An Open-Loop Synchronization Technique With Simple Structure for Phase Error Compensation and Frequency Estimation

The open-loop synchronization technique (OLST) features unconditional stability and fast dynamic performance. However, the estimated phase and amplitude errors occur in presence of the grid frequency drift. Moreover, the frequency prediction method recommended in literatures is complicated. To overcome these problems, this letter proposes a simple solution, which obtains the phase error by comparing the filtered signals with the original ones, and the frequency drift can be easily derived from the phase error. The proposed technique not only inherits the advantages of OLST but also enhances the adaptability to frequency and phase angle drifts. The effectiveness of the proposed OLST is verified by the experimental results.