The increasing integration of distributed generators (DGs) into AC microgrids (MGs) via power electronics reduces system inertia and causes frequency oscillations. To enhance the dynamic frequency response, this paper proposes a virtual asynchronous machine (VAM) control for the AC/DC interlinking converter (IC) that connects the MG and the heating system. Unlike conventional source-side methods (e.g., virtual synchronous generators) that provide inertia from generation units, this work addresses low inertia from the load side. The VAM emulates the slip-frequency regulation, natural damping, and self-regulating torque-speed characteristics of an asynchronous machine (AM). Furthermore, an adaptive virtual inertia and damping combination control is developed, which dynamically adjusts parameters based on frequency deviation and its rate of change. Meanwhile, the thermal inertia of buildings serves as a virtual energy buffer, allowing the VAM to temporarily reduce or increase power transmission to the heating system without compromising indoor thermal comfort. Simulation results demonstrate that the proposed VAM control reduces the maximum frequency deviation by 72% (from 0.25 Hz to 0.07 Hz) and the rate of change of frequency (RoCoF) by 64%.

This paper tackles denial-of-service (DoS) attacks and output constraints in secondary voltage control of islanded microgrids. While existing literature predominantly addresses communication security, it largely overlooks the operational boundaries of power converters. This oversight may result in control saturation, device failure and ultimately, compromised system stability. Furthermore, traditional consensus-based voltage regulation fails to facilitate necessary power interchange among sub-microgrids, limiting its practical applicability. To overcome these limitations, a novel distributed voltage control scheme based on the inclusion principle is proposed. Firstly, a distributed control system model incorporating output constraints is established. The nonlinearities of the system are effectively handled via a barrier Lyapunov function approach, ensuring strict adherence to the output voltage amplitude limits. Secondly, an adaptive state estimator with a switching mechanism is developed to mitigate intermittent communication failures induced by DoS attacks. The controller parameters are then obtained by solving a set of linear matrix inequalities, guaranteeing the semi-global uniform ultimate boundedness (SGUUB) of all closed-loop signals and the ultimate convergence of errors to a neighborhood of the origin. Simulation results verify that the proposed strategy effectively ensures voltage stability while simultaneously satisfying both output constraints and cybersecurity requirements.

The technology of distributed cooperative consensus has been widely used in inverter-based microgrids. However, the traditional information interaction will lead to the problem of data disclosure. Although privacy issues have been widely researched in the tertiary control layer of microgrids, the issues of secondary control layer have not been properly addressed. To fill this gap, taking voltage restoration as the object, the privacy preserving consensus problem for secondary control layer of nDGs islanded microgrids is considered in this paper. Output mask approach, the basic idea of which is to insert a dynamic mask to the transmitted information, is adopted to achieve an accurate consensus rather than a pre-specified convergence accuracy level by differential private method. After that, a newly state decomposition mechanism is proposed, the DG agent is decomposed into two subagents, called$x^{\alpha} _{i}$and$x^{\beta} _{i}$. Among the agent pairs$(x^{\alpha} _{i}, x^{\beta} _{i})$, choose only one subagent of pair$i$arbitrarily connected to one subagent of its neighbor agent pair. Furthermore, only the communication lines among the agent pairs are masked. Compared with the existing literature, the constraint on the communication topology can be first removed without additional computational burden. Moreover, the consensus and privacy analysis of the controlled system are carried out. In the end, the simulation results verify the effectiveness of the proposed privacy preserving mechanism in the MATLAB/Simulink environment. Note to Practitioners—With the rapid development of information and intelligent technology, the information system and the physical system of MGs have been deeply integrated to get a higher efficiency of energy utilization. However, the traditional information interaction will lead to the problem of data disclosure. Although privacy issues have been widely researched in the tertiary control layer of microgrids, the issues of secondary control layer have not been properly addressed. Motivated by this, an improved privacy-preserving consensus strategy is proposed for secondary voltage control of islanded microgrids based on a newly node decomposition mechanism and the output mask method in this paper. And the theoretical results of this paper can be easily extended to other multi-agent systems.

This article proposes an observer-based event-driven fault-tolerant (OBEDFT) secondary control strategy for AC microgrids (MGs) to achieve load voltage regulation. First, the input-output feedback linearization method transforms the voltage regulation issue into an output feedback tracking problem for linear multiagent systems (MASs) with nonlinear dynamics. This transformation provides the necessary preprocessing for load voltage regulation. Then, an OBEDFT secondary control protocol that considers full-state immeasurability is proposed. The actuators of distributed generators (DGs) may experience partial loss of effectiveness (PLOE) and bias faults, and these fault parameters may be heterogeneous and time-varying. The protocol introduces adaptive techniques to avoid information related to fault parameters while using event-driven mechanisms to achieve discrete measurements of neighboring DG. Additionally, the protocol uses boundary layers to construct smooth controllers that prevent the chattering effect caused by nonsmooth controllers. Finally, simulation results confirm the effectiveness of this load voltage regulation strategy.

Privacy issues and the cyberattacks are two typical threats in network operation, but the problem considering both of them has not been properly addressed. To fill this gap, this article investigates the privacy-preserving consensus strategy against the false data injection attacks (FDIAs) for secondary control of microgrids. An integral sliding mode observer and its supporting controller are developed to against the FDIAs on local units. Since the sliding motion is independent of the controller signal, the proposed strategy has a natural advantage for the FDIAs on the controller command. Furthermore, an observer-based resilient control strategy is proposed to against the FDIAs on the communication lines. It is worth mentioning that the$H_\infty$performance can be obtained by regarding the consensus errors as disturbance. Moreover, the edge-based privacy-preserving algorithm along with the observed-based resilient strategy is proposed. Finally, some simulation examples are used to verify the theoretical results.

Although privacy-preserving is often considered in energy management and energy scheduling of microgrids (MGs), to the best of authors’ knowledge, there are almost no literatures on distributed secondary control of MGs with privacy-preserving. To fill this gap, this article investigates the privacy-preserving problem for voltage restoration of an ac MG. First, the model of the MG is transformed into a linear multiagent system model by feedback linearization. Furthermore, output mask approach, which avoids divulging the initial condition by inserting a dynamic mask on the exchanged state information, is adopted to make the distributed generator agents exactly converge to the reference value rather than the value with a preset certain convergence error by differential private. Meanwhile, the sliding mode control scheme with simple structure is adopted to accelerate the convergence speed of the masked system. However, it is difficult to design the controller directly because of the strong nonlinearity brought by the mask function. To solve this problem, we first implement the controller for the original system, and then extend it to the masked system. After that, we carry out the consensus analysis of the controlled masked system. Finally, the effectiveness of the proposed control scheme is validated in the MATLAB/Simulink environment.