A Fault Identification Method Based on the Characteristic of Cross-correlation Coefficient of Single Modulus Current Waveform

Abstract

The invention discloses a fault identification method by using cross correlation coefficient features of a single current modulus waveform. The method comprises specific steps: 1, three-phase current i< phi >(k) (phi=A, B and C, and k=0, 1, 2,...,N) during a line voltage sag period is acquired, phase-mode transformation is carried out, mode current i<m><(0)>(k), i<m><(1)>(k) and i<m><(2)>(k) and combined current i<n>(k), i(k) and i<q>(k) are obtained through calculation; 2, a waveform cross correlation coefficient rho<lambda> (lambda=1, 2, 3,...,6) between the three-phase current i< phi >(k) (phi=A, B and C) and the combined current i<n>(k), i(k) and i<q>(k) and single modulus current i<m><(1)>(k) is calculated; 3, the number when the waveform cross correlation coefficient between the three-phase current i< phi >(k) (phi=A, B and C, and k=0, 1, 2,...,N) and the corresponding combined current i<n>(k), i(k) and i<q>(k) and the one modulus current i<m><(1)>(k) is one is used for realizing fault type identification; and 4, on the basis of the step three, the waveform cross correlation coefficient features between the three-phase current i< phi >(k) (phi=A, B and C, and k=0, 1, 2,...,N) and the corresponding combined current i<n>(k), i(k) and i<q>(k) and the one modulus current i<m><(1)>(k) is used for realizing fault phase identification. According to the fault identification method of the invention, the single current modulus through phase-mode transformation can reflect all fault types, the method has a simple principle, the calculation amount is small, the identification accuracy is high, and the method can be applied to engineering practice easily.

Description

technical field [0001] The invention belongs to the technical field of electric energy quality detection methods, and relates to a fault identification method utilizing the characteristics of the cross-correlation coefficient of a single modulus current waveform. Background technique [0002] Voltage sag is one of the most serious power quality problems in power systems, and voltage sag has become the most serious dynamic power quality problem that affects the normal and safe operation of many electrical equipment. Among them, the short-circuit fault is one of the main factors causing the voltage sag in the distribution network. Quickly and accurately identifying the fault phase is helpful for accurate compensation of the voltage sag by phase to meet the higher requirements of users. [0003] At present, many scholars at home and abroad have conducted various related researches on the identification of fault types that cause voltage sags in distribution networks, which are m...

AI Technical Summary

Problems solved by technology

The frequency domain method, that is, the symmetrical component method, can reflect all fault types with only one sequence component, but complex operations are required to calculate the sequence component, resulting in a large increase in the amount of calculation, which is not conducive to the improvement of the relay protection action speed

The time-domain method, the instant-domain fault phase selection method, usually uses the phase-to-mode transformation matrix of Clarke and Karenbauer to calculate the modulus to complete the fault phase selection. Although the required data window is short and the calculation speed is fast, it cannot use a single modulus to reflect all fault types

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