Synchronized sampling of process layer in digital substation

It is proposed to issue the unified sampling sync pulse by MU(Merging Unit) to ensure the synchronized sampling of all ECT/EVT(Electric Current Transducers and Electric Voltage Transducers) in one cell. The signal processing system of ECT/EVT divides or multiplies locks the frequency of local clock signal to lock its phase according to the sync pulse and sends the sampling time sequence to every A/D converter. The synchronization scheme of multi-reference clock is designed based on IEEE1588. The performance of synchronization system and the influence of network flow on it are tested and evaluated for clock synchronization between substations, between MUs within substation and between A/D sampling signals in ECT/EVT. It is also proposed to equip the synthetic time meter to online monitor the synchronization performance.