A GPS-free power grid monitoring system over mobile platforms

In smart grids, the deviation of frequency and phase angle serves as an important indicator of abnormal events, the detection of which is critical to maintain reliable and stable operations of the power grid. However, the high cost and low accessibility of current power grid monitoring systems restrict their large-scale deployment over highly distributed microgrids. In this paper, we present a practical frequency and phase angle monitoring system design over mobile platforms, which significantly reduces the cost of power grid monitoring by utilizing the functionalities of modern mobile devices. We harvest the 200 Hz Primary Synchronization Signal (PSS) embedded in the 4G Long Term Evolution (LTE) cellular signal for time synchronization in power grid monitoring, replacing the Pulse-Per-Second (PPS) signal that is retrieved from GPS receivers and being used by current monitoring systems. We implement our system over realistic smartphones with a few peripheral hardware, and realize a frequency monitoring accuracy of 0.2 mHz and a phase angle monitoring accuracy of 0.01 rad. Experiment results compared with the traditional Frequency Disturbance Recorders (FDRs) verify the effectiveness of our proposed system.