Phase-to-phase fault location method without pre-fault voltage memory

Abstract

The invention discloses a fault location method between phases of a line without voltage memory before the fault. The method of the invention firstly measures the two fault phase voltage mutations, the two fault phase current mutations and the normal phase voltage at the protection installation place of the transmission line, uses the normal phase voltage to calculate the fault phase-to-phase voltage during the normal operation of the transmission line, and then uses the phase-to-phase voltage after the line fault The single-end location of phase-to-phase short-circuit faults is realized by the characteristic that the voltage mutation amplitude at the short-circuit fault point (that is, equal to the fault phase-to-phase voltage amplitude when the transmission line is in normal operation) is the largest and monotonically decreases from the phase-to-phase short-circuit fault point to both ends of the transmission line. The method of the invention does not need to memorize the voltage before the line fault, and the relay protection hardware does not need to set the voltage holding circuit before the line fault. The method of the invention has no fault ranging dead zone when protecting an outlet phase-to-phase short circuit fault, eliminates the influence of transition resistance and load current on single-end fault ranging accuracy in principle, and has high ranging accuracy.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for locating faults between phases of lines without voltage memory before faults. Background technique [0002] The single-ended fault location method only uses the electrical quantity at one end of the transmission line for fault location, does not require communication and data synchronization equipment, has low operating costs and stable algorithms, and has been widely used in transmission lines. Single-ended fault location methods are mainly divided into traveling wave method and impedance method. The traveling wave method utilizes the transmission properties of fault transient traveling waves to perform single-ended fault location. It has high precision and is not affected by the operation mode and excessive resistance. However, it requires a high sampling rate, requires a special wave recording device, and has high application costs. ...

AI Technical Summary

Problems solved by technology

The traveling wave method utilizes the transmission properties of fault transient traveling waves to perform single-ended fault location. It has high precision and is not affected by the operation mode and excessive resistance. However, it requires a high sampling rate, requires a special wave recording device, and has high application costs.

The impedance method uses the voltage and current after the fault to calculate the fault loop impedance, and performs single-ended fault location based on the characteristic that the line length is proportional to the impedance. It is simple and reliable, but the fault location accuracy is seriously affected by factors such as transition resistance and load current. Especially when the transition resistance is large, the result of the impedance method distance measurement will seriously deviate from the real fault distance, and even the fault distance measurement fails or the fault distance measurement result exceeds the entire length of the line, which cannot provide accurate fault location information, making it difficult to inspect the fault line. It is conducive to the rapid elimination of transmission line faults and the rapid restoration of line power supply

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