Towards a Better Understanding of Harmonics and Power Electronics

This paper deals with the harmonic current emission of large self-commutated PV inverters. It disproves with new measurement results that modern inverters behave as current sources for harmonic currents, which is the general idea behind the accepted grid codes. Furthermore it presents new approaches to quantify the contribution of grid voltage distortion to measured harmonic emission under real world conditions. The conclusions which are drawn at the end of this paper are based on high precision harmonic current measurements, which have been carried out for a central inverter with a nominal power of 225 kVA. The harmonic emissions were measured for different types of grid configurations and background distortion.