Time-domain fault range finding method for co-tower double-loop DC power transmission line based on single-loop electrical quantity

Abstract

The invention discloses a time-domain fault range finding method for a co-tower double-loop DC power transmission line based on the single-loop electrical quantity. The method comprises the following steps that an impedance matrix and an admittance matrix are extracted; 2) a voltage decoupling matrix and a current decoupling matrix are obtained; 3) a single-loop voltage phase-mode transformation matrix from which a ground mode component is eliminated is constructed according to the obtained voltage decoupling matrix, and a single-loop voltage differential-mode component from which the ground mode component is eliminated is obtained; 4) a single-loop current phase-mode transformation matrix from which the ground mode component is eliminated is constructed according to the obtained current decoupling matrix, and a single-loop current differential-mode component from which the ground mode component is eliminated is obtained; 5) a most prominent component is selected according to distribution characteristics of different modulus in different pole wire faults, and modulus parameters corresponding to the modulus are selected; 6) voltage distribution along the line is calculated; 7) a fault positioning criterion based on mixed modulus is calculated; 8) fault time is calculated; and 9) a redundant data window is selected. The time-domain fault range finding method has advantages including that the calculating precision and the reliability are high, the needed data time window is short and realization is easy.

Description

technical field [0001] The invention relates to the technical field of power system relay protection, in particular to a time-domain fault location method for double-circuit DC transmission lines on the same tower based on single-circuit electrical quantity. A dual-terminal time-domain ranging algorithm for single-return measurement data of a line. Background technique [0002] High-voltage direct current transmission has the advantages of large transmission capacity, flexible and rapid control, and no synchronization and stability problems. It has a wide range of applications in the field of long-distance large-capacity power transmission and asynchronous grid interconnection. With the development of society and economy, the cost of power grid construction is gradually increasing due to the increasingly tight land resources. The erection of high-voltage lines on the same pole can effectively utilize the transmission corridor. It is not only widely used in AC power grids, b...

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Problems solved by technology

[0004] However, most current DC line fault location methods are limited to single-circuit bipolar DC lines, and only need to consider the influence of electromagnetic coupling between structurally symmetrical bipolar lines in the method

However, for the double-circuit DC transmission line on the same tower, due to the electromagnetic coupling relationship between the four poles of the double-circuit line, and the double-circuit DC line on the same tower does not use transposition measures in actual engineering, its fault coupling characteristics are very complicated

What is more noteworthy is that in practical applications, since the control and protection of each DC system is still based on the electrical quantity information of the current circuit, it is inevitable that the complete decoupling of each coupled electrical quantity cannot be achieved. Fault Analysis of DC Transmission Lines and the Difficulty of Accurate Fault Location

[0005] Therefore, the existing phase-mode conversion method and fault location algorithm for single-circuit DC transmission lines are no longer applicable to double-circuit DC lines on the same tower. It is urgent to study the applicable fault location method for the characteristics of double-circuit DC transmission lines on the same tower.

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