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Underwater long-distance high-voltage direct current transmission system can provide long-term, reliable, and sustainable energy for ocean observatories system which has higher reliability requirement than onshore or conventional underwater equipment. As the main network point for high-voltage direct current transmission system, medium-voltage converter of the primary node is at the top layer of power supply chain and its reliability will directly affect the reliability of high-voltage direct current transmission system. Based on a 2.5 kW medium-voltage converter, this study proposes a method to evaluate the reliability of medium-voltage converter with accuracy using the lifetime model of switch by analysis of component junction temperature providing theoretical foundation and technical guidance for medium-voltage converter design. Owing to the high power density of medium-voltage converter, the heat dissipation space is restricted to pressure vessel. This study proposes a thermal design method to ensure normal operation condition within appropriate temperature for medium-voltage converter and verified using ANSYS finite element analysis software.

New energy storage vehicles which use supercapacitors (SCs) as the unique source of traction power are developing rapidly recently. To satisfy the operating voltage requirement of energy storage vehicle, hundreds of SCs are needed to be connected in series. In this case, there is a voltage imbalance between the energy storage cells during rapid charging, resulting in reduced energy efficiency and service life of the energy storage device. A layered equalisation scheme is proposed to solve the problem of voltage imbalance. A single-input multiple-output synchronous rectification equalising circuit is proposed to ensure voltage consistency of series supercapacitor monomer in bottom module. The proposed circuit resolves the existing slow balancing speed and low-voltage balancing precision problems in the current supercapacitor equalising circuits. Meanwhile, an equalisation strategy based on module SOC is adopted to solve voltage imbalance problem of the upper supercapacitor module. The results of MATLAB/Saber co-simulation and experiment demonstrate that the layered equalisation system achieves the target of fast equilibrium and high precision balance.

In this paper, a reformed compensation network based on traditional LCL topology is proposed to realize robust reaction to large coupling variation that is common in dynamic wireless charging application. From the perspective of smoothing, the power characteristic against coupling factor and to achieve high efficiency simultaneously, extra reactive element is inserted into the resonant tank to provide higher degree of design freedom, forming the improved LCC type compensated inductive power transfer (IPT) system that features with distinct parameter design approach. Comparing to existing compensation topologies, the optimized LCC compensation topology shows more robust power characteristic against variation of coupling factor and, thus, minimizes the need for complex control which is usually undesired in dynamic charging scheme, thereby helping maintain effective power transfer in dynamic charging application and largely enhancing the systematic controllability. Finally, the effectiveness of the proposed method is experimentally verified. The power transfer profile is smooth against coupling factor to realize high tolerance to position as the power drop is no more than 20% within almost 200% of coupling factor variation.

This paper studies the optimization measures based on the operational DCS test strategy widely used in the second generation Nuclear Power Plant (NPP), to meet the more complex operational DCS test demands for the third generation NPP. The operational DCS is the monitoring and control center of equipment in NPP. As the third generation NPP is becoming the mainstream technology, the test activity of operational DCS is meeting with many new challenges like higher test complexity and longer test period, which lead to the situation that the test strategy currently used in the second generation NPP cannot meet the test demands of the third generation NPP. The test strategy currently used needs optimizing as early as possible. This paper firstly analyzes the current situation of the operational DCS test strategy used in second generation NPP and the existing shortfalls. Secondly, the paper analyzes the overall test strategy used in EPR NPP which is a third generation NPP. After that, these two kinds of test strategy are compared in four aspects leading to the conclusion that the EPR overall test strategy has obvious advantages in many aspects and is more applicable for complex DCS systems in third generation NPP. Moreover, the paper also presents that there are still some problems existing in EPR test strategy and suggests corresponding solutions for these problems. At last, the paper proposes a series of optimization suggestions on overall test strategy for operational DCS systems in the new-built third generation NPPs.

Darpa proposed a low-frequency (LF) transmitter operates by mechanically moving bound static charge. However, the bounding charge has a low carrier density and the existing high speed rotating technology limits the operate frequency. This paper introduces a parallel plate design to increase the density of charge density, by using mechanical amplification. The maximum displacement generated by the piezoelectric ceramic can be amplified. And the operation frequency can be extended to up to 100KHZ which covers most of the marine low frequency communication requirement.

Dynamic Wireless Power Transmission (DWPT) uninterruptedly charges the moving Electric Vehicles (EVs) through the powered roadway, providing a potential solution to the battery bottleneck. EVs need to obtain energy as much as possible to guarantee proper functioning. Meanwhile, it is necessary to fully utilize the powered roadway in order to economize energy and reduce paving cost. Based on the selected sectional track and detuned series-series (SS) topology, a Constant Maximum Power Point Tracking (CMPPT) control method in the secondary side without the real-time communication between primary and secondary sides is proposed. This method uses the perturbation of rectified DC voltage and tracks the maximum power point. Thus the DWPT system transfers constant and maximum power regardless of the varied magnetic coupling coefficient. A scale-down DWPT demonstration platform based on sectional track is built. The experimental results demonstrate the validity and feasibility of proposed control method for EVs where nearly constant and maximum power is received even when the coupling coefficient varies from 0.13 to 0.28.