Same-pole double-circuit line one-phase ground voltage ratio phase protection method based on SV network sampling

Abstract

The invention discloses a same-pole double-circuit line one-phase ground voltage ratio phase protection method based on SV network sampling. The method includes the steps that the fault-phase voltage of a first line, the fault-phase current of the first line, the zero-sequence current of the first line, the voltages of the other two normal phases of the first line and the zero-sequence current of a second line of a same-pole double-circuit line protection installing position are measured; the fault-phase voltage of the first circuit working normally is calculated through the voltages of the other two normal phases of the first line, the fault-phase voltage of a protection setting range of the first line is calculated, whether the phase angle of the fault-phase voltage of the protection setting range of the first line superior to the fault-phase voltage during normal work of the first line is larger than -90 degrees and smaller than 90 degrees or not is judged, and if yes, whether a one-phase ground fault of the protection setting range of the first line is generated or not is judged, and breakers at the two ends of the first line are switched off by a protection device. By means of the same-pole double-circuit line one-phase ground voltage ratio phase protection method based on SV network sampling, the influence of line-line zero-sequence mutual inductive impedance on protection motion performance is eliminated, false operation is avoided, and a good transition resistance and load current influence resistance effect is achieved.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a phase-comparison protection method for single-phase grounding voltage of double-circuit lines on the same pole based on SV network sampling. Background technique [0002] Impedance distance protection reflects the fault distance according to the measured impedance to distinguish whether the fault point is inside or outside the protection zone. Impedance distance protection is less affected by power system operation mode and structural changes, and the electrical quantity used to calculate and measure impedance is the full fault component, which is suitable for transmission line protection during the entire fault process of the line. [0003] Traditional transmission line single-phase ground distance protection assumes that the single-phase ground fault is a metallic short-circuit fault, calculates the measured impedance through the ratio of the fa...

AI Technical Summary

Problems solved by technology

Since the origin of the coordinates is located on the boundary of the action characteristic circle, there is a possibility of misoperation due to a single-phase ground short-circuit fault at the opposite outlet of the protection, and the larger the transition resistance is, the easier it is for the protection to malfunction when there is a single-phase ground short-circuit fault at the opposite direction outlet.

[0005] Due to the strong zero-sequence mutual inductance between double-circuit lines paralleled on the same pole, the traditional substation based on the secondary circuit of the cable, the single-phase grounding distance protection cannot obtain the zero-sequence current of the other circuit, and the algorithm model cannot eliminate the zero-sequence current between lines. Influenced by the zero-sequence mutual inductance and the influence of the zero-sequence mutual inductance between lines, when the traditional single-phase grounding distance protection is applied to double-circuit lines on the same pole, its protection range will be greatly expanded. There are often steady-state overshoots in the protection setting range. It is easy to cause misoperation when there is a fault outside the protection area, and it is easy to cause a large shift of power flow and cause large-scale power outages

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