Synchronizing low-cost probes for IEC61850 transfer time estimation

The growth of Smart Grids based on the IEC61850 standard makes the communication infrastructure a key factor of a successful application. Due to the distributed nature of the Smart Grid, the evaluation of the main performance indicators requires specialized distributed measurement system with dozens of measuring probes. Clearly, the scalability of the measurement system is tied to the cost of the single probe, and a tradeoff between cost and accuracy is needed. In this paper, the possibility of using low-cost probes for the estimation of the IEC61850 Transfer Time over Smart Grid communication infrastructure is investigated. The key feature to enable distributed measurement is the accuracy of the time synchronization that the probe (based on of-the-shelf microcomputer) can achieve. The paper presents an experimental evaluation of the measuring performance using some probe prototypes attached to an IEE1588 compliant infrastructure: the synchronization extended uncertainty is below 3 μs, and the IEC61850 Transfer Time measurement has an extended uncertainty below 15 μs.