US 12,237,663 B2
Line protection method and related apparatus for flexible grounding system of power distribution network
Hongwen Liu, Yunnan (CN); Xianping Zhao, Yunnan (CN); Jindong Yang, Yunnan (CN); Chenchao Chai, Yunnan (CN); Lijun Tang, Yunnan (CN); Ding Nie, Yunnan (CN); Quancong Zhu, Yunnan (CN); Yongjie Nie, Yunnan (CN); Dexu Zou, Yunnan (CN); Shaolei Zhai, Yunnan (CN); and Zhilei Zhang, Yunnan (CN)
Assigned to Electric Power Research Institute of Yunnan Power Grid Co., Ltd, Yunnan (CN)
Filed by Electric Power Research Institute of Yunnan Power Grid Co., Ltd, Yunnan (CN)
Filed on Mar. 9, 2023, as Appl. No. 18/181,482.
Application 18/181,482 is a continuation of application No. PCT/CN2022/124233, filed on Oct. 10, 2022.
Claims priority of application No. 202210492798.0 (CN), filed on May 7, 2022.
Prior Publication US 2023/0361552 A1, Nov. 9, 2023
Int. Cl. H02H 3/16 (2006.01); H02H 3/00 (2006.01); H02H 7/28 (2006.01)
CPC H02H 3/165 (2013.01) [H02H 3/006 (2013.01); H02H 7/28 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A line protection method for a flexible grounding system of a power distribution network, comprising:
outputting a first compensation voltage by a voltage source of a flexible grounding device of each line of a target power distribution network in the case where a ground fault occurs in the target power distribution network, wherein the first compensation voltage is opposite to a fault of a voltage corresponding to the ground fault;
detecting the ground fault by a zero-sequence impedance protection device to calculate the zero-sequence impedance of each line in real time;
after the first compensation voltage is output for a first output duration, adjusting the output voltage by the voltage source of the flexible grounding device to continuously output a second compensation voltage, and exiting from a voltage source compensation mode after the second compensation voltage is output for a second output duration;
calculating the zero-sequence impedance of each line in real time by the zero-sequence impedance protection device, wherein the zero-sequence impedance comprises a maximum zero-sequence impedance and a minimum zero-sequence impedance;
determining a fault line satisfying a zero-sequence impedance protection condition and a zero-sequence voltage protection condition according to the zero-sequence impedance by the zero-sequence impedance protection device, and cutting off the fault line to isolate the ground fault after a preset trip time delay of a line breaker; and
when a case that no case that the line satisfies the zero-sequence impedance protection condition and the zero-sequence voltage protection condition does not exist, the voltage source of the flexible grounding device continues to output the first compensation voltage after a preset compensation time delay.