With the development of electric vehicles, millions of electric vehicle service equipment (EVSE) are integrated into the power grid. These EVSEs are weakly protected from cyber-attacks. By exploiting vulnerabilities, attackers could establish a botnet integrating hundred-MW-level EVSE loads from the Internet. Dynamic load-altering attack (DLAA) is powerful to amplify the load disturbance to destabilize the power grid. However, different from large-scale loads controlled by existing DLAA, the EVSE botnet is formulated by tens of thousands of bots widely distributed on various power grid nodes, rendering it challenging to be coordinated. In this article, we analyze the approach to launching a DLAA from the distributed EVSE botnet. Firstly, we adopt a time-division model to evaluate the impact of communication limitations on the attack vectors of the botnet. Then we develop an analytical model to calculate the coordinated effect of attack vectors from different nodes and with varying phase angles; thus, we provide a foundation for the optimal coordination of distributed bots. Subsequently, considering the power grid has adopted defense measures to eliminate or suppress the attack, we formulate an optimization algorithm to make the attack robust against these potential defense measures. Numerical simulations validate the effectiveness of the proposed approach.

Extreme natural hazards may damage the pelagic island energy system (PIES) integrating distribution systems, cold storages and desalination stations, resulting in the electric service interruption, stored food deterioration, and freshwater shortage. To alleviate the energy demand of residents as much as possible before the arrival of mainland emergency resources, a novel self-sustaining strategy of post-disaster PIESs with mobile multi-energy storages is proposed in this paper. First, mobile multi-energy storages are used to delivery electricity, ice, and water among stations to increase the resource supply resilience. Their differences in resource delivery time and transportation energy consumption are modelled. On this basis, mobile multi-energy storages are coordinated with diesel generators, cold storages, desalination devices, network reconfiguration, and islanded grid merging for self-sustaining of post-disaster PIESs. The utility loss evaluation model of the common electric load shedding, food deterioration, and freshwater shortage is established, in order to better reflect and respond to the needs of residents. Robust optimization methods are also used to address the uncertainties of the renewable generation, multi-type load demand, and especially energy transmission (i.e., traffic congestion time and line repair time), making the restoration strategy reliable. Finally, case studies verified the superiority of the proposed strategy.

As a flexible type of energy transmission carrier, mobile energy storages usually are studied with a fixed driving speed, resulting in unsatisfactory system operation results. To address the problem, an optimal scheduling strategy of mobile energy storage capable of variable-speed energy transmission is proposed. Firstly, by analyzing the hydrogen-carrier vessel (HCV)’s variable speed-spatiotemporal characteristic mapping mechanism and the ability to supply hydrogen and electricity, an interisland energy variable-speed transmission model is developed. On this basis, an island energy microgrid (EMG) operation model compatible with variable-speed transmission energy is established, in order to reconcile HCV with hydrogen balance, power flow and frequency response. Additionally, considering the impact of uncertainties on the energy output, energy demand, frequency stability, and especially energy transmission sequencing, a stochastic dispatching strategy of the island energy microgrid groups (EMGG) is designed. This model is first linearized as a mixed-integer linear program (MILP) problem, and then is solved quickly by a two-layer algorithm, where the upper layer finely manages the possible optimal EMG power reserve that ensures the frequency security, and the lower layer optimally coordinates the inter-island variable-speed energy transmission and island EMG operation. Finally, case studies on Island groups in the South China Sea verify the effectiveness of the proposed strategy.

The battery swapping station has many batteries and V2G charging piles that enable emergency energy transfer to enhance the restoration of distribution systems. Studies have not been conducted yet to improve distribution system restoration via various battery swapping stations. Accordingly, this paper proposes a resilient restoration strategy based on multiple battery swapping stations for distribution systems. Firstly, single transportation models of electric trucks and batteries are presented, and the coupling constraints are established. Secondly, a clustered battery transportation model is built based on energy discretization, which is easier to solve. Then, a three-stage robust restoration model for distribution systems is proposed with the uncertainties in renewable energy, improving solving speed and optimality. The first stage uses the clustered battery transportation model to determine battery delivery plans quickly. The single-battery delivery plans based on the strategy from the first stage are generated in the second stage. The third stage employs the single battery model to optimize the power of all devices finely. Finally, numerical simulations are performed with a modified IEEE 33-node distribution system to verify the effectiveness of the proposed restoration strategy.

The unbalanced power generated by unintentional islanding is a tremendous challenge to the stable operation of the DC microgrid. When dealing with this challenge, the existing communication-free voltage-threshold-based coordinated control lags far behind the actual power variation, which exacerbates the risk of voltage violations in the microgrid. To address the drawback of the existing control, this paper proposes a new method based on the derivative of bus voltage. Firstly, based on the mathematical correlation between unbalanced power and the derivative of bus voltage, a coordination control strategy and its switching criterion before the battery energy storage system (BESS) exits operation is proposed. Meanwhile, we propose a communication-free approach to sense the operation state of the BESS based on the dynamic process of the derivative of bus voltage. Thus the information obtained under complicated circumstances could be further enriched. Subsequently, a new control strategy after BESS operates operation is established to coordinate different sources among the microgrid. Compared with the existing coordinated control methods, the proposed one can better utilize the information contained in the dynamic process of the bus voltage. Numerical results validate the effectiveness and advantages of the proposed method.