An Emergency Active and Reactive Power Exchange Solution for Interconnected Microgrids

In this article, an important application of interconnected microgrids (IMGs) is presented in order to handle an emergency condition of individual MGs, which causes an intolerable voltage magnitude or frequency deviation. In this method, the active and reactive powers are exchanged via an interlinking back-to-back converter (BTBC) and in accordance with voltage magnitude and/or frequency differences of individual MGs. In order to increase the IMG reliability and overcome the communication challenges, only local voltages and frequencies of both ac sides of the BTBC are used to determine the required active and reactive powers to be exchanged. A generalized droop control is employed to consider the impact of voltage magnitude and frequency differences on exchanging active and reactive powers separately for any type of interlinking lines. In this emergency power exchange method, a logical control is employed to detect the emergency condition, which results in the IMG formation, as well as to detect the normal condition and form the individual MGs operation again. The real-time results, obtained from the OPAL-RT simulator, practically show advantages of the proposed method, including voltage and frequency supports, postponing the load shedding, plug-and-play capability, good power sharing between the IMGs, and method compatibility with the controls of individual MGs.