Inverter, power system and island detection method

The invention provides an inverter, a power system and an island detection method. The inverter comprises an inversion power conversion module and a control module, the input end and the output end of the inverter are used for being connected with a direct current source and a public power grid respectively, and a common coupling point PCC of the inverter and the public power grid is connected with a load. The control module is used for controlling the inverter power conversion module to output reactive disturbance based on a first disturbance value and detecting the voltage frequency of the PCC, and the first disturbance value is a disturbance value corresponding to the first voltage frequency of the PCC in the current sampling period and is larger than or equal to a second disturbance value corresponding to the second voltage frequency of the PCC in the first sampling period; a previous sampling period of the current sampling period is a first sampling period; and the control module is also used for detecti