Research On Fault Location Algorithm For Incomplete Double-Circuit Transmission Lines On Same Tower

The corridor occupied double-circuit transmision lines on same tower is narrow, saving a lot of land resources, the investable benefit is remarkable, and the unit of transmission capacity is strong. It can meet the requirement of modern power system safe and stable operation. In the engineering practice it has assumed the responsibility of the pivotal line. With applying widely and meeting the requirement of all kinds of geographical environment, the double-circuit transmission lines has generated a variety of types of transmission lines, such as incomplete double-circuit transmission lines and different voltage levels of double-circuit transmission lines, etc. Currently, there has a lot of fault location studies on complete double-circuit transmission lines, and the different voltage levels one has also started gradually, but the incomplete one is rare. The incomplete double-circuit transmission lines compared the complete one, both in the type of fault and in the circuit structure, has a larger difference. Therefore, the aspects of fault location research for double-circuit transmission lines become more and more important.Firstly, the principle of the two terminals fault location of transmission line is introduced, and the problem of pseudo root on two terminal fault location is emphatically discussed. This paper proposes a new method of identification of pseudo root. And when applied to fault location for incomplete double-circuit transmission lines, it can effectively identify the pseudo root, which verifies superiority and effectiveness of the new method.Secondly, according to the relationship between the three-phase system and the double-circuit transmission lines system, and to regarding the six-sequence component method as the foundation, a new phase-mode transformation matrix applied to double-circuit transmission lines is deduced, which can be applied to both the steady state analysis and the transient state analysis, and using a single modulus can reflect all types of faults.Finally, Through deeply studying the characteristics of model made of the double-circuit lines and the single-circuit line, two types of fault location algorithm for double-circuit lines are proposed. The first algorithm is based on judging the fault branch of incomplete double-circuit lines. And the algorithm is divided into two steps, which firstly determining the fault branch and then finding out the fault location of the identification line according to the result of the judgment. The second one is based on segment parameters of the lines, which combines fault location with fault branch identification. As is shown in a large number of the simulation results, the proposed algorithm can be realized within the entire line. The principle is simple, easy to solve, and not affected by the types of fault, transition resistance and other factors. The results of fault location have a higher accuracy.