A Comprehensive Survey on Islanding Detection Methods of Synchronous Generator-Based Microgrids: Issues, Solutions and Future Works

Nowadays, the penetration of distributed generations (DGs) and microgrids (MGs) has been significantly increased due to the technical, social, environmental, and financial reasons. One of the most common types of DGs which is widely used in different networks is small-scale synchronous generators (SSSGs). Synchronous-based microgrids (SGBMGs) and SSSGs can operate under both grid-connected and islanded conditions. To guarantee a stable, uninterruptible, and safe autonomous operation, the unintentional islanding events should be quickly detected and then, appropriate control and precaution actions should be performed. Various islanding detection techniques have been proposed in the two past decades including remote and local methods. Meanwhile, local methods can be divided into two major groups, i.e. passive and active methods. To select the most suitable islanding detection scheme (IDS), various factors including the DG type and its technology should be considered. Therefore, the IDS for SGBMGs may be completely different from that for inverter-based microgrids. In this paper, the suitable IDS which can be practically applied to the SGBMGs are comprehensively investigated. To do so, at first, various suitable indices are introduced which can be properly employed by the system engineers and researchers to compare various IDS and select the most appropriate one. Then, various types of existing IDS are carefully investigated using these indices. Based on these investigations, it is concluded that local passive methods are more appropriate for SGBMGs due to their technical and economic benefits. Moreover, to enhance the existing IDS, some ideas are provided in this paper which can be considered in the future research works.