Unilateral power supply system has been used because of the management status of the power grid system, while, bilateral power supply system is adopted in the Soviet Union and France. The feasibility that whether bila...Unilateral power supply system has been used because of the management status of the power grid system, while, bilateral power supply system is adopted in the Soviet Union and France. The feasibility that whether bilateral system can be put applied in China is discussed. Compared with unilateral power supply system, bilateral system has better reliability and better capability of supply power system, which gives bilateral system more advantages over unilateral system on both engineering investment and operating efficiency. In this paper, voltage losses under the two different systems are calculated and also compared, the advantages of bilateral system is explored and then conclusion is drawn by referring to the practical data of passenger transport lines.展开更多
It is a known fact that the epileptic power situation in Nigeria has become a recurring decimal. In the light of this stark reality of a country like Nigeria which is constantly plunged into pitch darkness all year ro...It is a known fact that the epileptic power situation in Nigeria has become a recurring decimal. In the light of this stark reality of a country like Nigeria which is constantly plunged into pitch darkness all year round, it has become expedient for a sustainable and urgent remedy to be sought if our country will ever think of rubbing shoulders with the economies of the world. It is this pathetic scenario, we find ourselves in that it has given rise to this paper which tends to review possible ways and means of redressing the ugly trend. This paper examines the prospects and possible applications of Smart Grid Technology (SGT) to the Nigeria Power System. Nigeria Power System consists of 28 buses, 32 Transmission lines and 10 generating stations, with a view to reduce the high active and reactive transmission losses. The study shows that smart grid system will make the present network more efficient and reliable by connecting different sources of distributed generators into the existing grid. Basic requirements necessary for the application of SGT using the Nigeria Power System as a case study were discussed.展开更多
为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制...为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制系统(load power flexible control system,LPFCS)的拓扑结构及控制方式;其次,依据负荷功率和电池荷电状态来划分负荷工况,进而以负荷功率波动的平抑、防止电池过充过放以及提升储能系统应对极端工况的能力为原则,将LPFCS的工作模式分为空闲、填谷、削峰以及限幅4种模式;然后,建立系统网侧线损优化模型,求解模型得出功率补偿值的取值区间,并基于该区间确定不同工况下LPFCS的功率补偿值。最后,基于长江某岸电系统实测负荷数据,对LPFCS的工作性能进行仿真和实验验证。结果表明:LPFCS的补偿响应时间小于0.3 s,负荷功率波动抑制率达到90%,系统网侧线损率下降17.2%。展开更多
目的:分析并评价维持性血液透析病人动静脉内瘘失功的风险预测模型,以期为临床提供参考依据。方法:计算机检索Embase、the Cochrane Library、Web of Science、PubMed等英文数据库及中国知网、中国生物医学文献数据库、万方数据库等中...目的:分析并评价维持性血液透析病人动静脉内瘘失功的风险预测模型,以期为临床提供参考依据。方法:计算机检索Embase、the Cochrane Library、Web of Science、PubMed等英文数据库及中国知网、中国生物医学文献数据库、万方数据库等中文数据库中有关维持性血液透析病人动静脉内瘘失功预测模型的文献,由2名具有循证能力的研究者按照文章的纳入、排除标准提取文献,再根据预测模型研究的偏倚风险评估工具对纳入的文献进行偏倚风险及适用性评价。结果:共纳入6篇动静脉内瘘失功风险预测模型,其中回顾性队列研究3篇,前瞻性队列研究3篇;单中心研究5篇,多中心研究1篇,预测动静脉早期失功的模型3篇,预测动静脉内瘘晚期失功模型3篇。6个模型的受试者工作特征曲线下面积(AUC)均大于0.700,纳入模型中预测动静脉内瘘失功的预测因子最多的是年龄、血压、有无糖尿病、置管史、吻合的动脉静脉血管直径及病人的钙磷乘积等,6项研究使用性较好,但是均存在一定的偏倚风险。结论:维持性血液透析病人动静脉内瘘失功风险预测模型的研究尚处在发展阶段,未来临床工作者应该开发性能好、偏倚风险较低的预测模型,进行外部或内部验证,用于临床。展开更多
文摘Unilateral power supply system has been used because of the management status of the power grid system, while, bilateral power supply system is adopted in the Soviet Union and France. The feasibility that whether bilateral system can be put applied in China is discussed. Compared with unilateral power supply system, bilateral system has better reliability and better capability of supply power system, which gives bilateral system more advantages over unilateral system on both engineering investment and operating efficiency. In this paper, voltage losses under the two different systems are calculated and also compared, the advantages of bilateral system is explored and then conclusion is drawn by referring to the practical data of passenger transport lines.
文摘It is a known fact that the epileptic power situation in Nigeria has become a recurring decimal. In the light of this stark reality of a country like Nigeria which is constantly plunged into pitch darkness all year round, it has become expedient for a sustainable and urgent remedy to be sought if our country will ever think of rubbing shoulders with the economies of the world. It is this pathetic scenario, we find ourselves in that it has given rise to this paper which tends to review possible ways and means of redressing the ugly trend. This paper examines the prospects and possible applications of Smart Grid Technology (SGT) to the Nigeria Power System. Nigeria Power System consists of 28 buses, 32 Transmission lines and 10 generating stations, with a view to reduce the high active and reactive transmission losses. The study shows that smart grid system will make the present network more efficient and reliable by connecting different sources of distributed generators into the existing grid. Basic requirements necessary for the application of SGT using the Nigeria Power System as a case study were discussed.
文摘为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制系统(load power flexible control system,LPFCS)的拓扑结构及控制方式;其次,依据负荷功率和电池荷电状态来划分负荷工况,进而以负荷功率波动的平抑、防止电池过充过放以及提升储能系统应对极端工况的能力为原则,将LPFCS的工作模式分为空闲、填谷、削峰以及限幅4种模式;然后,建立系统网侧线损优化模型,求解模型得出功率补偿值的取值区间,并基于该区间确定不同工况下LPFCS的功率补偿值。最后,基于长江某岸电系统实测负荷数据,对LPFCS的工作性能进行仿真和实验验证。结果表明:LPFCS的补偿响应时间小于0.3 s,负荷功率波动抑制率达到90%,系统网侧线损率下降17.2%。
文摘目的:分析并评价维持性血液透析病人动静脉内瘘失功的风险预测模型,以期为临床提供参考依据。方法:计算机检索Embase、the Cochrane Library、Web of Science、PubMed等英文数据库及中国知网、中国生物医学文献数据库、万方数据库等中文数据库中有关维持性血液透析病人动静脉内瘘失功预测模型的文献,由2名具有循证能力的研究者按照文章的纳入、排除标准提取文献,再根据预测模型研究的偏倚风险评估工具对纳入的文献进行偏倚风险及适用性评价。结果:共纳入6篇动静脉内瘘失功风险预测模型,其中回顾性队列研究3篇,前瞻性队列研究3篇;单中心研究5篇,多中心研究1篇,预测动静脉早期失功的模型3篇,预测动静脉内瘘晚期失功模型3篇。6个模型的受试者工作特征曲线下面积(AUC)均大于0.700,纳入模型中预测动静脉内瘘失功的预测因子最多的是年龄、血压、有无糖尿病、置管史、吻合的动脉静脉血管直径及病人的钙磷乘积等,6项研究使用性较好,但是均存在一定的偏倚风险。结论:维持性血液透析病人动静脉内瘘失功风险预测模型的研究尚处在发展阶段,未来临床工作者应该开发性能好、偏倚风险较低的预测模型,进行外部或内部验证,用于临床。
