Recently, renewable generation has been increasingly used. Micro-grid systems show high potential for integrating renewable energy sources. In some cases, micro-grids operating in island mode can transfer excess electricity to an external network, which requires synchronization. Conventional techniques cannot synchronize two power grids remotely, and for local mode, the presence of an operator is required. The Micro-Phasor Measurement Unit (mu PMU) is a device that measures synchronized voltage and current values in electric power distribution grids. This paper presents a method for synchronizing micro-grids with main power systems using the mu PMU, which provides continuous, fast, and synchronized phasor measurement data. A reliable communication architecture transmits this data to a central controller for the micro-grids. The proposed synchronization algorithm was evaluated using MATLAB software. This method facilitates the integration of micro-grids into the main power system, and the mu PMU communication system enables remote control of synchronization operations. Another benefit is the reduction in fossil fuel use for electricity production, equivalent to the energy injected by the micro-grids.