A Novel Topology of Hybrid Multilevel Inverter with Minimum Number of Separated DC Sources

Multilevel inverter has become increasingly popular in recent years due to advantages of high power quality waveforms, low switching losses, and high-voltage capability. A novel multilevel inverter with minimum number of separated DC sources is presented in this paper. Three-phase output voltages of this inverter can easily be balanced because they are synthesized by using the same DC sources. A harmonic reduction method eliminating both the 5th and 7th harmonics is proposed. Finally, comparison results and spectral analysis are presented. Key words multilevel inverter - topology - DC source - harmonic reduction - spectrum Project supported by the Postdoctoral Science Foundation of Shanghai (Grant No. kO7)

Quasi-Z Source Inverter Control of PV Grid-Connected Based on Fuzzy PCI

The photovoltaic grid-connected inverter is an important interface between the photovoltaic power generation system and power grid.Its high-quality operation is directly related to the output power quality of the power grid.In order to further optimize the control effect of the quasi-Z source grid-connected photovoltaic inverter,a fuzzy proportional complex integral control(PCI)method is proposed for the current internal loop control.This method can eliminate the steady-state error,and has the characteristic of zero steady-state error adjustment for the AC disturbance signal of a specific frequency.The inductance-capacitance-inductance(LCL)filter is adopted in the grid-connected circuit,and the feedback capacitive current is taken as the control variable of the inner loop to form the active damping control method,which can not only effectively suppress the resonance of the LCL circuit,but also significantly inhibit the high-order harmonics in the grid-connected current.Finally,a system simulation model is built in MATLAB/Simulink to verify the superiority and effectiveness of the proposed method.

一种新型准Z源高增益DC-DC升压变换器

针对传统准Z源阻抗网络DC-DC升压变换器存在电压增益低和元件电压应力高的问题,提出一种新型准Z源高增益DC-DC升压变换器(HSQZSC)。首先,分析HSQZSC变换器两种模态工作原理,并对其进行稳态分析和参数设计。其次,与现已提出的Z源变换器进行性能对比,表明HSQZSC变换器具有高电压增益和元件电压应力低的优势。然后,对其建立状态空间模型进行小信号分析、稳定性分析和控制器的设计。最后,搭建100 W实物样机,实验结果验证了HSQZSC变换器的可行性与有效性。

海上风电场交流集电和多端柔直输电并网系统多目标优化规划

集电和输电并网系统的优化规划对海上风电场(offshore wind farm,OWF)的投资经济性和运行可靠性有着重要影响。对于OWF中交流集电和多端柔直输电的并网方式,建立了拓扑与潮流耦合的兼顾经济性和可靠性的多目标优化规划模型。模型中利用拓扑冗余度直接近似计算风机停运损失电量,并考虑了新型双边环形的交流集电系统拓扑结构和基于连通性约束的多端柔直输电系统拓扑结构,实现了对集电和输电系统拓扑连接,交流和直流海底电缆类型,海上升压换流站数量、容量、位置,和连接到海上升压换流站馈线数量的协调优化规划。并且,提出了一种直接求解多目标优化问题折中最优解的方法,通过凸化处理将原混合整数非线性规划模型转化为混合整数凸二次规划模型,以高效求解获得最优规划方案。最后,对2个分别含36台和78台风机的实际OWF算例进行分析,验证了所提出模型和方法的正确有效性。

开关电感型Quasi-Z源逆变器

提出了一种开关电感型Quasi-Z源逆变器的拓扑,该拓扑用开关电感代替传统Quasi-Z源的电感,在保留传统Quasi-Z源逆变器优点的同时,在相同直通占空比的情况下增大了其升压倍数,而且在较小的直通占空比情况下即可实现任意倍数的升压,给调制因子较大的取值空间,提高了输出电压的质量与系统的稳定性。采用改进的空间矢量实现了对改进Quasi-Z源逆变器的控制。仿真和实验证明了该拓扑在相同直通占空比的情况下具有更高的升压倍数的新特性。

改进型Quasi-Z源逆变器

传统Quasi-Z源逆变器通过直通零矢量实现单级升降压,但随着输出电压的升高,电容电压越来越大,增加了对器件的要求。提出两种改进型Quasi-Z源逆变器拓扑,在保留传统Quasi-Z源逆变器优点的同时,具有以下特点:有效降低电容电压峰值及稳态电压;有效降低电路启动时电感电流峰值;有效降低器件要求,提高了系统可靠性。在理论研究的基础上,通过仿真结果验证了改进型Quasi-Z源逆变器的正确性和优越性。

一种改进型Quasi-Z源逆变器

在保留Quasi-Z源逆变器优点的条件下,提出一种改进型Quasi-Z源逆变器拓扑.在升压能力相同时,改进型Quasi-Z源逆变器有效降低电容启动电压、稳态电压及电路启动的冲击电流.另外,在采用相同电容、电感器件的情况下,能承受更高的调制因子,提高了输出电压的质量与系统的稳定性.在理论研究的基础上,基于简单升压控制下的仿真结果验证了改进型的正确性和优越性.

考虑Gauss移动热源瞬态效应的传热结构拓扑优化

针对热源位置随时间发生变化的结构热传导问题,考虑Gauss移动热源进行瞬态热传导拓扑优化设计.分别以整个时间历程内传热结构散热弱度最小化与区域温度最大值最小化为设计目标,体积分数为约束条件,采用伴随变量法推导目标函数与约束条件的敏度信息,借助移动渐进线法更新设计变量,研究了不同Gauss热源移动路径与移动速度对拓扑优化结果的影响.结果表明,瞬态拓扑结构相较于稳态结果具有明显时变性,同时最佳传热构型受到热源加热时间和移动速度及路径的多重影响.

莺歌海盆地黄流组一段沉积物源综合识别

通过重矿物直观比对法确定了莺歌海盆地黄流组一段沉积物中各物源区的重矿物特征,并初步认识了其古母岩特征。研究区周围存在三大主要物源区,即海南岛、越南北部(红河)及越南中部。结果表明,越南物源以铁矿物、钛矿等沉积岩型重矿物组合为主;海南物源以锆石、电气石、金红石等酸性火山岩型重矿物组合为主。基于余弦距离及皮尔森相关系数的谱系聚类结果表明,莺歌海盆地黄流组一段锆石、电气石、金红石、锐钛矿、白钛矿等矿物受成岩作用影响较小,为该时期的稳定矿物组合。综合稳定重矿物复杂拓扑网络、地震属性、地震剖面及锆石年龄等方法对主导物源区进行划分,确定了莺歌海盆地东方13区及东方1区的部分扇体主要受控于越北红河物源,东方13区及东方29区的绝大多数扇体主要受越中物源及海南北部物源的双重影响,乐东区受控于海南南部物源。基于海南南部物源的古物源分布模式,建立了重矿物-地震特征-锆石年代学的物源识别方法。

非欧氏度量空间下的选线优化设计方法

作为城市基础设施之一,输电线路是城市治理中的关键环节。针对输电线路建设,综合考虑道路距离、变压器负载、故障率、施工成本等约束条件,设计了一种非欧氏度量空间下的优化线路设计方法。结合自适应邻近变压器点位搜索算法和基于近邻关系的点—线拓扑整合方法,实现了结合复杂时空要素的优化选线设计。以广州市海珠区、白云区为例,综合利用道路网络、变压器点位、维修驻点位置等多源数据,为区域内某一新建楼栋选择最佳供电变压器,并规划了输电线路,完整验证了该算法流程的可行性,为电力线路规划与建设提供了行之有效的决策支持工具。

Day-ahead Voltage-stability-constrained Network Topology Optimization with Uncertainties

A day-ahead voltage-stability-constrained network topology optimization(DVNTO)problem is proposed to find the day-ahead topology schemes with the minimum number of operations(including line switching and bus-bar splitting)while ensuring the sufficient hourly voltage stability margin and the engineering operation requirement of power systems.The AC continuation power flow and the uncertainty from both renewable energy sources and loads are incorporated into the formulation.The proposed DVNTO problem is a stochastic,largescale,nonlinear integer programming problem.To solve it tractably,a tailored three-stage solution methodology,including a scenario generation and reduction stage,a dynamic period partition stage,and a topology identification stage,is presented.First,to address the challenges posed by uncertainties,a novel problem-specified scenario reduction process is proposed to obtain the representative scenarios.Then,to obtain the minimum number of necessary operations to alter the network topologies for the next 24-hour horizon,a dynamic period partition strategy is presented to partition the hours into several periods according to the hourly voltage information based on the voltage stability problem.Finally,a topology identification stage is performed to identify the final network topology scheme.The effectiveness and robustness of the proposed three-stage solution methodology under different loading conditions and the effectiveness of the proposed partition strategy are evaluated on the IEEE 118-bus and 3120-bus power systems.

基于语音控制的声源定位演示实验仪

基于TC264微处理器自主设计了一款语音控制的声源定位演示仪。采用3D建模软件creo3设计并打印了新型麦克风阵列拓扑结构,将麦克风阵列采集到的声源信息传输到TC264微处理器中,应用时延估计算法(TDOA)实现了声源准确定位,并采用LD3320芯片对声音进行识别,实现了对整个系统的辅助人声控制。同时在上位机中利用QT(应用程序开发框架)开发了一款windows系统下用于上位和底层平台进行交互的应用软件,实现了串口通信助手、多通道声音波形显示、定位结果显示等多种功能。

一种新型高增益Quasi-Z源逆变器

为了解决传统Z源逆变器的升压能力不足,提出一种新型高增益Quasi?Z源逆变器。该新型拓扑结构将传统Quasi?Z源逆变器的两个电感用升压单元和改进型开关电感替换得以实现。在Matlab/Simulink下对该新型拓扑结构和传统Quasi?Z源拓扑结构的直流链电压、电容电压和负载电压进行仿真分析对比。结果显示,相比于传统的Quasi?Z源逆变器,该新型拓扑结构性能有了大幅度改善,提高了升压能力,使其可以有更加广泛的应用场合,有效抑制了启动冲击电流,从而避免了启动瞬间逆变器开关器件的损坏。

Generalized multilevel current source inverter topology with self-balancing current

A generalized single-phase multilevel current source inverter (MCSI) topology with self-balancing current is proposed, which uses the duality transformation from the generalized multilevel voltage source inverter (MVSI) topology. The existing single-phase 8-and 6-switch 5-level current source inverters (CSIs) can be derived from this generalized MCSI topology. In the proposed topology, each intermediate DC-link current level can be balanced automatically without adding any external circuits; thus, a true multilevel structure is provided. Moreover, owing to the dual relationship, many research results relating to the op- eration, modulation, and control strategies of MVSIs can be applied directly to the MCSIs. Some simulation results are presented to verify the proposed MCSI topology.

长距离直流电缆对柔性直流系统故障影响分析

远距离海上风电越来越多地选择柔性直流经海缆送出的方式。采用电缆的柔性直流(voltage source converter based high voltage direct current,VSC-HVDC)输电系统,其故障特性比传统架空线直流输电系统更加复杂。文中基于对称单极拓扑的双端VSC-HVDC海上风电送出工程,简化了电缆和VSC-HVDC输电系统的数学模型,分析换流变阀侧交流系统单相接地和直流电缆线路单极接地等典型故障下的故障特性,运用叠加原理对故障机理进行解释;根据不同故障类型的故障源等效出不同的故障回路,得到了长距离电缆显著的电容效应对VSC-HVDC系统故障特征的复杂影响;利用实时数字仿真平台,搭建远海风电送出系统硬件在环仿真模型,验证了故障机理解析分析的正确性。

接地网拓扑结构的组合源磁场叠加成像检测方法

现有研究中常通过电磁感应方法探测接地网拓扑结构,针对该方法弱磁场测量困难,提出了一种组合源磁场叠加成像检测方法。通过多根引下线向接地网周期性轮换注入电流,不同注入方式使电流在接地网中呈现不同流向,保证了接地网不同区域载流导体都能激发有效测量磁场,结合二次开发的超宽带定位系统实时定位阵列式传感线圈测量位置,实现了对地表水平x、y方向感应磁场的扫描式测量,最后采用形态学滤波方法消除异常数据干扰,进而通过Canny边缘检测算子进行接地网拓扑提取。仿真与实验结果表明:文中所述方法能够有效提高接地网拓扑结构的成像效果,接地网网格导体定位精度误差不高于3%。

Source Rocks of the Caledonian-Age Granitoid Rocks in Wanyanshan-Zhuguangshan, Southeast China (Ⅱ)——Topological Analysis in Isotopic Multispace

Topological analysis in Sr-Nd-O-Pb_3 six-dimensional isotopic space suggests that the source rocks of the Caledonian-age granitoid rocks in Wanyangshan-Zhuguangshan, southeast China, comprise three end-member components. Isotopic mixing model discrimination indicates that the granitoid rocks were produced through mixing of the three componentsin varying proportions. Comprehensive study of multiple isotopic systems and geochemistry of the granitoid rocks suggests that the three end-member components were crustal rocks which are continent-derived sediments, geosycline sediments and altered basic volcanic rocks.

混合线性非线性网络的多源miRNA-疾病关联预测方法

现有miRNA-疾病关联研究大多采用miRNA功能和疾病语义相似性作为输入,未考虑miRNA序列和疾病功能等相似性信息,并且在特征提取过程中忽略了线性与非线性特征间的信息互补,影响特征质量。本文提出一种miRNA-疾病关联预测模型GCNMSF,它基于miRNA和疾病多源相似性信息,融合嵌入卷积注意块的图卷积网络学习的非线性特征和非负矩阵分解方法学习的线性特征,实现信息互补,以预测miRNA-疾病关联。实验结果表明,GCNMSF模型优于现有的miRNA-疾病关联预测方法,可以有效预测miRNA-疾病关联。

Predictive Control Based on Ranking Multi-objective Optimization Approaches for a quasi-Z Source Inverter

In power converter control,predictive control has several merits,such as simple concept and fast response.However,the necessity to use the weighting factor inside the cost function makes the control design complex in the case of regulating multivariables where the value of the weighting factor is obtained by a nontrivial process.Also,it primarily depends on the system parameters and operating points of the control system.This paper aims to enhance the model predictive algorithm of the singlestage topology of a quasi-Z Source Inverter(qZSI).The concept of a multi-objective optimization approach is used in addition to the sub-cost function definition to remove the weighting factors.By using the sub-cost function definition,the inductor current is pushed away from the main loop of the predictive algorithm.Thus,no weighting factor is needed to manage the priority of the inductor current.The other two control targets,which are the capacitor voltage and load currents,will be controlled by the multi-objective optimization approach without using any weighting factors.A detailed theoretical analysis of the proposed technique will be given and validated based on simulation results.

配电网重构方法对比与技术展望

在“碳达峰、碳中和”目标下,配电系统正在演变为区域资源优化配置平台,对我国能源供给与消费的低碳化转型起到关键支撑作用。如何突破网架拓扑与系统运行的紧耦合实现灵活组网运行,以适应规模化分布式能源接入的配电系统柔性可控需求是现阶段研究重点。在此背景下,首先从网络拓扑、系统负荷、分布式电源、优化目标、约束条件、重构算法等6个方向出发,对配电网重构方法进行了总结,然后对其面临的交直流配电网重构算法、双高下交直流配电网时空解耦和灵活性量化等关键问题进行了分析和展望。