Effective ROCOF-based islanding detection technique for different types of microgrid

This article presents an adaptive rate of change of frequency (ROCOF)-based passive islanding detection technique (IDT) to overcome the non-detection zone (NDZ) issue and limitation of existing IDTs. The proposed ROCOF-based passive IDT relies on the settings of the phase-locked loop (PLL) closed-loop control system for frequency, ROCOF, and threshold ROCOF value for the PCC relay-setting calculations. So, the PLL results in alternate frequency and ROCOF output value with respect to the PLL settings modification. The PLL settings can be different in different types of microgrid systems. Therefore, the proposed adaptive ROCOF-based IDT provides a generic solution for islanding detection applications for the safe and reliable operation of different types of microgrid systems. The adaptive ROCOF-based IDT is developed and implemented on two different types of the microgrid systems such as i) generator-based microgrid ii) generator, PV, and storage-based hybrid microgrid in Matlab/Simpower system. Results showed that the proposed IDT successfully detected the islanding condition even with zero power mismatch and it is fully capable to distinguish between islanding (loss of mains and external fault) and nonislanding (internal fault, load switching, motor starting, etc.) conditions with a diverse range of operating conditions.