This paper presents the dual-loop control strategy in the hybrid reference frame for stand-alone single-phase inverters, which applies a capacitor voltage control loop in synchronous reference frame and a capacitor current shaping loop in the stationary reference frame.
[pdf] Droop control is one of the widely used methods that resolve the power sharing problem while maintaining the frequency and voltage of the system constant. Each inverter contains a droop controller connected with outer voltage control and inner current control loop.
[pdf] Anti-islanding protection is a commonly required safety feature which disables PV inverters when the grid enters an islanded condition. Anti-islanding protection is required for UL1741 / IEEE 1547. Knowledge of how this protection method works is essential for today’s PV system designers.
[pdf] 
