可调阻抗无互联线并联逆变器的控制方法

传统的无互联线并联逆变器PQ下垂法是由同步电机并网理论推导而来的,它具有稳态均流精度低和动态响应差等缺点.分析了逆变器并联系统的有功功率和无功功率的环流模型,并且基于传统的PQ下垂法,增加了具有阻抗调节功能的两个控制环节,提高了系统的动态和静态环流抑制能力,并且降低了系统对线阻抗等参数不平衡的敏感程度.仿真和实验结果均验证了该方案的良好性能.     

A new method for PQ disturbance detection and identification

A new method based on phase-shift and N-1 Support Vector Machines(SVMs)is presented for power quality(PQ)disturbance detection and identification.Through phase-shift and simple algebra operation,the method detects out the PQ disturbances easily and effectively.Then a data dealing process is carried out to extract features from the detecting outputs.Then SVM theory is introduced into the identification of PQ disturbances.N kinds of PQ disturbances are classified with an N-1 SVMs classifier.The testing results show that the proposed method can detect and classify the PQ disturbances successfully.Moreover,the classifier has a good performance on training speed and correct ratio.     

基于TMS320F28335的三相并网型光伏逆变器设计

为便于分布式光伏发电以微网形式接入到本地配电网中,根据空间矢量脉宽调制（SVPWM）和PQ控制算法的基本原理,设计了一套基于DSP处理器的并网型光伏逆变器,通过软硬件的结合,在DSP平台上进行调试和试验验证。利用TMS320F28335实现SVPWM波形具有控制算法简单、实现方便、速度快、控制准确等优点,光伏逆变器能稳定输出相电压有效值为（220±6．6）V、电压频率为（50±0．5）Hz的交流电,输出电压谐波含量较小,在光伏并网发电领域具有较好的应用前景。     

PEM fuel cell supported distribution static compensator for power quality enhancement in three-phase four-wire distribution system

One of the major problems in electrical power system is the lack of quality of power due to the rapid growth of nonlinear load and unbalanced load utilization in three-phase four-wire distribution system. In this paper, PEM (Proton Exchange Membrane) fuel cell supported four-leg Distribution Static Compensator (DSTATCOM) is modelled to mitigate harmonics, neutral current and load balancing under nonlinear load and unbalanced load conditions in three-phase four-wire distribution system. The instantaneous reactive power (IRP) theory control algorithm is proposed for four-leg DSTATCOM. The Real coded Genetic Algorithm (RGA) optimized Proportional Integral (PI) controller and Adaptive Neuro Fuzzy Inference System (ANFIS) controller are used for regulating the DC link voltage of DSTATCOM. This paper also investigates the performance of ANFIS based DSTATCOM with conventional method. The proposed system is modelled and its performance is analyzed in MATLAB/SIMULINK.     

微网综合控制与分析

考虑到微网内分布式电源和负荷所具有的分散性,根据分布式电源的类型以及与储能装置的不同组合方式,采用不同的控制策略分别进行了相应控制器的设计。基于下垂特性的电压/频率(V/f)控制实现了负荷功率变化时不同分布式电源间变化功率的共享,且在微网孤岛运行时能为微网系统提供频率支撑;PQ控制可根据实际运行情况实现分布式电源有功和无功功率的指定控制。通过对微网孤岛运行模式和联网运行模式之间切换、孤岛模式下切/增负荷以及微网内某一电源功率变化3种情况下的运行特性进行分析,获得了微网中相应分布式电源的功率、电压、电流及系统频率的变化规律,证明了PQ-V/f综合控制策略的正确性和有效性。     

Geometry and New and Future Spatial Patterns

Despite architects' preoccupation with designing geometric surfaces, there has remained a gap between design and construction. The realisation of complex architectural freeform shapes and the generation of panel patterns continues to be especially challenging, limited by material and manufacturing constraints. Here, Helmut Pottmann , Head of Geometric Modelling and the Industrial Geometry Group within the Institute of Discrete Mathematics and Geometry at Vienna University of Technology (TU Vienna), explores the possibilities thrown up by new research employing fabrication-aware design software. Copyright © 2009 John Wiley & Sons, Ltd.     

The shift of Bragg angular selectivity curve in darkness in glass-like photopolymer for holographic recording

The shift of Bragg angular selectivity curve after exposure was studied by recording single hologram and multiplexed holograms, respectively. The evolution of shift with probe time after recording, as well as the saturated shift with exposure energy, was investigated in detail. The mechanism of Bragg mismatch was analyzed. By optimizing parameters of material synthesis and holographic recording, the shift of Bragg matched angle was alleviated in PQ/PMMA photopolymer after hologram recording.     

微电网主/从控制策略的分析研究

在考虑微电源类型差异性和负荷分散性的基础上,结合微电源的两种不同运行模式,采用主/从控制策略,即将恒功率控制(PQ控制)和恒压、恒频控制(V/f控制)结合起来对微电网进行控制.在并网模式下,采用PQ控制,实现微电源对参考有功和无功的控制;在孤岛模式下,采用V/f控制,为微电网运行提供稳定的频率支撑.为了验证所设计的主/从控制策略能使微电网可靠运行,对微电网在联网运行模式和孤岛运行模式之间切换,以及孤岛模式下切/增负荷两种运行状况下的运行特性进行分析.通过Matlab仿真,对微电网母线电压、系统频率和功率的变化规律进行分析,证明了本文所设计的主/从控制策略的正确性和可行性.     

用于改进潮流计算中PV-PQ节点类型转换逻辑的非线性规划模型

由于无功容量的限制,电力系统潮流计算中经常要进行PV-PQ节点类型转换,传统转换逻辑容易引起数值振荡,甚至错误识别节点类型而导致潮流发散。针对该问题,文中提出一种非线性规划模型以改进PV-PQ节点类型转换逻辑,采用现代内点算法求解。模型以无功容量作为约束条件,通过目标函数控制系统电压,避开了节点类型转换。同时,无功的优化配置可以增强维持系统电压的能力,增大无功裕度;结合现代内点法求解,模型表现出了处理大规模和重负荷系统的优良性能。对IEEE-118系统和一个实际系统的仿真验证了该模型的优势。     

PQ钻具在寨上矿区地质钻探中的应用

介绍了PQ型绳索取芯钻具在甘肃寨上矿区地质岩芯钻探中的应用情况。在深孔的开孔阶段或浅部地层施工中,与单管施工工艺相比,该套钻具的优势主要有能够提高钻探效率,保证岩（矿）芯采取率,降低孔内事故发生几率。PQ型钻具在矿区岩金钻探中取得了很好的应用效果。同时,在钻探施工中,PQ钻具也存在一些问题,如钻具笨重,钻杆内易结泥皮,钻具施工深度还不够理想,与钻具配套的扩孔器非正常磨损严重。通过对其应用情况进行分析和总结,并针对存在的问题和缺陷提出了一些改进建议和解决方法,以便该施工工艺在矿区推广应用。