Comparison of DC Pollution Flashover Performance of Various Types of Long String Insulators

With the development of EHV/UHV DC transmission projects, it is inevitable to study DC pollution flashover performance of long insulator strings. The DC artificial pollution tests of five types of porcelain and glass insulators have been carried out in the artificial climate chamber. The paper analyzes the relationship between 50% flashover voltage U50 and string length, the relationship between U50 and salt deposit density, flashover voltage gradients and valid creepage distances of DC polluted insulators. Based on the test results of insulator strings of 5 - 23 units, there are linear relationship between the 50% DC flashover voltages and string length. The experimental results show that the pollution flashover performances of various types of insulators are different, and that the pollution degree exponents of polluted insulators are affected ainsulator materials and shapes, whose values are 0.3 to 0.36. Under the same pollution degree, the pollution performances of glass insulators have advantage of those of porcelain insulators with the same configuration and the flashover voltage gradient along creepage distance and valid creepage distances of glass insulators are higher than those of porcelain insulators.     

Numerical Simulation of Dynamic Response of Suspension Insulator String

Finite element method is applied to analyze the windage of suspension insulator strings under dynamic wind loads. The dynamic response of a suspension insulator string of 500 kV high voltage transmission line is numerically simulated with ABAQUS software, and results demonstrate that the windage angle of suspension insulator string is larger than that calculated by the conventional design code, which might be one of the main reasons of the frequently happened windage flashover accidents.     

STUDY OF SURFACE AC FLASHING PROCESS OF ICED INSQLATORS

From the testing results in the artificial climate room in Chongqing University, this paper discribes the AC flashover process of cylindoric insulators and suspensive ones, and presents the relations between iced insulators AC flashover processes and its leakage current.     

Optimization algorithm for forward problem with electric fields of defective insulator

The defective insulator can be detected by measuring electric field, however, the electric field calculation accuracy of the insulator strings is low. Charge simulation method (CSM), which is optimized by genetic algorithm (GA), is adopted to calculate high voltage electrostatic field. The optimal method principle and feasibility analysis is given. The objective function and optimization model of electric field distribution around insulator strings are constructed and analyzed. The results of calculation and analysis demonstrate that adopting the potential of check points near insulator strings as objective function and using GA to optimize the charge of simulation charge, better performance can be achieved for improving ability of global optimization, calculating precision, searching speed, simulating precision of CSM and accuracy of diagnosing defective insulator in the insulator strings.     

Analysis of fast optimization algorithm for inverse detecting faulty insulators

In order to improve the computational efficiency of the insulator electric field inverse problem, the fast multi-pole method has been introduced to the traditional simulation charge method. Tikhonov regularization is used to process the ill-posed characteristic of inverse problem solution caused by the interference. Newton method is used to search the optimum solution, and then the actual field source parameters of insulators and the practical voltage distribution on the surface of the insulators can be obtained. The fast optimization algorithm has been verified in point charge model. And 110 kV insulator string is carried out to demonstrate that the fast optimization algorithm is much faster and more efficient than traditional method.     

Research on Lightning Intruded Wave for 500 kV Substations

The study on overvoltage for 500 kV substation caused by lightning intruded wave is presented. In this paper, we calculate by using electromagnetic transient program (EMTP) and combine substation with incoming lines ,so some influence factors can be considered such as impulse voltage second characteristic of insulator strings, lightning stroke point on the incoming lines and impulse grounding resistance of towers. The results show that the method is close to the practice and some factors of incoming lines are important to overvoltage.     

Study of Lightning Impulse Breakdown Voltage Correction of PositiveRod-Plate Short Air Gaps on Altitude

The air pressure of the high altitude condition in the artificial climate chamber is simulated, and the laboratory investigation of positive rod plate lightning impulse discharge performance were carried out on the short air gaps of 200 mm, 300 mm and 450 mm according to the test method demanded in IEC 60.1. Based the tested results, it is put forward that the positive lightning impulse breakdown voltage of a short air gap at the air pressure of the high altitude district is a power function of the air pressure with a special index less than 1, which indicates that the effect of the air pressure on the breakdown voltage decreases by 8.7% with the increase of the altitude by 1 kilometer. According to the theoretical analysis, it is proposed that the air pressure suggests the comprehensive changes of the basic atmospheric parameters of the temperature, the reltive air density and the absolute humidity, thus it could be used as the characteristic variable which expresses the effect of the absolute humidity, thus it could be used as the characteristic variable which expresses the effect of the atmospheric condition on the breakdown voltage of an air gap.     

北京密云某养殖场雷电灾害事故分析与对策

雷电灾害事故分析有助于更好地掌握雷击途径和方式,认识雷电致灾规律,从而采取更有效的防护措施。针对2014年7月1日北京市密云县西田各庄镇某养殖场发生的雷电灾害事故,统计分析雷击时间段内该区域闪电定位资料;根据滚球法判断养殖场是否在直击雷保护范围内,计算牲畜位置处跨步电压和养殖棚雷电静电感应电压。通过逐项计算和分析,结果表明：牲畜遭旁侧闪络和接触电压致死。雷电的静电感应在金属棚上产生高电压,由于金属棚的支撑钢架结构未做接地,感应电荷释放通道不顺畅,与地面存在电位差,发生旁侧闪络,以及当牲畜接触到钢结构后,高电位通过牲畜向地面释放,致使牲畜死亡。最后提出了对应的防护措施和方法,减少或避免以后类似雷电灾害事故的发生。     

Analysis of Rural Ecological Pattern Based on FRAGSTATS: A Case Study of Puxing Village in Pidu District

According to the plant information of Puxing Village, a typical village in Chengdu Plain, the GIS map was drawn to analyze the landscape ecology pattern by FRAGSTATS software. The results show that in the past 10 years, although urbanization had a great impact on the rural ecological pattern, it was still in a stable ecological environment. The comparison of the landscape index shows that the replacement of the vegetation community pattern leads to the conversion of the source population from the original farmland to laurel, and the increase of whole vegetation community under artificial intervention is the most important factor for the change of the vegetation community richness. At the same time, the pattern analysis at the horizontal level also reveals the obvious effect of the fast road as an artificial product for the enhancement of nearby vegetation community richness.     

不同类型地膜的降解特征及其对马铃薯产量的影响

为探究不同类型降解地膜的降解特征及其对土壤温度、水分和马铃薯产量的影响,在即墨市蔬菜科技示范园进行了不同类型降解地膜覆盖马铃薯栽培试验。结果表明：全生物可降解膜的降解效果较好,0.006 mm,0.008 mm,0.010 mm的全生物可 降解膜在收获前的降解程度已分别达到5级,4级和3级,而普通PE地膜降解效果只达到了1级。全生物可降解膜有较好的增温保墒作用,但增温保墒性能较PE膜差。对不同地膜覆盖的地块进行马铃薯产量测定,0.006 mm,0.008 mm,0.010 mm全生物可降解膜及PE膜与未覆盖地膜相比,分别增产12.9%、33.3%、33.6%、14.9%。试验结果表明：全生物可降解膜覆盖可以提高土壤温度和马铃薯产量,且自身降解程度较快,无需再增加人工清理费用,对环境的污染较小。综合考虑不同厚度全生物可降解地膜的价格等因素,0.008mm厚度全生物可降解地膜更适合青岛地区马铃薯生产使用,对马铃薯有明显增产作用,同时也为残膜污染治理提供替代产品,有利于控制农业面源污染。     

A preventive control model for static voltage stability considering the power constraints of weak branches

The voltage instability of power system often occurs when the active power on one or more weak branches exceeds its transfer capability. A preventive control model for static voltage stability is proposed using the active power transfer capability of weak branches as static voltage stability constraints. A local line based voltage stability index is used to determine the critical contingencies, weak branches and transfer capability of each weak branch. A static security analysis method, which is based on DC power flow equations, is used to establish the non linear active power flow expressions on weak branches following each critical contingency. The active power constraints on weak branches can be obtained from the active power flow expressions and transfer capabilities of weak branches. A quadratic optimal model for preventive control including the proposed active power constraints on weak branches is presented. The simulation results for IEEEE14 bus system and IEEE118 bus system demonstrate the correctness and effectiveness of the proposed preventive control model.     

西藏野生油菜及其近缘种的遗传多样性中心

本文以100份西藏野生油菜及其近缘种种质资源为材料,运用群体遗传学的原理与方法,对西藏野生油菜及其近缘种种质资源的数量和遗传多样性指数的生态地理分布特征进行了研究。结果表明：1）在水平分布上,西藏野生油菜及其近缘种形成了28—31°N×88—94°E和29—32°N×96—99°E两个区域明显的遗传多样性中心,其中28—31°N×88—94°E的藏中地区野生油菜及其近缘种种质资源分布广泛,遗传多样性丰富,29—32°N×96—99°E的藏东横断山脉地区野生油菜及其近缘种种质资源数量和遗传多样性次之。2）在垂直分布上,以海拔3500－3600m、3800－3900m、4000－4200m为中心,形成了三个不同的遗传多样性中心区,并发现海拔3700－3800 m是低海拔遗传多样性丰富区和高海拔遗传多样性丰富区的临界带。3）据西藏野生油菜及其近缘种遗传资源的数量和遗传多样性指数的水平分布和垂直分布规律,提出了西藏野生油菜及其近缘种的遗传多样性中心及其多样性扩散方式。     

Numerical Simulation and Dynamic Test of Iced Conductors under Skew Winds

Galloping of iced conductors under skew winds is always controlling condition. The aerodynamic parameters of iced conductors under skew winds is the key factor of galloping. This paper studies aerodynamic characteristics of crescent iced conductors under skew winds. Under skew winds aerodynamic coefficients of iced conductors carries on the examination on the traditional oblique wind decomposition method.using computational fluid dynamics software FLUENT numerical simulation and wind tunnel test on two kinds of methods, the iced conductor in under skew wind aerodynamic characteristics are studied, the wind tunnel test measured data and numerical simulation results a comparison is drawn, numerical simulation and experimental results are in good agreement.     

威海近海人工鱼礁区沉积环境要素的时空分布与沉积物质量评价

为了解威海近海人工鱼礁区的沉积环境质量,对该海域表层沉积物中的沉积要素的含量进行了分析,并对其进行污染评价。根据2011年11月,2012年4月、6月、8月、11月和2013年6月、8月共7个航次沉积环境要素调查资料,分析了威海近海人工鱼礁区表层沉积物中总氮、总磷、有机碳和硫化物含量的分布特征,并采用单因子污染指数法和内梅罗污染指数法对沉积物质量进行了评价。结果表明：研究海域表层沉积物中总氮、总磷、有机碳和硫化物的含量均较低,且有机碳和硫化物的含量均符合GB 18668—2002《海洋沉积物质量》中的第一类标准,并呈现出明显的月际变化。单因子污染指数分析表明硫化物和有机碳未对研究海域沉积物产生污染。内梅罗污染指数分析海域沉积物质量的结果表明,研究海域沉积物质量等级为Ⅰ级,且鱼礁区和对照区表层沉积物质量无显著差别。     

Optimizing Design of Planar Transformers Based on Integrated Software Platform

A method of optimizing planar transformers' design based on integrated software platform iSIGHT is presented.Through integrating the circuit simulation tool Saber and Maxwell 3D to the optimization tool iSIGHT,the parasitic effects on planar transformers are studied carefully.Changing the thickness of the insulator layer between the primary and the secondary can obtain different values of parasitic parameters and a new method to avoid parasitic oscillations with dangerous high voltage spikes to improve the SMPS performance is established.Hence an optimal design of planar transformer is obtained.The final optimal simulation analysis results verify the correctness of above theoretical study.     

FDTD Method''s Application in the Research of Television Interference From High Voltage Transmission Line

The mechanism of television interference is discussed from High voltage transmission line. Then the computational model is established, and scattering fields are calculated with the finite-difference time-domain(FDTD) method, and the results are visualized. The scattering effects of High voltage transmission lines on horizontal polarization waves (corresponding to TM mode) are greater than on vertical polarization waves (corresponding to TE mode).     

Export trade and smog pollution: Empirical evidence from China

This paper examines the impact of China's export trade on smog pollution. Based on provincial panel data from 2006 to 2016 in China, we use spatial econometric methods to empirically investigate the smog pollution effects of China's export trade from two dimensions, export scale and export structure. It has been found that smog pollution in various regions of China has obvious spatial correlation; China's export trade has a significant positive impact on smog pollution, whether in terms of export scale or export structure. After establishing different forms of spatial weight matrices and considering alternative indicators of smog pollution, the results of this paper are still robust.     

花卉蔬菜秸秆对水环境影响的模拟研究

农田秸秆废弃物是导致面源污染的主要来源,云南滇池流域是中国重要的鲜切花、蔬菜生产地和集散地,年加工流通蔬菜、花卉量达400万t以上,同时也产生了大量的废弃物,大量农田固体废弃物的富集,加大了滇池流域面源污染治理的难度。笔者选择流域内5种代表性的蔬菜、花卉秸秆,分别进行浸入试验和人工模拟降雨试验,研究其对水质的影响。结果表明：（1）浸入试验中,在相同水平的秸秆投加量下,TN、TP在秸秆投入水中约14和21天左右达到最大值;蔬菜秸秆在水体中TN、TP的总释放量明显高于花卉秸秆;水体TN、TP含量与秸秆投加量均成显著正相关。（2）人工模拟降雨试验中,蔬菜花卉秸秆TN、TP均在中雨强度下达到最大值,且蔬菜秸秆TN、TP的总释放量高于花卉秸秆。     

利用水稻MAGIC群体关联定位抽穗期和株高QTL

利用多亲本高代互交系(multi-parent advanced generation inter-cross,MAGIC)群体(DC1、DC2和8way)及其复合群体DC12(DC1+DC2)和RMPRIL(DC1+DC2+8way)进行关联分析定位水稻抽穗期和株高QTL。2015年和2016年分别在江西和深圳收集3个MAGIC群体抽穗期数据,2016年在两地收集株高数据,结合Rice 55K SNP芯片进行基因分型,利用关联分析方法检测到3个影响抽穗期的主效QTL(q HD3、q HD6和q HD8),分别位于第3、第6和第8染色体,且分别与已知抽穗期基因DTH3、Hd3a和Ghd8在同一区域。检测到5个影响株高的QTL(q PH1.1、q PH1.2、q PH1.3、q PH4和q PH6),其中q PH1.1和q PH1.2位于已知基因Psd1和sd1附近,其余3个QTL为影响株高的新位点,但仅在1个群体和单个环境下被检测到,QTL表达受遗传背景和环境影响大。不同MAGIC群体定位抽穗期和株高的效果不同,在8亲本MAGIC群体8way及复合群体DC12和RMPRIL分别检测到5、5和6个抽穗期和株高QTL,明显多于4亲本群体DC1的2个和DC2的4个,而且作图的精度更高,表现在定位到的QTL显著水平高和与已知基因距离更近,尤其是复合群体的联合分析(如DC12和RMPRIL)的作图优势更为明显。