PRESENTING A NEW METHOD FOR IDENTIFYING FAULT LOCATION IN MICROGRIDS, USING HARMONIC IMPEDANCE

Abstract

Microgrid presents an efficient and novel solution for integrating many new energy generating resources with traditional distribution networks. Having an appropriate protective scheme is a fundamental challenge in achieving microgrid plans. It is proven that traditional protective plans are not efficient for protecting microgrid, since the network is dynamic and the level of fault current changes continually. Accordingly, this paper presents a novel method to detect fault in microgrids. Presented plan of this paper is based on calculating harmonic impedance. Harmonic impedance can be calculated using linear analysis in frequency domain. Generally, in this plan, communicative equipment is applied to monitor the network, and a Supervisory Remote Control Unit is used for calculations and commanding. Using this controller, the proposed method would be able to use online calculation for fault detection and unlike studies which use offline data, the proposed method is not limited to a special structure. Using the proposed method, different type of faults, especially high impedance faults, are detectable and locatable. Consequently, the presented method provides many features for protective system such as selectivity and also ability to detect symmetrical, asymmetrical, and high impedance faults. In addition, fault detecting is independent from microgrid control system and hence reliability and flexibility of protection and control system increased. The presented method is applied to IEEE 14 buses test network. The obtained results are reported and discussed.