A New Hybrid Synchronization PLL Scheme for Interconnecting Renewable Energy Sources to an Abnormal Electric Grid

Today, and especially with the growing interest in distributed renewable energy sources (DRESs), modern electric power systems are becoming more complex. In order to increase DRES penetration, grid side converter (GSC) control techniques require appropriate synchronization algorithms that able detect voltage status as fast accurately possible. The drawbacks of published phase-locked loop (PLL) were structured mainly around slow dynamic responses, inaccuracy extracting fundamental components voltages when they contain a DC offset, worsening imbalance rejection ability facing significant frequency changing. This paper proposes new PLL technique ensuring efficient reliable integration DRESs under normal, abnormal, harmonically distorted conditions. proposed uses mixed second- third-order generalized integrator (MSTOGI) prefiltering stage through its adaptability quality numerous conditions low sensitivity input inter-harmonics. Moreover, modified quasi type-1 (MQT1-PLL), which integrates two compensation blocks for phase amplitude errors, respectively, has been used loop. discussion sizing requirements effectiveness so-called MSTOGI-MQT1-PLL tested imbalances distortions confirmed simulation results compared double second-order (DSOGI-PLL), cascaded delayed signal cancellation (CDSC-PLL), multiple delayed-signal (MDSC-PLL).