Islanding detection method and apparatus, grid-connected inverter, and computer-readable storage medium

An islanding detection apparatus, comprising:

• a voltage frequency detection module, configured to continuously detect a voltage frequency at a point of common coupling;
• a frequency deviation calculation module, configured to calculate, according to the voltage frequency, a frequency deviation of the voltage frequency between two adjacent detections;
• a voltage phase obtaining module, configured to detect, when the frequency deviation is less than a preset frequency threshold, a voltage phase in a preset closed-loop phase-locking manner, and detect, when the frequency deviation is greater than or equal to the preset frequency threshold, the voltage phase in a preset open-loop phase-locking manner;
• a reference current obtaining module, configured to determine, according to the frequency deviation, the voltage frequency, and the voltage phase, a reference current for injecting a frequency perturbation;
• and
• an islanding effect determining module, configured to control, according to the reference current, the grid-connected inverter to output a current to the point of common coupling, and determine, when the voltage frequency exceeds a preset range, that an islanding effect occurs.