Generator stator monophase grounding protection by fault component phase angle diffrentiation

Abstract

A single-phase grounding protective method of the fault current component phase ratio type generator's stator, belongs to electric technique field. The method is as follows: adopt half in quadrature wavelet as start tool; collect the zero sequence voltage component at generator terminal and neutral point side as reference electric quantity, the voltage transformer's wiring form adopt standard wiring; the modulus maximum's judging through the wavelet analyzing by which the zero sequence voltage including fundamental wave zero sequence voltage and thrice harmonic zero sequence voltage, is taken as start criterion; according to whether the phase angle ratio of the thrice harmonic voltage increment at the terminal and neutral point side meet the request, judge the whither the generator takes place single phase grounding fault at the interior of stator.

Description

technical field [0001] The invention relates to a generator stator single-phase ground protection method, in particular to a high-sensitivity fault component phase angle ratio difference type generator stator single-phase ground protection method, which belongs to the field of electrical technology. Background technique [0002] At present, most large and medium-sized generating sets adopt the method of ungrounding the neutral point or grounding the neutral point through high impedance (such as the neutral point is grounded through the secondary resistance of the distribution transformer or the neutral point is grounded through the arc suppression coil, etc.). In this case, when a ground fault occurs in the stator winding of the generator, the ground fault current and voltage will mainly depend on the size and distribution of the ground capacitance of the generator stator winding, the winding structure and connection method, and the redistribution of the winding related to th...

AI Technical Summary

Problems solved by technology

However, when the capacity of the unit is further increased, the distributed capacitance of the random group to the ground will increase and the sensitivity of the protection action will be insufficient, especially for the hydro-generator unit.

As the capacitance to ground increases, the sensitivity will decrease accordingly

In addition, the sensitivity of these schemes is also greatly affected by the generator grounding method, which makes the selection of on-site protection schemes more complicated