Attenuation effect with non-linear loads for small stand-alone grids

This paper presents the effect of non-linear loads on the overall voltage quality in small powered stand-alone (islanded) systems. The iterative effect between current and voltage distortion is related to the source's impedance and this study illustrates the different harmonic behavior between power electronic (PE) inverters and electro-mechanical generators directly coupled to the load. A 2,5kW nominal power islanded system with non-linear loads is evaluated with both cases. The PE inverter is an off-the-shelf grid-interactive inverter designed for a combination of battery storage and solar power. The electro-mechanical generator is a synchronous machine with external speed and excitation control. Due to their inherently different behavior and output topology the attenuation effect is shown to be completely different with important complications for reliable operation of such systems.