Classification of Power Quality Disturbances Using Wavelet Packet Energy Entropy and LS-SVM

The power quality (PQ) signals are traditionally analyzed in the time-domain by skilled engineers. However, PQ disturbances may not always be obvious in the original time-domain signal. Fourier analysis transforms signals into frequency domain, but has the disadvantage that time characteristics will become unobvious. Wavelet analysis, which provides both time and frequency information, can overcome this limitation. In this paper, there were two stages in analyzing PQ signals: feature extraction and disturbances classification. To extract features from PQ signals, wavelet packet transform (WPT) was first applied and feature vectors were constructed from wavelet packet log-energy entropy of different nodes. Least square support vector machines (LS-SVM) was applied to these feature vectors to classify PQ disturbances. Simulation results show that the proposed method possesses high recognition rate, so it is suitable to the monitoring and classifying system for PQ disturbances.

基于FCS-MPC的分布式HESS功率协调控制

针对孤岛直流微电网中分布式混合储能系统(HESS)协调运行问题,提出一种基于有限控制集模型预测控制(FCSMPC)的功率协调控制策略。该策略采用小波包变换来分解分布式HESS的功率需求,由于分解后信号的特点和分布式HESS中蓄电池初始状态的不同,于是对分解后最低频信号基于蓄电池荷电状态(SOC)设计自适应因数来进一步再分解。由于DC/DC变换器开关状态组合数量较少,使得多步FCS-MPC的滚动优化计算量较少,于是采用FCS-MPC取代双闭环PI控制,提高系统动态响应。搭建含有分布式HESS的孤岛直流微电网模型,并做了3种方案的仿真对比,验证该策略有效平缓了直流母线波动并实现蓄电池SOC一致。该策略有利于提高电网运行的稳定性,并延长蓄电池使用寿命。

基于小波包变换与深度学习的超短期光伏功率预测

针对光伏功率序列的复杂多变特征,提出一种基于小波包变换(WPT)的门控循环单元(GRU)光伏功率组合预测方法。首先通过相关性分析挑选重要气象因子,并利用WPT将原始光伏功率序列分解为一组子序列;然后,提出一种基于莱维飞行天牛须搜索算法(LFBAS)的相似日选择方法,以选择相似于预测日的历史日作为输入数据集;最后,建立一组基于GRU网络的深度学习光伏功率预测模型,将每个子序列预测结果叠加得到光伏功率最终预测结果。仿真结果表明,该文所提出的预测方法在预测精度和计算效率方面具有显著优势。

基于软件定义安全的配电物联网分组转发异常检测

针对配电物联网“云、管、边、端”架构中云平台与边缘设备远程通信中存在的恶意的分组注入、篡改、丢弃与劫持攻击,提出基于软件定义安全的配电物联网分组转发异常检测机制,克服了传统网络通过插入随路径长度以线性尺度增加密码标签的方式实现分组转发检测引入的计算与带宽开销大的缺点。机制结合软件定义架构,通过地址跳变将网络流运行时间分割为随机的时隙,网络节点基于跳变的地址信息转发分组,流边缘入口与出口交换机采样该时隙内的分组并生成流量梗概,控制器基于流量梗概检测分组转发异常;最后,构建仿真网络实现了所提机制,分析与实验表明该开销小于同类机制,引入了不超过11%的转发延迟与低于10%的吞吐率损失,可有效检测物联网云边远程通信分组转发异常。

基于SPN算力网络承载底座的探索实践研究

该研究旨在深入探究基于切片分组网(Slicing Packet Network,SPN)算力网络承载底座的架构与特性。通过分析SPN承载底座的关键技术,结合实际案例研究,完成实际部署和性能评估,从而揭示SPN网络在处理大规模、高速数据传输和计算任务中的优势,为SPN的未来发展奠定基础。

基于接地线电流法的电力电缆绝缘在线监测

为提高电力系统的安全性,将接地线电流法作为核心方法,设计电力电缆绝缘在线监测系统。采用通用分组无线业务/码分多址(General Packet Radio Service/Code Division Multiple Access,GPRS/CDMA)通信方式作为电力电缆绝缘在线监测系统的核心,建立电缆各条线路之间的通信连接。利用电流互感器(Current Transformer,CT)检测电缆电流变化情况,有利于提高绝缘在线监测系统的检测精度。将绝缘在线监测应用于电力系统,可为电力系统的后续发展提供依据。

基于小波包分解的通信电源计量设备谐波故障诊断方法

传统的谐波故障诊断方法通常基于频谱分析和傅里叶变换,但实际应用中由于信号的非线性和时变性,无法准确识别谐波故障。因此,文章提出基于小波包分解的通信电源计量设备谐波故障诊断方法。在收集计量设备运行谐波信号的过程中进行降噪处理,并结合小波包算法分解能量信号,提取与谐波故障相关的特征。实验结果表明,基于小波包分解的通信电源计量设备谐波故障诊断方法的诊断效率高于传统方法。

基于改进DES的高压电网用户信息安全传输方法

为提高高压电网用户信息传输的带宽,减少信息传输的拥堵现象,提出基于改进DES的高压电网用户信息安全传输方法。利用改进DES加密算法对高压电网用户信息进行加密,并利用区域推进机制将加密后的数据推进到节点中,以此确保节点的均衡能耗,通过节点对数据包进行传输及接收,实现用户信息安全传输。实验结果表明,该方法在不同节点运动速度下,数据传输带宽下降速度慢,数据传输拥堵次数少,表明该方法的传输效果强,具有较高的实用性。

Extracting Power Transformer Vibration Features by a Time-Scale-Frequency Analysis Method

In order to take advantage of the merits of WPT and HHT in feature extraction from vibration signals of power transformer, a time-scale-frequency analysis method is developed based on the combination of these two techniques. This method consists of two steps. First, the desirable wavelet packet nodes corresponding to characteristic frequency bands of power transformer are selected through a Correlation Degree Threshold Screening (CDTS) technique for reconstructing a time-domain signal that contains useful information of power transformer. Second, the HHT is then conducted on the reconstructed signal to track the instantaneous frequencies corresponding to natural characteristics of power transformer. Experimental results are provided by analyzing a real power transformer vibration signal. Compared with the features extracted by directly using HHT, the features obtained by the proposed method reveal clearer condition pattern of the transformer, which shows the potential of this method in condition monitoring of power transformer.

Secure Packet Video Transmission over Wireless Multimedia Sensor Networks

This paper proposes a packet scheduling scheme thatoptimizing the coded video transmission overmultipath wireless multimedia sensor networks interms of received video distortion and power efficiencyenhances the security aspects of the underlyingsystem.When the aggregate transmission rateavailable at the network cannot support the requiredtransmission rate,the scheduling algorithm can selectivelydrop combinations of video packets prior totransmission to adapt the rate of the sender to thelimitations of the wireless channel capacity.Twoscheduling algorithms are proposed.The Baselinescheme utilizes a novel distortion prediction modeland decides upon which packet can be dropped priorto transmission based on the packet’s impact on thevideo distortion.In addition to the bandwidthlimitations,the Power aware packet scheduling is an extension of the Baseline capable of estimating thepower that will be consumed by each node during thetransmission;hence it can control the power consumptionby selectively drop packets of low importanceto the decoded video.Simulation results indicatethe efficiency of the proposed scheduling schemein terms of received video distortion(PSNR)andpower consumption.

Saturated Power Control Scheme for Kalman Filtering via Wireless Sensor Networks

We investigate the Kalman filtering problem via wireless sensor networks over fading channels. When part or all of the observation measurements are lost in a random fashion, we obtain the conclusion that the packet dropout probabilities depend upon the time-varying channel gains and the transmission power levels used by the sensors. We develop a satu- rated power controller which trades off sensor energy expenditure versus state estimation accuracy. The latter is measured by the expected value of the future covariance matrices provided by the associated time-varying Kalman filter. We study the statistical convergence properties of the error covariance matrix and pointed out the existence of the admissible packet arrival probability bound.

Design of Efficient Router with Low Power and Low Latency for Network on Chip

The NoC consists of processing element (PE), network interface (NI) and router. This paper proposes a hybrid scheme for Netwok of Chip (NoC), which aims at obtaining low latency and low power consumption by concerning wired and wireless links between routers. The main objective of this paper is to reduce the latency and power consumption of the network on chip architecture using wireless link between routers. In this paper, the power consumption is reduced by designing a low power router and latency is reduced by implementing a on-chip wireless communication as express links for transferring data from one subnet routers to another subnet routers. The average packet latency and normalized power consumption of proposed hybrid NoC router are analyzed for synthetic traffic loads as shuffle traffic, bitcomp traffic, transpose traffic and bitrev traffic. The proposed hybrid NoC router reduces the normalized power over the wired NoC by 12.18% in consumer traffic, 12.80% in AutoIndust traffic and 12.5% in MPEG2 traffic. The performance is also analyzed with real time traffic environments using Network simulator 2 tool.

基于小波包-模糊算法的混合储能功率分配策略

针对光储微网中混合储能功率分配不佳导致母线电压频繁波动的问题,提出一种小波包与模糊控制相结合的混合储能功率分配策略。首先利用小波包对光伏系统净功率进行一次分解,得到初次分频点,其次将混合储能荷电状态和电池温度作为模糊控制的参考因素制定模糊规则,对二阶低通滤波器时间常数进行可变调节,修正初次分频点,实现混合储能的最终功率分配。为验证策略的有效性,建模并进行仿真,结果表明所提策略能够有效避免储能电池过充过放,实现光储系统净功率的合理分配,有效平抑功率波动,使直流母线电压波动在±1%以内。

基于Power Architecture处理器的IP业务汇聚算法实现

在无中心自组网通信系统中,每个数据通信时隙可以传输的数据量是确定的,而不同业务终端及无线自组网设备自身进行网络维护所产生的数据包的长度是随机的。传输较短与传输较长的数据包需要消耗相同的时隙资源,存在较大的浪费。文章介绍了一种IP业务汇聚算法的实现方法,并基于Power Architecture处理器硬件平台对技术方案进行实现。结果标明,在不引入额外时延的基础上,本方法能够有效提升系统的传输效率。

基于改进小波包分解的混合储能系统容量配置方法

随着中国风电装机容量的增加,风电输出功率的随机性和波动性令电网调频难度加大,为解决此问题,可采用由能量型(锂离子电池)和功率型(飞轮)储能阵列组成的混合储能系统进行风功率输出平抑,因此亟需研究混合储能系统的容量配置方法,增大其利用率并降低所需容量。首先建立250 kW/50 kWh飞轮储能以及250 kW/150 kWh的锂离子电池储能单元模型,引入相应控制策略;接着根据储能系统的自身特性以及风电场输出功率的幅频特性,提出一种改进小波包分解方法,对风电场输出功率数据进行分解,获得混合储能系统的充放电指令;然后根据不同类型储能阵列的响应时间以及改进小波包分解后各节点能量分布,获得不同种类储能阵列充放电指令分配方法;最后,根据上述充放电指令的概率分布特性,采用概率分布函数进行拟合,以一定置信水平下的置信区间进行限制,引入衡量因子进行修正,提出混合储能系统容量配置方法,进而确定各种类储能单元数量,增大储能系统的利用率并降低其所需容量。针对某额定装机容量15 MW的风电场实际输出功率数据,结合仿真实验,验证了所提出混合储能系统容量配置方法的有效性。

SPNCC与一维双通道CNN-LSTM相结合的变压器局部放电故障音频检测

变压器运行时产生的声音信号包含了丰富的状态信息,可作为变压器故障诊断的重要依据。为提高变压器故障音频诊断效果,首先将变压器运行时现场采集的声音信号分为工作环境噪声信号、正常工作音频信号以及局部放电故障音频信号;然后通过卷积神经网络分类、小波包分解以及巴特沃斯带通滤波的方法去除原始音频信号中的非稳态环境噪声和短时稳态环境噪声信号;并建立了基于简化版幂律归一化倒谱系数特征的一维双通道卷积神经网络−长短时记忆网络的变压器局部放电故障识别模型。通过现场采集某500 kV变电站不同自然环境下的变压器运行声音信号与故障仿真实验,验证了提出的局部放电故障识别模型的可行性,相较于传统的音频故障诊断方法,提出的模型具有更快的收敛速度,更好的故障识别准确率与故障分类准确率。

基于小波包能量熵的电力变压器运行状态评估方法研究

振动在线检测法在电力变压器机械故障诊断中的应用越来越广泛,在此基础上将能量熵引入电力变压器绕组振动信号的特征提取中。通过实验提取一台电力变压器绕组正常运行和短路冲击运行时的振动信号,运用小波包分解重构原理分解出信号的子频带,采用频段-能量熵方法来检测电力变压器绕组不同运行条件下短路故障类型。实验结果表明,不同机械状态下电力变压器绕组振动信号特征向量之间的差异性可作为故障诊断的依据。

Application and improvement of wavelet packet de-noising in satellite transponder

The satellite transponder is a widely used module in satellite missions, and the most concerned issue is to reduce the noise of the transferred signal. Otherwise, the telemetry signal will be polluted by the noise contained in the transferred signal, and the additional power will be consumed. Therefore, a method based on wavelet packet de-noising （WPD） is introduced. Compared with other techniques, there are two features making WPD more suit- able to be applied to satellite transponders： one is the capability to deal with time-varying signals without any priori information of the input signals; the other is the capability to reduce the noise in band, even if the noise overlaps with signals in the frequency domain, which provides a great de-noising performance especially for wideband signals. Besides, an oscillation detector and an av- eraging filter are added to decrease the partial oscillation caused by the thresholding process of WPD. Simulation results show that the proposed algorithm can reduce more noises and make less distortions of the signals than other techniques. In addition, up to 12 dB additional power consumption can be reduced at -10 dB signal-to-noise ratio （SNR）.

基于改进小波包结合CS-BP的地面驱动螺杆泵故障诊断

针对目前地面驱动螺杆泵故障诊断存在效率不高、精度不足、损耗资源的问题,提出通过引入功率谱细化的思想改进小波包变换,再结合布谷鸟搜索(cuckoo search,CS)优化反向传播(back propagation,BP)神经网络的诊断方法。首先,通过改进的小波变换对螺杆泵有功功率分解重构得到特征向量;其次,与瞬时流量、进口回压等参数进行归一化处理,作为BP神经网络的输出层信息;再次,使用布谷鸟搜索寻优得到BP神经网络的权值和阈值,建立CS-BP故障诊断模型;最后,应用于螺杆泵不同故障类型的诊断,并通过与目前的主流诊断方法进行诊断效果的分析比较。结果表明,对于螺杆泵不同类型故障诊断的平均精度达到95.6%,对比分析证明了所提方法的可行性与优越性。

Performance of Cross-Layer Design with Power Allocation in Space-Time Coded MIMO Systems

A cross-layer design(CLD)scheme with combination of power allocation,adaptive modulation(AM)and automatic repeat request(ARQ)is presented for space-time coded MIMO system under imperfect feedback,and the corresponding system performance is investigated in a Rayleigh fading channel.Based on imperfect feedback information,a suboptimal power allocation(PA)scheme is derived to maximize the average spectral efficiency(SE)of the system.The scheme is based on a so-called compressed SNR criterion,and has a closed-form expression for positive power allocation,thus being computationally efficient.Moreover,it can improve SE of the presented CLD.Besides,due to better approximation,it obtains the performance close to the existing optimal approach which requires numerical search.Simulation results show that the proposed CLD with PA can achieve higher SE than the conventional CLD with equal power allocation scheme,and has almost the same performance as CLD with optimal PA.However,it has lower calculation complexity.