Time in Communication Networks, Protection and Control Applications – Time Sources and Distribution Methods

In conventional protection and automation control systems (PACS), a common time reference is used to identify the sequence of events. This helps operators and engineers to analyze and understand the system events. In recent years, with the adoption of IEC 61850-based PACS, a high accuracy common time reference is required for aligning digitized measurements from instrument transformers. Wide area control and monitoring applications based on IEEE C37.118 synchrophasor also require a high accuracy time synchronization to participating phasor measurement units (PMUs). Traveling wave-based applications such as fault location detection and time-domain protection demands a time synchronization accuracy of better than 1 microsecond. The recent development of many applications based on the industrial internet of things (IIOT) infrastructure in the power sector also requires time-synchronized sensor data. Many applications such as automated control, system stability analysis, and prediction, use time-synchronized sensor data. In power communication networks, a synchronized frequency is needed to ensure correct transmission.