A Software-based Low-Jitter Servo Clock for Inexpensive Phasor Measurement Units
For researchers and engineers building low-cost PMUs, this work offers a software-only solution to improve synchronization accuracy, though it is incremental in nature.
The paper presents a software-based servo-clock for low-cost PMUs that uses a PI controller to minimize synchronization error, achieving good long-term stability without dedicated hardware. The implementation on a BeagleBone Black board tracks a PPS reference with reduced jitter.
This paper presents the design and the implementation of a servo-clock (SC) for low-cost Phasor Measurement Units (PMUs). The SC relies on a classic Proportional Integral (PI) controller, which has been properly tuned to minimize the synchronization error due to the local oscillator triggering the on-board timer. The SC has been implemented into a PMU prototype developed within the OpenPMU project using a BeagleBone Black (BBB) board. The distinctive feature of the proposed solution is its ability to track an input Pulse-Per-Second (PPS) reference with good long-term stability and with no need for specific on-board synchronization circuitry. Indeed, the SC implementation relies only on one co-processor for real-time application and requires just an input PPS signal that could be distributed from a single substation clock.