An improved power line signaling technique based anti-islanding protection approach for distributed generation system

To deal with the issues remaining in existing power line signaling technique based anti-islanding protection approach for distributed generation system, this paper proposes the improved schemes for signal generation and detection. By firing the bi-directional thyristors alternately, the signal transformer can be prevented from saturation caused by one directional thyristor firing frequently and the anti-islanding detection can be speeded up by using new signal generation and detection ways. Also, the causes of signal interference were analyzed and the estimation formulas for selecting signal generator device were developed in this paper. It is verified that the detection signal and interference signal can be clearly recognized by simulation and field tests. It indicates that the goal of making detection rate doubled can be achieved without impacting stable operation for signal detection, which provides the theoretical foundation for power line signaling technique based anti-islanding protection widely used in the distributed system. © 2015 Chin. Soc. for Elec. Eng.