Ground fault relay protection method for UHV double-circuit lines paralleled on the same pole based on six-sequence component method

Abstract

The invention discloses a grounding fault relay protection method for UHV same-pole double-circuit lines based on the six-sequence component method. Using distributed parameters and the six-sequence component method to accurately describe the physical characteristics of UHV parallel double-circuit lines on the same pole, calculate the voltage drop amplitude from the protection installation point to the ground fault point of UHV parallel double-circuit lines on the same pole, and use UHV common pole The fault distance from the protection installation point of parallel double-circuit lines to the grounding fault point and the voltage drop amplitude have a hyperbolic tangent function relationship to directly calculate the fault impedance amplitude, and use the fault impedance amplitude and the set impedance amplitude to form the relay protection criterion. The invention eliminates the influence of transition resistance, load current, and zero-sequence mutual inductance between lines on the protection action performance; it adopts distribution parameters and six-sequence component method to model, has natural ability to resist the influence of distributed capacitance current, and is suitable for UHV same-pole Parallel double-circuit line ground fault relay protection.

Description

technical field [0001] The invention relates to the technical field of power system relay protection, in particular to a ground fault relay protection method for UHV same-pole parallel double-circuit lines based on the six-sequence component method. Background technique [0002] According to the "Unified Strong and Smart Grid Research Report" issued by State Grid Corporation of China, 47,000 kilometers of UHV AC transmission lines will be built by 2020, and a state grid pattern with UHV grids as the backbone and coordinated development of power grids at all levels will be basically built. . The establishment of UHV AC transmission lines can realize on-site power generation from coal and hydropower resources, and transmit electric energy in the form of electric energy to economically developed areas through UHV AC transmission lines, thereby helping to alleviate the current situation of electricity shortage in China. [0003] UHV AC transmission lines require wide transmissi...

AI Technical Summary

Problems solved by technology

Considering the influence of distributed capacitance along the line, the relationship between measured impedance and fault distance is a hyperbolic tangent function. The characteristics of the hyperbolic tangent function determine that the impedance relay has poor resistance to transition resistance, and the additional impedance brought by the transition resistance will seriously affect the action of the impedance relay. performance, it is easy to cause misoperation or refusal of protection, which seriously endangers the safety of the power grid

[0009] UHV double-circuit lines paralleled on the same pole have a strong zero-sequence mutual inductance between lines. Affected by the zero-sequence mutual inductance between lines, the traditional grounding impedance distance protection modeled by lumped parameters is likely to trip the normal phase by mistake, causing fault expansion , causing a greater impact on the security of the power grid

[0010] UHV double-circuit lines paralleled on the same pole often carry large-capacity loads and are heavy-duty transmission lines. Heavy-load currents will reduce the action sensitivity of impedance distance protection. The impact of heavy-load current on the action performance of impedance distance protection cannot be ignored.

Images