Abstract: A microgrid system and method of controlling same, the microgrid system comprising a storage battery (5000), an energy storage converter (1000), a monitoring circuit and a controllable switch (2000). When the microgrid system is in grid-connected mode, the energy storage converter outputs steady power under the control of an inner current loop unit (1220); in grid-connected mode, an outer voltage loop unit (1240) does not participate in control, but remains in an operating state, and on the basis of four outer voltage loop unit input signals, estimates in advance a specified current loop signal (Uvo) for handover from grid-connected mode to island mode. When the microgrid system hands over from grid-connected mode to island mode, the outer voltage loop unit goes into operation, and the inner current loop unit controls a steady output voltage and frequency from the energy storage converter according to the pre-estimated specified current loop signal output by the outer voltage loop unit.