Method for monitoring operating state of power transformer on line under direct-current magnetic bias condition

Abstract

The invention discloses a method for monitoring the operating state of a power transformer on line under the direct-current magnetic bias condition. The method comprises the following steps that a vibration signal of the wall of a transformer tank, a three-phase voltage signal of the transformer, a three-phase current signal of the transformer and a neutral-point direct current are collected; based on the K-means cluster analysis method, a transformer vibration cluster model is built; the amplitude of the 100Hz component of the measured vibration signal of the wall of the transformer tank is compared with the output quantity of the transformer vibration cluster model, and if the relative error between the amplitude and the output quantity is smaller than a threshold value, it is determined that the operating state of the transformer is normal; if the relative error between the amplitude and the output quantity is greater than or equal to the threshold value, it is determined that the operating state of the transformer is abnormal. The method can be used for effectively and highly sensitively monitoring the operating state of the transformer on line under the direct-current magnetic bias condition, and therefore transformer direct-current magnetic bias effective measures can be taken timely, alternatively the transformer can be maintained timely, and major faults are avoided.

Description

Technical field [0001] The invention relates to a signal detection method, in particular to an on-line monitoring method of the operating state of a power transformer under DC bias conditions. Background technique [0002] Under the national strategic policy of "power transmission from west to east and mutual supply between north and south", high voltage direct current (HVDC) has the advantages of large transmission capacity and long transmission distance in the long-distance power transmission of power from west to east in my country. It played a very important role and was widely used. [0003] There are three main operating modes of DC transmission systems: unipolar, bipolar and homopolar. Most of my country's DC transmission systems are systems with bipolar neutral grounding. However, when the HVDC power transmission adopts the single-maximum loop operation mode or the bipolar unbalanced operation mode, a current of up to several thousand amperes will be injected into the earth...

AI Technical Summary

Problems solved by technology

Local overheating will age the insulation and decompose the transformer oil, which will affect the life of the transformer and have a serious impact on the normal operation of the transformer

In addition, the DC bias makes the transformer a harmonic source in the power system, which not only increases the reactive power consumption of the transformer, but also may cause the protection relay to malfunction, so how to accurately monitor the working state of the transformer under the condition of DC bias Monitoring is a key link in power delivery

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