Study on black start strategy for multi-microgrids

Microgrids (MGs) is developing at an incredible speed in recent years, combined by multiple microgrids, multi-microgrids (MMGs) gradually become a new form of power grids. A stabilized and effective black start strategy for MMGs is in an urgent demand. In this paper, we analyze the topology and control system of the residential type MMGs with three-phase/single-phase (TP/SP) architecture. Then, we present the black start strategy based on the hierarchical control scheme is presented, including the stand-alone operation strategy, and the grid-connected operation strategy. After the selection of the main power supplies, the master MG is determined. When the synchronous connection condition is met, the slave SMGs which execute the stand-alone algorithm connect to the master MG who provides the voltage and frequency support. Meanwhile, the control algorithm transfers to the grid-connected algorithm, with the grid dispatching value set to zero. Finally, experimental results of the MMGs platform in the Clean Energy Technology Laboratory (CETLAB) are presented to verify the effectiveness and feasibility of the proposed black start strategy.