US 10,892,616 B2
Safe processing method for active voltage reduction of ground fault phase of non-effective ground system
Xiangjun Zeng, Hunan (CN)
Assigned to CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY, Hunan (CN)
Appl. No. 16/613,409
Filed by CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY, Hunan (CN)
PCT Filed Jul. 4, 2018, PCT No. PCT/CN2018/094402
§ 371(c)(1), (2) Date Nov. 13, 2019,
PCT Pub. No. WO2019/007348, PCT Pub. Date Jan. 10, 2019.
Claims priority of application No. 2017 1 0550400 (CN), filed on Jul. 6, 2017.
Prior Publication US 2020/0083702 A1, Mar. 12, 2020
Int. Cl. H02H 9/08 (2006.01); H02H 9/00 (2006.01)
CPC H02H 9/002 (2013.01) 10 Claims
OG exemplary drawing
 
1. A safe processing method for active voltage reduction of a ground fault phase of a non-effective ground system, for use in safe processing of a ground fault of a neutral point non-effective ground generator or distribution network, wherein
non-effective ground system side windings of a transformer are provided with a plurality of shunting taps, serial numbers of shunting taps of each phase are defined to sequentially increase from a neutral point to an output, the shunting tap X is short-circuited to a ground to force an output voltage of the phase to be Ux=E·(N−Nx)/N, and the larger serial number of the shunting tap short-circuited to the ground is, the lower the output voltage of the corresponding fault phase is;
when a single-phase ground fault occurs, a transformer shunting tap is selected according to a target value U2 of a voltage reduction operation of the ground fault phase, and selected the shunting tap with a smallest serial number, selected according to the fact that the number of turns of coils from the neutral point to the shunting tap is greater than N−N·U2/E, is short-circuited to the ground to implement safe operation processing of active voltage reduction,
wherein E is a power phase voltage, N is a total number of turns of coils of each phase of winding, Nx is a number of turns of coils from the shunting tap X to the neutral point in a fault phase winding, the target value U2 of the voltage reduction operation of the ground fault phase is (0, U1), and U1 is a fault phase voltage before the shunting tap is short-circuited to the ground.