Multifrequency Grid-Feeding Inverter Control Considering Various Frequency Component Separation Methods

This paper presents a control scheme for a multi-frequency current-controlled inverter. This can be seen as a core solution to using multiple channels in the packet-based energy internet concept. The main control solution is a PR controller with several resonant elements that correspond to one frequency each. In order to be able to decouple the control for each frequency, three frequency-component separation methods are investigated and compared. The proposed solution is demonstrated in a laboratory environment, where the effect of unbalanced grid voltages is also investigated. It is shown that using the presented control scheme it is possible to transfer power independently at distinct frequencies, and power reference signals are tracked fast and accurately even in unbalanced voltage conditions.