Circuit phase-to-phase fault locating method needless of voltage memory before fault occurs

Abstract

The invention discloses a circuit phase-to-phase fault locating method needless of voltage memory before a fault occurs. According to the method, firstly, two fault-phase voltage leaps, two fault-phase current leaps and normal phase voltage at a transmission line protection installation position are measured, fault voltage between phases formed when a transmission line operates normally is calculated by means of the normal phase voltage, and then circuit phase-to-phase short-circuited fault single-end positioning is achieved by means of the characteristic that a phase-to-phase short-circuited fault point voltage leap amplitude value which is formed after the circuit fault occurs and is equal to an amplitude value of the fault voltage between the phases formed when the transmission line operates normally is the largest and gradually reduces from the phase-to-phase short-circuited fault point to the two ends of the transmission line. According to the method, voltage before the circuit fault occurs does not need to be memorized, and relay protection hardware does not need to be provided with a retaining circuit of voltage before the circuit fault occurs. According to the method, fault distance measurement dead areas do not exist when protection outlet phase-to-phase short-circuited faults occur, influences of transition resistance and load currents on single-end fault distance measurement precision are eliminated in theory and high distance measurement precision is achieved.

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. ...

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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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