Novel Distance Protection Based on Distributed Parameter Model for Long-Distance Transmission Lines

Traditional distance protections mainly use a lumped parameter model and perform poorly under high-resistance ground fault and/or for long-distance transmission line. In order to overcome the defects, this paper presents a new distance protection method, which is developed based on the distributed-parameter transmission-line model and can distinguish internal faults from external faults based on the trend of the voltage distribution in the neighborhood of the setting point of protection. The criterion of this new distance protection is also put forward. The effectiveness of the proposed method and the error involved are discussed in detail. This new distance protection is simple in principle and easy to implement. In addition, without having to calculate the voltage distribution along the entire line, this algorithm has low computational complexity. In particular, the proposed distance protection still operates correctly under high-transition-resistance faults. Both simulations in distributed parameter transmission-line models and 750-kV power-line field data have demonstrated validity and feasibility of the proposed protection method.