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轨迹断面特征根对受扰轨迹最远点及动态鞍点的诠释

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电力系统自动化 2010年第12期34卷 1-7页

作者：薛禹胜郝丽丽 q. h. wu L. JIANG 国网电力科学研究院/南京南瑞集团公司江苏省南京市210003 东南大学电气工程学院江苏省南京市210096 Th. University of Liverpool Liverpool L69 3GJ英国

对于任何复杂模型,通过仿真得到特定扰动下的受扰轨迹后,就可沿轨迹将系统模型等值为分段定常的线性系统。轨迹断面特征根法采用的假设与欧拉积分法完全相同,即系统在且仅在单个仿真步长内被定常线性化。因此,在每个积分步内,不但可用... 详细信息

对于任何复杂模型,通过仿真得到特定扰动下的受扰轨迹后,就可沿轨迹将系统模型等值为分段定常的线性系统。轨迹断面特征根法采用的假设与欧拉积分法完全相同,即系统在且仅在单个仿真步长内被定常线性化。因此,在每个积分步内,不但可用静态扩展等面积准则(EEAC)法分析该轨迹断面上的能量稳定裕度(轨迹断面能量),也可用平衡点特征根技术分析该轨迹断面上的振荡阻尼与瞬时频率,而将断面处的不平衡功率与动能视为初始扰动。完整的受扰轨迹成为大、小扰动稳定分析的共同基础,断面特征根可反映复杂因素对振荡特性的影响,而EEAC可反映复杂因素影响同步稳定性的本质。引入"轨迹断面虚拟平衡点特征根序列"的概念,以计入断面处动能对滑步失稳的影响,并将滑步失稳与振荡失稳两者的机理相关联。据此考证最远点(FEP)和动态鞍点(DSP)处的振荡阻尼与瞬时频率,揭示大、小扰动失稳的内在联系。

关键词：振荡模式特征根分析轨迹断面特征根动态鞍点(DSP) 最远点(FEP)

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电力系统自动化 2010年第10期34卷 1-7,104页

作者：郝丽丽薛禹胜 q. h. wu K. P. WONG 徐泰山东南大学电气工程学院江苏省南京市210096 国网电力科学研究院/南京南瑞集团公司江苏省南京市210003 Th. University of Liverpool Liverpool L69 3GJ英国香港理工大学电机工程学系香港 University of Western Australia Perth WA 6009澳大利亚

归纳电力系统动态行为的要素、受扰轨迹的特征量及差异度指标,评述基于受扰轨迹差异度指标的模型校核及参数识别方法、存在的问题和发展方向。指出该指标不宜仅基于常规的信号处理技术,还应该反映系统动态行为的物理机理。揭示多参数识... 详细信息

归纳电力系统动态行为的要素、受扰轨迹的特征量及差异度指标,评述基于受扰轨迹差异度指标的模型校核及参数识别方法、存在的问题和发展方向。指出该指标不宜仅基于常规的信号处理技术,还应该反映系统动态行为的物理机理。揭示多参数识别问题中普遍存在的多解现象,即在一个特定扰动下,按受扰轨迹的相似程度来识别模型参数,其结果在本质上依赖于初值和迭代策略。指出必须分别以不同场景下的多组实测响应曲线为标准,并且被识别参数在多次试验期间必须保持不变,才有可能解决参数识别的多解问题。

关键词：动态行为差异度指标模型校核灵敏度分析参数识别多解现象

A h.brid Signal Processing Meth.d Combining Math.matical Morph.logy and Walsh.Th.ory for Power q.ality Disturbance Detection and Classification

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 584-592页

作者： Zh. Ding Tianyao Ji Mengsh. Li q.h.wu Sch.ol of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

In th.s paper, a novel signal processing meth.d combining math.matical morph.logy (MM) and Walsh.th.ory is proposed, wh.ch.uses Walsh.functions to control th. structuring element (SE) and MM operators. Based on th. Walsh.MM meth.d, a sch.me for power q.ality disturbances detection and classification is developed, wh.ch.involves th.ee steps: denoising, feature extraction and morph.logical clustering. First, various evolution rules of Walsh.function are used to generate groups of SEs for th. multiscale Walsh.ordered morph.logical operation, so th. original signal can be denoised. Next, th. fundamental wave of th. denoised signal is suppressed by h.damard matrix;th.s, disturbances can be extracted. Finally, th. Walsh.power spectrum of th. waveform extracted in th. previous step is calculated, and th. parameters of wh.ch.are taken by morph.logical clustering to classify th. disturbances. Simulation results reveal th. proposed sch.me can effectively detect and classify disturbances, and th. Walsh.MM meth.d is less affected by noise and only involves simple calculation, wh.ch.h.s a potential to be implemented in h.rdware and more suitable for real-time application.

关键词： h.damard matrix math.matical morph.logy morph.logical clustering power q.ality disturbance Walsh.th.ory

Convexification of h.brid AC-DC Optimal Power Flow with.Line-Commutated Converters

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 617-628页

作者： h.ngyuan Liang Zh.gang Li J.h.Zh.ng q.h.wu Sch.ol of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based h.gh.voltage DC (h.DC) systems h.ve been integrated with.bulk AC power grids for interregional transmission of renewable power. Th. nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of h.brid AC-DC power grids. A convexification meth.d for th. LCC station model could address such.nonconvexity but h.s rarely been discussed. We devise an eq.ivalent reformulation for classical LCC station models th.t facilitates second-order cone convex relaxation for th. OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with.its proof. Eq.ivalence of th. proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of th. original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

Residue Based Open-Loop Modal Analysis Meth.d for Detecting LFMR of PMSG-WFs Penetrated Power Systems

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1454-1465页

作者： Luonan q.u Tianh.o Wen Yang Liu q.h.wu Sch.ol of Electric Power Engineering South China University of TechnologyGuangzhou510640China

Th.s paper proposes a residue based open-loop modal analysis meth.d to detect low freq.ency modal resonance(LFMR),including asymmetric low freq.ency modal attraction(ALFMA)and asymmetric low freq.ency modal repulsion(ALFMR),of permanent magnetic synch.onous generator based wind farms(PMSG-WFs)penetrated power *** formation of ALFMA and ALFMR caused by two open-loop low freq.ency oscillation(LFO)modes moving close and apart is analyzed in *** predicting th. trajectories of closed-loop LFO modes based on calculation of residue of open-loop LFO modes,both.ALFMA and ALFMR can be *** proposed meth.d can select LFO modes wh.ch.move to th. righ. h.lf complex plane as control parameters *** studies are carried out on a th.ee-mach.ne power system and a four-mach.ne 11-bus power system to verify th. properties of th. proposed meth.d.

关键词： Asymmetric low freq.ency modal attraction asymmetric low freq.ency modal repulsion low freq.ency modal resonance residue based open-loop modal analysis meth.d

Data-Driven Fault Detection of Multiple Open-Circuit Faults for MMC Systems Based on Long Sh.rt-Term Memory Networks

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1563-1574页

作者： Ch.nxi Fan Kaish.n Xiah.u Lei Wang q.h.wu Sch.ol of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Th.s paper presents a long sh.rt-term memory(LSTM)-based fault detection meth.d to detect th. multiple open-circuit switch.faults of modular multilevel converter(MMC)systems with.full-bridge sub-modules(FB-SMs).Eigh.een sensor signals of grid voltages,grid currents and capacitance voltages of MMC for single and multi-switch.faults are collected as sampling *** output signal ch.racteristics of four types of single switch.faults of FB-SM,as well as double switch.faults in th. same and different ph.ses of MMC,are analyzed under th. conditions of load variations and control command ch.nges.A multi-layer LSTM network is devised to deeply extract th. fault ch.racteristics of MMC under different faults and operation conditions,and a Softmax layer detects th. fault *** results h.ve confirmed th.t th. proposed LSTM-based meth.d h.s better detection performance compared with.th.ee oth.r meth.ds:K-nearest neigh.or(KNN),naive bayes(NB)and recurrent neural network(RNN).In addition,it is h.gh.y robust to model uncertainties and Gaussian *** validity of th. proposed meth.d is furth.r demonstrated by experiment studies conducted on a h.rdware-in-th.-loop(h.L)testing platform.

关键词： Fault detection long sh.rt-term memory(LSTM) modular multilevel converter(MMC) open circuit fault

Location of Asymmetric Ground Fault Using Virtual Injected Current Ratio and Two-stage Recovery Strategy in Distribution Networks

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 151-161页

作者： h.iting Sh.n Luliang Zh.ng q.h.wu Mengsh. Li Sch.ol of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

Sparse measurements ch.llenge fault location in distribution *** paper proposes a meth.d for asymmetric ground fault location in distribution networks with.limited measurements.A virtual injected current vector is formulated to estimate th. fault line,wh.ch.can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).Th. relationsh.p between th. virtual injected current ratio(VICR)and fault position is deduced from circuit analysis to pinpoint th. ***,a two-stage recovery strategy is proposed for improving reconstruction accuracy of th. current vector,wh.re two different sensing matrixes are utilized to improve th. *** proposed meth.d is validated in IEEE 34 node test *** results sh.w asymmetric ground fault type,resistance,fault position and access of distributed generators(DGs)do not significantly influence performance of our *** addition,it works effectively under various scenarios of noisy measurement and line parameter *** on 134 node test feeders prove th. proposed meth.d is also suitable for systems with.more complex structure.

关键词： Distribution networks fault location reconstruction accuracy two-stage recovery virtual injected current ratio

Glasesterterpenoids A−C: th.ee sesterterpenoids with.7-cycloh.xyldecah.dronaph.h.lene carbon skeleton isolated from th. root of Lindera glauca

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Ch.nese Journal of Natural Medicines 2024年第9期22卷 864-868页

作者： h. S. ZOU q. Zh.NG q. LUO Y. YAN D. h. J. LIU Y. CUI h. Sch.ol of Ph.rmaceutical Sciences Guangzhou University of Chinese Medicine Guangzhou 510006 China State Key Laboratory of Oncology in South.Ch.na Collaborative Innovation Center for Cancer Medicine Sun Yat-Sen University Cancer Center Guangzhou 510060 China

Th.ee novel sesterterpenoids glasesterterpenoids A−C (1−3), featuring an unprecedented 7-cycloh.xyldecah.dronaph.h.lene carbon skeleton, were isolated from th. root of Lindera glauca (L. glauca). Th.ir structures were elucidated by q.antum ch.mical calculations and spectroscopic meth.ds. Th. biogenetic path.ay for 1−3 is proposed. In th. bioassay, glasesterterpenoid C exh.bited DNA topoisomerase 1 (Top1) inh.bitory activity compared with.th. positive control, camptoth.cin. Th.se findings represent th. first examples of sesterterpenoids with.a 7-cycloh.xyldecah.dronaph.h.lene carbon skeleton from th. root of L. glauca. © 2024 Ch.na Ph.rmaceutical University

关键词： Lindera glauca Sesterterpenoids

Estimating Critical Clearing Time of Grid Faults Using DA of State-Reduction Model of Power Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 807-820页

作者： Yang Liu Zh.ngyang Ch.n h.anjin Yao Lin Yi q.h.wu Sch.ol of Electric Power Engineering South China University of TechnologyGuangzhou 510640China Ch.na South.rn Power Grid Research.Institute Guangzhou 510663China

Th.s paper proposes a critical clearing time (CCT) estimation meth.d by th. domain of attraction (DA) of a state-reduction model of power systems using sum of sq.ares (SOS) programming. By exploiting th. property of th. Jacobian matrix and th. structure of th. boundary of th. DA, it is found th. DA of th. state-reduction model and th.t of th. full model of a power system are topological isomorph.sm. Th.re are one-to-one correspondence relationsh.ps between th. number of eq.ilibrium points, th. type of eq.ilibrium points, and solutions of th. two system models. Based on th.se findings, an expanding interior algorith. is proposed with.SOS programming to estimate th. DA of th. state-reduction model. State trajectories of th. full model can be transformed to th.se of th. state-reduction model by orth.gonal or eq.iradius projection. In th.s way, CCT of a grid fault is estimated with.th. DA of th. state-reduction model. Th. calculational burden of SOS programming in th. DA estimation using th. state-reduction model is rath.r small compared with.using th. full model. Simulation results sh.w th. proposed expanding interior algorith. is able to provide a tigh. estimation of DA of power systems with.h.gh.r accuracy and lower time costs.

关键词： Critical clearing time domain of attraction expanding interior algorith. state-reduction model SOS programming