A Novel Distributed Security Control for AC Microgrids Under Model-Free DoS Attacks

In actual ac microgrids (MGs), the design of distributed secondary control methods requires information exchanges between distributed generators (DGs) by a communication network. This means MGs are potentially suffering from model-free Denial of Service (DoS) attacks and are affected by the constraints of transmission rate simultaneously. Accordingly, we develop a novel distributed security control strategy based on quantization to ensure the stable and economic operation of ac MGs. Considering DoS attacks can exacerbate the rate constraints inherent in communication networks, a quantization controller with a minimal quantization level is designed to account for extreme scenarios. This ensures that ac MGs achieves their control objectives by transmitting only 1 bit of data at each successful transmission instance while guaranteeing that the quantized signal does not exceed the range of quantizer throughout the entire process. In addition, the developed control strategy can synchronize the output voltage and frequency of DGs to their reference values, respectively, and achieve active power-sharing. Besides, the quantization level can be dynamically adjusted according to the actual situation of ac MGs to improve the operation effect of the algorithm. Finally, the performance of the proposed distributed security control strategy and comparisons with other research are evaluated on an ac MG composed of seven DGs in real-time testing equipment built on RT-LAB.