Decentralized Frequency Control of AC Microgrids: An Estimation-Based Consensus Approach
Yousef Khayat, Rasool Heydari, Mobin Naderi, Tomislav Dragičević, Qobad Shafiee, Mohammad Fathi, Hassan Bevrani, Frede Blaabjerg
Abstract
In this article, a decentralized secondary control (SC) based on the active power estimation (APE) is presented. This achievement is realized by employing the unique feature of frequency as a global variable in autonomous ac microgrids (MGs). The APE is merely based on the droop coefficient of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P-{\omega }$ </tex-math></inline-formula> characteristics. The decentralized SC, utilizing a consensus protocol, restores the MG frequency to the nominal value while maintaining accurate power sharing of the droop mechanism. The consensus protocol is estimation-based and does not require communication infrastructure. In addition to the proposition of stability analysis method, experimental results with four distributed generation units (DGUs) also verify the effectiveness of the proposed SC structure.