METHOD OF REGULATING FREQUENCY OF PLURALITY OF UNINTERRUPTIBLE POWER SUPPLY UNITS AND CORRESPONDING UNINTERRUPTIBLE POWER SUPPLY UNIT

A method of regulating frequency of plurality of uninterruptible power supply units and corresponding uninterruptible power supply (UPS) unit. The method includes broadcasting, to a controller of a UPS unit, an expected synchronization direction to other UPS units via a communication link, the expected synchronization direction being determined based on a frequency of the corresponding UPS units and a frequency of a grid. The method includes obtaining the expected synchronization directions of other UPS units via the communication link; determining a major synchronization direction based on the expected synchronization direction of each UPS unit; and regulating a frequency of each UPS unit based on the major synchronization direction.