In this paper, a decentralized frequency control of ac microgrid (MG) governed by P − ω droop characteristics is presented. This approach is realized by applying an active power estimation to eliminate the required communication infrastructure in the secondary control layer. The proposed decentralized frequency control is achieved by employing the unique feature of the frequency as a global variable in autonomous ac MGs. By utilizing a consensus protocol, the proposed method restores the MG frequency to the nominal value while maintaining accurate power sharing of the droop mechanism. The consensus protocol is an estimation-based approach and does not require communication infrastructure. Experimental results verified accurate power-sharing and the frequency restoration to the nominal value without any communication requirement.
