Intelligent Reflecting Surface Aided Wireless Clock Synchronization for Indoor Substation

The intelligent revolution in substations desires wireless networks to provide high-precision timing services while ensuring clock synchronization among intelligent electronic devices (IEDs) to support the collaboration of time-sensitive grid applications, such as phasor measurement unit (PMU), saving the cost on disposing communication elements and timing elements for the IED separately. However, the unreliable nature of the wireless network in the indoor substation may give rise to the loss of timestamp packets, which plays a negative role in the clock synchronization accuracy. This paper constructs a novel intelligent reflecting surface (IRS)-aided wireless clock synchronization framework to solve the aforementioned problem. First, an IRS-assisted incomplete observation clock synchronization model is established based on the two-way timestamp exchanging mechanism. Then quantitative analyses of the relationship between the reliability of the wireless channel and the steady-state clock synchronization estimation error covariance are given. In addition, we formulate a clock synchronization optimization problem to balance the system clock synchronization accuracy and fairness among IEDs. In the case of obtaining the Pareto fronts, the proposed clock synchronization framework outperforms the other representative methods, since IRS brings out more reliable transmission of timestamp packets when serving multiple IEDs.