The invention discloses a micro-grid island detection method and
system. The method comprises the following steps that the
voltage of a common connection point is collected, and the phase and frequency are obtained; whether an island phenomenon occurs is determined, if YES, the method is completed, and otherwise, a next step is followed; and a disturbance current is input, the
voltage of the common connection point is collected again, whether the island phenomenon occurs is determined again, if YES, the method is completed, and otherwise, the first step is returned to. The
system comprises a PWM driving module, a collection module and an island detection module, the collection module obtains the
voltage, phase and frequency of the common connection point, and sends the voltage, phase and frequency to the island detection to compare the frequency and voltage of the
power grid, a detection
signal is sent to the PWM driving module, and thus, an
inverter of a
distributed power generation
system is controlled, and the disturbance current waveform corresponding to output of the
inverter is generated. Thus, micro-grid island detection can be realized rapidly, the validity of island detection can be still ensured under the condition of distributed energy devices, and interference of
harmonic waves is reduced.