The advantages, such as the mature control method, less volume of the converter and generator, make the doubly fed induction generator system prevalent in the wind power industry. Nevertheless, the doubly fed induction generator is more susceptible to grid faults and disturbances. The instantaneous high voltage fault may occur due to the excessive local reactive power after the doubly fed induction generator system achieving low voltage ride through, and then the wind turbine might be disconnected again. Hence, not only the low voltage ride through but also high voltage ride through capability should be required for the doubly fed induction generator system to meet the grid code requirements. A comprehensive review of the state of the art low voltage ride through and high voltage ride through technologies for the doubly fed induction generator system is presented. Firstly, different types of common low voltage ride through and high voltage ride through techniques are classified according to their features, i.e. auxiliary hardware, linear or nonlinear control strategies etc. The pros and cons of different low voltage ride through and high voltage ride through techniques are given. Furthermore, the latest developments of low voltage ride through and high voltage ride through technologies are introduced. Finally, the future trends of both the low voltage ride through and high voltage ride through technologies are discussed. 1 INTRODUCTION Wind energy has become one of the most extensively disseminated new energy sources owing to the clean and efficient characteristics. The wind power industry has developed rapidly in China since the beginning of the 21st century. The installed capacity of grid-connected wind power will be expected to reach 210 GW by the end of 2020 [1]. Wind energy development and utilisation have started to develop in a decentralised manner, especially at the end of the power grid. Due to the long distance of the transmission line, the impedance of the power grid seen from the wind turbines increases, and the short circuit ratio (SCR) becomes small, which is the main characteristic of the weak grid. As the proportion of grid-connected wind power is increased and scattered into the weak grid, operational characteristics of the power grid, such as weak inertia, low SCR, This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.