Abstract：With the development of power electronics technology，microgrid type energy storage inverters with

virtual synchronous generator（VSG）function have also been widely used. In VSG technology，due to the presence

of inertial frequency regulation loop and voltage regulation loop，the inverter can realize the grid frequency

regulation and voltage regulation function independently when it is connected to the grid，and it can realize the

parallel power without communication when it is off-grid. However，in the microgrid system，due to the access of

load and transformer，the parallel black start technology is one of the urgent problems to be solved when the

inverter is off-grid. Through theoretical simulation analysis，an industrial frequency synchronous soft start method

was proposed，which can realize smooth bus voltage establishment. The parallel power equalization of two VSGs

during the soft start process achieved the completion of the black start of the whole system. Finally，the

effectiveness of the parallel VSG black start control strategy was verified through experimental analysis.

      Key words：frequency synchronization；black start；virtual synchronous generator （VSG）