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This paper studies a battery energy storage system based on the hexagonal modular multilevel direct ac/ac converter with focus on a control method for state-of-charge (SOC) balancing of the battery units. First, the system structure and the operating principle of the hexagonal multilevel converter, including the branch voltage and the power, are analyzed and simulated, respectively. Then, the mathematical model of the energy storage submodule consisting of the battery energy storage unit and H-bridge submodule cell is developed in PSCAD/EMTDC software. After that, a SOC balancing control strategy is proposed, including the branch SOC balancing between the converter’s six branches and the individual SOC balancing between the 14 cascaded converter cells in each branch, which is realized by controlling currents in branch modules. Currents in the branches are controlled by the internal model principle. Finally, the effectiveness of the control strategy is verified in simulation.

The emergence of microgrid technology provides a new method for distributed generation connecting to the grid. However, it creates a new problem that people need to think about how to manage a number of microgrids in a certain area to obtain higher power supply reliability. This paper studies a new distribution network topology named honeycomb distribution network which is proposed by our research group. Firstly, this paper makes a brief introduction of the topology and active microgrids and smart power/information exchange base stations in the topology. Secondly, mathematical probability method is used to analyze the power supply reliability of the topology. Finally, in order to show the high reliability of the topology more intuitively, revised formulas based on the minimum cut set method are introduced to calculate the reliability parameters of modificative IEEE-RBTS BUS6 F4 test system. Calculation results are shown to verify the high reliability of honeycomb distribution network.

This paper proposes a novel energy exchange node topology which can connect the AC and DC microgrids easily. On this basis, a reliable power flow control strategy is proposed to improve the performance of microgrids. A comprehensive analysis of the control strategies commonly used in AC and DC microgrids is presented. Then, the topology and power flow control strategy of the novel energy exchange node which can redistribute the energy of the island group are proposed. In order to verify its effectiveness and performance, a physical model is built and the simulation verification is carried out on MATLAB/Simulink software. The results show that the novel energy exchange node can effectively cooperate with the microgrid control strategies to realize the power flow exchange among the microgrids, which mean the realization of the energy redistribution among island group.

Route map based on car navigation, multi-point navigation of the same area in different locations and voice navigation with voice broadcast was studied. Achieved an overall system with car navigation map information distribution and voice broadcast using GPS positioning methods MapXtreme technology and improved ant colony optimization based on occasional algorithm. The system solved navigation problems of the shortest path between two points, the shortest time, the optimal K paths and multi-point route planning, as well as the voice-based navigation problems. The whole system worked well and could meet the travel navigation requirements of travelers and relevant departments.

In the paper, the mobile payment technology is applied to smart travel. Firstly, we design the overall functional structure diagram of the mobile payment system and describe the main function modules. Secondly, we design database system and a hybrid encryption algorithm based on DES and ECC, which ensures the security of the system. Finally, we test and analyze the result of the mobile payment system.

In the intelligent transportation system, the calculation of the shortest path and the best path is an important link of the vehicle navigation function. Due to more and more real-time information to participate in the calculation, the calculation requires high efficiency for the algorithm. This paper studied navigation system based on vehicle terminal, designed the overall framework of the system and gave the function of each module. The system can provide optimal service path for the user's choice and needs. The optimization of the design and application of Dijkstra algorithm saved the intermediate result storage space in the process of system operation, improved the accuracy of the navigation path, reduced the complexity of the Dijkstra algorithm and greatly improved the efficiency of the system.