Fuzzy Adaptive Control of Stochastic Nonlinear Systems with Unknown Virtual Control Gain Function

The problem of track control is studied for a class of strict-feedback stochastic nonlinear systems in which unknown virtual control gain function is the main feature. First, the so-called stochastic LaSalle theory is extended to some extent, and accordingly, the results of global ultimate boundedness for stochastic nonlinear systems are developed. Next, a new design scheme of fuzzy adaptive control is proposed. The advantage of it is that it does not require priori knowledge of virtual control gain function sign, which is usually demanded in many designs. At the same time, the track performance of closed-loop systems is improved by adaptive modifying the estimated error upper bound. By theoretical analysis, the signals of closed-loop systems are globally ultimately bounded in probability and the track error converges to a small residual set around the origin in 4th-power expectation.

INTELLIGENT VIRTUAL CONTROL:MEASURING INSTRUMENT FROM WHOLE TO PART

A new concept called intelligent virtual control (IVC), which can be drivenby measuring functions, is put forward. This small 'intelligent measurement instrument unit (IMIU)',carrying with functions of instrument, consists of different types of intelligent virtualinstrument (IVI) through individual components together as building blocks and can be displayeddirectly on the computer screen. This is a new concept of measuring instrument, and also animportant breakthrough after virtual instrument (VI). Virtual control makes instrument resourcesobtain further exploitation. It brings about a fundamental change to the design and manufacturingmode. The instrument therefore, can not only be produced directly inside a PC, but the product isinvolved in the 'green product' system. So far, all the present digital instruments will grow to bereplaced by intelligent control with green characteristics.

Review on grid-forming converter control methods in high-proportion renewable energy power systems

Grid-forming(GFM)converters can provide inertia support for power grids through control technology,stabilize voltage and frequency,and improve system stability,unlike traditional grid-following(GFL)converters.Therefore,in future“double high”power systems,research on the control technology of GFM converters will become an urgent demand.In this paper,we first introduce the basic principle of GFM control and then present five currently used control strategies for GFM converters:droop control,power synchronization control(PSC),virtual synchronous machine control(VSM),direct power control(DPC),and virtual oscillator control(VOC).These five strategies can independently establish voltage phasors to provide inertia to the system.Among these,droop control is the most widely used strategy.PSC and VSM are strategies that simulate the mechanical characteristics of synchronous generators;thus,they are more accurate than droop control.DPC regulates the active power and reactive power directly,with no inner current controller,and VOC is a novel method under study using an oscillator circuit to realize synchronization.Finally,we highlight key technologies and research directions to be addressed in the future.

RESEARCH ON MECHANICAL MEASUREMENT-ORIENTED INTELLIGENT VIRTUAL CONTROLS

Intelligent virtual control (IVC) is an intelligent measurement instrumentunit with the function of actual measurement instruments, and the unit can be used as basic buildingblock for a variety of more complex virtual measurement instruments on a PC. IVC is a furtheradvancement from virtual instrument (VI), and it fuses the function modules and the controls modulesso that the relationship between the functions and controls of an instrument is imbedded in one ormore units. The design, implementation and optimization methods of IVCs are introduced. The computersoftware representation of IVCs is discussed. An example of an actual VI constructed with thebuilding blocks of IVCs is given.

Robust force tracking control via backstepping sliding mode control and virtual damping control for hydraulic quadruped robots

In order to improve the force tracking performance of hydraulic quadruped robots in uncertain and unstructured environments,an impedance-based adaptive reference trajectory generation scheme is used.Secondly,in order to improve the robustness to environmental changes and reduce the contact force errors caused by trajectory tracking errors,the backstepping sliding mode controller is combined with the adaptive reference trajectory generator.Finally,a virtual damping control based on velocity and pressure feedback is proposed to solve the problem of contact force disappearance and stall caused by sudden environmental change.The simulation results show that the proposed scheme has higher contact force tracking accuracy when the environment is unchanged;the contact force error can always be guaranteed within an acceptable range when the environment is reasonably changed;when the environment suddenly changes,the drive unit can move slowly until the robot re-contacts the environment.

Finite-time tracking control and vibration suppression based on the concept of virtual control force for flexible two-link space robot

The dynamic modeling, finite-time trajectory tracking control and vibration suppression of a flexible two-link space robot are studied. Firstly, the dynamic model of the system is established by combining Lagrange method with assumed mode method. In order to ensure that the base attitude and the joints of space robot can reach the desired positions within a limited time, a non-singular fast terminal sliding mode(NFTSM) controller is designed, which realizes the finite-time convergence of the trajectory tracking errors. Subsequently, for the sake of suppressing the vibrations of flexible links, a hybrid trajectory based on the concept of the virtual control force is developed, which can reflect the flexible modes and the trajectory tracking errors simultaneously. By modifying the original control scheme, a NFTSM hybrid controller is proposed. The hybrid control scheme can not only realized attitude stabilization and trajectory tracking of joints in finite time, but also provide a new method of vibration suppression. The simulation results verify the effectiveness of the designed hybrid control strategy.

NUMERICAL MODELING OF MULTI-CYLINDER ELECTRO-HYDRAULIC SYSTEM AND CONTROLLER DESIGN FOR SHOCK TEST MACHINE

A high fidelity dynamic model of a high-energy hydraulically-actuated shock test machine for heavy weight devices is presented to satisfy the newly-built shock resistance standard and simulate the actual underwater explosion environments in laboratory as well as increase the testing capability of shock test machine. In order to produce the required negative shock pulse in the given time duration, four hydraulic actuators are utilized. The model is then used to formulate an advanced feedforward controller for the system to produce the required negative waveform and to address the motion synchronization of the four cylinders. The model provides a safe and easily controllable way to perform a ＂virtual testing＂ before starting potentially destructive tests on specimen and to predict performance of the system. Simulation results have demonstrated the effectiveness of the controller.

Design of in-line multipoint initiation control system

In order to improve the power of initiating explosive warheads, besides exploring new type of high explosive, multipoint initiation technology becomes the research focus. With research on electronic safety and arming devices （ESADs）, pulse power devices and slapper detonators, a hardware control circuit was designed for multipoint initiation control system based on complex programmable logic device （ CPLD ）. In addition, a real-time monitoring interface based on virtual instru- ments technology was designed by the prevailing software of Laboratory Virtual Instrument Engineer- ing Workbench （LabVIEW）. It provides users a real-time status of the hardware circuit system. Mo- reover, a series of experiments were done on the software and hardware platform. The results show that the signals transmission, collection, analysis and display can be realized reliably through a serial port line. It is verified that using a serial bus controller for multiple initiators is reasonable. Successful design of the platform will play an important foundation for the theory and engineering of the fu- ture weapon system. Surely, it will become one of the development directions for intelligent initia- tion system.

Fractional-order Virtual Inertia Control and Parameter Tuning for Energy-storage System in Low-inertia Power Grid

As conventional synchronous generators are replaced by large-scale converter-interfaced renewa-ble-energy sources(RESs),the electric power grid en-counters the challenge of low rotational inertia.Conse-quently,system frequency deviation is exacerbated and system instability may occur when the frequency deviates beyond the acceptable range.To mitigate this effect,this study proposes a virtual inertia control(VIC)strategy based on a fractional-order derivative and controller parameter-tuning method.The tuning method uses the stability boundary locus and provides a stability criterion for identifying the stability region in the parameter space.The controller parameters are then optimized within the identified stability region to suppress frequency deviation and enhance system robustness.The proposed controller and tuning method is applied to a battery energy-storage system(BESS)in a low-inertia power system with the integration of RESs.Time-domain simulations are carried out to verify the stability region and compare the per-formance of the optimized proposed controller to that of the traditional integral-order controller.The simulation results show that the stability-analysis method is effective and that the fractional-order VIC,tuned with the pro-posed method,outperforms the traditional method in both frequency-regulation performance and parametric robustness.

Design of Power System Stabilizer for DFIG-based Wind Energy Integrated Power Systems Under Combined Influence of PLL and Virtual Inertia Controller

Wind energy systems (WESs) based on doubly-fed induction generators (DFIGs) have enormous potential for meeting the future demands related to clean energy. Due to the low inertia and intermittency of power injection, a WES is equipped with a virtual inertial controller (VIC) to support the system during a frequency deviation event. The frequency deviation measured by a phase locked loop (PLL) installed on a point of common coupling (PCC) bus is the input signal to the VIC. However, a VIC with an improper inertial gain could deteriorate the damping of the power system, which may lead to instability. To address this issue, a mathematical formulation for calculating the synchronizing and damping torque coefficients of a WES-integrated single-machine infinite bus (SMIB) system while considering PLL and VIC dynamics is proposed in this paper. In addition, a power system stabilizer (PSS) is designed for wind energy integrated power systems to enhance electromechanical oscillation damping. A small-signal stability assessment is performed using the infinite bus connected to a synchronous generator of higher-order dynamics integrated with a VIC-equipped WES. Finally, the performance and robustness of the proposed PSS is demonstrated through time-domain simulation in SMIB and nine-bus test systems integrated with WES under several case studies.

Virtual Machine软件在火力发电厂控制系统及课件培训中的应用

论文就Virtual Machine软件在火力发电厂Windows XP控制系统中应用遇到的问题进行了论述,并针对问题提出了相应的措施及方案,以期为Virtual Machine软件在更多领域中应用提供参考资料。

Study on control information network and its real-time property

The control network is an important developmental orientation in the remote control system. As the control network and information network are comparatively alike in the framework and technology, we can build a control network which is similar to the common information network. In the era when the information network is becoming increasingly mature, it is a royal road to construct or rebuild a control information network in the development of the control network by relying on the achievements made in the information network or current information resources. This paper expounds the construction idea of the control information network, gives the idiographic realization method and then researches into the real-time problem encountered in the control information network, and presents a three-closed-loop control system based on virtualized reality. The feasibility of the idea is validated via experiments and simulations separately.

基于虚拟领导节点改进的孤岛微电网完全分布式二次调频策略

传统分布式二次调频策略在虚拟领导节点频率信息出现故障时会导致微电网系统频率无法恢复,针对该问题提出并设计一种完全分布式二次调频策略。首先分析传统分布式二次调频策略虚拟领导节点故障对二次调频过程产生的影响;然后,结合一致性算法对传统分布式二次调频控制器加以改进,通过将调频补偿量与频率偏差的对消作为“频率引导项”加入各分布式控制器中,使得各分布式发电单元完全对等,以保证虚拟领导节点去除后频率的正常恢复,实现完全分布式控制;最后,通过仿真验证所提方法在保证频率恢复方面的有效性与优越性。

Design and implementation of an expert system for remote fault diagnosis in ship lift

In this paper an expert system for remote fault diagnosis in the ship lift was developed by analysis of the fault tree and combination with VPN. The fault tree was constructed based on the operation condition of the ship lift. The diagnosis model was constructed by hierarchical classification of the fault tree structure, and the inference mechanism was given. Logical structure of the fault diagnosis in the ship lift was proposed. The implementation of the expert system for remote fault diagnosis in the ship lift was discussed, and the expert system developed was realized on the VPN virtual network. The system was applied to the Gaobaozhou ship lift project, and it ran successfully.

地铁轨道交通环控系统的虚拟仿真设计与实现

环控系统是保证地铁轨道安全运营的关键环节。为此,基于项目功能需求和虚拟仿真技术,对深圳地铁轨道环控系统进行了虚拟仿真设计与开发。首先设计虚拟仿真系统项目开发流程,进行三维模型和场景的构建,然后采用PBR的渲染流程制作高真实感纹理贴图,并运用Unity3D进行系统开发。该系统的开发为轨道交通环控系统的运维、救灾和培训实验建立了新的模式,有利于提高工作效率,降低培训和运营成本。

基于自抗扰的直驱风电机组强迫振荡抑制研究

风剪切和塔影效应会导致直驱式风电机组产生强迫功率振荡,影响系统的安全稳定运行。因此,提出了一种基于自抗扰控制的虚拟惯量控制方法,该方法通过扩张状态观测器观测估计系统扰动量,同时利用跟踪微分器调整系统频率的参考值,优化风电机组控制功率。仿真结果表明,相比传统的虚拟惯量控制,所提方法具有更好的抗干扰性,能更有效地对扰动进行观测估计并补偿,达到抑制直驱式风电并网系统强迫振荡的目的。

一种雷达转台双电机驱动系统设计与同步控制方法

作为机械传动系统的一个重要组成,转台被广泛应用于雷达系统中,为满足雷达检测等领域对转台驱动系统惯量、功率、性能方面的要求,提出采用双电机同步驱动转台的方式。利用双电机伺服系统的电消隙原理和差速耦合负反馈的同步控制方法,由控制器将控制量经数/模转换送入驱动器,以实现系统的消隙功能、同步补偿功能,提高转台驱动系统的精度和同步控制性能,并将其运用到雷达转台伺服系统中,结果证明了方法的可行性,能够提高所设计雷达转台双电机驱动系统的精确性。

基于数字孪生的桥式起重机自主运行系统研究

为了提高桥式起重机的智能化水平和数字化水平,借助数字孪生技术,对一桥式起重机的安全自主运行系统进行了仿真和实验研究。首先,采用数字孪生思想构建了起重机自主运行系统整体架构,根据桥式起重机的实际运行情况,采用四模型(即虚拟模型、物理动力学模型、行为控制模型和规则计算模型)的方法,构建了起重机的孪生模型;然后,在起重机孪生实验平台上进行了起重机路径规划和大小车轨迹跟踪仿真实验,采用了变论域模糊PID控制器,对起重机大小车轨迹跟踪进行了控制;最后,对该数字孪生系统进行了互联互通实物验证实验。研究结果表明:在起重机数字孪生系统中可以同步进行虚拟仿真和实物实验;在起重机大小车轨迹跟踪实验中,使用所提变论域模糊PID控制方法时,大车跟踪误差在±7 cm内,小车跟踪误差可达±6 cm,表明该控制方法的先进性;同时,该系统初步达成数字孪生技术虚实同步、虚实融合、虚实对照的目标,并且具有良好的三维可视化效果,可为推动机电装备的数字化进程提供一种思路。

基于虚拟仿真技术的高精度数控机床自动控制系统

为实现高精度数控加工,设计基于虚拟仿真技术的高精度数控机床自动控制系统。该系统依托SolidWorks、Deep Exploration等软件,建立数控机床虚拟仿真三维模型,设计数控机床控制约束关系,获取数控机床运行数据,并将该数据内的跟随误差、误差积分、误差微分等作为控制输入变量,设计由神经网络和PID组成的混合控制器,利用该混合控制器输出数控机床自动控制量,实现高精度数控机床自动控制。实验表明:该系统在各种运行环境下的软件移植完整程度均超过95%,在控制数控机床运动速度时,跟随误差始终保持在-50~50 mm/min,应用效果较为显著。

基于MMC的分布式储能系统及其快速SOC均衡控制策略

提高基于模块化多电平换流器(modular multilevel converter,MMC)的分布式储能系统(distributed energy storage systems,DESS)的能量利用率,解决储能子模块(energy sub-module,ESM)荷电状态(state of charge,SOC)均衡问题至关重要。针对现有的SOC均衡控制策略的不足,提出内外分层的快速SOC均衡控制策略。外层针对桥臂间或相间的SOC差异,通过改进MMC模型预测控制(model predictive predictive control,MPC),配合自适应均衡系数,快速调整功率差额。内层引入自适应虚拟电阻法,根据ESM的SOC情况确定主导ESM,自适应调节各单元的虚拟电阻,产生相应的电压梯度,结合MMC排序算法使ESM按照各自SOC进行功率分配,从而实现ESM的SOC快速均衡,提高DESS能量利用率。通过在Matlab/Simulink构建仿真模型,证明了所提控制策略的有效性和可行性。