With the development of wind energy and power electric control technology， more wind farms with variable speed wind plant systems（VSWPSs） are integrated into power grids. The structure and control of VSWPSs are much more different from traditional fixed-speed wind plant systems（FSWPSs）， which make VSWPSs more powerful and flexible to connect with power grids. While VSWPSs improve the stability of systems to some extent， several new problems are introduced into power grid， such as the advanced controller significantly increasing the complexity of system and the power converter emitting harmonic currents then reducing the power quality. In addition， how to implement affiliated control for VSWPSs to coordinate with transmission and storage system to improve system performance is another important issue currently. This paper provides an overview to the latest research issues related to the integration of wind farms with VSWPSs.