With the rapid development of new energy, power consumption becomes prominent in renewable-rich regions. Diode Rectifier Unit (DRU) based High Voltage Direct Current (HVDC) is adopted to solve the issue, however, DRU lacks grid-forming capability, making it urgent to deploy grid-forming energy storage to ensure the safe operation of the power grid. At the same time, due to climate impacts, wind farm power generation exhibits strong randomness and volatility. When actual generation does not match the planned output, an “imbalance penalty cost” must be incurred. Therefore, the energy storage system of the wind farm must smooth power fluctuations on a short time scale and balance power output on a longer time scale to reduce the economic costs associated with imbalances. This paper proposes a grid-forming hybrid energy storage system capable of scheduled power generation for wind farms. An objective function is established which includes battery operating losses, wind farm imbalance penalty costs, and overall system benefits. Based on ultra-short-term wind power forecasting, model predictive control (MPC) rolling optimization is applied to control the grid-forming hybrid energy storage system. To minimize the annual economic cost, the capacity ratio of the grid-forming hybrid energy storage system is optimized.

With computing demand continuously increasing, data centers in extreme-climate regions typified by the Middle East and North Africa (MENA) face challenges including persistently high cooling energy consumption and a temporal mismatch between computing-driven cooling demand and the availability of natural cooling resources. Considering the regional climatic characteristics of high daytime temperatures and large diurnal temperature swings, a novel thermal management structure integrating phase-change materials (PCM), cooling towers, and heat pumps is proposed. By leveraging the thermal buffering capability of PCM together with the cooling tower’s nighttime natural cooling potential, peak shaving and valley filling for cooling is achieved, which alleviates the temporal mismatch between computing-driven cooling demand and availability of natural cooling resources and increases the natural cooling resources utilization. Furthermore, to coordinate the coupled interactions among transferable computing workloads, electricity pricing, and natural cooling resources in the novel structure, a “computing-electrical-thermal” coordinated optimization model is proposed to reduce electricity cost and optimize the allocation of cooling resources. Since the proposed coordinated optimization model features strong variable coupling and nonlinear characteristics, which cause parameter-propagation delays when conventional hierarchical solution methods are applied, a global solution algorithm is proposed to jointly optimize key variables, including cooling tower power, heat-pump power, and computing workloads migration. Considering a certain data center as a case study, compared with a conventional air–liquid cooling system, electricity consumption is reduced by 17% and the daily operating cost is decreased by USD 2,075 by using the novel thermal management structure. In addition, compared with a conventional electrical–thermal coordination model, the daily operating cost is decreased by USD 556 by using the “computing–electrical–thermal” coordinated optimization model”.

Due to the influence of fault control strategies in inverter-based power source, the performance of conventional current differential protection may further deteriorate in fully renewable power system. This paper first introduces the fault control strategies of fully renewable power system and analyzes the underlying mechanisms responsible for the degradation of current differential protection performance. To address this issue, a novel longitudinal protection scheme based on Current Distribution Entropy (CDE) is proposed. The proposed method utilizes the high sensitivity of the entropy-based index to phase-angle variations to distinguish between internal and external faults. Simulation results obtained using PSCAD/EMTDC demonstrate that the proposed protection scheme can accurately identify various fault types within 5 ms after fault occurrence, while exhibiting strong robustness against transition resistance and external disturbances.

With the high proportion of wind and photovoltaic power and other new energy sources integrated into the power grid, the short-circuit characteristics of their power electronic interfaces differ fundamentally from those of traditional synchronous generators. This often leads to convergence difficulties in iterative calculations based on the conventional Newton–Raphson method. Existing improvements mainly fall into two types: one enhances convergence by refining new energy models and improving iterative strategies, while the other focuses on improving the solver for nonlinear equation systems itself. However, these methods still exhibit insufficient convergence and robustness in sparse matrix computations for large-scale power grids with high penetration of renewable energy. To address this, this paper first develops a piecewise function model for the fault transient output characteristics of doubly-fed induction generators (DFIGs) and photovoltaic (PV) power sources, aiming to accurately represent their strong nonlinearity. Subsequently, for the resulting large-scale sparse nonlinear equation system, an iterative computation method based on Newton–HSS (Newton–Hermitian and Skew-Hermitian Splitting) is proposed. This method employs Newton iteration in the outer layer to handle nonlinearity, while the inner layer efficiently solves the linear system using the HSS splitting technique. Through parameter adjustment, it achieves adaptive allocation of computational effort, significantly improving convergence speed and robustness while ensuring accuracy. Simulation results verify that compared with traditional methods, the proposed approach exhibits superior convergence performance in short-circuit calculations for large-scale power grids with high penetration of renewable energy.

Aiming at the emergency repairs of distribution network, a strategy of expanding the scope of restoring power supply by using both mobile energy storage (MES) and the main power supply in the grid as black-start power supply is proposed. Firstly, the MES model, the coupled network model and the mathematical model of the MES power supply network are established. Furthermore, on the basis of fully considering the constraints of power grid, road network and the logic of emergency repair task, the work plan of road emergency repair and power emergency repair is arranged as a whole with the objective of minimizing the weight of power loss of all load nodes. The simulation results show that the proposed strategy can significantly improve the power supply situation of the post-disaster load nodes and alleviate the problem of power shortage during emergency repair.

The external equivalence of inverter interfaced distributed generation (IIDG) to a controlled current source alters the passive linear characteristics of power grid’s power frequency fault component (PFFC) network. This transformation undermines the theoretical foundation of power frequency superimposed distance protection (PFSDP) and potentially degrades its performance. To address this issue, this article investigates the mechanism behind the degraded sensitivity of PFSDP installed at IIDG side by analyzing the PFFC sequence component voltages during faults. We then propose control strategies that temporarily restrict the positive-sequence current output of the IIDG during faults while permitting negative-sequence current injection into the grid. This approach achieves two objectives: 1) mitigating the adverse effects of positive-sequence current output by the IIDG on PFSDP; and 2) enabling PFSDP’s reliable operation by leveraging negative-sequence PFFC current. Simulations and tests demonstrate that the proposed strategies effectively improve the sensitivity and reliability of PFSDP in inverter-dominated grids.

The participation of Mobile Energy Storage Systems (MESS) in the electricity market can not only increase its own profit but also alleviate power transmission congestion and increase market clearing balance. However, relevant market trading strategies have yet to be explored. Accordingly, this paper proposes a resilient market bidding strategy for MESS considering the operation of transportation network. Firstly, this paper proposes a joint optimization framework of energy and transportation systems. In this framework, the upper layer is to make decisions on the space-time distribution and bidding strategy of MESS, and the lower layers is designed for the equilibrium of the transportation network and electricity market clearing. Subsequently, for the newly introduced transportation layer, this paper proposes a Logit-type Robust Stochastic User Equilibrium (LRSUE) to calculate the uncertain transfer time of MESS in the transportation network. Further, based on strong duality theory and Karush-Kuhn-Tucker Conditions (KKT) conditions, the two-layer model can achieve an efficient solution. Finally, two cases were provided to validate the proposed methods, demonstrating that MESS increase its revenue, alleviate power transmission congestion, and increase the electricity market clearing balance.

The control strategy of inverter-based power sources in a fully renewable energy grid causes a significant imbalance in the positive and negative sequence current distribution coefficients at the energy storage (ES) side. This imbalance leads to faulty operations in the Superimposed Current Magnitude (SCM)-based Faulty Phase Selector (FPS). This paper investigates the current distribution characteristics on the ES side during faults, revealing the mechanism behind the performance degradation of the SCM-based FPS. To solve this problem, we propose a positive-sequence superimposed current suppression strategy based on fault component regulation. By controlling the positive-sequence current from the renewable energy side, this approach equalizes the positive and negative sequence current distribution coefficients on the ES side, thus restoring the phase selector's performance. Simulation results verify that our solution successfully restores the performance of the traditional SCM-based FPS in an islanded system. The findings indicate that existing superimposed current phase selection schemes can still be adapted to power grids with high, and even full, penetration of renewable energy.

Typhoons can cause large-area blackouts or partial outages of distribution networks.We define a partial outage state in the distribution network as a gray state and propose a gray-start strategy and two-stage distribution network emergency recovery framework.A phase-space reconstruction and stacked integrated model for predicting wind and photovoltaic generation during typhoon disasters is proposed in the first stage.This provides guidance for second-stage post-disaster emergency recovery scheduling.The emergency recovery scheduling model is established in the second stage,and this model is supported by a thermal power-generating unit,mobile emergency generators,and distributed generators.Distributed generation includes wind power generation,photovoltaics,fuel cells,etc.Simultaneously,we con-sider the gray-start based on the pumped storage unit to be an important first step in the emergency recovery strategy.This model is val-idated on the improved IEEE 33 node system,which utilizes data from the 2022 super typhoon"Muifa"in Zhoushan,Zhejiang,China.Simulations indicate the superiority of a gray start with a pumped storage unit and the proposed emergency recovery strategy.

The superior current-limiting performance of superconducting fault current limiter (SFCL) makes them a promising solution for limiting escalating short-circuit currents (SCC) in modern power grids. However, their high investment cost remains a major barrier to widespread deployment. To address this economic challenge, this paper proposes a global cooperative configuration strategy for SFCL that incorporates life cycle cost assessment. First, a simplified life loss model for SFCL is established to quantify the relationship between fault current magnitude and equipment degradation. Based on this, a comprehensive life cycle cost function is formulated, integrating initial investment, operational loss, and maintenance expenses. The Pareto-optimal set of basic configuration schemes is then efficiently generated using the NSGA-II multi-objective genetic algorithm. Furthermore, a Monte Carlo-based model is constructed to evaluate the operational cost and long-term economics. Simulation on the IEEE 30-node system demonstrates that the proposed method effectively identifies the configuration with the minimal total annual cost, providing a more economically viable solution for the practical engineering application of SFCL.

The typhoon–rainstorm–flood disaster chain poses a significant flooding risk to urban distribution network (DN) equipment, often leading to power system outages. The increasing frequency and severity of this disaster chain in East Asia, driven by global warming, population growth, and land‐use changes, highlight the need for improved disaster preparedness. Traditional studies focusing on individual meteorological disasters, such as typhoons or floods, may be insufficient for developing efective mitigation strategies. To address this gap, this study proposes a novel risk analysis method for enhancing the disaster defence strategy of DNs. First, a hybrid deep learning model is developed to forecast a 48‐h rainstorm time series following a typhoon's landfall. Second, a one‐dimensional pipe network and a two‐dimensional surface‐coupled urban flood model are constructed to predict flood depth based on the typhoon–rainstorm time series. Third, an influence factor set is established from environmental and societal perspectives, and spatial correlation analysis is applied to assess DN outage risk. To validate the proposed method, Typhoon Talim (2023), which made landfall in China, is used as a case study. The results demonstrate that the model effectively captures disaster‐causing mechanisms and accurately identifies high‐risk areas. This research provides a theoretical foundation for outage risk prevention in developing countries, particularly in mitigating the impacts of the typhoon–rainstorm–flood disaster chain.

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.

Currently, many island microgrids rich in renewable energy have been established. Some of them are geographically close and have the potential to achieve energy sharing and improve power supply reliability through interconnection. However, the traditional method, laying submarine cables among island microgrids, may lead to issues such as easy damage and poor economy. Therefore, in this paper, an energy cooperation alliance is first proposed. An energy transporter is designed as the initiator of the alliance, achieving inter-island transfer of electricity by dispatching all-electric ships. Secondly, an energy scheduling model is established, including models for island microgrids and the energy transporter. Thirdly, the stability coefficient of the cooperation alliance is presented, and a benefit allocation strategy based on the asymmetric Nash bargaining model is applied. The renewable energy consumption rate and the role imbalance coefficient are considered. Finally, simulation studies on island microgrids in the South China Sea indicate that the proposed energy cooperation strategy is effective and beneficial.

When many distributed generators (DGs) are connected to active distribution networks (ADNs), the performance of conventional overcurrent protection can seriously deteriorate. In response, single-ended transient-based boundary protection is considered an effective scheme for improving relay performance in ADNs due to its independence from power supply properties and its ability to cover an entire protected feeder. However, this approach depends on the filtering effect of the line boundary. This paper finds that capacitive voltage transformers (CVTs), metal-oxide arresters (MOAs), and the stray capacitances of the other apparatuses can serve together as line boundaries at substations and switching stations, and their excellent high-frequency filtering characteristics can assist in boundary protection design. A protection criterion is constructed based on the differences in high-frequency spectral energy between the internal and external fault-generated traveling waves (TWs). Furthermore, a novel two-stage boundary protection scheme is formed by reasonably coordinating the operation sequence and the protection scope of the first-and second-stage boundary protection. Finally, based on the PSCAD platform, the effectiveness, sensitivity, and reliability of the proposed protection scheme are verified under different fault scenarios.

Abstract To solve the problems of the rapid deterioration of the three-stage overcurrent protection performance after the extensive access of inverter distributed generators, the deterioration of the traditional longitudinal protection performance, and the problems of 0/0 calculation results and insufficient waveform difference measurement of the existing similarity protection algorithms, a longitudinal protection scheme based on M_T comprehensive similarity was proposed. Firstly, the transmission communication delay of the 5G core network is analyzed, and the mini-slot technology is proposed to effectively reduce the communication delay. Secondly, the M-K mutation initiation algorithm adapted to the characteristics of inverter DG faults was used to replace the traditional phase current mutation detection algorithm. The fault self-synchronization with higher precision was realized. Finally, M_T comprehensive similarity is constructed to describe the difference between the short-circuit current waveform of the system side and the inverter-distributed generator side. The changes in the similarity coefficient of faults in and out of the area are analyzed. A new principle of longitudinal protection based on the comprehensive similarity of M_T is formed. The simulation results show that the proposed new protection principle can reliably identify faults in and out of the area, will not have the anomaly of 0/0 of Pearson coefficient and cosine similarity calculation results, and has better anti-transition resistance ability than the Tanimoto similarity algorithm, which is fully suitable for distribution networks with distributed generators.

The delayed operation of a zone-2 impedance relay for handling faults on the end-section of a protected line can exacerbate power system instability. To accelerate the trip of a zone-2 circuit breaker (CB), many accelerated trip (AT) schemes have been proposed for AC power grids. However, these schemes remain by their pre-fault operating conditions, tripping modes, fault resistance, and fault types. Considering these limitations, this paper presents a novel AT scheme based on open-switching traveling waves (TWs) generated by CB operation. First, characteristic differences in the oscillation period and wavefront polarity of the open-switching TWs generated by remote CB operation under internal, remote busbar, and external faults are analyzed. Then, an identification criterion for open-switching TWs utilizing the order and number of wavefront polarities is proposed, thereby forming a new AT scheme. Finally, based on the PSCAD/EMTDC software, the effectiveness, sensitivity, and reliability of the proposed AT scheme are verified. The proposed AT scheme can operate at high speed without being affected by pre-fault operating conditions, tripping modes, or fault types, and its ability to endure fault resistance reaches 300 Ω.

Renewable resources are crucial for green development of offshore islands. However, land resources in island are much more precious than mainland, and renewable energy will occupy the living space, which hinders the concept of green development. It is worth noting that there exist islands not habitable but also have abundant resources. Therefore, the ideal development mode for offshore islands would be to construct energy generation on uninhabitable islands and transmit electricity to the load island through cables. However, due to route restrictions and investment effectiveness, there are plentiful resource islands not suitable for constructing cable, hence a large amount of renewable resources cannot be utilized. Aiming at the challenge, the paper proposes a novel strategy of isolated power generation to collaborate with existing idle ships nearby resource islands to supply energy to load island. Considering the multi-subject investments of island, two-level model containing upper-level isolated power generation model and lower-level day-ahead electricity market clearing model has been established. Simulation results show that the proposed strategy can maximize social benefits while improving the profits of isolated power generation on resource island, verifying the feasibility of utilizing isolated power generation in offshore islands.