Analysis And Research On Special Relaying Protection Problems Of 1000kV UHV Line

With the development of our country's social economy and the increasing electrical demand, the growing UHV transmission technology is becoming a significant measure to coordinate the development of power and social economy .The UHV transmission lines are gradually becoming the backbone of the unified national power grid.1000kV UHV transmission systems have large capacity, long distance transmission and low loss characteristics, compared with 500kV transmission lines, the equivalent diameter of wire is better, the impedance declines, impedance angle gets bigger, the transmission power becomes bigger, the phase-to-phase and phase-to-earth distributed capacitance is bigger , and so well as the capacitance current, which bring tremendous impacts on relay protection.In the discussion and analysis based on the successful experiences of other countries, this paper poses an idea on researching and solving the technical problems in the development of our country's UHV transmissions and on the scheme of relay protection .This paper also introduces the protection configuration of 1000kV AC UHV experimental demonstration project-lines, transformers, reactors, breakers in southeast Shanxi-Nanyang-Jingmen .The most commonly used current protection and distance protection, for example, is analyzed on transient performances to get some beneficial conclusions on the application of traditional protection in UHV grid. The paper focuses on power frequency variation distance protection analysis and putting forward a new principle based on long-term equation and a large amount of simulation analysis.