discusses the multifaceted statistical characterisation of these emissions in a large PV plant. The topics addressed are harmonic current magnitude and its phase angle in relation to PV power output level and background harmonic voltages. Harmonic current emission in PV systems should be recorded during any single 1-week period throughout a full year. Because power quality metres are expensive, it is more economical to measure this type of emission with simple, cost-effective equipment. This paper thus presents a new assessment method for harmonic emission based on PV power output level, which is the main parameter affecting the emission, and which is easily monitored by most PV inverters. This new method uses statistical data to define a dependence model for the PV power output of PV harmonic current emissions. Such a model is rarely provided by PV inverter manufacturers. However, the simpler dependence model required for this method can be obtained by inexpensive power quality metres. This new method also produces accurate results at low process costs. Copyright © 2013 John Wiley & Sons, Ltd.