Transmission line transient state high frequency component processing differential motion pilot protection method

Abstract

The invention provides an electric power transmission line transient state protection scheme. Due to the fact that a transmission line produces a great quantity of transient state high frequency signals under a short trouble condition, stray capacitance exists in a bus over the ground, fault currents or voltage high frequency components strikingly decrease when the fault currents or the voltage high frequency components pass through the bus, and a valve, detected on the inner side of a bus of a protected line, of the same fault high frequency component is always greater than or richer than a value detected on the outer side. The principle is used, currents or voltage on the inner side and the outer side of the bus at two ends of the protected line are acquired, high frequency components of the currents or the voltage are extracted and processed appropriately, differences of transient state high frequency component processing capacity on the inner side and the outer side of the bus, such as an energy difference or an entropy difference or a complexity difference or specificity difference or module maximum value difference or other processing capacity differences are calculated, area-in and area-out faults are judged and distinguished based on differences of the transient state high frequency component processing capacity at two ends of the transmission line, and thus protection of the line is achieved. The protection principle is simple, has an absolute selectivity, is stable and reliable in performance, is quick in motion, and can protect the total length of the line.

Description

technical field [0001] The present invention relates to the protection technology of electric power transmission line, especially relates to the use of the difference in the processing capacity of the transient high-frequency component of the transmission line (the difference in the processing capacity of the high-frequency component of the transient current, or the difference in the processing capacity of the high-frequency component of the transient voltage), In order to realize the identification of the fault in the protection area or the fault outside the area, the method of protection is carried out. Background technique [0002] Current differential protection is one of the most widely used protection principles in power systems. This principle is known as fast protection with absolute selectivity. However, with the increasing scale of the power system, the time required for relay protection to remove faults is shorter. At present, the longitudinal protection scheme ...

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, so that the calculated ratio cannot fully reflect the actual situation, and it is prone to instability and poor anti-interference, which eventually leads to a decrease in the reliability of the protection device.

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.

[0004] Therefore, in view of the disadvantages and deficiencies of traditional differential protection that the action speed is not fast enough, and the current transient protection performance is not stable enough, it is not reliable enough, and it is necessary to study a new method of ultra-high-speed transient protection with better performance.

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