Islanding Detection for Inverter-Based DG Coupled With Frequency-Dependent Static Loads

Islanding detection is an essential protection requirement for distribution generation (DG). Antiislanding techniques for inverter-based DG are typically designed and tested on constant RLC loads and, hence, do not take into account frequency-dependent loads. In this paper, a new antiislanding technique, based on simultaneous P-f and Q-V droops, is designed and tested under different islanding conditions considering different load types. The behavior of frequency-dependent static loads during islanding operation is discussed. The developed antiislanding technique is designed to fully address the critical islanding cases with frequency-dependent static loads and RLC-based loads. The performance of the proposed method is tested to accommodate load switching disturbances and grid voltage distortions. Theoretical investigation coupled with intensive simulation results using the Matlab/Simulink software is presented to validate the performance of the proposed antiislanding technique. Unlike previously proposed methods, the results show that the proposed islanding detection method is robust to frequency-dependent loads and system disturbances.