Under the background of the carbon peaking and carbon neutrality goals

new power systems in China will present a "dual high" characteristic

and the strength of the power systems is gradually weakening

therefore the grid-forming control strategies of power electronic equipment have broad prospects. Among them

the grid-forming droop control and the virtual impedance technology that can optimize droop effect have received comprehensive attention from both academia and industry due to the concise static characteristics of droop control

and have also achieved certain research and application results. However

there is still a lack of discussion on the causal relationships

dynamic characteristics

action mechanism

and deep essence implied in droop control

and the impact of virtual impedance on the reactive power-voltage characteristic of source output is not yet clear. Therefore

this paper focuses on the deep essence and natural adaptability of droop control

as well as the influence of virtual impedance on the source output characteristics in droop control. Then

the output characteristics are compared with those of classic Thevenin voltage source with constant impedance load system

combined with MATLAB/Simulink simulation results. On this basis

a design approach for voltage reference value in grid side and a bidirectional virtual impedance design method are proposed

which can help to improve the droop control effect and grid-forming voltage support ability during normal system operation

and can effectively suppress fault overcurrent. The problem that traditional virtual impedance cannot simultaneously suppress overcurrent and voltage support is solved in this paper.