Mechanisms of Extending Operation Region in the HL-1M Tokamak

Stable operating region in the HL-1M tokamak has been extended by means of wall conditioning, core fuelling and current control techniques. The mechanisms of the extension are analyzed in this paper. Lithiumization diminishes the impurities and hydrogen recycling to the lowest level. After lithiumization a high density up to 7×1019 m-3 was obtained easily by strong gas puffing with ordinary ohmic discharge alone. More attractively we found that metal Li-coating exhibited the effects of wall stabilization. The low qα limit with higher density was extended by a factor of 1.5-2 in comparison with that for boronization, and 1.2 for siliconization. Siliconization not only extended stable operating region significantly by itself, but also provided a good target plasma for other experiments of raising density limit. Core fuelling schemes are favourable especially for siliconized wall with a higher level of medium-Z impurity (Z = 14). After siliconization the maximum density near to 1020 m-3 was achieved by a combination of supersonic molecule beam injection and multipellet injection. The new defined slope of Hugill limit illustrating more clearly the situation under low qα and high ne discharges was created to indicate the new region extended by combining IP ramp-up with core fuelling. The slope with a large Murakami coefficient increased by a factor of 50-60 %.

Voltage Security Operation Region Calculation Based on Improved Particle Swarm Optimization and Recursive Least Square Hybrid Algorithm

Large-scale voltage collapse incidences, which result in power outages over large regions and extensive economic losses, are presently common occurrences worldwide. To avoid voltage collapse and operate more safely and reliably, it is necessary to analyze the voltage security operation region(VSOR) of power systems, which has become a topic of increasing interest lately. In this paper, a novel improved particle swarm optimization and recursive least square(IPSO-RLS) hybrid algorithm is proposed to determine the VSOR of a power system. Also, stability analysis on the proposed algorithm is carried out by analyzing the errors and convergence accuracy of the obtained results. Firstly, the voltage stability and VSOR-surface of a power system are analyzed in this paper. Secondly, the two algorithms,namely IPSO and RLS algorithms, are studied individually.Based on this understanding, a novel IPSO-RLS hybrid algorithm is proposed to optimize the active and reactive power,and the voltage allowed to identify the VSOR-surface accurately. Finally, the proposed algorithm is validated by using a simulation case study on three wind farm regions of actual Hami Power Grid of China in DIg SILENT/Power Factory software.The error and accuracy of the obtained simulation results are analyzed and compared with those of the particle swarm optimization(PSO), IPSO and IPSO-RLS hybrid algorithms.

Exact Box-Constrained Economic Operating Region for Power Grids Considering Renewable Energy Sources

The growing integration of renewable energy sources manifests as an effective strategy for reducing carbon emissions. This paper strives to efficiently approximate the set of optimal scheduling plans(OSPs) to enhance the performance of the steady-state adaptive cruise method(SACM) of power grid, improving the ability of dealing with operational uncertainties. Initially, we provide a mathematical definition of the exact boxconstrained economic operating region(EBC-EOR) for the power grid and its dispatchable components. Following this, we introduce an EBC-EOR formulation algorithm and the corresponding bi-level optimization models designed to explore the economic operating boundaries. In addition, we propose an enhanced big-M method to expedite the computation of the EBCEOR. Finally, the effectiveness of the EBC-EOR formulation, its economic attributes, correlation with the scheduling plan underpinned by model predictive control, and the significant improvement in computational efficiency(over twelvefold) are verified through case studies conducted on two test systems..

农业与农村可持续发展的地理学研究

农业和农村可持续发展是世界性的重大论题，对中国尤其重要。地理学应该以自己独特的视角和理论、方法，针对我国农业与农村可持续发展所面临的关键问题，联系国际经验以及我国传统农业中的可持续因素，以自然结构为基础，以人地关系为核心，探讨农业与农村可持续发展的转换机制，从区域尺度探讨农业与农村可持续发展的指标体系、实现途径及区域系统模式，为实施农业和农村发展的“两个转变”和“两大战略”提供区域对策和操作手段。

如何在Windows NT环境下进行远程访问

The meteorological operation system production database used in the stations at the extension of Lanzhou Regional Meteorological Center (LRMC), is an important part of the second period project setting up items. The system includes the database, function module and self-safeguard system. The products of the system can be easily explanted from VMS to UNIX, and their functions can not be affected.

Control design approaches for nonlinear systems using multiple models

It is difficult to realize control for some complex nonlinear systems operated in different operating regions. Based on developing local models for different operating regions of the process, a novel algorithm using multiple models is proposed. It utilizes dynamic model bank to establish multiple local models, and their membership functions are defined according to respective regions. Then the nonlinear system is approximated to a weighted combination of the local models. The stability of the nonlinear system is proven. Finally, simulations are given to demonstrate the validity of the proposed method.

平潭海域精细化三维温盐流业务化数值预报系统

根据平潭附近海域实际需求和地理区位特点,研发了三维温、盐、流高分辨率业务化数值预报系统,对该系统采用的模式、配置、预报结果验证和业务化运行等情况进行了详细介绍。该系统基于ROMS海流模式,采用正交曲线网格和网格嵌套技术;建立了包含数据预处理、温盐流预报和预报产品后处理等子程序的业务化数值预报系统。结果表明:模式预报产品具有较高精度,整个业务流程运行在30 min之内,系统运行稳定,达到业务化预报的要求。