Based on the droop control characteristics

the concept of virtual governor and exciter is introduced to endow the inverter power source with frequency inertia and voltage inertia and dynamic characteristics similar to a synchronous generator. Attention focuses on the research of the grid-connecting pre-synchronized dynamic process of the inverter power sources based on droop control and virtual synchronous generator control in the non-ideal condition. In order to highlight the comparison of external characteristics of two inverters while considering the inertia of the grid

the inverter power source can be annexed to the synchronous generator with a load in the grid-connecting pre-synchronized process. The frequency and voltage dynamic characteristics during the grid-connecting pre-synchronized process of the two power sources above are compared and analyzed with MATLAB/Simulink. Simulation results show that the frequency and voltage of inverter power source based on the droop control changes suddenly and the change rate is large

while the inverter power source based on the virtual synchronous generator has no abrupt change but one that is rather gentle in the grid-connecting pre-synchronized process. This work is supported by National Basic Research Program of China (973 Program) (No. 2013CB228200).