In the islandedcontrol system of the large scale new energy power generation throughvoltage source converter based high voltage direct current transmission (VSC-HVDC) station in Zhangbei area, the capacity of the converter station at the feed end is less than the total capacity of the pure new energy power source. In order to ensure that the power fluctuation of the converter station will not exceed the limit in a short time, a fast over-limit power control of converter station is designed in this paper, including fallback power control system when exceeding the limit and the emergency virtual frequency control system, so as to effectively pre-control when the power exceeding the converter station and ensure the safety of the converter station. Firstly, the operation data of new energy power generation in Zhangbei area is analyzed, and the short-time fluctuation characteristics of new energy active power in Zhangbei area are obtained. Through probability statistics, the maximum fluctuation rate occurring in a certain time scale is determined, which provides support for the system parameter design. Then, the structure of the power off-limit fallback control system, the process of the new energy power pre-control, the principle of setting key parameters and the principle of calling the new energy execution station for the power fallback are introduced in details. The emergency virtual frequency control system serves as a backup for fallback power control system in case of communication interruption. Finally, the simulation models of the converter station master station and the executive station controller are built on the PSCAD/EMTDC electromagnetic transient simulation platform for verification.