Micro-grid island detection method

The invention relates to the field of protection and control of micro-grids of electric power systems and particularly relates to a micro-grid island fast detection method. The method is sued for an inverter-based distributed generation (IBDG) with a PQ (power quest) decoupling control strategy; a corresponding reactive power control strategy is adopted in the method on the basis of measuring a voltage effective value UPCC and the load reactive power of a common coupling point PCC in real time through comparing the voltage effective value UPCC with the voltage effective value under a normal condition; when island determination is performed, firstly, a voltage threshold value and a frequency threshold value are predetermined, the voltage effective value UPCC is compared with the voltage threshold value, if the voltage effective value UPCC exceeds the threshold value, the PCC is directly determined be in an island state and the island detection is finished, and if the voltage effective value UPCC does not exceed the threshold value, the voltage frequency f of the PCC is compared with the frequency threshold value, the PCC is determined to be in the island state if the voltage frequency f of the PCC exceeds the threshold value. With the adoption of the detection method, the micro-grid island detection can be realized fast, and the effectiveness of the island detection can be ensured even under the existence of a plurality of inverter-based distributed generations.