Method and device for limiting secondary arc current of extra-high voltage same tower double circuit line

Abstract

The invention provides a method for limiting secondary arc current of an extra-high voltage same tower double circuit line, which comprises the following steps: when the extra-high voltage same tower double circuit line has single phase earthing faults, judging the type of the single phase earthing faults; selecting a neutral point low electric impedance value corresponding to the current fault type according to the type of the single phase earthing faults; and switching the extra-high voltage same tower double circuit line to the neutral point low electric impedance value corresponding to the current fault type, thereby selecting corresponding neutral point low electric impedance value according to the type of the concrete single phase earthing faults generated by the power transmission line, thus the resistance of neutral point low electric impedance is not fixed, but changes along with the operating condition of the power transmission line, namely the resistance of neutral point low electric impedance is controllable; and when the operating conditions of the extra-high voltage same tower double circuit line are different, neutral point low electric impedance with optimal resistance can be selected to be accessed to the power transmission line, thereby effectively limiting the secondary arc current generated by the single phase earthing faults.

Description

technical field [0001] The invention relates to the technical field of UHV relay protection, in particular to a method and device for limiting the submerged current of UHV double-circuit lines on the same tower. Background technique [0002] According to the operating experience of my country's 220kV and 500kV power grids, single-phase ground faults account for 80-90%, and for single-phase ground faults, the success rate of single-phase reclosing is above 80%. Therefore, the operation practice of power grids with voltage levels of 220kV and above in my country shows that the widespread use of single-phase reclosing technology is an important measure to ensure the safe and stable operation of the power grid. Therefore, single-phase reclosing technology is also used in my country's UHV AC transmission system. [0003] However, when one phase of the UHV line is cut off due to a single-phase ground fault, due to the coupling effect of mutual inductance and capacitance between p...

AI Technical Summary

Problems solved by technology

However, the latent supply current and recovery voltage are still much larger than those of single-circuit lines

On the other hand, under the condition of small reactance at the neutral point with fixed resistance, the submerged supply current is relatively large when the phases with the same name and different names of the two circuits fail, and whether it can meet the requirements of reclosing for about 1s still needs to be verified by experiments

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