Flexible linear clock-based distributed self-triggered active power-sharing secondary control of AC microgrids

Traditional active power sharing in microgrids,achieved by the distributed average consensus,requires each controller to continuously trigger and communicate with each other,which is a wasteful use of the limited computation and communication resources of the secondary controller.To enhance the efficiency of secondary control,we developed a novel distributed self-triggered active power-sharing control strategy by introducing the signum function and a flexible linear clock.Unlike continuous communication–based controllers,the proposed self-triggered distributed controller prompts distributed generators to perform control actions and share information with their neighbors only at specific time instants monitored by the linear clock.Therefore,this approach results in a significant reduction in both the computation and communication requirements.Moreover,this design naturally avoids Zeno behavior.Furthermore,a modified triggering condition was established to achieve further reductions in computation and communication.The simulation results confirmed that the proposed control scheme achieves distributed active power sharing with very few controller triggers,thereby substantially enhancing the efficacy of secondary control in MGs.

ACS algorithm-based adaptive fuzzy PID controller and its application to CIP-I intelligent leg

Based on the ant colony system （ACS） algorithm and fuzzy logic control, a new design method for optimal fuzzy PID controller was proposed. In this method, the ACS algorithm was used to optimize the input/output scaling factors of fuzzy PID controller to generate the optimal fuzzy control rules and optimal real-time control action on a given controlled object. The designed controller, called the Fuzzy-ACS PID controller, was used to control the CIP-Ⅰ intelligent leg. The simulation experiments demonstrate that this controller has good control performance. Compared with other three optimal PID controllers designed respectively by using the differential evolution algorithm, the real-coded genetic algorithm, and the simulated annealing, it was verified that the Fuzzy-ACS PID controller has better control performance. Furthermore, the simulation results also verify that the proposed ACS algorithm has quick convergence speed, small solution variation, good dynamic convergence behavior, and high computation efficiency in searching for the optimal input/output scaling factors.

CONVEX CONTROLLER DESIGN APPLIED TO AC INDUCTION MOTOR TO SATISFY MULTIPLE SIMULTANEOUS SPECIFICATIONS

The application of a closed-loop specification oriented feedback control design method, which addresses the design of controllers to satisfy multiple simultaneous conflicting closed-loop performance specifications is presented. The proposed approach is well suited to the design of controllers which must meet a set of conflicting performance specifications. Gain tuning is central to the design process, however, the tuning process is greatly simplified over that presented by the problem of tuning a PID controller for example. The proposed control method is applied to an AC induction motor, with an inner-loop flux vector controller applied to design a position control system. Experimental results verify the effectiveness of this method.

Comparison and Performance Analysis of FACTs Controller in System Stability

In large inter connected power systems, inter-area oscillations are turned to be a severe problem. Hence inter-area oscillations cause severe problems like damage to generators, reduce the power transfer capability of transmission lines, increase wear and tear on network components, increase line losses etc. This paper is to maintain the stability of system by damping inter-area oscillations. Implementation of new equipment consists of high power electronics based technologies such as FACTs and proper controller design has become an essential to provide better damping performance than Power System Stabilizer (PSS). With development of Wide Area Measurement System (WAMS), remote signals have become as feedback signals to design Wide Area Damping Controller (WADC) for FACTs devices. In this work, POD is applied to both SVC and SSSC. Simulation studies are carried out in Power System Analysis Toolbox (PSAT) environment to evaluate the effectiveness of the FACTs controller in a large area power system. Results show that extensive analysis of FACTs controller for improving stability of system.

TMS320VC54xx系列与AC97编解码器AD1885的接口设计

AC97是Intel公司提出的关于音频编解码器的标准.文中简要介绍了AC97接口规范和符合AC972.1标准的编解码芯片AD1885;分析了TI公司的C54xx系列片上外设McBSP的特点;设计了三种C54xxDSP控制AC97编解码器的接口方案,并详细分析了其中一种方法的软硬件配置.该设计实现了AC97标准在DSP系统中的应用,可以为嵌入式系统提供更好的音效.

基于AC97标准的嵌入式音频系统设计与实现

AC97是 Intel公司提出的针对音频设备的业界标准。本文介绍了其在嵌入式系统中的一种实现方案。首先介绍了 AC97音频系统的基本框架 ,然后从模拟和数字两个方面讲述了基于 Intel XScale PXA2 5 5的音频系统的实现 ,以及基于嵌入式 Linux的软件驱动的实现。

高频链AC-DC矩阵变换器的变控制频率软开关调制策略

针对高频链AC-DC矩阵变换器的高效率要求,提出了一种变控制频率软开关调制策略。该调制策略在基于零矢量嵌入的分段同步控制策略基础上,以单控制周期平均功率不变为原则,通过改变控制周期长度,并调整一个控制周期内的电压矢量排布,优化脉冲宽度,使变换器在换流时全部开关器件的零电压开通成为可能。通过仿真分析和实验证明,采用本文提出的变控制频率调制策略,变换器在整流和逆变模式下,均可实现网侧电流三相平衡正弦,功率因数达到0.981,输出电压纹波小,最高效率达到96.9%,实现了高性能、高效率运行。

嵌入式系统中基于AC’97标准的音频驱动的设计与实现

介绍了由INTELXscale处理器和UCB1400编解码芯片构成的音频系统体系结构及工作原理,接着描述了嵌入式WinCE操作系统下基于AC’97协议标准的音频设备驱动程序的设计与实现。其中着重讲述了采用DMA描述器传输模式的音频驱动程序的设计与实现。针对音频系统使用效果、功耗控制等方面,作了一些改进。此设计方案已在嵌入式系统中得到使用,运行效果良好。

AC'97音频控制器的多时钟域设计方法

根据同步装置基本概念和AC'97音频协议,着重强调从系统设计角度优化同步装置的方法和正确的电路综合方法,以此构成AC'97音频控制器的多时钟域设计方法。结果分析表明同步装置在略微增加电路面积的同时,有效降低了同步错误概率,提高了AC'97音频控制器的性能。

C5400系列DSP与AC97 Codec的接口

本文分析了利用TI公司的C5400系列DSP控制满足AC97标准的音频编解码器,在详细分析DSP片上外设McBSP和DMA特点的基础上,提出了一种非常灵活的接口实现方案。

Study on Transformer Magnetic Biasing Control Method for AC Power Supplies

This paper presents a novel transformer magnetic biasing control method for high-power high-performance AC power supplies. Serious consequences due to magnetic biasing and several methods to overcome magnetic biasing are first discussed. The causes of the transformer magnetic biasing are then analyzed in detail. The proposed method is based on a high-pass filter inserted in the forward path and the feedforward control. Without testing magnetic biasing of transformer, this method can eliminate magnetic biasing of transformer completely in real-time waveform feedback control systems though the zero error of the Hall effect sensors varies with time and temperature. The method has already been employed in a 90KVA AC power supply. It is shown that it offers improved performance over existing ones. In this method, no sensors are used such that the zero error of the Hall effect sensors has not any influence on the system. It is simple to design and implement. Furthermore, the method is suitable for various power applications.

不平衡电网下AC-DC矩阵变换器的新型模型预测控制

为降低AC-DC矩阵变换器在输入不平衡条件下网侧有功功率波动,以及离散型模型预测控制中开关频率不固定的问题,提出一种新型模型预测控制方法。通过根据电网电流相位角选择有效矢量,避免了传统模型预测控制评估价值函数计算的负担。提出了一种二阶扩展复数卡尔曼滤波器,计算精度可以达到泰勒级数展开的二阶项,新型模型预测控制能够在不平衡电网系统中应用。仿真结果表明:所提控制策略在输入电压不平衡工况下,能够有效抑制网侧电流谐波,稳定系统输出的有功功率,并且表现出良好的性能。

REALIZATION OF FUZZY-FILTER CONTROL ON A BRUSHLESS AC GENERATOR

The transistor voltage regulators have been widely adopted in the brushless AC generators in aircraft. This paper researches the digital voltage regulator. The paper presents the hardware platform of the digital voltage regulator, which is based on a DSP chip — TMS320C32. A novel fuzzy filter control structure is developed from normal fuzzy control strategy. And the fuzzy filter control algorithm is adopted in the hardware platform successfully. The computer simulation has been conducted. Some control parameters have been obtained through the simulation. The same parameters have been applied in the digital regulation experiments on a brushless AC generator. In the experiment, the digital voltage regulator results in good responses. From the experiment results, it can be seen that the new control algorithm is efficient for the digital voltage regulator.

A Review of Nonlinear Kalman Filter Appling to Sensorless Control for AC Motor Drives

Sensorless control of AC motor drives,which takes the advantages of cost saving,higher reliability,and less hardware,has been developed for several decades.Among the existing speed sensorless control methods,nonlinear Kalman filter-based one has attached widespread attention due to its superb estimation accuracy and inherent resistibility to noise.However,the determination of noise covariance matrix and robustness of model uncertainties are still open issues in practice.A great number of studies try to solve these problems in resent years.This paper reviews the application of extended Kalman filter(EKF),unscented Kalman filter(UKF),and cubature Kalman filter(CKF)in speed sensorless control for AC motor drives.As an iterative algorithm,EKF has advantages in processor implementation.However,EKF suffers from the linearization error and model uncertainties when applying to sensorless control system.This paper presents the predominant improvements of EKF which is also applicative in UKF and CKF mostly.

基于PLI的AC97 Codec快速仿真模型设计

随着数字系统日趋复杂,仿真的时间也越来越长。文中针对AC97的仿真提出了一种加快其仿真速度的方案:设计AC97 Codec的快速仿真模型,即使用Verilog PLI(程序语言接口)设计AC97 Codec数字接口部分周期精确的仿真模型来加速仿真。相对于Verilog,Verilog PLI具有可以灵活地处理数组和存储器、过程控制能力强、可以灵活地处理数据流和控制流等优点,因此便于高层建模。该方案具有通用性强、易于实现、开销低等优点,同时加速效果明显,仿真时间减少了约35%。

A Review of Sensorless Control Methods for AC Motor Drives

In recent years,the application of sensorless AC motor drives is expanding in areas ranging from industrial applications to household electrical appliances.As is well known,the advantages of sensorless motor drives include lower cost,increased reliability,reduced hardware complexity,better noise immunity,and less maintenance requirements.With the development of modern industrial automation,more advanced sensorless control strategies are needed to meet the requirements of applications.For sensorless motor drives at low-and zero-speed operation,inverter nonlinearities and motor parameter variation have significant impact on the stability of control system.Meanwhile,high observer’s bandwidth is required in high-speed region.This paper introduces the state of art of recent progress in sensorless AC motor drives.In addition,this paper presents the sensorless control strategies we investigated for practical industrial and household applications.Both advanced sensorless drives of induction motor(IM)and permanent magnet synchronous motor(PMSM)are presented in this paper.

基于电流应力优化和6脉波调制的双有源桥AC/DC变换器控制策略

针对双有源桥(dual active bridges,简称DAB)AC/DC变换器,该文提出基于电流应力优化和6脉波调制的双有源桥AC/DC变换器控制策略.DAB和三相逆变器(three phase inverter,简称TPI)是双有源桥AC/DC变换器的两个关键单元.对DAB采用电流应力优化,对TPI采用6脉波调制.仿真实验结果表明:相对于单移相(single phase shift,简称SPS)调制策略,该文策略的电感电流的峰值更小,即能更有效地降低电流应力.因此,该文所提策略具有优越性.

基于改进MFAC的交直流微电网分布式二次控制

针对现有交直流微电网分布式二次控制(distributed secondarycontrol,DSC)受分布式电源一次控制参数影响较大、通信拓扑结构复杂、二次控制参数难以整定等问题,提出基于改进MFAC的交直流微电网DSC(MFAC-DSC),利用分布式电源的历史采样数据在线估计其动态线性化参数,解决了传统方法受一次控制参数影响较大的问题;通过优化DSC的通信结构和控制策略,避免了互联变流器参与二次控制通信,解决了互联变流器通信失效影响DSC的问题;推导了MFAC-DSC系统收敛性,给出了稳定收敛条件。基于交直流微电网实验平台在多种工况下验证了MFAC-DSC的可行性,与传统的DSC策略的对比结果表明:MFAC-DSC方法有效减少分布式电源下垂系数变化带来的功率波动,保证下垂系数有更大的调节范围,同时解决了互联变流器通信失效造成的控制失效和母线电压偏移等问题。

基于ARM9的AC＇97控制器的电路的改进

针对基于ARM9框架下AC＇97控制器在录放音时有噪音的不足以及在FPGA验证下频繁出现异常重启的缺点，该文对该控制器的异步FIFO进行改进——重新设计FIFO状态判断标志以正确地配合DMA对其进行读写的时序。在对其进行Verilog硬件代码的修改后．在Altera公司的StratixⅡ系列FPGA上进行功能验证。

OBLIVIOUS TRANSFER WITH ACCESS CONTROL AND IDENTITY-BASED ENCRYPTION WITH ANONYMOUS KEY ISSUING

In ACM'CCS 2009,Camenisch,et al.proposed the Oblivious Transfer with Access Control(AC-OT) in which each item is associated with an attribute set and can only be available,on request,to the users who have all the attributes in the associated set.Namely,AC-OT achieves access control policy for conjunction of attributes.Essentially,the functionality of AC-OT is equivalent to the sim-plified version that we call AC-OT-SV:for each item,one attribute is associated with it,and it is requested that only the users who possess the associated attribute can obtain the item by queries.On one hand,AC-OT-SV is a special case of AC-OT when there is just one associated attribute with each item.On the other hand,any AC-OT can be realized by an AC-OT-SV.In this paper,we first present a concrete AC-OT-SV protocol which is proved to be secure in the model defined by Camenisch,et al..Then from the protocol,interestingly,a concrete Identity-Based Encryption(IBE) with Anonymous Key Issuing(AKI) is given which is just a direct application to AC-OT-SV.By comparison,we show that the AKI protocol we present is more efficient in communications than that proposed by Chow.