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AC submarine cable is an important component in AC transmission system of offshore wind farms. However, the issue of charging current limits its application in offshore wind power with long-distance and large-capacity. Taking HYJQF41-F290/500 kV single-core AC submarine cable as an example, the overvoltage distribution along the cable in different working conditions is analyzed, considering the long-distance and high-voltage transmission. The simulation model of the cable is established and its parameters are corrected firstly. According to the different compensation degrees of the shunt reactor, the capacity of the shunt reactor under the configuration scheme of single-end compensation and two-end compensation calculated out. Finally, based on the single-phase grounding fault, the closing and opening conditions in the high-voltage and long-distance wind farm models, and the distribution law of overvoltage along the submarine cable under different reactive power compensation schemes is tested by simulation. The results show that the maximum overvoltage of submarine cables appears in different positions with different compensation schemes. Based on this, the selection methods for high-voltage submarine cable and overvoltage in insulation level design of substation equipment are given out under different compensation schemes, which have certain guiding significance for engineering practice.

With the significant increase in the scale of energy storage configuration in wind farms, improving the smoothing capability and utilization of energy storage has become a key focus. Therefore, a wind power fluctuation smoothing control strategy is proposed for battery energy storage systems (BESSs), considering the state of charge (SOC). First, a BESS smoothing wind power fluctuation system model based on model predictive control (MPC) is constructed. The objective function aims to minimize the deviation of grid-connected power from the target power and the deviation of the BESS's remaining capacity from the ideal value by comprehensively considering the smoothing effect and the SOC. Second, when the wind power's grid-connected power exceeds the allowable fluctuation value, the weight coefficients in the objective function are adjusted in real time using the first layer of fuzzy control rules combined with SOC partitioning. This approach smooths wind power fluctuations while preventing overcharging and overdischarging of the BESS. When the grid-connected power is within the allowable fluctuation range, the charging and discharging power of the BESS is further refined using a second layer of fuzzy control rules. This enhances the BESS's capability and utilization for smoothing future wind power fluctuations by preemptively charging and discharging. Finally, the proposed control strategy is simulated using MATLAB R2021b with actual operational data from a wind farm as a case study. Compared to the traditional MPC control method, the simulation results demonstrate that the proposed method effectively controls the SOC within a reasonable range, prevents the SOC from entering the dead zone, and enhances the BESS's ability to smooth wind power fluctuations. [ABSTRACT FROM AUTHOR]

The inter‐turn short‐circuit fault of a power transformer has a large current in the winding, which will cause serious heating and deformation of the winding and may threaten the safety of the power transformer. Under this background, this paper proposes a scheme based on open‐delta voltage monitoring and identification of inter‐turn short circuits in power transformers. First, the mathematical modeling and analysis of the principle of inter‐turn short‐circuit monitoring of power transformers are carried out, and the mathematical expression to characterize power transformers with different short‐circuit turns are given. Second, the magnetic field distribution of the power transformer under different short‐circuit conditions, the relationship between the eigenvalue and the number of short‐circuit turns etc. are given. Finally, the experimental study verifies the correctness of the proposed scheme. [ABSTRACT FROM AUTHOR]

China’s railway is experiencing a restructuring from taking fossil fuels as leading resources to electrical energy with renewable energy sources (RESs). As a major consumer of energy, the railway system with RESs integration in China is discussed in this paper, and the relevant applications have been summarized and analyzed. At the same time, the development situations have not yet reached the expected target at present, and China is selecting the route for technical, investment, managerial, market and incentive policy approaches to exploit RESs potential for intelligent railway applications. Furthermore, the next-generation intelligent electrified railway with RESs is proposed and investigated, and the relevant core technologies, systems and incentive policies are summarized and elaborated. Referring to advanced experiences from other countries, the characteristics and objectives of railway energy management system based RESs are also obtained. Based on high-proportion of RESs integration, a win-win situation for railway system and RESs is expected in both economy and environment in China in the future. [ABSTRACT FROM AUTHOR]