Advanced Synchronization Check Method Using Hilbert Transform-Based Voltage Envelope Analysis

When connecting a generator to a power system in operation, it is important to synchronize the two systems. If the two systems are not exactly synchronized, it causes some instantaneous disturbances that may lead to instability or damage to both systems. In the past, the generator voltage was manually adjusted by an operator to match the system voltage. However, with the use of an auto-synchronizer (Device 25A) and a sync-check relay (Device 25), the synchronization procedure can be performed automatically. The auto-synchronizer controls the generator’s excitation system and speed governor. And the sync-check relay checks the synchronization conditions and sends an electric signal in order to connect the generator to the power system. For safe and faultless synchronizations, the algorithms used for auto-synchronizers and sync-check relays are very important. This paper is written to propose an advanced sync-check method used for Device 25 based on a voltage envelope analysis using Hilbert transform.