Application of distributed fault line selection device in digital substation

At present, the small analog signal transmission is adopted between process level and bay level in most of the digital substation systems below 35kV. Considering the characteristic of the structure and the special request for the earth fault line selection device, the design of line selection device is proposed for the digital substations. With distributed structure, the device consists of two parts, i.e. the lower part and the upper part. The former takes samples from small analog signals and then upload the signals to upper part to complete line selection; the latter sends synchronized signals to the lower part to keep in pace with it. The ways to realize each section are deeply analyzed and site experiments have proved the correctness and feasibility of the technology.