A fast phase selection method for transmission line faults based on s-transform

Abstract

The invention discloses a transmission line fault fast phase selection method based on S conversion. The transmission line fault fast phase selection method based on S conversion includes following steps: (1) collecting the current of the protection element at the line side at real time; (2) executing phase-mode transformation on the fault component current and extracting the model component of the fault component current after filtering the power frequency component for the corrected current; (3) executing S conversion on the model component current signal to obtain complex time-frequency matrix of each model, obtaining the model and phase angle, judging the ground fault or non-ground fault according to the characteristic of the zero model phasor, using the relationship among the line model phasors for having fast phase selection operation; (4) respectively integrating for the wave form of the phase current at two sides of the time axis, describing the wave form characteristic and recognizing the fault phase while the fault is dual-phase ground fault. The method adopts the S conversion for extracting the single frequency model component of each model component at special time, the fault type is determined according to the relationship among the model phasors, the method has the advantages of high sensitivity, fast action speed and exact recognition.

Description

technical field [0001] The invention relates to a fast phase selection method for transmission line faults based on S transformation. Background technique [0002] With the gradual advancement of the strategic pattern of power transmission from west to east and mutual supply between north and south, in the next 10 years, my country will build a large number of super (ultra) high voltage transmission lines, and then form a strong power transmission with super (ultra) high voltage lines as the backbone grid. network. The important position of ultra-(ultra) high-voltage lines in the power grid requires relay protection devices to have faster fault removal speeds, higher reliability and sensitivity, and the protection principle of using fault traveling waves or transients has become a effective way of protection. With the development of ultra-high-speed traveling wave protection and transient protection, line protection puts forward higher requirements for the rapidity and reli...

AI Technical Summary

Problems solved by technology

However, due to the neglect of the coupling current on the non-faulted phase, when a single-phase or two-phase ground fault occurs at the far end of the line, using the magnitude relationship between the zero modulus and the line modulus for phase selection may lead to misjudgment

[0009] "Research on Fault Type Identification of EHV Transmission Lines Using Current Traveling Waves" identifies fault types based on various characteristics of (phase, mode) current traveling wave amplitude and polarity during different types of faults. This method is not affected by CT saturation and system Oscillation, but its reliability depends on the accurate identification of the wave head, and the shape and polarity of the wave head are related to the change of the wave impedance at both ends of the line (ie, the busbar structure), and the amplitude is closely related to the time when the fault occurs. Therefore, the reliability of phase selection is poor

[0010] "Fault Phase Selection of EHV Transmission Lines Based on Transient Quantities" According to the structure and coupling strength of the three-phase conductors in the actual line, a fault phase selection method for judging the fault phase based on the size and relative relationship of the three-phase fault transient quantities is proposed , this method is fast and reliable, and is basically not affected by the fault type, fault transition resistance, etc., but a three-phase short circuit that occurs when a certain phase voltage crosses zero may be misjudged as a two-phase phase-to-phase short circuit

[0011] It can be seen that there is no phase selection method with high reliability, fast phase selection speed and high sensitivity in the existing phase selection methods based on fault traveling waves or transient quantities.

Images