Fault Phase Selection Method for Mixed Voltage and Same Tower Based on Waveform Correlation Coefficient and Current Mutation

Abstract

The invention discloses a fault phase selection method for mixed voltage and same tower based on waveform correlation coefficient and current sudden change. According to the characteristics that the phase angle and amplitude of the fault phase may change after a fault, the autocorrelation coefficient and virtual autocorrelation coefficient are introduced. When the phase selection element is judged as a single-phase fault by the sudden change of phase current difference, under the influence of the zero-sequence mutual inductance under the connection of the strong magnetic field, the characteristics shown by the above correlation coefficients are used for further auxiliary judgment: first, if there is If the autocorrelation coefficient of the phase is less than -0.9, it is judged as a faulty phase and the phase selection is completed. Otherwise, the virtual autocorrelation coefficient of the suspected faulty phase is further judged. If it is less than -0.9, the phase is judged as a faulty phase and completed. phase selection. Otherwise, the final phase selection result is the same as the phase selection result of the phase current difference sudden change. The invention can avoid the misselection problem of the phase selection element in the sudden change of phase current difference when the cross-voltage non-grounding fault of the four-circuit line of the same tower with mixed voltage occurs.

Description

technical field [0001] The invention relates to the field of electric power systems, in particular to a phase selection method for mixed-voltage and same-tower faults based on waveform correlation coefficients and current mutations. Background technique [0002] With the increasingly tight land resources and the increasing requirements for transmission capacity, the technology of erecting multi-circuit transmission lines with different voltage levels on the same tower (referred to as "mixed voltage and multi-circuit lines on the same tower") has developed rapidly. When a short-circuit fault occurs in a line of a certain voltage level across a line of another voltage level in the four-circuit line of mixed voltage on the same tower (there are two lines of different voltage levels), the phase selection element may have a wrong phase selection due to sudden changes in phase current difference problem (referred to as "misselection"). The cross-voltage faults of the four-circuit...

AI Technical Summary

Problems solved by technology

However, in the existing phase selection methods, there is a lack of an improved scheme for phase selection of phase current difference mutations in the case of misselected phases. Therefore, there is an urgent need in the field for a method that can realize the cross-voltage fault phase current of four-circuit lines on the same tower with mixed voltage. A new scheme for correct phase selection of phase selection element with differential mutation

Images