应用P2P技术的互联网电机控制方法

针对在internet场景下的网络化控制系统(networked control system,NCS)通常要面临的两个问题:第一是不同网域内的控制节点无法直接通信;第二是internet环境下不稳定的网络链路质量会导致控制系统性能的下降甚至引发系统故障,首先提出一种基于端对端(peer-to-peer,P2P)技术的NCS系统,解决了internet范围上控制节点间的通信问题;然后设计了控制任务的共享功能:被控端节点可以向网络中发布被控对象的控制算法文件,而系统内的其他远程计算机都可以通过下载控制任务文件成为远程控制器。上述方法实现了internet环境下NCS系统的拓扑动态性和数据链路的冗余性,从而增强了系统的容错能力。最终通过实验证明了P2P技术搭建的NCS系统在internet范围上的拓扑动态性,且验证了冗余控制策略增强系统容错能力的有效性。     

基于Internet的工业控制网络

随着以太网和TCP/IP技术越来越多地进入控制领域，以往独立、封闭的工业‘控制网络正面临着严峻挑战。鉴于此，文中通过对基于TCP/IP协议的网络化智能仪表和嵌入式Internet技术的深入分析，提出了一种新型的网络体系结构——基于因特网的工业控制网络。并对实现该网络目前所具备的技术基础和条件进行了分析，对今后的发展趋势进行了评估。     

Internet-based monitoring of distributed control systems-Anundergraduate experiment

This paper presents the development of an Internet-based system to allow monitoring of important process variables from a distributed control system (DCS). The system is formulated as an add-on to an undergraduate experiment on the development of a desktop DCS. This paper describes the hardware and software design considerations which enable the users to access the process variables on the DCS, remotely and effectively, using only a commonly available Web browser     

Process control using a fiber-optic unified cabling systems

In an ideal world, communications cabling for process control would be simple-buy all the computer, instrumentation, and electrical equipment from a single vendor, and connect it all together using a single cabling standard. But real life is never that simple; rarely are the programmable logic controllers (PLC), distributed control systems (DCS), drives, motor controls, field instrumentation, and computers all purchased from the same vendor. Supplying power to all this different equipment certainly doesn't require separate cabling structures, so why shouldn't the same be true for communications needs? Wouldn't a standard cabling infrastructure minimize the cabling infrastructure cost and complexity? The engineering group of a Canadian pulp and paper mill wondered about these two questions. They were designing a new steam plant and decided to investigate the possibility of making a single process communication cabling "utility" through the plant. The result was a design methodology that allowed a standardized cabling system to serve all communications needs throughout the process areas. Fiber-optic cable was chosen for all communications cabling outside of the control or electrical rooms. While the noise immunity and high data carrying capacity of fiber-optic cable was a factor, the primary reason was that fiber-optic cabling was the only system that could provide a single medium suitable for the very wide range of communications equipment in the mill     

Real-time control of power systems using nodal prices

This article presents a novel control scheme for achieving optimal power balancing and congestion management in electrical power systems via nodal prices. We develop a dynamic controller that guarantees economically optimal steady-state operation while respecting all line flow constraints in steady-state. A benchmark example illustrates the effectiveness of the proposed control scheme.     

远程控制系统时延补偿策略研究

为了克服互联网时延对系统性能的影响,提出了采用变采样率方法的双层控制系统结构。低层闭环控制结构采用较高的恒定采样频率以保证控制系统的稳定性;而高层的闭环控制结构采用了较低的可变采样频率以减少网络负荷和避免数据丢失。为了更好地处理大时延和数据包丢失的问题,基于双层控制结构利用动态矩阵预测控制器设计了前向时延和反馈时延补偿策略。仿真结果表明在随机互联网时延的环境下采用前向、反馈时延补偿策略能够有效地改善控制系统的动态性能。     

Optimal voltage control in distribution systems using PV generators

Recently, renewable energy technologies such as wind turbine generators and photovoltaic systems have been introduced as distributed generation. The connection of large number of distributed generators causes voltage deviation beyond the statutory range in a distribution system. In this paper, a methodology for voltage control in proposed by using the tap changing transformers and the inverters interfaced with the distributed generators. In the proposed method, information of the voltage and power is collected via a communication network. Based on these information, the optimal reference values are calculated at the control center, and sent to the transformers and the inverters. The proposed method accomplishes a coordinated operation among the control equipments and reduces the voltage deviation. Effectiveness of the proposed method is verified by the numerical simulation results.     

Adaptive control of Wiener-type nonlinear systems using neural networks

This paper proposes new adaptive control schemes with neural networks for Weiner-type nonlinear systems which have output nonlinearity. First, by adopting a robust adaptive control law and a functional link network (FLN), we present an adaptive linearizing scheme as a primary step for a model reference control scheme, where the FLN compensates the output nonlinearity. Second, we analyze the stability of the adaptive linearizing scheme by using a robust adaptive control technique, and demonstrate that all of the parameters are bounded and that the boundedness of all of the signals in the closed loop is guaranteed under some reasonable conditions. Third, based on the linearizing scheme, we present a new direct model reference adaptive control scheme by choosing the reference output appropriately. The stability of the system is guaranteed under several conditions in a similar manner. Finally, we illustrate the effectiveness of the proposed scheme through some numerical examples. © 1998 Scripta Technica. Electr Eng Jpn, 122(1): 37–48, 1998     

Modeling and design of networked control systems using a stochastic switching systems approach

A networked control system (NCS) is a control system in which plants, sensors, controllers, and actuators are connected through communication networks. In this paper, we consider NCSs modeled by stochastic switching systems, and propose a new method for modeling and optimal control. First, a recursive representation of the expected value of the state is proposed. Next, after an over‐approximation of this recursive representation is derived, the optimal control problem is reduced to a linear programming problem. Finally, the effectiveness of the proposed method is shown by a numerical example. The proposed method provides us an easy‐to‐use control method for NCSs. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Decentralized adaptive linear control of complex systems using relative deadzones

This paper aims to analyse the system stability when decentralized adaptive controllers are applied to multi-input/multi-output non-linear interconnected systems. The local adaptive controllers are designed based on linear models by employing relative deadzones. Using a small-gain-type argument, we can derive an M-matrix test condition for local stability. If the system to be controlled can be described by global Lipschitz functions, a global stable closed-loop system is obtained. © 1997 by John Wiley & Sons, Ltd.     

Synthesis of electric drive control systems using quality coefficient estimates

Possible application of the coefficient estimates of stability, quality, and accuracy of the electric drive control system, as well as their sensitivities to the parameter variations, are considered. The coefficient estimates can be used both in the solution of the analysis problems and in the synthesis of relatively simple controllers for higher-order objects. The examples of coefficient-estimate synthesis are presented. The conditions are found under which the models considered are applicable to digital control systems.     

Adaptive learning systems: building an educational infrastructure

We are at the dawn of a knowledge based economy. Telecommunications deregulation, industrial restructuring, and the World Wide Web are drivers and enablers of this revolution. But how much farther down the information highway must we travel before information access and connectivity truly enrich and simplify our daily lives? Education is an area of particular need, where the impact of information technology can be enormous. The United States spends more than $608 billion annually on education and training. Yet achievement levels do not always meet expectations, and some US citizens lack access to education resources altogether. Similar problems exist in the US workplace. By some estimates, as few as 10% of the US work force receives formal training on the job (and the fraction is even lower in small companies). Industry is searching for more cost effective methods of education and training. The Adaptive Learning Systems (ALS) Focused Program, just introduced by the Advanced Technology Program (ATP) of the National Institute of Standards and Technology (NIST) is a cost sharing program designed to buffer risks faced by companies that are willing to undertake high risk projects that otherwise would be underfunded or ignored. The program focuses on enabling technologies that ultimately will support flexible, network-centric, Web based learning systems.     

Stability analysis of quantized iterative learning control systems using lifting representation

This paper presents a stability analysis of the iterative learning control for discrete‐time systems with data quantization. Three quantized iterative learning control schemes are considered by using different quantized signals, including system output quantized signal, tracking error quantized signal, and control input quantized signal. The logarithmic quantizer is introduced to decode these signals with a number of quantization levels, and the sector bound method is used to deal with the quantization error. Based on the supervector formulation for iterative learning control systems, some convergence conditions for these iterative learning control laws are given, respectively. It is shown that iterative learning control laws with system output quantized signal and control input quantized signal only guarantee that the tracking error converges to a bound and the bound depending on quantization density and desired trajectory. Thus, the iterative learning control law with tracking error quantized signal can obtain zero tracking error. These results are illustrated by 2 examples.     

Extremum seeking control of nonlinear dynamic systems using Lie bracket approximations

In this article, we consider extremum seeking problems for a general class of nonlinear dynamic control systems. The main result of the article is a broad family of control laws which optimize the steady-state performance of the system. We prove practical asymptotic stability of the optimal steady-state and, moreover, propose sufficient conditions for the asymptotic stability in the sense of Lyapunov. The results generalize and extend existing results which are based on Lie bracket approximations. In particular, our approach does not rely on singular perturbation theory, as commonly used in extremum seeking of nonlinear dynamic systems.     

基于分散控制理论的多机系统低频振荡抑制

常规的电力系统低频振荡抑制措施是在发电机励磁系统中加装电力系统稳定器(PSS),然而它在多机电力系统中的应用并没有充分的理论研究.将大系统分散控制原理应用于多机电力系统低频振荡抑制问题,只要分散阻尼控制器(DDC)的阶数足够高,分散闭环控制系统的低频振荡模态总可以在复平面内任意配置.分析了PSS与DDC的关系,论证了PSS是DDC的一种特殊形式,因而从理论上说明了DDC比PSS优越.将DDC的优化配置表示为一个带不等式约束的非光滑优化问题并用遗传算法求解.以新英格兰测试系统和我国西北电网为算例的计算结果表明,在发电机励磁系统中加装DDC是一种有效的低频振荡抑制新措施.     

Confusion diagnosis and avoidance of discrete event systems using supervisory control

Nondeterministic firing of concurrent transitions in Petri nets (PNs) may lead to the disappearance of conflicts. The disappearance implies that the partial conflicting transitions in a conflict become disabled before the resolution of the conflict. The phenomenon is called confusions that are caused by the interlacement of conflicting and concurrent transitions in PNs, which generates incomplete and faulty system conflicting behavior such that conflicts cannot be correctly resolved. In this paper, conflict‐increasing confusions (CICs) and conflict‐decreasing confusions (CDCs) in a PN are investigated. The relation graph of conflicts and confusions (RGC²) in a PN is proposed to detect the structure of confusions. To avoid the occurrence of confusions in a PN, an algorithm based on generalized mutual exclusion constraints (GMECs) is proposed, which can generate confusion‐avoidance supervisors such that the occurrence of conflicts can be ensured in a PN. Finally, an example of confusion detection and avoidance in a flexible assembly system is presented. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Decentralized guaranteed cost control for uncertain large‐scale systems using additive control gain

This paper investigates an application of additive control gain to the guaranteed cost control (GCC) problem of decentralized robust control for a class of discrete‐time uncertain large‐scale systems. Based on the Linear Matrix Inequality (LMI) design approach, a class of decentralized local fixed state feedback controllers with additive control gain is established. The novel contribution of this paper is that multiobjective control is attained by using the additive control gain. Although the additive control gain is included in the uncertain large‐scale systems, the closed‐loop system is asymptotically stable. In order to demonstrate the efficiency of our proposed controller, using the fuzzy logic control as the additive control gain, the simple numerical example is given. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(3): 18–32, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20726     

运用细菌群体趋药性优化的电力系统广域阻尼控制

分析了广域阻尼控制器(WADC)的超前-滞后环节补偿广域测量信号大时滞的效果.介绍了确定WADC参数的方法.根据时滞引起的广域信号滞后角的大小选择超前或滞后补偿,并确定时间常数.介绍了细菌群体趋药性(BCC)优化算法及其应用,并采用BCC优化算法获得WADC的增益以改善电力系统阻尼.优化过程中采用时间加权误差平方的积分(ITSE)作为性能指标.4机2区域测试系统大扰动仿真结果表明,这种WADC在运行点大范围变化的情况下可以抑制互联电网中出现的低频振荡,有效改善电力系统稳定性.     

Robust excitation control design using sliding-mode technique for multimachine power systems

An output feedback controller is proposed to enhance the transient stability of nonlinear multimachine power systems considered as a classical model with flux decay dynamics. Combining high-order sliding-mode techniques with a robust high-order sliding-mode differentiator, a robust decentralized controller is obtained. Numerical results are presented to illustrate the performance of the proposed control scheme and its robustness properties.     

Experimental modeling of dynamic systems: an educational approach

An engineering course, Simulation and Experimental Modeling, has been developed that is based on a method for direct estimation of physical parameters in dynamic systems. Compared with classical system identification, the method appears to be easier to understand, apply, and combine with physical insight. It is based on a sensitivity approach that is useful for choice of model structure, for experiment design, and for accuracy verification. The method is implemented in the Matlab toolkit Senstools. The method and the presentation have been developed with generally preferred learning styles in mind. In a comprehensive evaluation of the course, student responses to a course questionnaire and to an Index Of Learning Styles Questionnaire are analyzed and correlated.