Multi-channel DMA Based Design of Voltage Monitoring Using Synchronous Frequency Trace-Sampling Technique

In order to eliminate the influence of frequency change on real-time voltage acquisition,a low-cost solution of voltage monitoring was proposed using the multi-channel DMA synchronous frequency trace-sampling technique.In-chip resources of the designed voltage monitor were fully utilized in hardware design to reduce external devices.The MQX RTOS was used to perform the functional tasks flexibly and efficiently;especially the Ethernet communication applications and USB device connection were realized using its TCP/IP protocol stack and USB driver.In addition,to ensure the safety of electrical records,data statistics and alarm information management were also implemented through the management of the storage in FLASH.The test results show that the voltage monitor designed in this paper has the advantages of accurate measurement,strong resistance to frequency interference and low cost,and can be widely applied in the field of voltage monitoring in distribution networks.

Exponential synchronization of chaotic Lur'e systems with time-varying delay via sampled-data control

In this paper, we study the exponential synchronization of chaotic Lur＇e systems with time-varying delays via sampled-data control by using sector nonlinearties. In order to make full use of information about sampling intervals and interval time-varying delays, new Lyapunov-Krasovskii functionals with triple integral terms are introduced. Based on the convex combination technique, two kinds of synchronization criteria are derived in terms of linear matrix inequal- ities, which can be efficiently solved via standard numerical software. Finally, three numerical examples are provided to demonstrate the less conservatism and effectiveness of the proposed results.

Exponential synchronization of complex dynamical networks with Markovian jumping parameters using sampled-data and mode-dependent probabilistic time-varying delays

In this paper, the problem of exponential synchronization of complex dynamical networks with Markovian jumping parameters using sampled-data and Mode-dependent probabilistic time-varying coupling delays is investigated. The sam- pling period is assumed to be time-varying and bounded. The information of probability distribution of the time-varying delay is considered and transformed into parameter matrices of the transferred complex dynamical network model. Based on the condition, the design method of the desired sampled data controller is proposed. By constructing a new Lyapunov functional with triple integral terms, delay-distribution-dependent exponential synchronization criteria are derived in the form of linear matrix inequalities. Finally, two numerical examples are given to illustrate the effectiveness of the proposed methods.

Sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays

In this letter, a distributed protocol for sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays is proposed, and a brief procedure of convergence analysis for such algorithm over undirected connected graphs is provided. Furthermore, a simple yet generic criterion is also presented to guarantee synchronized oscillatory motions in coupled harmonic oscillators. Subsequently, the simulation results are worked out to demonstrate the efficiency and feasibility of the theoretical results.

Stochastic asymptotical synchronization of chaotic Markovian jumping fuzzy cellular neural networks with mixed delays and the Wiener process based on sampled-data control

We investigate the stochastic asymptotical synchronization of chaotic Markovian jumping fuzzy cellular neural networks （MJFCNNs） with discrete, unbounded distributed delays, and the Wiener process based on sampled-data control using the linear matrix inequality （LMI） approach. The Lyapunov–Krasovskii functional combined with the input delay approach as well as the free-weighting matrix approach is employed to derive several sufficient criteria in terms of LMIs to ensure that the delayed MJFCNNs with the Wiener process is stochastic asymptotical synchronous. Restrictions （e.g., time derivative is smaller than one） are removed to obtain a proposed sampled-data controller. Finally, a numerical example is provided to demonstrate the reliability of the derived results.

Free-matrix-based time-dependent discontinuous Lyapunov functional for synchronization of delayed neural networks with sampled-data control

This paper is concerned with the synchronization of delayed neural networks via sampled-data control. A new technique, namely, the free-matrix-based time-dependent discontinuous Lyapunov functional approach, is adopted in constructing the Lyapunov functional, which takes advantage of the sampling characteristic of sawtooth input delay. Based on this discontinuous Lyapunov functional, some less conservative synchronization criteria are established to ensure that the slave system is synchronous with the master system. The desired sampled-data controller can be obtained through the use of the linear matrix inequality（LMI） technique. Finally, two numerical examples are provided to demonstrate the effectiveness and the improvements of the proposed methods.

Fault tolerant synchronization of chaotic systems based on T-S fuzzy model with fuzzy sampled-data controller

In this paper the fault tolerant synchronization of two chaotic systems based on fuzzy model and sample data is investigated. The problem of fault tolerant synchronization is formulated to study the global asymptotical stability of the error system with the fuzzy sampled-data controller which contains a state feedback controller and a fault compensator. The synchronization can be achieved no matter whether the fault occurs or not. To investigate the stability of the error system and facilitate the design of the fuzzy sampled-data controller, a Takagi Sugeno （T-S） fuzzy model is employed to represent the chaotic system dynamics. To acquire good performance and produce a less conservative analysis result, a new parameter-dependent Lyapunov-Krasovksii functional and a relaxed stabilization technique are considered. The stability conditions based on linear matrix inequality are obtained to achieve the fault tolerant synchronization of the chaotic systems. Finally, a numerical simulation is shown to verify the results.

Impulsive effect on exponential synchronization of neural networks with leakage delay under sampled-data feedback control

We consider the impulsive effect on the exponential synchronization of neural networks with leakage delay under the sampled-data feedback control. We use an appropriate Lyapunov-Krasovskii functional combined with the input delay approach and some inequality techniques to derive sufficient conditions that ensure the exponential synchronization of the delayed neural network. The conditions are formulated in terms of the leakage delay, the sampling period, and the exponential convergence rate. Numerical examples are given to demonstrate the usefulness and the effectiveness of the results.

Pinning sampled-data synchronization for complex networks with probabilistic coupling delay

We deal with the problem of pinning sampled-data synchronization for a complex network with probabilistic time-varying coupling delay. The sampling period considered here is assumed to be less than a given bound. Without using the Kronecker product, a new synchronization error system is constructed by using the property of the random variable and input delay approach. Based on the Lyapunov theory, a delay-dependent pinning sampled-data synchronization criterion is derived in terms of linear matrix inequalities （LMIs） that can be solved effectively by using MATLAB LMI toolbox. Numerical examples are provided to demonstrate the effectiveness of the proposed scheme.

直扩水声通信机的码同步技术研究

为了降低扩频码同步技术对硬件的依赖,提高水声通信机的性能,对传统直接序列扩频码同步技术进行了一些改进。扩频码同步技术包括码捕获和码跟踪两个阶段,在码捕获阶段,采用双倍补零法扩展接收信号与接收机本地扩频码序列,使两者满足基二快速傅里叶变换运算的要求;在控制逻辑部分采用蓄水池抽样算法来确定范围内载波频偏值的计算顺序,无需按照固定顺序遍历范围内的载波频偏值,从而减少了计算量。在码跟踪阶段,采用了全时间超前-滞后非相干相关同步跟踪回路,采用双Δ值延迟锁相环的设计,扩大了跟踪范围,降低了失锁概率。最后基于DSP平台实现了直接序列扩频水声通信系统,该系统通过了水箱实验环境的测试。

改进细菌觅食算法的永磁同步电机参数辨识

应用群智能算法对永磁同步电机(PMSM)进行参数辨识后期容易进入局部最优,从而导致辨识误差大,为此提出一种融合小生境技术的改进细菌觅食算法(MBFA)。通过构建目标追踪函数,利用电机电流、电压和转速等直接测量的信号实现对电机d轴电感、q轴电感、定子电阻和永磁体磁链的快速、准确辨识;辨识过程中通过引入格型准则对目标解空间进行拟蒙特卡罗采样提高算法的全局搜索能力;基于小生境技术进行在线多种群协同搜索策略提高算法的搜索效率和寻优精度;最后通过引入一种种群实时监测和动态更新机制保证了算法在整个寻优过程的鲁棒性。仿真和实验结果表明,所提算法在参数辨识的快速性、准确性、稳定性方面均表现优越,辨识结果能够满足对永磁同步电机进行建模和仿真的精度要求。

基于同步采样SDFT的高性能单相锁相环方法研究

在电力机车及动车组的牵引传动控制系统中,网侧变流器通过锁相环获取相位信息并进行精确控制。牵引供电网电压的幅值及频率存在波动,而且网压经常出现严重畸变及含有大量谐波,复杂的电网环境对锁相环性能提出了很高的要求。文章结合同步采样,提出一种基于SDFT的高性能锁相环方法,并通过数字仿真及半实物仿真对所述方法的性能进行了验证。仿真结果表明,与其他几种主流的锁相环对比,该方法稳态锁相精度高,动态响应速度快,并有较强的谐波抑制能力与抗偏置能力,适宜在轨道交通领域应用。

基于改进零脉冲插入法的永磁同步电机相电流重构策略

直流母线单电流采样永磁同步电机系统存在相电流重构盲区,导致电流采样失真,提出一种改进零脉冲插入法,实现相电流重构。首先,分析传统固定零脉冲插入法的缺点,由于各相插入零脉冲作用时间相同,未能发挥“双开关PWM”模式抑制电流纹波的优势;其次,通过各相PWM占空比调整零脉冲时间,延长电流采样窗口,提出改进零脉冲插入法重构策略,消除重构盲区,并针对该方法重构盲区出现其他扇区有效电压矢量的情况,分析其空间电压矢量合成关系,证明参考电压矢量合成的准确性;最后,基于戴维南电路法,提出不同电压矢量作用时的电路简化模型,对比两种方法的电流纹波幅值,并搭建永磁同步电机实验平台进行实验。结果表明,改进零脉冲插入法的电流重构误差低于3%,相比传统方法,电流纹波抑制效果达到50%,相电流畸变率从12.72%下降到6.87%。

同步采样下的智能分布式馈线自动化配电网网格化规划方法

分布式馈线自动化配电网网格化规划合理性直接影响供电效果,目前提出的规划方法合理性较差。为了解决上述问题,文章在同步采样分析基础上研究了一种新的智能分布式馈线自动化配电网网格化规划方法,采用网格化定位技术建立分布式馈线自动化配电网,将配电网电力需求的预测值作为定位依据,在配电网供电区域内划分出多个用电范围,分析用电要求,通过告警和闭锁研究实现信息配置,采用层级分析法完成网格分类,计算待规划范围的电力负荷技术参数,采用差异性导入方法实现网格化规划。实验结果表明:同步采样下的智能分布式馈线自动化配电网网格化规划方法规划合理性在90%以上,能够很好地满足配电网的规划要求,很少出现断电事故,更适合于实际应用。

基于FPGA的永磁同步电机三相电流同步采样方案

在永磁牵引控制平台中,为了实现永磁同步电机控制更优,需根据控制周期对电机的三相电流进行同步采样;同时,为了满足过流故障的实时保护,需要对电流以较小的时间间隔进行持续采样。为此,文章基于FPGA设计了一种利用一套ADC芯片同时满足永磁同步电机控制所需电流同步采样和过流实时保护需求的快速定时采样方案。该方案通过实时获取用户配置的同步采样周期,并结合定时采样周期,智能地生成ADC转换启动信号的方式,从而实现对永磁同步电机电流的同步采样和定时采样控制。最后,基于实际永磁牵引控制平台进行实验,结果验证了所提方案的可行性和有效性。

智慧分布式馈线自动化配电网网格化规划探究——以同步采样为基础导向

分布式馈线自动化配电网规划能够对电力系统正常稳定运行产生显著影响。通过查阅相关文献,简要阐述分布式馈线自动配电网网格化规划的概念与意义。同时,结合同步采样策略,按照网格化定位、信息配置、网格化规划的逻辑完成智慧分布式馈线自动化配电网网格化规划。为验证所提策略的有效性,进行实验验证,结果表明在应用设计的规划策略背景下,故障率仅为5.34%。证实所提策略在结构复杂度、线路长度、供电可靠性等方面具有优异的表现,能够为我国当前电力网络正常运行提供一定理论支持。

基于采样控制的时滞Lur’e系统的渐近同步分析

本研究探讨了基于采样数据控制的时滞Lur’e系统的全局渐近同步问题。首先构建了时滞主从系统的模型,并设计了相应的采样控制器。接着,通过构造新的李雅普诺夫函数并结合稳定性理论,再利用不等式性质及时滞分解技术,推导出了时滞Lur’e系统渐近同步的新判据,并以矩阵不等式形式加以表述。最后,利用数值模拟来验证了所得结果的有效性与实用性。

Real-Time Synchronous Integration of Radar and Raingauge Measurements Based on the Quasi Same-Rain-Volume Sampling

A technique for real-time synchronous integration of radar and raingauge measurements based on the concept of the quasi same-rain-volume sampling（QSVS） is presented.Because of the temporal and spatial discrepancies and resolution differences,the integration of radar measurements with raingauge observations has long been a difficult task.Observations indicate that there exists a correlation that conforms to the power law between hourly accumulated raingauge measurement（Q_G） and detected radar echo（Z_（OH）） over the raingauge.On the basis of this,a concept of the QSVS and five direct correspondent formulas of radar and raingauge samples are built up,aiming to eliminate the temporal and spatial discrepancies.A convenient and practical sampling method—the time integral vertical synchronous sampling（TIVS） is proposed and the Z_（OH）—Q_G relationship is studied.It is significant that under the fixed exponent,the coefficient A_B or A_M varies flexibly in accordance with the temporal and spatial variability of natural precipitation,having the function of synchronously integrating the Z—R conversion and the gauge adjustment into a single equation,and thus the precipitation estimation errors caused by detecting resolution differences between radar and raingauge can be obviously mitigated.The real-time synchronous integration technique using the Z_（OH）—Q_G relationship to estimate the ground hourly rainfall accumulation is called the radar-gauge synchronous integration method（RASIM）.The experiments of two cases show that the accuracy of estimated surface hourly rainfall accumulation within 230 km is about 90%,and the average relative error for the point estimation over the whole process is about 20%. Through the detailed analysis of the applicability of TIVS in three environmental fields with various wind drifts,the physical essence of TIVS is explored：it is an approximate QSVS.By analyzing the data pairs of radar and raingauge,an effective quality-control procedure is established,which can greatly improve the stability and rationarity of the Z_（OH）—Q_G relationship.The forecasting product of hourly rainfall accumulation derived from the RASIM has been put into operation.It is demonstrated that the RASIM plays an important role in the quantitative monitoring and forecasting of short-term torrential rainfall.

Vibration-based synchronous sampling and its application in wind-turbine drive-train-condition monitoring

Utilizing shaft-speed information to analyse vibration signals is an important method for fault diagnosis and condition monitoring of rotating machineries,especially for those running at variable speeds.However,in many cases,shaft-speed information is not always available,for a variety of reasons.Fortunately,in most of the measurements,the shaft-speed information is embedded in the vibration response in many different forms,such as in the format of the fundamental shaft-rotation-frequency response and its harmonics,and the gear-meshing-frequency response and its harmonics,etc.Proper signal processing can be used to extract the shaft instantaneous speed from the measured vibration responses.In existing instantaneous shaft-speed-identification methods,a narrow-bandpass filtering technique is used explicitly or implicitly.In a complex gearbox system,such as that used in a wind turbine,the gear-meshing-response component could be modulated by many other shaft speeds,due to the configuration of the gearbox or due to the existence of component damage.As a result,it is very difficult to isolate a single vibration-response component for instantaneous shaft-speed detection.In this paper,an innovative approach is presented.The instantaneous shaft speed is extracted based on maxima tracking from the vibration-response spectrogram.A numerical integration scheme is employed to obtain the shaft instantaneous phase.Digital-domain synchronous resampling is then applied to the vibration data by using the instantaneous phase information.Due to the nature of noise suppression in the numerical integration,the accuracy of synchronous sampling is greatly improved.This proposed approach demonstrates the feasibility and engineering applicability through a controlled laboratory test case and two field wind-turbine cases.More detailed results and conclusions of this research are presented at the end of this paper.

Electro-optical sampling non-synchronous delay scanning measurement of electron beam bunch length at BFEL

The Electro-optical sampling delay scanning technique can be used for electron beam bunch length measurement. A novel non-synchronous delay scanning technique based on the electro-optical sampling measurements is presented. Based on Beijing Free Electron Laser （BFEL）, the electron beam bunch length was measured with the electro-optical sampling technique for the first time in China. The result shows that the electron beam bunch length at BFEL is about 5.6±1.2 ps.