Transmission line grounding distance protection stage iii protection method

Abstract

The invention discloses a power transmission line grounding distance protection III segment protection method. The method is characterized in that grounding fault phase voltage, grounding fault phase current, grounding fault phase negative sequence current, and zero sequence current of a power transmission line protection installation part can be measured; a grounding arc voltage phase can be calculated by using the phase of the grounding fault phase negative sequence current, and a grounding arc voltage amplitude of a power transmission line grounding fault point can be calculated, and a voltage amplitude variable quantity corresponding to a power transmission line grounding fault front / rear grounding fault point can be calculated, and then the grounding distance protection III segment protection criterion can be formed by using the voltage amplitude variable quantity corresponding the grounding fault point and the power transmission line rated phase voltage amplitude. The power transmission line grounding distance protection III segment protection criterion can be formed by using the grounding arc voltage amplitude characteristic of the power transmission line grounding fault point, and in principle, the influence of the additional impedance caused by the transition resistance on the grounding distance protection III segment protection motion performance can be eliminated, and then the capability of tolerating the strong transition resistance and the strong load current influence can be provided, and therefore the power transmission line grounding distance protection III segment protection correct motion can be guaranteed, the power grid flow big transfer caused by the back-up distance protection motion can be effectively prevented, and the safety and stability of the operation of the power grid can be enhanced.

Description

technical field [0001] The invention relates to the technical field of impedance distance protection of electric power systems, in particular to a protection method for section III of grounding distance protection of transmission lines. Background technique [0002] Traditional earth impedance distance protection measures fault impedance z relay The calculation formula is because therefore That is, traditional grounding impedance distance protection measures fault impedance z relay The calculation result of is composed of two parts: one part is the fault impedance xz that reflects the real fault distance 1 , the other part is the additional impedance caused by the transition resistance In the above formula, is the ground fault phase voltage; is the voltage at the ground fault point; is the ground fault phase current; is the zero-sequence current; φ is the ground fault phase: A phase, B phase, C phase; z 1 is the positive sequence impedance of the transmis...

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Problems solved by technology

[0003] The additional impedance generated by the transition resistance will cause the refusal or malfunction of the impedance distance protection. The refusal of the protection will make the fault unable to be isolated from the grid in time, which is not conducive to the stable operation of the grid; Transfer, and then lead to the occurrence of large-scale power outage accidents

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