Study On Fault Location Of Multiple-Circuit Transmission Line On Same Tower

An accurate fault locator makes it possible for fast restoration and availability of the power system, especially in increasing complex modern power transmission systems. Multi-parallel transmission lines are widely used in power system today, and on the other hand, frequently subject a variety of technical problems in the view of protection engineering. These problems are mainly due to the mutual coupling between lines, which requires decoupling between lines on the same tower.In this paper, a new one-terminal fault location algorithm for parallel transmission line is introduced. Then twelve-sequence component method is introduced in this paper to decouple mutual electromagnetic effect between the four lines. The twelve -sequence components are independent from each other. The characteristic of the twelve-sequence components is studied and the related sequence networks are introduced. The twelve-sequence component method can not only be the basic method of the fault analysis but also the basic theory of the fault location and relay protection for the four-parallel lines. Based on the twelve-sequence component method a location algorithm for four-parallel lines is introduced which is independent of source impedance, fault type, fault resistance and mutual coupling between four-parallel lines. A lot of results of EMTP simulation indicate that the twelve-sequence component method is correct and valid for fault analysis. All the algorithms have been tested by EMTP simulations, which indicate high accuracy under various fault conditions.