###### Abstract  
Nowadays, the integration of distributed generators with the main utility grid is highly increasing due to the benefits which can be obtained, such as increasing the system efficiency and reliability. Apart from that, many technical and safety issues appear in the system due to this integration. One of these issues is the islanding condition, which has to be detected effectively and quickly before having any detrimental effects on the protection, stability, and security of the system. This study provides a detailed overview of several islanding detection approaches, which are divided into traditional methods, including local and remote methods, and modern methods, including methods based on signal processing and computational intelligence. Moreover, a comparison between each method based on various criteria, such as non-detected zone, quality factor, response time, implementation cost, degrading power quality, reliability, suitability for the type of distributed generators, suitability for multi-distributed generators system, and sensitivity to cyber-attacks, is carried out. Therefore, this review will offer a solid background in order to help researchers interested in this field distinguish between islanding detection methods and their relative advantages and disadvantages, as well as to be able to choose the most suitable islanding detection method among the others to be implemented in the network. point of common coupling; distributed generation; islanding detection +
Footnote †: journal: Expert Journal  
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In this case, this phenomenon has to be sensed during the absence of utility-controlled generation to cease energizing the grid. Otherwise, if the generation in the islanding area operates exceeding the normal voltage and frequency levels, the equipment can be damaged, and the energized lines can cause a shock hazard to workers who think the lines are not energized. Islanding can occur either intentionally or unintentionally. The system is well-designed to handle the parameters altering in the case of intentional islanding, and the DG controls the fluctuating voltage and frequency. The DG is not suited to manage the voltage and frequency when the islanding is unintentional. The distribution grid continues to receive power from the DG even though the voltage and frequency may have exceeded the permitted limits, opening the switching mechanism between the DG and the rest of the utility grid. Numerous islanding detection techniques have been developed and proposed. The islanding detection methods can be broadly divided into two groups: traditional methods and modern methods. These include active, passive, and hybrid local islanding detection methods, remote islanding detection methods, signal processing-based methods, and computationally intelligent-based methods. The local methods basically depend on measuring the parameters of the system at the DG, whereas remote methods rely on the main grid and DG's communication link. Signal processing-based methods depend on feature extraction, and computational intelligent methods depend on data training and pattern recognition. The methods used to detect islanding still have several limitations and downsides, such as the failure to detect islanding when a non-detected zone (NDZ) is present, the issues related to system stability and power quality, false operation in case of multiple DG, the requirement of installing additional equipment or circuits, and high implementation cost.To get over these restrictions and downsides, more islanding detection method research and development is needed [1]. Reviewing the widespread usage of islanding detection techniques in DG grid-connected systems is the primary goal of this work. Each islanding technique's fundamental work will be presented. Moreover, a comparison based on the advantages and disadvantages  
Figure 1: Islanding Mode in Micro-grid. of each method is carried out. Later on, a conclusion is provided.