Analysis and improvement for WXH-802 distance protection malfunction;

Analysis on the reason of the differential protection malfunction of the start & stand-by auxiliary transformer

Analysis and disposal of primary transformer protection misoperation;

Analysis of the main transformer differential protection misoperation for the failure outside of the region;

Due to manufacturing defects in some equipment,many problems were discovered during the on-site electrical test,such as structure defects and protection misoperations,etc.

Malfunction analysis and improvement measure of closed abrupt direction high frequency protection on closing the ring;

Discussion of high frequency protection against disturbance for substation;

The analysis for false action of high frequency protection and its anti - accident measure;

Analysis of abnormal operation of 220 kV high-frequency protection and its countermeasures;

In 220 kV election power system,application of high-frequency protection based on microcomputer is very extensive,and whether its action is right or not directly relative to electric power network s safe operation.

The LZ96 high-frequency protection was used as the quick motion main protection in the whole transmission line.