A load and single-phase-to-ground fault identification method based on voltage plane

Abstract

A voltage plane-based load and single-phase ground fault recognition method. The method comprises the steps of: determining a phase compensation voltage U̇'φat a relay location and a positive sequence compensation voltage U̇'φ１ takingaφ phase as a reference at the relay location; determining movement tracks of the phase compensation voltage U̇'φ at the relay location and the positive sequence compensation voltage U̇'φ１ takingtheφ phase as a reference at the relay location; and judging whether a fault occurs by comparing the phases of the movement tracks of the phase compensation voltage U̇'φ at the relay location and the positive sequence compensation voltage U̇'φ１ takingtheφ phase as a reference at the relay location. The method can improve the action performance of the existing power transmission line distance protection during overload, which is of great importance to a safe and stable operation of a grid and to limiting the expansion of the scope of an accident.

Description

Technical field: [0001] The invention relates to a fault identification method, in particular to a voltage plane-based load and single-phase ground fault identification method. Background technique: [0002] In the ultra-high voltage transmission line, the increase of its transmission capacity and the transfer of the load after the line fault will cause the overload of the transmission line, and the overload of the transmission line will affect the action performance of the distance protection (especially the distance protection section III). When the load impedance When it is less than the set impedance of the distance protection, the distance protection will malfunction, resulting in the expansion of the scope of the accident, and in severe cases, a large area of ​​power failure will be caused. [0003] Aiming at the problem that the distance protection may malfunction under overload, the current measures are mainly to set the load limit line on the impedance plane to avoi...

AI Technical Summary

Problems solved by technology

[0002] In the ultra-high voltage transmission line, the increase of its transmission capacity and the transfer of the load after the line fault will cause the overload of the transmission line, and the overload of the transmission line will affect the action performance of the distance protection (especially the distance protection section III). When the load impedance When it is less than the set impedance of the distance protection, the distance protection will malfunction, resulting in the expansion of the scope of the accident, and in severe cases, it will cause a large area of ​​power failure.

[0003] Aiming at the problem that the distance protection may malfunction under overload, the current measures are mainly to set the load limit line on the impedance plane to avoid the load, but this method will sacrifice the sensitivity of the distance protection. As the load continues to increase, the distance The action area of ​​the protection will be greatly reduced. For a single-phase ground fault, due to the large range of transition resistance, when the transition resistance is large, due to the influence of the load limit line, the distance protection will refuse to operate, and the distance protection's ability to withstand transition resistance significantly weakened

[0004] In addition, the load limit line needs to be set manually; in the case of overload, if the setting is unreasonable, it will cause mis-setting accidents

[0005] To sum up, due to the limitations of avoiding the load by setting the load limit line on the impedance plane, it is impossible to completely solve the problem of misoperation of the distance protection when it is overloaded.

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