There have been many renewable energy tripping accidents caused by overvoltage all over the world

and the overvoltage has become a prominent issue restricting the development of renewable energy

especially in weak grids prone to voltage fluctuations. According to the span of the time scale

the mechanism analysis and suppression strategy of transient overvoltage in the short time scale and power frequency overvoltage in the long time scale are studied in this paper. Firstly

the mechanism of transient overvoltage is analyzed based on the controlled voltage source model. Secondly

the mechanism of power frequency overvoltage is analyzed based on the controlled current source model. Then

an adaptive overvoltage suppression strategy for different time scales is proposed. Transient overvoltage is suppressed by introducing the adaptive variable voltage regulation coefficient

and power frequency overvoltage is suppressed by absorbing additional reactive current. Finally

experiments are carried out. The experimental results show that the proposed strategy in this paper has a good suppression effect on both types of overvoltage issues.