Study on Impact of Modulational Instability of Inverters on Electrical Energy Systems

This paper reports an experimental study on the output of interconnected power inverters on electrical energy systems when operated under weak modulational instability conditions. It is found that, accompanying with the 60Hz fundamental frequency power flow; there exist some high-frequency components that have some unexpected features. Despite the similarities to the high-frequency components in the electromagnetic transients, generated by faults, or the ordinary harmonics generated from non-linear active sources, these high-frequency components have their unique counter-intuitive features: 1. they do not exhibit spatiotemporal decays in dispersive power lines, 2. the frequencies of these components are at an ultra-high level that a single active resource can provide. The confirmation experiments and further investigations show that these high-frequency components are not the results of an ordinary resonance effect and cannot be filtered by power filters.