Development of frequency-based anti-islanding protection models for synchronous distributed generators suitable for real-time simulations

This study proposes simulation and analytical models of frequency-based protection functions (under and over frequency, rate of change of frequency and vector surge) used to detect islanding of synchronous distributed generators. All relay models are validated by using the concept of performance curves and two commercial relays. By using the performance curves, it is possible to make a comparison between the models and the commercial relays for a large number of islanding situations. In addition, the simulation models are suitable for real-time analysis. A real time digital simulator operating in a closed-loop mode is used to run the simulations and data acquisition. The results indicate that the models and commercial relays present a similar behaviour, showing that the models are able to properly simulate the commercial relays for islanding detection analyses of distributed generators, being acceptably accurate.