The purpose of this paper is to explore the applicability of linear time-invariant dynamical systems with polytopic uncertainty for modeling and control of islanded dc microgrids under plug-and-play (PnP) functionality of distributed generations (DGs). We develop a robust decentralized voltage control framework to ensure robust stability and reliable operation for islanded dc microgrids. The problem of voltage control of islanded dc microgrids with PnP operation of DGs is formulated as a convex optimization problem with structural constraints on some decision variables. The proposed control scheme offers several advantages including decentralized voltage control with no communication link, transient stability/performance, PnP capability, scalability of design, applicability to microgrids with general topology, and robustness to microgrid uncertainties. The effectiveness of the proposed control approach is evaluated through simulation studies carried out in MATLAB/SimPowerSystems Toolbox.

This paper proposes a decentralized control strategy for the voltage regulation of islanded inverter-interfaced microgrids. We show that an inverter-interfaced microgrid under plug-and-play (PnP) functionality of distributed generations (DGs) can be cast as a linear time-invariant system subject to polytopic-type uncertainty. Then, by virtue of this novel description and use of the results from theory of robust control, the microgrid control system guarantees stability and a desired performance even in the case of PnP operation of DGs. The robust controller is a solution of a convex optimization problem. The main properties of the proposed controller are that: 1) it is fully decentralized and local controllers of DGs that use only local measurements; 2) the controller guarantees the stability of the overall system; 3) the controller allows PnP functionality of DGs in microgrids; and 4) the controller is robust against microgrid topology change. Various case studies, based on time-domain simulations in MATLAB/SimPowerSystems Toolbox, are carried out to evaluate the performance of the proposed control strategy in terms of voltage tracking, microgrid topology change, PnP capability features, and load changes.

Electric vehicle charging stations (EVCSs) heavily rely on communication systems, making them vulnerable to cyber uncertainties such as communication delays and False Data Injection (FDI) attacks. In this study, the techno-economic evaluation of the EVCS based on the developed and data-driven Takagi-Sugeno-Kang Fuzzy System & Multi-Agent Deep Reinforcement Learning (TSKFS&MADRL) method is presented to detect and compensate for cyber uncertainties such as FDI attacks and communication delay. In addition, the proposed approach provides a fast dynamic response and enhances the resilient operation of EVCS in the presence of FDI attacks. First, the target points of hackers such as communication systems and transducer sensors are modeled, and then, using the Euclidean norm theory, weighted least square error method, and residual error technique resulting from comparing measured data with reference values based on probability distribution functions, FDI cyber-attacks are detected. Then, the network control and recovery requirements are enabled by the proposed controller based on the TSKFS&MADRL method. The proposed approach has been implemented in the IEEE 33 bus network. The experimental operating cost is 7.33% less than the RL method and 12.15% less than the CNN method. Also, the experimental results of the proposed method show a 40% detection time reduction compared to other methods.

This paper addresses the event-triggered distributed cooperative secure secondary control for islanded cyber-physical inverter-based ac microgrids (MGs) under the energy-limited denial of service (DoS) attacks. The DoS attack refers to the prevention of information exchange among Distributed Energy Resources (DERs) in the secondary control level. In this paper, an event-triggered mechanism (ETM) is employed to improve communication efficiency and reduce control command updates. Based on the last successful local and neighboring transmission attempt, an estimator is proposed which is only activated over attack periods. In addition, this study investigates the contribution of both DERs and Distributed Energy Storage Systems (DESS) in ac MGs. Finally, the performance of the proposed control scheme is evaluated by an offline digital time-domain simulation on a test MG system through different scenarios in MATLAB/Simulink environment. Also, the effectiveness and accuracy of the controller are verified by comparison with several previous studies.

In this article, we investigate the impact of potential state-dependent false data injection cyber-attacks on frequency synchronization and active power management in islanded ac microgrids. One potential way of affecting microgrid reliability is by forcing a generation outage. Thus, the attacker could potentially aim to desynchronize inverter-based resources in microgrids by manipulating their frequency with malicious injections. The attack signals are injected to manipulate control input channels, sensor nodes, reference values, and the information exchanged through communication networks. In order to mitigate the adverse impacts of such cyber-attacks, first, the conventional distributed consensus-based secondary control approach is modified and complemented in the presence of cyber-attacks. Second, a resilient cooperative distributed secondary control scheme is proposed by utilizing the concept of a virtual layer interconnected with the main network layer. Third, theoretical stability, resilience analysis, and design considerations of interconnection matrices are also provided. Finally, simulations through MATLAB/Simulink and experimental results are presented in order to illustrate the robust performance of the proposed control scheme.

Constant power loads (CPLs) impose instability issues in DC microgrids due to their negative impedance characteristics. This paper studies the problem of voltage control design of DC microgrids with CPLs. It is assumed that the power of CPLs is uncertain and belongs to a given interval leading to an infinite number of equilibrium points of the system. We develop a polytope model for DC microgrids with uncertain CPLs. Using this model, a robust two-degree-of-freedom (2DOF) feedback-feedforward voltage control framework is then proposed. The voltage controller is obtained by a solution of a set of linear matrix inequalities. The voltage control design strategy for each distributed generation (DG) unit is scalable and independent of the other DGs. The effectiveness of the proposed control approach is evaluated through simulation studies in MATLAB/SimPowerSystems Toolbox.