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Summary Compared with conventional AC transmission systems of PV generation, its DC counterpart is more resilient for improving the PV utilization. However, in the clamped double submodule‐modular multilevel converter (CDSM‐MMC) and DC/DC converter‐based PV grid‐connection system, pole‐to‐ground and pole‐to‐pole fault characteristics still need investigation. The equivalent model of PV stations and current circuits of the CDSM‐MMC, before and after the fault, are studied first. Secondly, the influence of different connection groups of the converter transformer on the DC fault characteristic and that of DC faults on AC‐side electrical quantities are discussed. Subsequently, development stages of DC faults are divided according to the charging and discharging processes of the CDSM‐MMC and the DC/DC converter, and corresponding equivalent models are established and solved. Finally, the DC transmission system of the PV generation is modeled in Power Systems Computer Aided Design/Electromagnetic Transients including DC to verify the theoretical analysis. The DC fault analysis can provide reference for the subsequent protection system design.

For the bidirectional wireless power transfer system of electric vehicles, the topology proposed in this paper includes a direct three-phase AC–AC matrix converter as the pre-stage main circuit, a bilateral inductor–capacitor–capacitor–inductor (LCCL) as the resonance compensation network, and a full-bridge converter as the latter stage circuit. According to the characteristics of the system topology, a new control strategy is proposed based on the de-re-coupling method. The control principle of the coordination work of the scheme is expounded, and the corresponding switch combination logic is designed. According to the three-phase voltage amplitude relationship at different stages, combined with the resonant frequency, the switch arms of the matrix converter are alternately controlled separately. The number of switching operations is reduced, the system efficiency and safety are improved, and the full range of soft switching operations of the converter is realized. The theoretical analysis of the bilateral LCCL resonance compensation network is carried out, and its constant voltage/current output characteristic and high power factor transmission characteristic are obtained. Finally, the effectiveness and feasibility of the bidirectional wireless power transfer system for electric vehicles proposed in this paper are verified by simulation analysis.

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In order to study the multi-type of generators scheduling optimization model,this paper is based on the LHS method and Mean - CVaR model for research. LHS method is informed as an improved method which can overcome the disadvantage of wind power simulation method of the most commonly used - the monte carlo method which needs a lot of statistical data. Scheme - CVaR model set the minimum electric abandon the wind as the goal, then select the minimum system energy consumption of power generation cost and the minimum pollutant emissions from power generation as the objective function of system combined power generation performance of scheduling ,then under certain constraints, and finally reach the purpose of optimized we expected. Key words: LHS method, Mean - CVaR model, Kantorovich distance

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The model of photon energy distribution in biological tissue has a very important significance in the diagnosis and treatment of biomedical area. The history and development of optical transmission and distribution in the biological tissue is outlined. The structural characteristics and optical properties of biological tissue are explained and discussed. To demonstrate the model of photon propagation in biological tissue, several methods about laser and biological tissue interaction of transmission theory are summarized and the physical meaning of the tissue optical parameters on is considered. On this basis, we simulated near infrared light distribution of the biological tissue with Monte Carlo methods and obtained meaningful results.

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