Composite voltage protection method for non-phase interline earth fault of double-circuit lines based on zero sequence current actual measurement of adjacent lines

Abstract

The invention discloses a composite voltage protection method for a non-phase interline earth fault of double-circuit lines based on zero sequence current actual measurement of adjacent lines. The method includes the steps of measuring the fault phase voltage, fault phase voltage abrupt change, fault phase current, fault phase current abrupt change, zero sequence current and two fault phase voltage at the protection installation part of a circuit line I of double parallel-circuit lines on same tower, calculating the zero sequence phase angle, zero sequence current of a circuit line II, calculating the fault phase voltage of the circuit line I under normal operation, and determining whether the fault phase voltage abrupt change amplitude at the protection setting scope of the circuit line I is smaller than the fault phase voltage amplitude of the circuit line I under normal operation so as to decide whether to send trip-out signals or not. Only the electrical amount of single-end single circuit line is used, and the method is good in adaptation capability. The influence of interline zero sequence mutual inductance on protection action performance is eliminated, and the hardware design of a protective relaying device is simplified. No protection dead zone for a non-phase interline earth fault in a positive outlet exists, and error action of a non-phase interline earth fault in a reverse outlet is prevented.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a composite voltage protection method for non-identical phase cross-line grounding faults of double-circuit lines based on the zero-sequence current measurement of adjacent lines. Background technique [0002] The double-circuit line paralleled on the same pole has a small footprint, low cost, and stable and reliable operation when connected to the grid. It has become a common transmission line connection method in the power system. There is zero-sequence mutual inductance between double-circuit lines on the same pole, and the zero-sequence mutual inductance affects the zero-sequence compensation coefficient, thereby generating additional impedance. The additional impedance caused by the zero-sequence mutual inductance will cause the fault impedance measured by the protection device to be greater than the actual fault When a ground fault occurs near...

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 for a ground fault at the outlet in the opposite direction of protection, and the larger the transition resistance is, the easier it is for the protection to malfunction when there is a ground fault at the outlet in the opposite direction.

[0005] Due to the strong zero-sequence mutual inductance between double-circuit lines on the same pole, the existing single-phase grounding distance protection cannot obtain the zero-sequence current of the other circuit, and the algorithm model cannot eliminate the influence of zero-sequence mutual inductance between lines. Due to the influence of zero-sequence mutual inductance between lines, when the traditional single-phase grounding distance protection is applied to parallel double-circuit lines on the same pole, its protection range will be greatly expanded. Faults in the protection setting range often have steady-state overshoots, which makes it easy for faults outside the protection area. Misoperations may easily cause a large shift of power flow and cause large-scale power outages

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