High-speed low-power voltage-programmed driving scheme for AMOLED displays

A new voltage-programmed driving scheme named the mixed parallel addressing scheme is presented for AMOLED displays, in which one compensation interval can be divided into the first compensation frame and the consequent N-1 post-compensation frames without periods of initialization and threshold voltage detection. The proposed driving scheme has the advantages of both high speed and low driving power due to the mixture of the pipeline technology and the threshold voltage one-time detection technology. Corresponding to the proposed driving scheme, we also propose a new voltage-programmed compensation pixel circuit, which consists of five TFTs and two capacitors(5T2C). In-Zn-O thin-film transistors(IZO TFTs) are used to build the proposed 5T2C pixel circuit. It is shown that the non-uniformity of the proposed pixel circuit is considerably reduced compared with that of the conventional 2T1C pixel circuit. The number of frames(N) preserved in the proposed driving scheme are measured and can be up to 35 with the variation of the OLED current remaining in an acceptable range. Moreover, the proposed voltage-programmed driving scheme can be more valuable for an AMOLED display with high resolution, and may also be applied to other compensation pixel circuits.     

基于SystemView的2FSK调制解调系统的仿真设计与分析

SystemView是一种适用于通信系统设计与仿真分析的软件工具,可以对通信系统的工作过程进行实时仿真分析。本文采用SystemView构建2FSK调制解调仿真系统。通过使用SystemView分析窗口观察信号的波形和频谱,我们能直接观测到信号在传输过程中的波形和频谱的变化,这有助于我们更深刻地理解2FSK调制解调系统的工作原理和各个设备的功能。     

城市微网接地方案探讨

针对低压微电网在不同接地方式下运行的安全稳定性问题,提出了典型微网的接地方案。基于国家/行业标准,结合理论分析和实践应用比较,对低压微电网主变压器接地方式、微源接地方式、低压微网系统接地方式分别进行了比选,给出了不同情况下各种接地方式的适用条件和场合。结合微网系统特点得出了适用低压微网的接地方案,即主变优选用D,yn11连接组别,中性点有效接地,微源并网时中性点不接地,孤岛时仅主电源中性点接地。整个微网系统采用TN-S/TN-C-S与TT混合接地方式,微源和三相用户采用四级开关,单相用户采用两级开关。     

Optimal Placement of Phasor Measurement Units with Linear and Non-linear Models

Abstract—This article presents a non-linear programming-based model for the optimal placement of phasor measurement units. The optimal phasor measurement units placement is formulated to minimize the number of phasor measurement units required for full system observability and to maximize the measurement redundancy at all buses in a power system. A sequential quadratic programming algorithm is used for the solution of the proposed model. The existence of power flow and injection measurements, the limited phasor measurement units channel capacity, the lack of communication facilities in substations, and the single phasor measurement units loss are also incorporated into the initial proposed formulation. The non-linear programming model is applied to IEEE 14- and 118-bus test systems in MATLAB. The accuracy and the effectiveness of the proposed method is verified by comparing the simulation results to those obtained by a binary integer programming model also implemented in MATLAB. The comparative study shows that the proposed non-linear programming model yields the same number of phasor measurement units as the binary integer programming model. A remarkable advantage of the non-linear programming against binary integer linear programming is its capability to give more than one optimal solution, each one having the same minimum number of phasor measurement units (same minimum objective value), but at different locations.     

Moving ion fronts in mixed ionic‐electronic conducting polymer films

The aim of this paper is to analyze moving front dynamics of ions and holes in a planar, mixed ionic‐electronic conducting polymer film. As cations invade the film, holes evacuate; thus, an ionic current is converted to an electronic signal. Recent experiments show that the location of the advancing ion front increases as the square‐root of time, a scaling typically associated with diffusive transport, which is surprising given the large driving voltages utilized. Ionic and electronic transport is modeled via the drift‐diffusion equations. A similarity transformation reduces the governing partial differential equations to ordinary differential equations that are solved numerically. The similarity transformation elucidates the origin of the square‐root‐of‐time front scaling. The similarity solution is then compared to the numerical solution of the full drift‐diffusion equations, finding excellent agreement. When compared with experimental data, our model captures the front location; however, qualitative differences between the ion profiles are observed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1447–1454, 2015     

基于multisim10.0的非线性电路分析方法仿真研究

非线性电路具有频率变换作用,在通信系统中广泛应用于对信号的调制、解调和混频等处理功能。非线性电路不满足叠加定理,通常采用开关函数分析法、时变电路分析法和环形电路分析法等解析法对其分析,数学分析复杂,较难理解。Multisim10.0电路仿真软件仪器丰富、器件齐全,电路仿真波形观察直观。借助于Multisim10.0电路仿真软件,对上述3种非线性电路分析方法进行了仿真,并根据仿真结果从非线性电路输入、输出波形变换和频谱变换两方面分析了非线性电路的作用。基于Multisim 10.0的电路仿真分析,简化了非线性电路分析方法,有助于对非线性电路频率变换作用的理解。     

油纸绝缘变压器介质响应极化谱的探索与研究

基于扩展德拜模型,建立油纸绝缘变压器绝缘状态与介质响应等值电路之间的关系,并仿真分析模型(时间常数、支路数)改变引起回复电压特征参数和极化谱的变化规律。仿真分析结果表明,极化谱回复电压峰值与主时间常数可作为变压器绝缘诊断的判据,且时间常数不同的RC支路在回复电压极化谱的对应区段才有所影响。通过研究多台不同绝缘状态的变压器,总结出绝缘老化程度与支路数取值的内在联系,由此获取的等值参数最优,所建立模型与变压器实际状况相吻合,可作为油纸绝缘系统状态准确诊断和研究的基础。     

计及网络约束的有序用电综合决策方法

有序用电是缓解高峰时期电力不足的重要手段,为此提出了周前有序用电综合决策模型。综合了基于用户负荷形态以及参与意愿的4种错避峰手段,考虑了负荷的网络分布以及线路阻塞,利用改进的直流潮流方法近似考虑了网损,建立了以有序用电错避峰手段补偿成本最小及网损最小为目标的多目标优化模型。通过只考虑高峰时段约束等求解策略缩减求解时间。算例分析表明,本模型可以基于用户负荷特性制定个性化的有序用电方案,通过时间与空间维度的有序用电实现对有限的电力资源的优化配置,在消纳用电缺口的同时降低网损、消除网络阻塞,提高了电网运行的安全性与经济性。     

基于净负荷分步建模的旋转备用优化确定风险分析方法

由于采用净负荷预测误差模型描述风电和负荷共同预测误差,优化系统旋转备用配置的多场景概率风险分析方法尚难以全面考虑风电的不确定性,如从网络安全和经济性方面必须考虑的弃风因素以及风电功率预测误差存在的非正态分布情况。为此,基于分步建模的策略改进多场景概率风险分析方法中净负荷预测误差模型,使其在计算系统失负荷风险时能够计及弃风和考虑不同类型概率分布的风电功率预测误差,并将弃风惩罚成本引入机组组合优化模型的目标函数中,以实现风电功率的合理消纳和系统旋转备用的优化确定。采用混合整数线性规划方法,对含风电场的IEEE-RTS 26机测试系统进行仿真分析,验证了改进模型的有效性。     

基于频谱比较的直流线路差动保护闭锁判据

为解决目前直流线路差动保护动作时间过长的问题,提出了一种基于频谱比较的直流线路差动保护闭锁判据。分析了差动电流的频谱特征,由分析可知区内故障时差动电流含有较多直流分量,区外故障时差动电流含有较多50 Hz和100 Hz分量,根据这一区别设计了闭锁判据。该判据能够有效识别区内、区外故障,且具有可靠性高、对采样频率要求较低等优点。基于某实际直流系统建立了EMTDC仿真模型。仿真结果表明,该判据能够在区外故障时闭锁差动保护,提高了保护的可靠性。