An Algorithm for Short-Circuit Current Interval in Distribution Networks with Inverter Type Distributed Generation Based on Affine Arithmetic

During faults in a distribution network,the output power of a distributed generation(DG)may be uncertain.Moreover,the output currents of distributed power sources are also affected by the output power,resulting in uncertainties in the calculation of the short-circuit current at the time of a fault.Additionally,the impacts of such uncertainties around short-circuit currents will increase with the increase of distributed power sources.Thus,it is very important to develop a method for calculating the short-circuit current while considering the uncertainties in a distribution network.In this study,an affine arithmetic algorithm for calculating short-circuit current intervals in distribution networks with distributed power sources while considering power fluctuations is presented.The proposed algorithm includes two stages.In the first stage,normal operations are considered to establish a conservative interval affine optimization model of injection currents in distributed power sources.Constrained by the fluctuation range of distributed generation power at the moment of fault occurrence,the model can then be used to solve for the fluctuation range of injected current amplitudes in distributed power sources.The second stage is implemented after a malfunction occurs.In this stage,an affine optimization model is first established.This model is developed to characterizes the short-circuit current interval of a transmission line,and is constrained by the fluctuation range of the injected current amplitude of DG during normal operations.Finally,the range of the short-circuit current amplitudes of distribution network lines after a short-circuit fault occurs is predicted.The algorithm proposed in this article obtains an interval range containing accurate results through interval operation.Compared with traditional point value calculation methods,interval calculation methods can provide more reliable analysis and calculation results.The range of short-circuit current amplitude obtained by this algorithm is slightly larger than those obtained using the Monte Carlo algorithm and the Latin hypercube sampling algorithm.Therefore,the proposed algorithm has good suitability and does not require iterative calculations,resulting in a significant improvement in computational speed compared to the Monte Carlo algorithm and the Latin hypercube sampling algorithm.Furthermore,the proposed algorithm can provide more reliable analysis and calculation results,improving the safety and stability of power systems.

东海OBN和三维DAS-VSP数据的联合采集与处理方法研究

近年来,光纤传感技术已经应用于地面地震数据、海洋地震数据、井中地震数据和井地联合地震数据的采集,推动了光纤传感技术在地球物理特别是地震数据采集中的应用。井地或井海联合地震勘探是陆地或海洋三维地震与三维DAS-VSP勘探相结合形成的三维立体地震勘探方法,利用井海联采的三维DAS-VSP数据,可以获得地下井周围准确的时深关系、地层速度、反褶积算子、球面扩散补偿因子、吸收衰减因子、各向异性参数和井筒周围的高分辨率构造成像,这些参数可以基于井驱处理提高陆地或海洋三维地震数据的处理质量。在中国东海某OBN数据勘探中首次开展了井下套管内铠装光缆同步采集的三维DAS-VSP数据的处理方法研究以及成像处理。首先,采用常规的三维VSP数据成像处理技术对三维DAS-VSP数据进行常规处理,具体处理流程包括:观测系统定义、预处理、初至拾取、静校正、振幅补偿、反褶积、波场分离、速度分析与建模和利用上行反射波进行井周围地层的构造成像;然后,再根据海上三维DAS-VSP数据下行多次波的特点,研发了海上三维DAS-VSP数据的下行多次波成像技术,扩展了三维DAS-VSP数据成像范围,提高了三维DAS-VSP数据成像的整体质量。与本工区早期的三维OBC数据成像结果相比,本次三维DAS-VSP数据的下行多次波成像结果表明,井周围三维构造成像质量得到了显著改进,大幅度扩展了成像范围;新采集的OBN数据和三维DAS-VSP数据的成像结果展示了更为详细和较高分辨率的构造成像,基于新的成像资料,对储层顶部和储层内流体的识别与追踪变得更加容易和清晰。井海联采技术生产效率高且成本低,既能快速获得三维DAS-VSP数据及成像,还能对三维海洋地震数据进行井驱提高分辨率处理。此外,三维OBN或OBC数据和三维DAS-VSP数据还能够进行融合处理,实现井地或井海同步采集数据的联合偏移成像,可以大幅度提高三维海洋地震数据的成像品质,值得在有条件的地方推广应用。

采用非稳相偏振滤波的DAS-VSP数据P/S波分离方法及其应用

分布式光纤声学传感(DAS)因成本低、易布设以及高密度采样等优势正成为重要的地震观测技术,尤其是越来越多地与垂直地震剖面(VSP)结合,用于主动地震勘探或被动地震监测.DAS传感器通过感知弹性波场产生的轴向应变或应变速率来观测地震波场振动.然而,目前单分量DAS-VSP数据未完整地记录地下弹性波场的三维矢量振动信号,因此如何从中分离出P波或S波用于后续地震成像与参数反演是重要且很有挑战的课题.以弹性波传播理论为基础,本文根据P波和S波的频散关系估算接收点处各自的偏振方向,通过随频率和空间位置变化的偏振滤波实现DAS-VSP数据的P/S波分离.理论模型合成数据与东海实际DAS-VSP数据实验结果表明,该方法能有效地将P波和S波信号从单分量DAS-VSP数据中分离出来,可为后续纵横波速度反演、PP与PS波成像提供关键的数据预条件处理.

Distributed antenna wireless communication system coverage design and field trial over higher frequency band

This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band applications,the cumulative distribution of simulated user throughput in a cellular is investigated firstly.It shows that capacity improvement can be obtained using higher operating frequency band,especially in hotspot scenarios.Secondly,the architecture of the distributed antenna system(DAS) is introduced to overcome the disadvantages of weak coverage and rank deficient for the traditional multiple-input multiple-output(MIMO) systems using higher frequency bands in line-of-sight(LOS)environments.In addition,a software-defined-radio(SDR) based Gbps wireless transmission system with scalable hardware architecture is designed and implemented.Finally,a demo of outdoor DAS coverage for high data throughput application is given.Field trials show that 1 Gbps data rate and a large coverage in outdoor environments can be achieved over 6.05 GHz.It is proved that the Gbps DAS system at a higher frequency band can be a successful model for future wireless broadband coverage in hotspot scenarios.

A distributed control system for picosecond accelerator at SINAP

The picosecond accelerator (PA) is a low energy electron linear accelerator facility under commissioning, which is built for the experiment of ps level pulse radiolysis in Shanghai Institute of Applied Physics (SINAP). A practical distributed DA&C system for this facility has been developed. In view of the upgrading-ability and main-tainability of the control system and controlled devices, Advantech? distributed intelligent DA&C products are adopted into the control system. ADAM 5000/TCPs with the protocol of Modbus/TCP are employed to accomplish data acquisition and device control. The PC-compatible programmable logic controller, ADAM-5511, is also adopted to handle the interlocks and the emergency events. On the software side, the integrated software package King-view?V6.5, which friendly supports all Advantech products, has been used to develop the upper layer control logic and process the data. This paper describes the control system design and system architecture. The intelligent ADAM controllers and the software platform are also discussed in detail.

Outage Analysis of Distributed Antenna Systems over Shadowed Nakagami-m Fading Channels

This paper presents an outage analysis of distributed antennas system(DAS) suffering from shadowed Nakagami-m fading environment where the desired signal also suffers from co-channel interference. The desired signal and interfering signal are subjected to path loss,multipath and shadowing fading. Based on Wilkinson's method,the signal to interference ratio(SIR) probability density function(PDF) of fixed DAS is obtained. Some numerical results of outage probability with different parameters are analyzed. The analysis results can provide sufficient precision for evaluating the outage performance of DAS.

Optimal antenna placement in distributed antenna systems

To minimize the outage probability of the cell （OPC） in downlink distributed antenna systems with selection transmission, a complex-encoding genetic algorithm （GA） is proposed to find the optimal locations of the antenna elements （AEs）. First, the outage probability at a fixed location in the cell is investigated. Next, an analytical expression of the OPC is derived, which is a function of the AE locations. Then the OPC is used as the objective function of the antenna placement optimization problem, and the complex- encoding GA is used to find the optimal AE locations in the cell. Numerical results show that the optimal AE locations are symmetric about the cell center, and the outage probability contours are also given with the optimal antenna placement. The algorithm has a good convergence and can also be used to determine the number of AEs which should be installed in order to satisfy the certain OPC value. Lastly, verification of the OPC＇s analytical expression is carried out by Monte Carlo simulations. The OPC with optimal AE locations is about 10% lower than the values with completely random located AEs.

基于DA算法的FIR滤波器硬件实现

高速 FIR滤波器是数字接收机中中频处理的关键组成部分 ,传统的基于通用 DSP的实现方法往往满足不了要求 ,而基于 FPGA的硬件设计在速度上有很大的优势。因此 ,研究了采用 DA算法的 FIR硬件设计 ,分析了如何在逻辑资源占用和处理速度上进一步提高性能 ,并以 1 6抽头 8bits FIR滤波器为例在XCS0 5的 FPGA芯片中进行了实现。

基于改进DA算法的高效FIR滤波器设计

针对当前分布式算法(DA)实现高阶FIR滤波器,存在硬件资源占用多和功耗高的缺点,提出一种低功耗、低面积的改进算法。在无查找表结构的基础上,将采样数据最高位从移位寄存器首先输出,部分和累加由传统的右移变为左移。其次,在数据选择器的输入端添加三态缓存器,减少了加法器的翻转次数。为验证改进算法的高效性,设计不同阶长的FIR滤波器,在ISE平台对硬件代码进行综合仿真。结果表明,改进DA算法相比传统DA算法,逻辑单元和存储器占用分别减少38.44%、83.72%,功耗降低26.12%。

DA自适应数字滤波器在FPGA中实现的改进研究

在自适应滤波器的设计中,滤波阶数增加时,保持滤波器的吞吐量成为了设计的难点。文章根据最小均方(LMS)算法自适应FIR数字滤波器的基本原理,介绍了一种改进型分布式算法DA自适应FIR数字滤波器在FPGA中的设计方法。设计在Quartus II中编译、仿真、综合后下载到Stratix FPGA中较好地解决了滤波器阶数增加与吞吐量之间的关系。

基于改进DA算法和流水线技术的FIR数字滤波器设计

提出了一种改进的分布式算法和一种具有流水线结构的加法树乘法器,设计了一种在FPGA上实现的FIR数字滤波器。介绍了改进的DA算法,对采用FPGA实现直接型结构移位相加乘法器FIR滤波器和改进DA算法的高速FIR滤波器的性能进行了比较。用VHDL在Quartus II平台上进行了仿真,给出了实现高效滤波功能的设计结果及不同算法的资源占用比较。

基于位并行DA结构的高速FIR滤波器

针对目前利用FPGA实现基于分布式算法(DA)FIR滤波器的不足,以及为了实现高速FIR滤波器,提出了一种位并行分布式算法结构的解决方案。采用位并行分布式算法和流水线式并行加法器树,在Xilinx Virtex5系列FPGA上实现了高速FIR滤波器。该滤波器工程经ISE12.3综合、布局布线后,利用Modelsim SE 6.5和Matlab联合仿真。仿真结果表明,该设计可以提高滤波器处理速度,32阶的滤波器最高时钟频率可达到399.624MHz。对滤波器进行进一步优化,节约了硬件资源占用。

基于DA算法的二维离散余弦逆变换的ASIC设计

离散余弦变换已成为图像压缩中一标准技术，本文给出了基于DA的二维离散余弦逆变换（2－DIDCT）的ASIC设计。本设计通过采用快速1－DIDCT算法及基于DA算法的乘法累加器来减少面积、加快速度。设计采用自顶向下设计方法，用VHDL进行描述，整个系统在SYNOPSYS工具上进行设计及仿真，最终综合到门级电路。

DTS/DAS技术在水平井压裂监测中的应用现状与展望

压裂水平井技术在我国非常规油气藏开发中已有较为广泛的应用,但在水平井压裂动态监测方面仍面临许多技术难题。分布式光纤监测技术近年发展十分迅速,已形成了分布式光纤温度/声波(DTS/DAS)配套监测技术,在美国、加拿大等非常规储层压裂动态监测中已有较多应用,并取得了较好的应用效果。阐述了分布式光纤温度/声波测试的基本原理,介绍了DTS/DAS在水平井压裂监测中的最新应用及研究进展,这些应用包括压裂液注入分布监测及漏失诊断、人工裂缝起裂及延伸监测、压裂完井有效性分析和裂缝参数定量解释,指出了DTS/DAS技术在水平井压裂监测中目前存在的不足,并对水平井分布式光纤监测技术的发展趋势进行了分析。对于加速分布式光纤监测技术在我国非常规油气藏开发中的应用进程、提高我国水平井压裂监测和压裂效果评价技术水平具有重要意义。

基于DA算法的FIR数字滤波器的FPGA设计

凭借规整的内部逻辑块阵列和丰富的连线资源,FPGA特别适合细粒度和高并行度结构特点的数字信号处理任务。文章提出一种采用分布式算法实现16阶FIR低通滤波器的FPGA设计方法。通过MATLAB提取符合设计指标的参数,采用Verilog HDL描述数字逻辑设计过程,在QuartusⅡ集成开发环境下进行综合,并且在Modelsim中进行实验仿真和验证。

基于特殊DA方案的DLMS自适应滤波器设计

为了提高DLMS自适应滤波器的处理速度、降低其FPGA实现时所消耗的逻辑资源,提出了一种特殊DA方案。此方案基本结构主要包含I-LUT和K-LUT两个模块,前者用于存放输入采样值的所有可能组合之和,后者用于更新该滤波器的权值并且计算其输出信号。Matlab软件仿真验证了该自适应滤波器设计的可行性和正确性,Quartus II硬件仿真证明,基于此DA方案的自适应滤波器比基于通常的MAC方案的自适应滤波器具有更高的处理速度且消耗更少的逻辑资源。

基于DA的高性能2-D IDCT处理器设计

为提高2-D IDCT的解码速度,文中设计了一种基于DA的2-D IDCT处理器.该处理器在算法上用1-D IDCT实现2-D IDCT,用Chen算法实现1-D IDCT,用DA实现乘加结构.通过将输入数据分成高6位和低6位两组加快了处理器的速度,通过查找表的共用及将输入数据投影到(-1,1)的编码减少了查找表的数量及大小.通过在Q0上预存四舍五入值省去了四舍五入所需的加法运算.使用Altera的EP2C20F484C7对该处理器进行综合,时钟最高频率可达165.37MHz.

ASIC Design of DA-Based 2-D Inverse Discrete Cosine Transform

Aim To present an ASIC design of DA based 2 D IDCT. Methods\ In the design of 1 D IDCT is utilized a Chen based fast IDCT algorithm, and multiplier accumulators based on distributed algorithm contributes in reducing the hardware amount and in enhancing the speed performance. Results and Conclusion\ VHDL simulation, synthesis and layout design of system are implemented. This 2 D IDCT ASIC design owns best timing performance when compared with other better designs internationally. Results of design prove to be excellent.

DAS测量路径温度非均匀分布对谱线线强影响的研究

为研究直接吸收光谱法(DAS)测量路径温度非均匀分布对谱线线强的影响,通过温度分布拟合法构建了受物理条件约束的4种温度分布模型,选用1.4μm附近的两条吸收谱线,仿真研究了在4种温度分布模型下谱线吸收线强的变化规律,讨论了沿测量路径谱线吸收线强分别以路径温度积分和路径线强积分两种计算方法的谱线线强值和谱线位置与理想条件下标准值的相对误差。实验以马弗炉实际测量温度分布结合温度分布模型D,利用1392.805和1392.185 nm两条谱线,结合谱线线强路径积分公式获得温度非均匀分布环境中谱线线强随温度变化曲线,并且得到谱线交点位置变化规律,证明了在DAS计算公式中,谱线线强值需结合实际测量环境的温度分布模型讨论。

FIR基于FPGA的高并行度DA结构

有限长单位冲击响应滤波器(FIR)是合成孔径雷达(SAR)系统的重要组成部分。为综合考虑资源与性能对系统的影响,基于现场可编程门阵列(FPGA)设计实现了位宽、阶数可配置的SAR雷达信号处理FIR系统,首次完成了合理范围内的只读存储器(ROM)地址位宽和所有输入并行度设置下的分布式算法(DA)结构对比实验,并对不同结构实现下的系统性能资源比进行了全面分析和比较,得到了最优化高并行度DA结构。实验结果表明在ROM地址位宽为4或5时性能资源比最好;性能资源比随输入并行度的提高而提高,当输入并行度为输入数据位宽时,性能资源比提高24%至117%。对比传统的全串行结构、全并行结构和DA结构,经ROM地址位宽和输入并行度优化后的DA结构的性能资源比分别提高了3 110%,76%和86%。