针对配用电通信网中长距离线路场景,提出了一种基于多频中继组网的超长距电力线载波通信(Power line communication,PLC)协议技术,通过频率自适应技术,为不同站点选择最佳工作频率和带宽,可快速适应电力线载波信道的变化,提高通信成功...针对配用电通信网中长距离线路场景,提出了一种基于多频中继组网的超长距电力线载波通信(Power line communication,PLC)协议技术,通过频率自适应技术,为不同站点选择最佳工作频率和带宽,可快速适应电力线载波信道的变化,提高通信成功率。同时,采用多频中继组网技术,可有效减少中继的个数和跳数,满足电网的业务需求。基于MATLAB的仿真和现场测试表明,利用频率自适应、中继多频组网技术,可以最大化直接和主站相连的节点个数,显著改善了网络的吞吐量和时延性能,提高单跳通信距离,扩大网络的覆盖范围。展开更多
图卷积网络由于能够直接处理图结构数据的优点而受到广泛研究。当前的多数图卷积网络是基于图信号的平滑性(低频信息),且不能根据各节点适合的接受域生成对应的节点嵌入,随着网络层数的增加,易出现图卷积网络特有的过平滑问题而导致性...图卷积网络由于能够直接处理图结构数据的优点而受到广泛研究。当前的多数图卷积网络是基于图信号的平滑性(低频信息),且不能根据各节点适合的接受域生成对应的节点嵌入,随着网络层数的增加,易出现图卷积网络特有的过平滑问题而导致性能下降。为此,提出了基于自适应频率和动态节点嵌入的图卷积网络模型(adaptive frequency and dynamic node embedding based graph convolutional network,FDGCN)。FDGCN模型能够自适应聚合不同频率的信息,同时利用每层网络的输出,平衡每个节点来自全局和局部领域的信息,动态地调节节点嵌入。通过在4个公共数据集上进行实验,对比了6个现有模型,证明了FDGCN模型的有效性。展开更多
为解决风机受谐波干扰引起电压畸变和频率波动从而影响风机并网稳定运行的问题,提出频率自适应锁相方法,以谐波提取电路为基础,设计具有滤除风机谐波功能的NSOGI (new second-order generalized integrator)锁相环。首先,在谐波提取电...为解决风机受谐波干扰引起电压畸变和频率波动从而影响风机并网稳定运行的问题,提出频率自适应锁相方法,以谐波提取电路为基础,设计具有滤除风机谐波功能的NSOGI (new second-order generalized integrator)锁相环。首先,在谐波提取电路中加入基波谐振电路,验证谐波提取前后锁相环的锁频精度;其次,在传统锁相环基础上加入直流抑制器,对输入信号的频率进行跟踪;最后,进行理论和仿真分析,对比DSOGI-FLL谐波提取前后电路中的频率偏差,验证2种锁相环的锁频精度。结果表明:在谐波提取电路中加入基波谐振电路,减少了谐波对基波源的影响,提升了谐波提取的效果;在抑制风机电压畸变和直流谐波方面,NSOGI锁相环效果较好,锁频精度较高,验证了方法的可行性和正确性。采用NSOGI对电压和频率进行控制,能够提升供电可靠性,改善并网电能质量,为风机并网稳定运行提供了理论参考。展开更多
A control strategy of frequency self-adaptation without phase-locked loop(PLL)underαβstationary reference frame(αβ-SRF)for a VSC-HVDC system is presented to improve the operational performance of the system under ...A control strategy of frequency self-adaptation without phase-locked loop(PLL)underαβstationary reference frame(αβ-SRF)for a VSC-HVDC system is presented to improve the operational performance of the system under severe harmonic distortion conditions.The control strategy helps to eliminate the cross-coupling under dq synchronous reference frame(dq-SRF),and is achieved through two key technologies:1)positive phase sequence(PPS)and negative phase sequence(NPS)fundamental components are extracted from the AC grid voltage with an improved multiple complex coefficient filter(IMCF),and 2)grid instantaneous frequency is rapidly and precisely tracked using a frequency self-adaptation tracking algorithm(FATA)without PLL.The proposed strategy is applied to a point-to-point VSCHVDC system and validated by means of simulations.The results are compared to those with the traditional vector control strategy under dq-SRF.Simulation results illustrate that the proposed strategy results in better system performance than that with the traditional strategy in terms of harmonic suppression under normal and severe operating conditions of the AC system.展开更多
In neurodegenerative disorders such as Parkinson＇s disease （PD）, deep brain stimulation （DBS） is a desirable approach when the medication is less effective for treating the symptoms. DBS incorporates transferring...In neurodegenerative disorders such as Parkinson＇s disease （PD）, deep brain stimulation （DBS） is a desirable approach when the medication is less effective for treating the symptoms. DBS incorporates transferring electrical pulses to a specific tissue of the central nervous system, obtaining therapeutic results by modulating the neuronal activity of that region. DBS has certain advantages such as reversibility and adjustability features over medication, since the neuronal firing patterns can be recorded and used to alter the parameters of the DBS signal （Benabid et al., 2009）. One of the DBS indications is its ability to suppress the abnormal neuronal activity to treat symptoms like tremor, akinesia and dystonia.展开更多
The evoked spike discharges of a neuron depend critically on the recent history of its electrical activity. A well-known example is the phenomenon of spike-frequency adaptation that is a commonly observed property of ...The evoked spike discharges of a neuron depend critically on the recent history of its electrical activity. A well-known example is the phenomenon of spike-frequency adaptation that is a commonly observed property of neurons. In this paper, using a leaky integrate-and-fire model that includes an adaptation current, we propose an event-driven strategy to simulate integrate-and-fire models with spike-frequency adaptation. Such approach is more precise than traditional clock-driven numerical integration approach because the timing of spikes is treated exactly. In experiments, using event-driven and clock-driven strategies we simulated the adaptation time course of single neuron and the random network with spike-timing dependent plasticity, the results indicate that （1） the temporal precision of spiking events impacts on neuronal dynamics of single as well as network in the different simulation strategies and （2） the simulation time in the event-driven simulation strategies. scales linearly with the total number of spiking events展开更多
文摘针对配用电通信网中长距离线路场景,提出了一种基于多频中继组网的超长距电力线载波通信(Power line communication,PLC)协议技术,通过频率自适应技术,为不同站点选择最佳工作频率和带宽,可快速适应电力线载波信道的变化,提高通信成功率。同时,采用多频中继组网技术,可有效减少中继的个数和跳数,满足电网的业务需求。基于MATLAB的仿真和现场测试表明,利用频率自适应、中继多频组网技术,可以最大化直接和主站相连的节点个数,显著改善了网络的吞吐量和时延性能,提高单跳通信距离,扩大网络的覆盖范围。
文摘图卷积网络由于能够直接处理图结构数据的优点而受到广泛研究。当前的多数图卷积网络是基于图信号的平滑性(低频信息),且不能根据各节点适合的接受域生成对应的节点嵌入,随着网络层数的增加,易出现图卷积网络特有的过平滑问题而导致性能下降。为此,提出了基于自适应频率和动态节点嵌入的图卷积网络模型(adaptive frequency and dynamic node embedding based graph convolutional network,FDGCN)。FDGCN模型能够自适应聚合不同频率的信息,同时利用每层网络的输出,平衡每个节点来自全局和局部领域的信息,动态地调节节点嵌入。通过在4个公共数据集上进行实验,对比了6个现有模型,证明了FDGCN模型的有效性。
文摘为解决风机受谐波干扰引起电压畸变和频率波动从而影响风机并网稳定运行的问题,提出频率自适应锁相方法,以谐波提取电路为基础,设计具有滤除风机谐波功能的NSOGI (new second-order generalized integrator)锁相环。首先,在谐波提取电路中加入基波谐振电路,验证谐波提取前后锁相环的锁频精度;其次,在传统锁相环基础上加入直流抑制器,对输入信号的频率进行跟踪;最后,进行理论和仿真分析,对比DSOGI-FLL谐波提取前后电路中的频率偏差,验证2种锁相环的锁频精度。结果表明:在谐波提取电路中加入基波谐振电路,减少了谐波对基波源的影响,提升了谐波提取的效果;在抑制风机电压畸变和直流谐波方面,NSOGI锁相环效果较好,锁频精度较高,验证了方法的可行性和正确性。采用NSOGI对电压和频率进行控制,能够提升供电可靠性,改善并网电能质量,为风机并网稳定运行提供了理论参考。
基金supported by the Science and Technology Project of the State Grid Corporation of China(SGRIZLKJ[2015]457)。
文摘A control strategy of frequency self-adaptation without phase-locked loop(PLL)underαβstationary reference frame(αβ-SRF)for a VSC-HVDC system is presented to improve the operational performance of the system under severe harmonic distortion conditions.The control strategy helps to eliminate the cross-coupling under dq synchronous reference frame(dq-SRF),and is achieved through two key technologies:1)positive phase sequence(PPS)and negative phase sequence(NPS)fundamental components are extracted from the AC grid voltage with an improved multiple complex coefficient filter(IMCF),and 2)grid instantaneous frequency is rapidly and precisely tracked using a frequency self-adaptation tracking algorithm(FATA)without PLL.The proposed strategy is applied to a point-to-point VSCHVDC system and validated by means of simulations.The results are compared to those with the traditional vector control strategy under dq-SRF.Simulation results illustrate that the proposed strategy results in better system performance than that with the traditional strategy in terms of harmonic suppression under normal and severe operating conditions of the AC system.
文摘In neurodegenerative disorders such as Parkinson＇s disease （PD）, deep brain stimulation （DBS） is a desirable approach when the medication is less effective for treating the symptoms. DBS incorporates transferring electrical pulses to a specific tissue of the central nervous system, obtaining therapeutic results by modulating the neuronal activity of that region. DBS has certain advantages such as reversibility and adjustability features over medication, since the neuronal firing patterns can be recorded and used to alter the parameters of the DBS signal （Benabid et al., 2009）. One of the DBS indications is its ability to suppress the abnormal neuronal activity to treat symptoms like tremor, akinesia and dystonia.
文摘The evoked spike discharges of a neuron depend critically on the recent history of its electrical activity. A well-known example is the phenomenon of spike-frequency adaptation that is a commonly observed property of neurons. In this paper, using a leaky integrate-and-fire model that includes an adaptation current, we propose an event-driven strategy to simulate integrate-and-fire models with spike-frequency adaptation. Such approach is more precise than traditional clock-driven numerical integration approach because the timing of spikes is treated exactly. In experiments, using event-driven and clock-driven strategies we simulated the adaptation time course of single neuron and the random network with spike-timing dependent plasticity, the results indicate that （1） the temporal precision of spiking events impacts on neuronal dynamics of single as well as network in the different simulation strategies and （2） the simulation time in the event-driven simulation strategies. scales linearly with the total number of spiking events
