Droop-based Converter Scheme for Linking Multiple Hybrid Microgrids

This paper presents a novel droop-based converter scheme for linking multiple hybrid microgrids. The ac grid frequency, dc grid voltage and active power through the converter are coupled in the droop controller via three scaling factors which are used to define the voltage and frequency droop coefficients at the dc and ac ends of the converter, respectively. Any load change within individual grids will vary either of these global variables and the converter power can be managed accordingly. An interlinked hybrid microgrid consisting of two dc grids and one ac grid is simulated in PSCAD/EMTDC. The results show that the proposed scheme can successfully manage bidirectional power flow among the grids. Due to coupling between ac and dc sections, a small variation is observed between defined droop coefficient and actual converter response. Nonetheless, the scheme is totally autonomous and does not require multiple parallel converters for grid interaction. The simplicity of the control is a major distinguishing feature which will be particularly useful in future hybrid grids.