Influence of Sampled Data Packet Dropout on Line Differential Protection

Witch-centric Ethernet communication is facing two main problems: time delay and data packet dropout. Sampled data may cause packet dropout events due to physical line faults, equipment faults, network congestion and routing errors during transmission over switching Ethernet. According to the number of loss points of sampled data, packet dropout events are divided into four categories: single-point packet dropout, single multi-point packet dropout, multi-interval single-point packet dropout, multi-interval continuous multi-point packet dropout. When the sampled data point is lost, the fundamental wave of the synthesized phasor is smaller than that without dropout. The more the loss, the greater the deviation between the two, which may lead to maloperation and rejection of differential protection. A simulation model is built in PSCAD / EMTDC, and the influence of packet dropout events on differential protection is demonstrated by examples.