Accurate arc extinction method for single-phase earth fault of small-current grounding system

Abstract

The invention discloses a small-current grounding system single-phase grounding fault accurate arc extinction method, which comprises the following steps: step 1, when judging that a grounding fault occurs, calculating to obtain a fault point residual current Ig; 2, injecting current or voltage into the small-current grounding system, and calculating residual current Ig of a fault point in real time; step 3, adjusting the injection value of the current or the voltage according to the change of the residual current Ig of the fault point, and if the Ig is reduced, continuing to adjust the injection value in the original direction; if the Ig is increased, the injection value is adjusted in the reverse direction; setting a threshold value, and if the threshold value is greater than the threshold value, continuing to adjust the injection value; if yes, adjustment is ended, and the current injection value is maintained. The arc extinction method can solve the problem that single-phase grounding at the tail end of a heavy-load long line cannot be accurately compensated.

Description

technical field [0001] The invention belongs to the field of relay protection of power systems, and particularly relates to a method for precise arc suppression of single-phase grounding faults in a low-current grounding system. Background technique [0002] In the 3kV-66kV small current grounding system (also known as the neutral point non-effective grounding system), single-phase grounding is a more common type of fault. When a single-phase grounding occurs in a small-current grounding system, the fault-to-ground voltage decreases, the non-fault-to-ground voltage increases, and the line voltage is still symmetrical. 2h. However, due to the non-fault phase arc overvoltage, it is easy to cause the breakdown of the weak insulation, the saturation of the voltage transformer core, the system overvoltage, and the fault phase arc burns the cable, which is easy to cause personal electric shock injuries and other problems. It is necessary to isolate the single-phase ground fault ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide an accurate arc suppression method for single-phase grounding faults in small current grounding systems, which can solve the problem that single-phase grounding at the end of heavy-duty long lines cannot be accurately compensated

Images