One main issue of degrading IEEE 802.15.4performance is the beacon conflict which increases the energy consumption.However,IEEE 802.15.4does not address a solution to avoid the beacon conflict.In order to reduce this ...One main issue of degrading IEEE 802.15.4performance is the beacon conflict which increases the energy consumption.However,IEEE 802.15.4does not address a solution to avoid the beacon conflict.In order to reduce this beacon conflict,an individual time division(ITD)algorithm based on IEEE 802.15.4is proposed.In this algorithm,a coordinator assigns the time division(TD)for each associated coordinator so that different coordinators transmit a beacon frame at different time slice.In this way,the beacon conflict is decreased substantially.The experimental results show that ITD reduces both the beacon conflict and the network energy consumption,and improves the network performance.展开更多
The existing liability division methods for harmonic pollution are either inexplicit or incomplete in physical meaning. To compensate these defects, two new methods are proposed based on line-transferred power compone...The existing liability division methods for harmonic pollution are either inexplicit or incomplete in physical meaning. To compensate these defects, two new methods are proposed based on line-transferred power components in this paper. At first, all harmonic sources are represented by ideal equivalent current source, line current components and bus voltage components of a source are determined by stimulation of this source with all other sources disabled. Then, the line-trans- ferred power component owing to a source under all sources action together is determined by the theory of line-transferred power components, and called source’s line-transferred power component. At last, the liability of a source for line-end harmonic pollution is divided by two methods: the ration of the source’s line-transferred active power component to the total line-transferred power, and the ration of projection of the source’s line-transferred complex power component to absolute value of the total line-transferred complex power. These two methods are taken into account not only harmonic voltage but also harmonic current in the liability division. Simulation results show that the proposed liability division method based on active power component is the most effective and ideal one.展开更多
准确求解谐波阻抗是谐波治理和合理划分谐波责任的前提。现有谐波阻抗估计方法须满足背景谐波波动小且用户侧谐波阻抗远大于系统侧谐波阻抗的条件,但大量电力电子设备在电力系统中的使用导致这些条件可能难以被满足,因此文中提出一种基...准确求解谐波阻抗是谐波治理和合理划分谐波责任的前提。现有谐波阻抗估计方法须满足背景谐波波动小且用户侧谐波阻抗远大于系统侧谐波阻抗的条件,但大量电力电子设备在电力系统中的使用导致这些条件可能难以被满足,因此文中提出一种基于互信息数据优选的系统侧谐波阻抗估计方法。首先通过独立分量分析(independent component analysis,ICA)求解系统侧谐波电流,然后筛选公共连接点(point of common coupling,PCC)处谐波电流与系统侧谐波电流互信息小的数据段,最后利用筛选出的数据段对应的PCC处谐波电流与系统侧谐波电压协方差为0的特性对谐波阻抗进行估计。仿真和实际案例分析表明:与现有方法相比较,在用户侧谐波阻抗非远大于系统侧谐波阻抗时,文中所提方法的系统侧谐波阻抗估计结果更准确,适用范围更广泛。展开更多
基金supported by the National Natural Science Foundation of China(61202440)the Natural Science Foundation of Jiangsu Province(BK20141230)
文摘One main issue of degrading IEEE 802.15.4performance is the beacon conflict which increases the energy consumption.However,IEEE 802.15.4does not address a solution to avoid the beacon conflict.In order to reduce this beacon conflict,an individual time division(ITD)algorithm based on IEEE 802.15.4is proposed.In this algorithm,a coordinator assigns the time division(TD)for each associated coordinator so that different coordinators transmit a beacon frame at different time slice.In this way,the beacon conflict is decreased substantially.The experimental results show that ITD reduces both the beacon conflict and the network energy consumption,and improves the network performance.
文摘The existing liability division methods for harmonic pollution are either inexplicit or incomplete in physical meaning. To compensate these defects, two new methods are proposed based on line-transferred power components in this paper. At first, all harmonic sources are represented by ideal equivalent current source, line current components and bus voltage components of a source are determined by stimulation of this source with all other sources disabled. Then, the line-trans- ferred power component owing to a source under all sources action together is determined by the theory of line-transferred power components, and called source’s line-transferred power component. At last, the liability of a source for line-end harmonic pollution is divided by two methods: the ration of the source’s line-transferred active power component to the total line-transferred power, and the ration of projection of the source’s line-transferred complex power component to absolute value of the total line-transferred complex power. These two methods are taken into account not only harmonic voltage but also harmonic current in the liability division. Simulation results show that the proposed liability division method based on active power component is the most effective and ideal one.
文摘准确求解谐波阻抗是谐波治理和合理划分谐波责任的前提。现有谐波阻抗估计方法须满足背景谐波波动小且用户侧谐波阻抗远大于系统侧谐波阻抗的条件,但大量电力电子设备在电力系统中的使用导致这些条件可能难以被满足,因此文中提出一种基于互信息数据优选的系统侧谐波阻抗估计方法。首先通过独立分量分析(independent component analysis,ICA)求解系统侧谐波电流,然后筛选公共连接点(point of common coupling,PCC)处谐波电流与系统侧谐波电流互信息小的数据段,最后利用筛选出的数据段对应的PCC处谐波电流与系统侧谐波电压协方差为0的特性对谐波阻抗进行估计。仿真和实际案例分析表明:与现有方法相比较,在用户侧谐波阻抗非远大于系统侧谐波阻抗时,文中所提方法的系统侧谐波阻抗估计结果更准确,适用范围更广泛。