Abstract: The growing integration of renewable energy sources, primarily photovoltaic (PV) and wind power, is leading to a decline in the inertia level and frequency support capability of the power system. Consequently, frequency stability has emerged as a crucial aspect of the safety, stability, and efficient utilization of renewable energy sources in today's power systems. Fast active power-frequency response and active support capability of grid-connected renewable energy generation units and stations are the research focus. According to the main line of "fast active power control of unit-fast active power control of energy station-fast frequency support of energy station", the state of the art in fast active power control and frequency support for renewable energy stations is reviewed. Meanwhile, the factors limiting the rapidity of frequency response of renewable energy stations are analyzed from the perspectives of frequency measurement, communication time delay, control response mode, etc. It is pointed out that mechanical load of wind turbine, hundred-millisecond-level active power control of wind farm, frequency regulation mode selection and optimization of renewable energy stations, and transient active-reactive power cooperative control are the four key issues to improve the fast active power-frequency response capability of renewable energy generation units and stations. Finally, the future research focuses are provided and discussed.