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Abstract Among all types of onboard load demands in all‐electric ships (AESs), the propulsion power predominates (usually >70%), and a large‐scale hybrid energy storage system (HESS) tends to be installed to provide multi‐timescale flexibility. A two‐part dynamic power management method is therefore proposed consisting of a novel multi‐scenario propulsion power model, which models the impacts of floating conditions separately from other uncertain factors, and a three‐layer dynamic allocation strategy based on feedforward control to coordinate the main/auxiliary generators and the HESS. Three case studies are adopted to verify the validity of the proposed method, including a real‐time simulation experiment in RT‐Lab. The proposed method has three advantages: (1) the proposed multi‐scenario propulsion power model accounts for power fluctuations brought by floating conditions, which greatly alleviates the required regulating flexibility for AESs; (2) the proposed three‐layer dynamic power allocation strategy better shares the power demand on the main/auxiliary generators and the HESS, which reduces battery power fluctuations and prevents the overdischarging/overcharging of HESS; and (3) the RT‐Lab experiment proves that the proposed method can be used in real‐time applications for AESs.

Abstract Hybrid energy storage systems (HESSs) have gradually been viewed as essential energy/power buffers to balance the generation and load sides of fully electrified ships. To resolve the balance issue of HESS under multiple power resources, that is, shipboard diesel generators and fuel cells (FCs), this study proposes a robust sizing method implemented with a power allocation strategy. The proposed method is hierarchically formulated as two sequential sub‐problems: (1) a robust programming to determine the power/energy capacities of HESS under the maximal power demand scenario and (2) a control framework to fulfil the power allocation under multiple power resources. A ship case with one diesel engine and one FC is studied to show the validity of the proposed method. The simulation results show that the integration of HESS facilitates the power supply of critical propulsion loads. Compared with no HESS, HESS integration can reduce the deviation of direct current bus voltage sag by 56% and reduce the power fluctuations of the main engine and FC by 7.3% and 55.9%, respectively.

Abstract Due to the short distance between stations, frequent acceleration and braking for urban rail trains cause voltage fluctuation in the traction network and the regenerative braking energy loss. In this study, a hybrid energy storage system (HESS) was proposed to recover braking energy and stabilize the traction network voltage, where the on‐board ultracapacitors were used to accommodate the rapid exchange of acceleration and braking energy of the permanent magnet traction system while the lithium batteries installed in the bilateral stations provided stable and long‐lasting energy exchange, which can stabilize traction network voltage and be charged at off‐peak night time. In order to realize the energy coordinated control between the permanent magnet traction system and HESS, a real‐time energy management strategy was proposed to dynamically allocate the traction power based on the principle of giving priority to on‐board ultracapacitors while lithium batteries as auxiliary power supply. Moreover, the charging and discharging voltage thresholds of the lithium batteries were dynamically set according to train positions and their charge status. Comparing with the traditional strategies, the RT‐LAB semi‐physical real‐time simulation shows that the proposed strategy can provide more effective energy allocation, and stabilize the voltage fluctuation while maximizing the energy saving.

With the development of wind turbines to the large scale with high rated powers, how to reduce fatigue loads is the key factor for modern wind turbine control. Aiming at reducing the wind turbine structural fatigue loads, an individual pitch control (IPC) method based on SVM estimation of blade root loads was proposed in this paper. The blade root loads were dynamically estimated by a SVM model according to light detection and ranging (LIDAR) wind speed data. Two approximate decoupling systems for yaw moments and pitch moments were then obtained through Coleman transform. Meanwhile, two individual pitch controllers were designed to reduce the loads and a wind speed feedforward controller was adopted to improve the pitch control performance. The proposed method was verified by a FAST, LIDAR and RT-LAB semi-physical real-time combined simulation system. On this basis, a master control unit was developed and the overall unit was further verified by a CRRC wind turbine master control and pitch joint test platform. Compared with collective pitch control (CPC) and the IPC based on azimuth, the proposed method is effective on reducing fatigue loads and vibration.

In this paper, the superplastic forming (SPF) potential of two fine-grained 5083 aluminum alloys were studied under various stress states with the use of both high temperature tensile testing and pneumatic bulge testing. Experiments with the pneumatic bulge test were performed at temperatures ranging from 475 to 525 °C under three different strain paths ranging from equi-biaxial to approaching plane strain. The effects of temperature on total elongation, m-value, final thickness distribution, dome height, and cavitation were investigated for the case of uniaxial and equi-biaxial stretching. Increased temperature in bulge forming was found to improve the thickness distribution in the formed parts, but did not have a significant effect on dome height. The shape of the forming limit diagram (FLD) was found to be significantly different than that of FLDs commonly used in room temperature stamping. Results indicate that determination of forming limits in SPF cannot be represented with a simple FLD and additional metrics such as external thinning and internal cavitation need to be considered to determine a material's SPF potential. [ABSTRACT FROM AUTHOR]