Method for detecting transmission line fault direction

Abstract

The invention provides a method for detecting transmission line fault direction, and comprises: step 100, respectively obtaining wave-head polarities (MMI alpha, MMI beta and MMI gamma) of three modulus current fault transient state travelling waves of a power transmission line; step 200, respectively obtaining initial polarities (S alpha, S beta, and S gamma) of power frequency components in the three modulus current fault transient state travelling waves of the power transmission line; and step 300, respectively comparing the wave-head polarities (MMI alpha, MMI beta and MMI gamma) of three modulus current fault transient state travelling waves with the initial polarities (S alpha, S beta, and S gamma) of power frequency components in the three modulus current fault transient state travelling waves, and determining the fault direction of the power transmission line according to the judgment result. The invention solves the long-standing difficulty that travelling wave fault direction detecting elements applied in actual power systems and the travelling wave direction is hard to realize which are caused by capacitive voltage transformer can not transmit and transform the wave-head of voltage fault transient state travelling wave.

Description

technical field [0001] The invention relates to the technical field of relay protection and fault detection of power systems, in particular to the field of fault direction detection of power transmission lines. Background technique [0002] The parameters of high-voltage transmission lines, especially EHV and UHV long-distance transmission lines, have obvious distribution parameter characteristics. The traditional relay protection based on power frequency electrical quantities is affected by factors such as the distributed capacitance of the transmission line and the saturation of the current transformer, and cannot accurately detect faults on the line. But in fact, the fault transient traveling wave after the fault contains a wealth of fault information. The voltage fault transient traveling wave head and current fault transient traveling wave head signal after a fault is a signal with a wide spectrum range, and it is a signal of the whole frequency domain in theory. As e...

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Problems solved by technology

However, existing studies have shown that current transformers used in power systems can effectively transmit transient traveling waves of current faults. Capacitive voltage transformers, which are widely used in power systems with 220kV and above voltage levels, only It can transmit and change the voltage signal of a very narrow frequency band around the working frequency (50 Hz or 60 Hz), and cannot effectively transfer the transient traveling wave head of the voltage fault on the primary side of the power system to the secondary side of the transformer

Therefore, fault direction detection and directional protection based on voltage fault transient traveling waves and current fault transient traveling waves cannot be realized, which is also an unresolved technical problem in the field of power system traveling wave protection research for many years

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