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  • Author or Editor: Azita Azarfar x
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Abstract

Microgrids (MGs) are capable to work at different operation modes, namely grid-connected or islanded, which make a significant change in the network fault current level. These changes may lead to problems and should be detected fast to do the proper protection actions accordingly and prevent blackouts. Moreover, some island detection methods suffer from the drawbacks of high computation burden and time-consuming procedure of training data to detect the islanded mode. For this purpose, in this paper, a faster and less computation burden island detection scheme without the need for training data is proposed which detects the islanded mode by analyzing the fault current data obtained from a continuous sampling using the phasor measurement unit (PMU). The sampled data are utilized in the fuzzy c-means (FCM) clustering to determine the network operation mode. The proposed scheme works in two phases. In the offline phase, the root mean square (RMS) of the current amplitude for islanded mode is determined, and in the online phase, the center of the measured data is compared to the RMS value to detect the MG operation mode at a decision making procedure. It is proved that the proposed island detection scheme is an applicable technique for detecting the islanded mode in MGs.

Open access

Abstract

Microgrid (MG) is a system of production and distribution of electrical energy that can operate both in grid-connected and islanded modes. This capability leads to significant variations in the fault current level. Moreover, dynamic changes corresponding to the line outage contingencies or outages of the distributed generations (DGs) that are implemented for local generation in the MGs lead to the changes in the fault current level. These changes in the fault current level make some miscoordination between the overcurrent relays (OCRs) in the conventional protection schemes. To overcome this drawback, there is a need for an adaptive protection scheme that can adapt to both operational and dynamic changes and takes effective protection decisions accordingly. This paper first presents a statistic-based review of MG and its protection including total publications, type of publications, the ten most researchers, and the ten most sources. Finally, comprehensive remarks of the 30 most cited papers related to adaptive protection of MG are presented. This paper will help the researchers of the MG protection to learn the most desirable techniques and the concentration of studies in adaptive protection of MGs for future works.

Open access