Estimation of Islanding Events in Utility Distribution Grid With Renewable Energy Using Current Variations and Stockwell Transform

Abstract

This research work has designed an algorithm to identify islanding events using the current signals in a distribution grid interfaced with renewable energy (RE) sources and remote areas. A medianbased islanding recognition factor (MIRF) is designed by processing the current signal using Stockwell transform (ST). A current rate of change of islanding recognition factor (CRCIRF) is computed by differentiating the root mean square (RMS) current concerning time. The MIRF and CRCIRF are multiplied element by element to calculate the current-based islanding recognition factor (IRFC) used to recognize islanding events and non-islanding events. Simple decision rules are used to discriminate Islanding events from the faulty and the operational events by comparing peak magnitude of IRFC with pre-set threshold values. This IDM effectively recognizes islanding events in the presence of noise with 10 dB signal-to-noise (SNR) level. The performance of IDM is established on a practical distribution feeder. Developed work is executed in MATLAB/Simulink.

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

“…ST makes use of the amplitude or phase time–frequency spectrum to help identify disturbances like electrical faults or islanding, as well as to observe local spectral patterns 51 . The ST is used in 40 to assess the inverter output current and produce a MIRF, which is the first step in the Active IDM. To determine the CIRFC, the RMS current is differentiated over time to determine the rate of change of MIRF.…”

“…Lastly, there is yet another class of IDMs based on passive detection that enhances robustness, dependability, and efficiency through the use of SP techniques. These include the following: Mathematical Morphology (MM) 39 , ST 40 , FT 41 , WT 42 , KF 43 , VMD 44 , and EMD 45 .…”

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

“…In this scenario, several design methodologies have been proposed. In [57], for instance, is proved that, for a K designed according to (31) the method is capable of eliminating the NDZ for a range of f Q that goes from 0 to the chosen value of…”

“…In [31] is proposed a based AIP that applies the ST to process the inverter output current and create a medianbased islanding recognition factor (MIRF). The current rate of change of the MIRF is then calculated by differentiating the root mean square current over time to get the currentbased islanding recognition factor (IRFC).…”

“…These methods, however, depend on a high computational burden and on an elevated number of sensors depending on how much are the inputs of the algorithm. Finally, there is another set of AIP methodologies based on passive detection that use signal processing methods to improve durability, reliability, and effectiveness, namely: Fourier Transform (FT) [29], Wavelet Transform (WT) [30], Stockwel Transform (ST) [31], Mathematical Morphology (MM) [32], Kalman Filter (KF) [33], Variation Mode Decomposition (VMD) [34] and Empirical Mode Decomposition (EMD) [35].…”