Coupling double line down distance measuring method using six-phase system new phase mode transformation

Abstract

Disclosed is a fault distance measurement method for a coupled double loop line through mode transformation of a six-phase system, belonging to the technical field of relay protection for an electric power system. In the method, a mode transformation matrix suitable for the loop lines is deduced from the fact that a single module is capable of reflecting the new mode transformation matrix of a common three-phase system according to the relationship between the impedance matrix of the common three-phrase system and the impedance matrix of the system of the double loop lines within the same tower. The invention provides a time domain fault locating method for double loop line based on new mode transformation. The method fabricates the criterion for distance measurement by making use of the transfer characteristics of the arc voltage and current under certain module. The method is characterized in that the measurement is carried out in time domain, the needed time window is short and the method avoids wave filtration; with the method of least square, the distance measurement precision is improved and the distance measurement precision is free from the influences from transition resistance, fault type and impedance change of the opposite system. A large number of electromagnetic transient simulation results show that the method is highly precise.

Description

technical field [0001] The invention relates to a coupled double-circuit line fault ranging method using new phase-mode transformation of a six-phase system, which belongs to the technical field of electric power system relay protection. Background technique [0002] The double-circuit line on the same tower shares the pole tower, and the required outlet corridor is narrow. It has the advantages of fast construction speed, strong transmission capacity, and investment saving. It can well meet the requirements of modern power systems for power supply reliability and large-capacity transmission. It is widely used in external power systems. However, when the double-circuit line on the same pole uses the same tower, there is not only mutual inductance between the phases, but also mutual inductance between the lines. The current decoupling methods such as the six-sequence component method cannot reflect all fault types of the double-circuit line. Sometimes dual-mode The amount ca...

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Problems solved by technology

Among them, the symmetric component transformation contains complex factors, which is more complicated to calculate. It is suitable for the phase-mode transformation under power frequency steady state. The elements in the transformation matrices such as Clarke transformation and Karenbauer transformation are all real numbers, which are suitable for frequency domain analysis and also for time domain analysis. Domain analysis, but the research found that the Clarke and Karenbauer transformation must use dual modulus or cooperate with phase selection in fault analysis, which greatly increases the amount of calculation

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