State Grid Corporation of China

Xj Group Corporation

Xj Electric Co., Ltd

Xuchang Xj Software Technology Co., Ltd.

Xuchang Xj Software Technologies Ltd

Jiangsu Electric Power Company Research Institute

Xintao Dong

Lei Gao

Chuankun Ni

Xu Li

Yingying Xi

Baowei Li

Xin Shi

Meng Li

Junhong Qiu

Huawei Jia

Jiansong Zhao

Jingwan Liang

Qiang Niu

Huizhen Hao

Wenzheng Li

Shuai Jiang

Yongjian Tao

Yongxin Liu

Yake Xi

Ziqiang Jiang

Yantao Qiao

Feng Li

Quanxia Ma

Yu Tang

Yanmei Tang

Liping Meng

The present disclosure relates to a method for preventing a maloperation of differential protection of an optical fiber caused by saturation of a single Current Transformer (CT) of 3/2 connection. By applying a combination of the differential judgment and the sub-CT current judgment, reliable identification of internal and external faults is ensured, and the problem of misjudging of the internal fault as the external fault can be prevented as well.

Method for preventing differential protection maloperation of optical fiber caused by saturation of single CT of 3/2 connection

The invention relates to a method of differential protection in the power distribution networks based on phase difference principles. The method comprises the following steps: collecting the current and voltage signals of each loading switch; calculating phase difference between the corresponding currents at two adjacent loading switches, wherein at least one of the two adjacent loading switches accords with &#x394;I&#x3e;n&#xb7;&#x394;I+&#x394;I; tripping the two adjacent loading switches if the phase difference corresponding to the two adjacent loading switches being greater than a threshold then a section between the two adjacent loading switches being determined as a fault section. The method only needs to calculate the phase difference between the corresponding currents at the two adjacent loading switches, and achieves the fault determination according to the phase difference being greater than the threshold. The method has low data synchronizing requirements, and processes the fault determination according to the collected signals. The time required for the entirely determining process is short, and a fast protecting response is achieved, thus the problem of slowly protecting response in the existing relay-protection method for the power distribution networks is solved.

Method of differential protection in the power distribution networks based on phase difference principles

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Xuchang, China

Xintao Dong