State Grid Corporation of China

Xj Group Corporation

Xj Electric Co., Ltd

Xuchang Xj Software Technology Co., Ltd.

Yun Gong

Chuankun Ni

Feng Xiao

Shasha Hu

Jidong Huang

Ning Yang

Baowei Li

Yingying Xi

Xu Li

Dongxiao Yao

Heke Ma

Lijuan Lv

Jiansong Zhao

Jingli Zhang

Maojun Deng

Jirui Chen

Hui Tang

Zhiyong Wang

Guangjie Feng

Shusheng Li

Yanhai Zhang

The present disclosure relates to a method for quickly identifying disconnection of a Current Transformer (CT) in protection of a 3/2 connection mode based bus. The present disclosure can quickly and accurately identify the disconnection of the CT, thereby avoiding the problem of a maloperation in protection of a bus caused by the disconnection of the CT.

Method for quickly identifying disconnection of CT in protection of 3/2 connection mode based bus

The present invention relates to a prevention method of abnormal action protection of UHV regulating compensation transformer with no-load input, the prevention method includes: first determining a value of differential current of regulating compensation transformer, if the value of differential current is smaller than a pre-setting threshold, then, identifying whether an uninterruptible point of differential current waveform meets an pre-setting regulation according to original value of differential current or sampling value of differential difference current, and determining comprehensively whether the regulating compensation transformer is in no-load input or in fault directly with a value of second harmonic content of logic differential current together; if a value of differential current before pre-setting period is larger than the pre-setting threshold, the regulating compensation transformer is diagnosed to have external CT saturation, determining comprehensively whether the regulating compensation transformer is in no-load input or in fault by using result of the uninterruptible point after delaying and the value of second harmonic content of logic difference together, and corresponding inactivating or activating differential protection. By using the value of differential current before a pre-setting period, characteristics of the original value of differential current and the sampling value of differential difference current, and second harmonic inrush to discriminate an pre-setting regulation, the present invention can avoid the regulating compensation transformer occurring abnormal action when no-load switching transformer of UHV substation is charging, and isolating the fault quickly when the no-load switching transformer is in fault state.

Prevention method of abnormal action protection of UHV regulating compensation transformer with no-load input

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Xuchang, China

Yun Gong