# Comparative Study of Different Approaches for Islanding Detection of Distributed Generation Systems
## 1 Introduction  
In the present power system with distributed generators (DGs), there are some issues that are not resolved yet. One of these issues involves a fast and very accurate detection of islanding [1, 2]. The number of DGs introduced into electricity distribution systems is increasing day by day, and it is the most challenging concept in modern power system scenarios, since DG islanding can cause degraded proficiency, excellence, reliability and quality of supply [3, 4]. The concept of Distributed Energy Resources (DER) is moving from being a local issue towards a system issue [5]. With the connection of DGs, the power system becomes more complicated [6]. With the introduction of the reference power transition link, the grid connection process is further ensured to be smooth [7, 8]. The main difficulties that researchers encounter are not the lack of data, but the efficiency of usingcomplex electrical quantities [9]. The issue of unintentional islanding in DGs grid interconnection still remains a huge challenge in grid-connected systems, since the system may not succeed at activating the protective devices during the islanded condition [10; 11]. This results in the issues related to the power quality, protection, reverse power flow and system stability [12]. Hence, the condition of islanding must be detected and cleared as fast as possible as per the recommendation of grid codes [13]. The maximum time to respond to the islanding detection is recommended to be 2 s by IEEE [14]. The islanding protection devices being used in the future have to reflect this. Safety measures must be taken for correct operation of these new DGs so as to prevent uncontrolled and undesired power injection into the grid and possible damages to equipment and personnel [15]. Thus, a thorough study is needed in solving this issue. Hence, anti-islanding with fast response time is essential for a DG connected grid system [10; 16]. To overcome the challenges from islanding DGs, researchers proposed a numerous model that deals with the consequences of intentional islanding, and clears it as fast as possible [11; 12; 17; 18; 19; 20; 21; 22; 17; 23; 24; 25; 26; 27; 28; 29]. Different organizations such as the IEEE, IEA and IEC also set the standards and were updated regularly to emphasize the importance of islanding detection in a DG connected grid, so that a DG connected system will operate smoothly [14; 30; 31; 32].  
In this study, the comparative study of different islanding detection is discussed based on the literature review. This paper is intended to study the comparative analysis between two techniques: one traditional auto grounding method, and a relatively new data-mining-decision-tree technique. This study first introduces the issues of islanding detection techniques and its requirements. Section 2 presents the literature review of different topics associated with the concept of islanding and anti-islanding methods, and their comparisons. In Section 3, applied methodologies and approaches are explained. Section 4 presents the research outcome and their discussion. Finally, in Section 5, conclusions are drawn.