Research on the SPLL based single-phase voltage sag detection technique

The drop of voltage amplitude and the jump of phase angle are two important parameters of the voltage sag. The design of Dynamic Voltage Restorer (DVR) compensation voltage with voltage sag parameters is discussed and a single-phase sag parameter detection method based on synchronous d-q transformation is proposed in the paper. The transformation needed frequency or phase angle information of the fundamental voltage is provided by Soft Phase Locked Loop (SPLL). By analyzing the responses of SPLL when sag happens, it can be found that the phase synchronous method is suitable for the SPLL used in DVR. The simulation results verify the correctness of the analysis.