Resumo:
The modernization of electrical power systems, characterized by the increasingly intensive integration of new electrical equipment, communication elements, and bidirectional energy flow, has given rise to the concept of smart grids and, consequently, to a specific approach known as microgrids. Microgrids are systems capable of operating either in connection with or in isolation from the main grid, with their operation supported by dedicated communication technologies. These technologies, depending on the transmission medium and propagation conditions, are subject to information loss or issues related to data security and cyber-attacks, concerns that have received growing attention in recent years. The objective of this study is, therefore, to evaluate the performance of the communication system employed in the microgrid, with a focus on secure data transmission and on the implementation of mechanisms for the prevention and mitigation of malicious cyber-attacks. To this end, the control signals of the analyzed network were configured with additive watermarks, which were tested for their effectiveness in detecting and mitigating replay attacks initiated by external agents. Initial simulations were carried out using the IEEE 13-Bus circuit to validate the proposed methodology, while subsequent tests were based on a model of the power grid of Unifei. The IEEE 13-Bus system exhibited satisfactory performance under the implemented simulation scenarios, successfully authenticating commands containing valid watermarks and rejecting those lacking authentication or containing invalid signatures. Four distinct test environments were implemented for the Unifei microgrid model, incorporating varying levels of noise and attenuation introduced by the communication channel. The results indicated that, even under adverse conditions, the transmitted signals were successfully recovered with low failure rates, with noise being identified as a more significant degradation factor than attenuation. Furthermore, although increased latency and energy consumption were observed during operation, their impact on the performance of the microgrid was minimal. In summary, the main contributions of this work include the characterization of the resilience of watermarking mechanisms under degraded communication conditions, as well as an analysis of the impacts on performance and energy efficiency within the microgrid environment.
