Trade‐off design ofpositive‐feedbackbased islanding detection

Abstract

Background: Positive feedback (PFB) based anti-islanding schemes have gained wide popularity in islanding detection. However, the disturbance injected by the PFB methods can easily cause the destabilization of the gridconnected distributed generation (DG) system. Therefore, how to effectively balance the normal operation of the grid-connected system and the effectiveness of the islanding detection is essential. Purpose: In this study, the trade-off design of the PFB control gain is given, where the requirements of grid-tied control and islanding detection are simultaneously considered. Design/Method: Firstly, the small-signal models are established to investigate the stability of a DG system in both islanded and grid-connected mode. Meanwhile, the minimum and maximum PFB gains are obtained by root loci method, thus, the PFB gain can be accurately determined without trial and error. Additionally, the Sensitivity analysis is conducted for the DG system. Factors such as grid impedance, phase-locked loop (PLL) bandwidth, proportional-integral (PI) controller gains, inverter output current rating, and load quality factor are thoroughly taken in account, which provides the guideline of the PFB gain design. Finally, simulations and experiment tests are performed to confirm the theoretical analysis. Results: This paper presents a trade-off design of the PFB control gain for a DG system from the essence of the PFB algorithm. The essence of PFB as well as the cause of the interconnected system instability are revealed. In addition, the minimum and maximum PFB gains are obtained by the stability analysis. Conclusions: A high PFB gain will contribute to the islanding detection but deteriorate the grid-connected system stability. Further, it is found that 1) the maximum PFB gain decreases with the grid impedance increasing, 2) the increase in PLL bandwidth and the integral gain in current loop lead to a decrease in the maximum PFB gain, 3) the minimum PFB gain which reflects

Enhancing grid resiliency in distributed energy systems through a comprehensive review and comparative analysis of islanding detection methods

“…Thus, it can be concluded that the approach experiences less interference from the reactive load characteristics once the voltage is less affected by the reactive power flow of the grid. Conversely, the primary drawbacks of the SVS are its effects on inverter stability and decrease PQ 131 . A MSVS that employs an exponential change in the gain of the voltage positive feedback was presented by 132 in an attempt to lessen the method's shortcomings.…”

Anti-Islanding Techniques for Integration of Inverter-Based Distributed Energy Resources to the Electric Power System

“…The same considerations can be generalized for the remote techniques and for those that do not insert any disturbance on the PCC variables. The hybrid and the active solutions, by the other hand, are inherent linked to perturbation insertion and, therefore, have the potential to negatively impact inverter stability, especially those that use positive feedback [62]- [63].…”

“…On the other hand, the main disadvantages of the SVS are the power quality degradation and the impacts on the inverter stability [63]. In order to diminishes the method drawbacks, [140] proposed a Modified Sandia Voltage Shift (MSVS) that uses an exponential adjustment in the gain of the voltage positive feedback.…”