The growing penetration of high-proportion renewable energy and power electronic devices

known as the “dual high” characteristics

is fundamentally reshaping the voltage formation in power systems

introducing new transient voltage stability issues. This paper analyzes the impact of “dual high” characteristics on transient voltage formation mechanisms across generation

transmission

distribution

and consumption stages. Key influences include the decrease of synchronous generators

reduction of reactive power sources with strong overload and active support capabilities

the rise of current-source devices

and increased uncertainty in both sources and loads. The paper also discusses new transient voltage stability issues caused by factors such as power angle-voltage coupling effects

the low-voltage ride-through characteristics of renewable energy

and the spatio-temporal uncertainty of sources and loads. Additionally

it reviews research progress in optimizing the reactive power output of grid-following devices

increasing the proportion of grid-forming devices

and enhancing the active control capability of new loads. Finally

the paper highlights critical issues and technical directions that require further research.