Online monitoring method and system for operating state of secondary current circuit neutral line

An online monitoring method for an operating state of a secondary current circuit neutral line, comprising:

• collecting neutral line current, by a high-precision sensor, and processing the collected neutral line current through a composite filtering algorithm to obtain fundamental components of secondary currents of each of neutral lines in a substation free from influences of harmonics and transients, and uploading the fundamental components to a protection information master station;
• retrieving information from an original configuration connected to the protection information master station to acquire three-phase secondary current circuit information of each bay in the substation, summarizing secondary current information of all monitoring ranges, and performing grouping and classification marking by substation, bay and winding;
• and
• conducting operation and analysis through collected information, automatically identifying and confirming an operating state of a line first, and calculating a linearity of outlier deviation and continuous dynamic trend deviation degree of each winding in each bay according to the operating state.