T link fault distance measurement method

Abstract

The invention discloses a T link fault distance measurement method. The method comprises the steps of: when an optical fiber channel is normal, identifying a faulty branch by using a T-point compensation voltage; when the optical fiber channel is abnormal, identifying the faulty branch by using a three-terminal fault distance measurement result; then determining a three-terminal fault removal timeaccording to the relationship between a minimum fault current and a set maximum fault current threshold; after the fault is removed, calculating a fault distance measurement per-unit value accordingto a single-terminal distance measurement method, and converting the fault distance measurement per-unit value into the distance from a fault point to a T point. The T link fault distance measurementmethod disclosed by the invention is used in an existing line protection device, for a T link, normal fault distance measurement can still be performed when the communication of a longitudinal channelis abnormal, and particular in the case of a single-phase high resistance ground fault, the distance measurement accuracy can be ensured.

Description

technical field [0001] The invention relates to a fault location method for a T-connected line, belonging to the technical field of power system relay protection. Background technique [0002] At present, there are two main types of fault location algorithms used in transmission lines: single-ended ranging algorithms and double-ended ranging algorithms. For the double-ended ranging algorithm, it is only applicable to the double-ended system. For the T-connected line (three-terminal system), the principle of the double-ended ranging algorithm is no longer applicable; for the single-ended fault location algorithm, the general metallic fault has only one end. The line can be accurately located, and the fault location results are not accurate due to the existence of the branch circuit at the other two ends. For the fault location algorithm of T-connected line, some traveling wave methods and wave impedance methods are currently studied. Generally, the calculation amount of the ...

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Problems solved by technology

For the T-connection line fault location algorithm, some traveling wave methods and wave impedance methods are currently being studied. Generally, the calculation amount of the algorithm is large or the principle is complicated, and the engineering is difficult.

In an adaptive fault location method applied to T-connected lines, Yao Liang et al. proposed a method of using T-point compensation voltage to identify the fault branch and then using a single-ended fault location algorithm to determine the fault point. The principle is simple and the amount of calculation is small. It is suitable for engineering, but the ranging result of this method is greatly affected by the transition resistance, and the selection result is heavily dependent on the three-terminal synchronization data

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