International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-2, Issue-6, January 2014 94 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Pvt. Ltd. Abstract— Micro-grids usage among consumers has become a new attraction due their several of advantage. Its major function is to ensure the stable operation during the fault and a variety of utility grid disruption. Since the utilization of micro-grid became common, the correct application and operation of micro-grid is importance and significant. One of the main challenges in micro-grids operation is islanding detection methods. There are several methods that are handles the islanding detection that each one have advantage and some disadvantage. This paper presents and investigates the Reactive Power imbalance Method for islanding detection. The passive algorithm implements in this paper due to the low cost operation, however it got the higher non-detection zone (NDZ) and slower response time compare some active methods. The micro-grid simulation is modeled in Matlab/Simulink program and the results of the monitoring are discussed as well. As the result, the performance of the Reactive Power Imbalance method for the islanding detection state is compared with the simulation model without control algorithm. Finally, the micro-grid model capability with control algorithm is shown in order to meet the load demand. Index Terms—Micro-grid, Islanding Detection, Passive method, Distributed Generation. I. INTRODUCTION Micro-grid is a small power system that does not have transmission line. Micro-grid system is also known as a stand-alone system that has its own generator, controller and load. The generator of a micro-grid system is also known as Distributed Generator (DG). DG is a small source which is producing energy located at or nearly the point of use in micro-grid. DG typically includes internal gas turbines, micro-turbines, photovoltaic, fuel cells and many types of renewable energy [1, 2]. This micro-grid and utility grid such as Tenaga Nasional Berhad (TNB) in Malaysia supplies the same load as shown in Fig 1. The demand on the power supply is being shared by the DG. Both the DG and the utility grid are connected at the Point of Common Coupling (PCC). When the fault occurs in the utility grid, the islanding switch will open. At this point, micro-grid will tend to perform the operations of an islanding mode. Manuscript received January, 2014. Meysam Shamshiri, Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Durian Tunggal, Malaysia. Ahmad Farid Sapar, Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Durian Tunggal, Malaysia. Chin Kim Gan, Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Durian Tunggal, Malaysia. Revinnath Tengga Daram, Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Durian Tunggal, Malaysia. Mohd Ruddin AbGhani, Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Durian Tunggal, Malaysia. Fig. 1. Construction of a Utility Grid with the Distribution Generator (DG). Islanding mode has two types such as intentional and unintentional Islanding [3]. Intentional islanding happens with a planned shutdown of the utility grid during maintenance whereby unintentional islanding mode happens during unplanned shutdown of the utility grid due to fault. This unintentional islanding mode is unknown because the load is still managing to supply power by the DG. One of the most important issues of micro-grid is when the grid become unavailable the micro-grids must be isolated itself from the grid and must not transfer the power to the grid. It is important in terms of safety to let to the utility grid to stay in normal operation and restore the power to the system. The islanding detection method includes two important categories which are Local and communication methods. Local methods are divided into major group; passive and active methods. Passive methods are based on measuring some parameters of the power system at Point of Common Coupling (PCC) and analysis them to detect the islanding. Each parameter has certain range and normal operation; if the measured value is not satisfied with the range the algorithm will detect the islanding. The measured parameters can be voltage, current, frequency, power and etc. Active methods will decrease the errors of passive methods with positive feedback or distortion controller. Communication methods are based on measuring the critical element of a power system in both utility grid and micro-grids and collect these data and transfer the signal data with using communication. The important point of communication methods is the way of transferring data. In Power Line Carrier Communication (PLCC) the interface data transfer is a power transmission line but in Supervisory Control and Data Acquisition (SCADA) the data exchange interface can be any kind of communication methods such as wireless, mobile, high speed LAN, broadband and etc. [4]. There are few advantages of using a micro-grid system such as flexible of locating DG nearer to the load area. It is because DG is a small-scale power system grid. Besides, DG is capable of improving the reliability of power usage at load. It supplies power although power failure occurs in the utility grid line. In addition, DG also reduces transmission losses, reduces cost of cables to set up transmission network, reduces the peak demand at national grid system, and defers the Reactive Power Imbalance Method for Islanding Detection in Micro-Grid Operation Meysam Shamshiri, Ahmad Farid Sapar, Chin Kim Gan, Revinnath Tengga Daram, Mohd Ruddin AbGhani