Anti-islanding today, successful islanding in the future

Distributed generation (DG) is gaining popularity in the United States and across the world. The Florida Public Service Commission recently passed rules encouraging the use of renewable resources. Integrating DG with the utility network poses challenges for anti-islanding schemes. These schemes detect islanding conditions and trip the DG. Fig. 1 shows a typical network configuration for DG installations. Failure to trip islanded generators can lead to problems such as threats to personnel safety, out-of-phase reclosing, and degradation of power quality. This paper discusses a wide-area measurement-based islanding detection scheme (IDS_WA) that uses time-synchronized measurements to calculate the slip frequency and acceleration between two systems to detect islanded conditions. The proposed scheme has significant advantages compared to traditional anti-islanding schemes, specifically when the power mismatch is minimal. Local-area measurement-based schemes (IDS_LA) complement the IDS_WA. The paper also discusses the use of a real-time digital simulator to model DG along with the rest of the system to validate the proposed anti-islanding scheme. The paper shows the performance of the scheme for different system configurations and load flow conditions. The paper presents a successful islanding scheme that monitors the system power exchange, takes remedial actions when islanding occurs, and maintains quality of service in the islanded system.