Abstract:In the process of monitoring system retrofit of 500kV Ouhai substation without power cut, because there is no design of remote control outlet plate on the measuring and control device, the remote control checking work cannot be completed by traditional method. After further study of the new and old monitoring system structure and the Siemens 8FW protocol, this paper presents a new method of remote control checking, and applies it in the field successfully, which improved the reliability and efficiency of the remote control checking work significantly. The retrofit scheme in this paper provided certain reference for the same type substation monitoring system retrofit in future.