Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical polluti...Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.展开更多
Being one of the most expensive components of an electrical power plant, the failures of a power transformer can result in serious power system issues. So fault diagnosis for power transformer is highly important to e...Being one of the most expensive components of an electrical power plant, the failures of a power transformer can result in serious power system issues. So fault diagnosis for power transformer is highly important to ensure an uninterrupted power supply. Due to information transmission mistakes as well as arisen errors while processing data in surveying and monitoring state information of transformer, uncertain and incomplete information may be produced. Based on these points, this paper presents an intelligent fault diagnosis method of power transformer using fuzzy fault tree analysis (FTA) and beta distribution for failure possibility estimation. By using the technique we proposed herein, the continuous attribute values are transformed into the fuzzy numbers to give a realistic estimate of failure possibility of a basic event in FTA. Further, it explains a new approach based on Euclidean distance between fuzzy numbers, to rank the basic events in accordance with their Fuzzy Importance Index.展开更多
为有效推动“双碳”目标的实现,针对系统碳排放量大、综合成本高和优化调度迭代寻优困难的问题,提出了计及车网互动的热电联供微网(combined heat and power microgrid,CHP-MG)优化调度方法。以微网运行成本和碳排放量最小为目标,建立...为有效推动“双碳”目标的实现,针对系统碳排放量大、综合成本高和优化调度迭代寻优困难的问题,提出了计及车网互动的热电联供微网(combined heat and power microgrid,CHP-MG)优化调度方法。以微网运行成本和碳排放量最小为目标,建立了考虑车网互动的CHP-MG模型,同时,考虑用户需求变化,设置了优先满足电负荷需求和优先满足热负荷需求2种模式;给出改进的树种优化算法,将种群划分为4部分,更有效的进行全局搜索;该算法还引入了枯萎过程和位置置换变异策略,以增加种群多样性、避免局部最优,从而提高收敛时间和寻优能力。以英格兰东北部地区为例进行了仿真验证,结果表明,改进后算法的寻优结果和收敛时间明显优于未改进的树种优化算法。展开更多
基金financially supported by the National Key Research and Development Program(2017YFD0600101)the Central University Basic Research and Operating Expenses of Special Funding(2572016CB04)the Harbin Application Technology Research and Development Projects(2016RQQXJ134)
文摘Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.
文摘Being one of the most expensive components of an electrical power plant, the failures of a power transformer can result in serious power system issues. So fault diagnosis for power transformer is highly important to ensure an uninterrupted power supply. Due to information transmission mistakes as well as arisen errors while processing data in surveying and monitoring state information of transformer, uncertain and incomplete information may be produced. Based on these points, this paper presents an intelligent fault diagnosis method of power transformer using fuzzy fault tree analysis (FTA) and beta distribution for failure possibility estimation. By using the technique we proposed herein, the continuous attribute values are transformed into the fuzzy numbers to give a realistic estimate of failure possibility of a basic event in FTA. Further, it explains a new approach based on Euclidean distance between fuzzy numbers, to rank the basic events in accordance with their Fuzzy Importance Index.
文摘为有效推动“双碳”目标的实现,针对系统碳排放量大、综合成本高和优化调度迭代寻优困难的问题,提出了计及车网互动的热电联供微网(combined heat and power microgrid,CHP-MG)优化调度方法。以微网运行成本和碳排放量最小为目标,建立了考虑车网互动的CHP-MG模型,同时,考虑用户需求变化,设置了优先满足电负荷需求和优先满足热负荷需求2种模式;给出改进的树种优化算法,将种群划分为4部分,更有效的进行全局搜索;该算法还引入了枯萎过程和位置置换变异策略,以增加种群多样性、避免局部最优,从而提高收敛时间和寻优能力。以英格兰东北部地区为例进行了仿真验证,结果表明,改进后算法的寻优结果和收敛时间明显优于未改进的树种优化算法。