Mains Synchronisation for Thyristor Rectifiers

Grid connected power electronic converters must be synchronized to the mains voltage by using suitable converter control circuit and gate signals, in order to function correctly. Without proper synchronization, the operation of the converter is adversely affected. This paper proposes a method to synchronize power converters to the mains voltage without using a phase-lock-loop (PLL). This is achieved by estimating the magnitude and phase of the positive sequence component of the mains voltage in dq-reference frame. This method offers structural simplicity and immunity to voltage unbalance, mains harmonics, voltage sag etc.