Research on fast phase synchronization in single-phase power systems

The prompt and accurate phase detection is an essential qualification for the control of power converters. Aiming at the shortcomings of the traditional single-phase PLL such as long response time and inability to operate properly under distorted utility conditions, a novel fast synchronization method is provided based on Park transformation, which is capable of processing utility network signals containing sudden, simultaneous changes of the amplitude, phase and frequency, as well as eliminating phase errors due to harmonics by adopting the Delayed Signal Cancellation (DSC) scheme. An accurate generation method of imaginary orthogonal signals based on mathematical deduction is introduced first, and then the accuracy of phase synchronization is improved in the rotating coordinate system. A real-time open-loop phase synchronization method is further proposed, which requires no self-tuning closed-loop control process and therefore significantly enhances the real-time performance. Finally, the DSC method is utilized to effectively suppress the phase errors due to harmonics. Experiments under different operating conditions validated the proposed phase synchronization method and its fast and accurate qualities, as well as the adaptive performance even in harsh utility environments.