Patent ID: 6678134
Filing Date: 2004-01-13
Classification: H02H

Abstract:
A digital protective relay system in an electric power system, having two or more terminals being coupled to form a pair, and protective relay devices provided at each of the terminals, comprising:receiving sections that respectively are connected to the protective relay device, each receiving section receiving an electric wave from a satellite and outputting a fixed cycle pulse; clock signal generating sections that respectively are set in each protective relay device, each clock signal generating sections generating a clock signal; sampling pulse generating sections that respectively are set in each protective relay device, each sampling pulse generating section generating a sampling pulse with a fixed frequency in accordance with the clock signal; timing difference measurement sections that respectively are set in each protective relay device, each timing difference measurement section measuring a timing difference of the fixed cycle pulse and the sampling pulse; correcting sections that respectively are set in each protective relay device, each correcting section correct a frequency of the sampling pulse from each sampling pulse generating section in accordance with the timing difference; digital converting sections that respectively are set in each protective relay device, each digital converting section generating an electrical quantity data in digital form by sampling an electrical quantity of the electric power system in accordance with the sampling pulse of each sampling pulse generating section; transmitting sections that respectively are set in each protective relay device, each transmitting section transmitting and receiving the electrical quantity data between each protective relay device; calculating sections that respectively are set in each protective relay device, each calculating section performing a calculation for a protective function by using the electrical quantity data obtained at each protective relay device; and outputting sections that respectively are set in each protective relay device, each outputting section outputting the result of the calculating section at each protective relay device.