Three-phase multi-frequency energy transfer system for realizing the energy internet

Abstract

The endeavor to increase the integration of distributed power generation systems (DPGS) into the electric power system brings about new research areas, one of them is the energy internet concept. Similarly to the information internet, the energy internet would transfer packets as the units of energy. To avoid congestions in the packet dispatching process, routers and routing methods have been suggested in literature. Our proposal is to use multiple channels simultaneously. In this paper, the possibility of three-phase multi-frequency energy transfer is investigated. This task is performed by using grid-forming and grid-feeding converters. To have a balanced three-phase multi-frequency power system, the third harmonic component of the fundamental frequency is added to the power system as a zero-sequence signal. The control system consists of two parts. The grid-forming controller is responsible for the voltage and the respective frequency. The grid-feeding controller controls the powers and current of the grid-feeding converter. For doing so, both control systems should be able to decouple the frequencies from each other. As a result, the active and reactive powers can be transferred separately at different frequencies.