Research on the Effects of Grid-Forming Control on Islanding Detection Effectiveness of Distributed Energy Resources

With the proliferation of Distributed Energy Resources (DER), advanced inverter functions such as Grid-forming (GFM) have been developed. Aiming to maintain the frequency and voltage stability, such functions, however, may deteriorate the effectiveness of islanding prevention. This issue has not yet been thoroughly studied and the impact of GFM on active islanding detection schemes remains unclear. To fill the void, this paper evaluates the performance of the widely used Slip-Mode Frequency Shift (SMS) method operating together with the classic droop control. The relationship between main electrical quantities in a typical islanded operating system is firstly investigated, and its small-signal state space model with the droop and SMS control is derived. Based on this model, eigenvalues and sensitivity of key parameters are analyzed, and the effect of droop control on the detection effectiveness of SMS is investigated. In addition, the range of SMS coefficients to guarantee a successful islanding detection under the droop control is characterized. Finally, Matlab/Simulink simulation is performed to validate the above analysis. Results show that parameters dominating the effectiveness of islanding detection include the Q-v coefficient of droop control and the SMS coefficient. Additionally, the SMS coefficient should exceed 0.72 to guarantee an islanding prevention in the studied system.