基于LabVIEW的机载28V直流用电设备测试系统的设计

设计了一套用于验证机载28V直流用电设备在承受飞机供电特性标准MIL-STD-704中规定的正常电压瞬变下能否正常工作的测试系统,该测试系统通过LabVIEW编程产生直流浪涌电压信号作为测试用信号,并通过高精度采集板卡实现对测试系统输出信号的采集、储存、回放与显示;硬件采用电流反馈环节实现主功率电路中并联MOS管的均流,提高了系统的可靠性及输出功率;经实验证明,该测试系统操作方便,工作稳定,输出信号良好,产生的浪涌电压信号满足飞机供电特性标准MIL-STD-704的要求。     

Cooperative work in mission operations: Analysis and implications for computer support

This paper describes cooperative work in real-time flight operations in the SAMPEX Mission Operations Room at NASA Goddard Space Flight Center. This domain is an example of distributed supervisory control, where a team of human operators supervises a dynamic, complex, highly automated system. Such operational environments differ in important ways from artifact-centered collaboration (e.g., collaborative drawing, writing, design). This paper explores those differences and also articulates the need for activity management tools for dynamic control environments. Candidate models from the human-machine systems engineering literature are proposed to provide the underlying structure for such tools.     

基于微分方程对称的分布参数系统稳态控制

应用对称群理论中经典对称, 以无穷小生成元为分析工具, 考虑分布参数系统的控制问题已有研究, 在此基础上, 本文给出利用微分方程对称实现分布参数系统稳态控制的方法. 通过求解微分方程的对称, 借助其和无穷小生成元之间的关系, 研究给出符合控制目标稳态要求的分布参数系统边界控制条件. 针对两个例子,说明了利用微分方程对称实现分布参数系统稳态控制的过程, 设计了边界控制条件, 进行了仿真说明. 相较基于经典对称获得分布参数系统无穷小生成元的过程, 利用微分方程对称, 避免了空间延拓过程, 并可能获得与其不同的无穷小生成元形式.     

基于PID整定的分布式并网电压不平衡调节研究

分布式发电由于投资小、可靠性高、环境兼容性强等特点,在现代电力系统中得到越来越多的应用。然而当分布式电网并入大电网时,难免会导致电网运行的一些故障,其中两种可能故障情形就是电压调节与无功功率调节。本文在分布式发电系统的基础上,针对并网所引起的三相电压不对称问题,结合经典PID控制理论,在Matlab/simulink中搭建系统仿真模型并进行仿真验证,仿真结果表明本文所提出的电压调节系统具有良好的稳态性能。     

基于紧急功率支援的直流输电系统研究

VSC-HVDC通过利用全控期间的电压源型换流器,在一定程度上,克服了传统直流输电的不足之处,同时实现了有功功率和无功功率的独立控制。本文通过在仿真软件PSCAD/EMTDC中搭建了基于电压源型换流器的三端直流输电系统,并设计采用了改进型PID控制算法与功率支援模块用以快速改变直流线路传输功率,通过动态电流限幅环节抑制交流侧故障过电流,针对逆变器交流侧的几种常见故障和直流线路故障时系统的运行状况进行了仿真分析,并对不同的故障设计了不同的运行方案,仿真结果表明该系统在多种故障情况下均能够有效的保持系统频率与电压的稳定。     

基于大数据的风电设备远程故障监测与诊断系统研究

大数据、云计算等新一代信息技术的快速发展,推动风电设备状态监测技术进步。文章通过风电设备远程监测与故障诊断平台建设实践,从系统功能、平台建设、故障分析等层面,论述了如何基于大数据实现对风机故障预诊断,提升风力发电机组监控与管理水平。通过对机组运行状态的实时在线监测,利用系统内智能数据报警策略准确筛选机组异常,借助于人工智能分析诊断系统和远程专家的综合分析评价,滚动预测故障未来的发展趋势,帮助用户优化风机维护检修工作,减少停机损失,降低维护成本,提高风机利用率。在集控中心预检测平台建立大数据存储、处理、分析、诊断服务器,收集风场各项数据后与专业厂家存储的数据资源整合,建立各种类型风机故障模型,集控中心培训诊断分析师可通过对比找出故障曲线特点和规律,对实时数据经诊断分析后提出整改措施,提前预防风机故障的扩大,开发相关监视及报警系统,联合风机传统监控系统提高监控中心的设备管理能力。     

三相光伏逆变器并网时故障状态仿真分析

当光伏发电系统在并网点处发生故障时,会对光伏微网内部的电能质量包括电流、电压和相位产生严重的影响,采取合适的控制策略使光伏逆变器恢复并网点电能质量是目前的研究热点和难点之一.在Matlab/Simulinkh建立光伏发电系统并网运行时故障仿真模型,对单相接地故障、两相接地故障、断路器单相重合闸故障以及三相重合闸故障进行仿真.以分布式光伏并网逆变器电路的拓扑结构为基础,三相光伏逆变器利用软件锁相环技术为坐标系变换提供相位支撑,PQ控制策略采用功率和电流的双闭环控制.当故障排除后,通过三相光伏逆变器的调节控制作用,使得光伏微网内部的电能质量能在很短的时间内恢复到正常值,锁相准确,谐波小,对稳定电能质量具有良好效果.     

汽油发电机转速前馈-反馈控制系统

汽油机的转速稳定性是影响汽油发电机电气性能指标的一个重要因素,本文在分析其工作原理的基础上提出了一种电流前馈、转速负反馈式的系统结构,并且把反馈控制器设计为模糊控制、PID控制和保持模态相结合的多模态控制器.利用MATLAB工具进行的仿真和实际配机试验结果都表明,采用此算法后该转速控制系统的稳态性能和动态切换性能都比采用常规PID控制时有明显改善,证实了所提方法的有效性.     

有源电力滤波器的预测电流控制方法研究

针对三角波电流控制方法和滞环电流控制方法的不足,详细分析并实现了有源滤波器预测电流控制方法.该方法具有控制精度高,响应速度快,主电路开关频率恒定等优点.理论分析和实验结果验证所提出的控制方法的有效性,基于预测电流控制方法的有源电力滤波器具有良好的工作性能.     

一种软启停正负双直流电源的设计

变形镜驱动器正负电源加电或者断电不同步,导致其在加电瞬间或者断电瞬间,输出端会输出一个-38.0V和86.0V的冲击电压,这个冲击电压使得变形镜在未开始工作时就产生了较为严重的面形畸变,为此研制了基于微处理器的软启停直流电源,它输出两路按一定时序变化的输出电压作为后续两个继电器的控制端,再通过这两个继电器分别控制变形镜驱动器正、负电源的导断,从而使得变形镜驱动器的正负电源同时加载或者卸载。在硬件平台了进行了实验验证,结果表明,使用软启停直流电源后,变形镜驱动器加电瞬间或断电瞬间,其产生的脉冲电压的峰-峰不超过0.45V,远远小于未使用软启停直流电源前的冲击电压,满足了系统的设计要求。     

Optimal placement of distributed generation units in distribution systems via an enhanced multi-objective particle swarm optimization algorithm

This paper deals with the optimal placement of distributed generation （DG） units in distribution systems via an enhanced multi-objective particle swarm optimization （EMOPSO） algorithm. To pursue a better simulation of the reality and provide the designer with diverse alternative options, a multi-objective optimization model with technical and operational con- straints is constructed to minimize the total power loss and the voltage fluctuation of the power system simultaneously. To enhance the convergence of MOPSO, special techniques including a dynamic inertia weight and acceleration coefficients have been inte- grated as well as a mutation operator. Besides, to promote the diversity of Pareto-optimal solutions, an improved non-dominated crowding distance sorting technique has been introduced and applied to the selection of particles for the next iteration. After verifying its effectiveness and competitiveness with a set of well-known benchmark functions, the EMOPSO algorithm is em- ployed to achieve the optimal placement of DG units in the IEEE 33-bus system. Simulation results indicate that the EMOPSO algorithm enables the identification of a set of Pareto-optimal solutions with good tradeoff between power loss and voltage sta- bility. Compared with other representative methods, the present results reveal the advantages of optimizing capacities and loca- tions of DG units simultaneously, and exemplify the validity of the EMOPSO algorithm applied for optimally placing DG units.     

A Dantzig–Wolfe decomposition algorithm for linear economic model predictive control of dynamically decoupled subsystems

This paper presents a warm-started Dantzig–Wolfe decomposition algorithm tailored to economic model predictive control of dynamically decoupled subsystems. We formulate the constrained optimal control problem solved at each sampling instant as a linear program with state space constraints, input limits, input rate limits, and soft output limits. The objective function of the linear program is related directly to the cost of operating the subsystems, and the cost of violating the soft output constraints. Simulations for large-scale economic power dispatch problems show that the proposed algorithm is significantly faster than both state-of-the-art linear programming solvers, and a structure exploiting implementation of the alternating direction method of multipliers. It is also demonstrated that the control strategy presented in this paper can be tuned using a weighted ℓ₁-regularization term. In the presence of process and measurement noise, such a regularization term is critical for achieving a well-behaved closed-loop performance.     

Impact of wind farms on disturbance detection and classification in distributed generation using modified Adaline network and an adaptive neuro-fuzzy information system

A new disturbance detection and classification technique based on modified Adaline and adaptive neuro-fuzzy information system (ANFIS) is proposed for a distributed generation system comprising a wind power generating system (DFIG) and a photovoltaic array. The proposed technique is based on a fast Gauss–Newton parameter updating rule rather than the conventional Widrow–Hoff delta rule for the Adaline network. The voltage and current signals near the target distributed generation (DG), particularly the DFIG, whose speed varies from minimum to the maximum cut-off speed, are processed through the modified Adaline network to yield the features like the negative sequence power, harmonic amplification factor (HAF), total harmonic distortion (THD), etc. These features are then used as training sets for the ANFIS, which employs a gradient descent algorithm to update its parameters. The proposed technique distinguishes the islanding condition of the distributed generation system with some other disturbances, such as switching faults, capacitor bank switching, voltage swell, voltage sag, distorted grid voltage, unbalanced load switching, etc. which are referred to as non-islanding cases in this paper.     

基于单片机的数控直流电流源设计

本文介绍了基于单片机的数控直流电流源设计方案,给出了硬件组成及软件系统。本系统以单片机AT89S52为核心部件,由键盘、显示、D/A及A/D转换,V/I转换、功率放大等模块组成。采用负反馈闭环控制系统,单片机实时将预置值和实测值进行比较、调整控制,提高了电流源的输出精度。所设计的数控直流电流源采用PID算法实现了量程可选、输出可调、步进精确、纹波电流极小的功能,而且可将输出电流预置值、实测值在LED上同时显示。经实验证明具有较高的控制精度。     

基于任务和角色的分布式工作流授权控制模型

针对传统工作流访问控制模型的缺陷和分布式工作流管理系统的特性，在基于角色的访问控制模型的3层访问控制结构的基础上明确引入任务的概念，构造了4层访问控制结构（用户-角色-任务-权限），对系统中的任务进行了较好的访问控制，有效解决了传统工作流安全模型的缺陷。同时使管理员的安全控管工作更加灵活、简便。