A detection algorithm for islanding-prevention of dispersed consumer-owned storage and generating units

One of critical concerns in the operation of grid-connected dispersed generating units is the occurrence of islanding. It is known that islanding may pose hazards to electric utility personnel and complicate the orderly reconnection of the grid. Hence, in this paper, a new algorithm, based on the monitoring of the change in ∂f/∂P _L, to detect such islanding is proposed. By the proposed method, a detection index can be evaluated that serves as a useful reference to activate protective relays. This approach has been applied to investigate different scenarios, including loss of grid and parallel operation. The effects of load change and power-quality disturbances on the detection performance are also examined. From these test results, the the feasibility and effectiveness of the approach are shown