Differential protection method using single-ended transient signal high-frequency component throughput of transmission line

Abstract

The invention relates to a differential protection method using single-ended transient signal high-frequency component throughputs of a transmission line, belonging to a single-ended transient protection scheme for a power transmission line. When the line is in short circuit, a large number of high-frequency signals are generated due to a fault and are propagated to the two ends of the line; and as a bus has ground distributed capacitance, the high-frequency signals are remarkably reduced when the high-frequency signals pass through the bus, and high-frequency component values detected at a proximal fault side of the bus are always greater than those detected at a distal fault side of the bus. According to the differential protection method, fault signals of the inner side and the outer side of the bus at a line protection mounting position are acquired by using the above-mentioned principle, fault transient signals are subjected to lossless segmentation by using a perfect reconstruction filter bank, then, the difference value of certain throughputs of subband components of the inner side and the outer side of the bus is calculated, and whether the fault is an internal fault or an external fault is judged according to a majority voting mechanism by using the difference value; and signals for constructing criteria are a plurality of subband high-frequency signals covering the full high-frequency band, and subband frequencies can be adaptively adjusted along with the change of a sampling frequency. The differential protection method has the advantages that the scheme is simple and reliable, the line of total length can be protected, the requirements on the distributed capacitance of the bus are low, and the fault tolerance and the reliability are enhanced from principle and hardware implementation manners.

Description

technical field [0001] The present invention relates to the protection technology of power transmission lines, in particular to the use of the single-ended transient high-frequency component processing capacity difference of the transmission line (the difference in the transient current high-frequency component processing capacity, or the transient voltage high-frequency component processing capacity difference ), so as to realize the identification of the fault in the protection area or the fault outside the area, so as to carry out the protection method. Background technique [0002] The transient protection constructed by using the transient high-frequency components of line faults not only improves the protection action speed to a greater extent, but also has insensitivity to fault types, fault locations, fault impedances, fault initial angles, and is not subject to current transformer saturation, power frequency, etc. Influence of short circuit level etc. With the cont...

AI Technical Summary

Problems solved by technology

There are inherent defects in this principle. The fault conditions of the actual power system are very complex and changeable. The high-frequency components and low-frequency components contained in the transient signals generated under different fault conditions are very different, resulting in some cases of out-of-area faults. The energy ratio of the high and low frequency components of the fault may be much larger than the energy ratio of the high and low frequency components in the case of an internal fault, resulting in the energy ratio of the high and low frequency components when an external fault is detected at one end of the line. If the ratio is large, the protection will malfunction

At the same time, because the method of using the energy ratio to form the fault criterion uses division, it is easy to amplify the interference of small signals (for example: 1 divided by 0.01 equals 100), so that the calculated ratio cannot fully reflect the actual situation and is prone to instability , poor anti-interference, and ultimately lead to reduced reliability of protection devices

In addition, the ratio of two values ​​that are very large but very close to each other is relatively small (for example: 10500 divided by 10000 equals 1.0500), which is not conducive to the setting of the protection setting value.

Other methods based on the ratio of single-ended transient signal processing volume, such as the ratio of transient signal entropy, transient signal singularity ratio, signal complexity ratio, etc., have similar inherent defects and deficiencies in principle.

[0003] Therefore, in view of the disadvantages and deficiencies of the traditional differential protection action speed not fast enough, the current transient protection performance is not stable enough, not reliable enough, it is necessary to study a new method of ultra-high-speed transient protection with better performance

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