Robust coordinated time for power substation networks via ℓ1-norm regularization

Implementing the process bus (PB) constitutes a milestone in the deployment of smart-grids. It provides the protection and monitoring devices of a busbar with synchronized digital samples of voltages and currents that are collected at the bays and communicated across the power substation (PS). One major deterrent for the implementation of the PB is the absence of a standard technology for the coordination of time sources within the PS. Proprietary IRIG-B and pulse-per-second (PSS) coordination schemes have been developed, which do not take advantage of the ethernet deployed for the PB. The precision time protocol (PTP) offers a packet-based solution for synchronization, but does not capitalize on the full information provided by the multiple PS clocks, and it suffers of the time-jump effect when grandmasters are switched. We propose a coordination method to average time references in a PS of campus scale, utilizing components of the PTP standard for interoperability and legacy compatibility. The main novelty of the paper is the incorporation of sparsity-aware statistical tools for outlier rejection that result in an automatic rule to include or discard the references received from each master clock.