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Robust Optimal Output Tracking Control of A Midwater Trawl System Based on T-S Fuzzy Nonlinear Model

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China Ocean Engineering 2013年第1期27卷 1-16页

作者：周华陈英龙杨华勇 state key laboratory of Fluid power transmission and Control Zhejiang University

A robust optimal output tracking control method for a midwater trawl system is investigated based on T-S fuzzy nonlinear model. A simplified nonlinear mathematical model is first employed to represent a midwater trawl system, and then a T-S fuzzy model is adopted to approximate the nonlinear system. Since the strong nonlinearities and the external disturbance of the trawling system, a mixed H2/H∞ fuzzy output tracking control strategy via T-S fuzzy system is proposed to regulate the trawl depth to follow a desired trajectory. The trawl depth can be regulated by adjusting the winch velocity automatically and the tracking error can be minimized according to the robust optimal criterion. In order to validate the proposed control method, a computer simulation is conducted. The simulation results indicate that the proposed fuzzy robust optimal controller make the trawl net rapidly follow the desired trajectory under the model uncertainties and the extemal disturbance caused by wave and current.

关键词： trawl system output tracking robust optimal control Takagi-Sugeno (T-S) fuzzy systems nonlinear systems

Collisionless tool orientation smoothing above blade stream surface using NURBS envelope

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第3期14卷 187-197页

作者： Jing-hua XU Shu-you ZHANG Jian-rong TAN Ri-na SA state key laboratory of Fluid power transmission and Control Zhejiang University

In five-axis machining,tool orientation above a blade stream surface may lead to tool collision and a decrease in workpiece ***,collisionless tool orientation smoothing(TOS)becomes an important *** the basis of a constant scallop height tool path,the triangular facets in the faces,vertices format are constructed from cutter contact(CC)using the Voronoi incremental *** cutter location(CL)points candidate set is represented by an oblique elliptic cone whose vertex lies at CC using NURBS *** the CL point is above its CC is judged by the dot product between the normal vector and the point on triangulation nearest to the CL *** curvatures at CC are obtained by fitting a moving least square(MLS) quadratic patch to the local neighborhood of a vertex and calculating eigenvectors and eigenvalues of the Hessian *** surface elastic energy is employed as the weight in selection from the NURBS *** collision is judged by NURBS surface *** can then be expressed by selecting a CL point for each CC point and converted into a numerical control(NC)code automatically according to the postprocessor type of the machine *** proposed method is verified by finishing of a cryogenic turboexpander impeller of air separation equipment.

关键词： Tool orientation smoothing(TOS) Blade stream surface Triangular facet NURBS envelope Surface elastic energy

Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

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Plasma Science and technology 2014年第8期16卷 749-757页

作者：刘兴华咸日常孙学峰王涛吕学宾陈素红杨帆 state Grid Zibo power Supply Company state Grid Shandong Electric power Company state Grid Shandong Electric power Research Institute state key laboratory of power transmission equipment & System Security and New technology Chongqing University

Investigating the corona mechanism plays a key role in enhancing the performance of electrical insulation systems. Numerical simulation offers a better understanding of the physical characteristics of air corona discharges. Using a two-dimensional axisymmetrical kinetics model, into which the photoionization effect is incorporated, the DC air corona discharge at atmosphere pressure is studied. The plasma model is based on a self-consistent, multi-component, and con- tinuum description of the air discharge, which is comprised of 12 species and 22 reactions. The discharge voltage-current characteristic predicted by the model is found to be in quite good agree- ment with experimental measurements. The behavior of the electronic avalanche progress is Mso described. 0＋ and N＋ are the dominant positive ions, and the values of 0- and 02 densities are much smaller than that of the electron. The electron and positive ion have a low-density thin layer near the anode, which is a result of the surface reaction and absorption effect of the electrode. As time progresses, the electric field increases and extends along the cathode surface, whereas the cathode fall shrinks after the corona discharge hits the cathode; thus, in the cathode sheath, the electron temperature increases and the position of its peak approaches to the cathode. The present computational model contributes to the understanding of this physical mechanism, and suggests ways to improve the electrical insulation system.

关键词： air corona discharge atmospheric pressure numerical simulation mechanism

Performance Analysis of Corroded Grounding Devices with an Accurate Corrosion Model

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CSEE Journal of power and Energy Systems 2023年第3期9卷 1235-1247页

作者： Yihua Dan Zhanlong Zhang Pengfei Gan Huarui Ye Qiaoyi Li Jun Deng state key laboratory of power transmission equipment&System Security and New technology Chongqing UniversityChongqing 400030China Test Centre of EHV transmission Company China Southern Power GridGuangzhou 510663China

Grounding devices are significant to the operation of the power transmission line and power *** soil and leakage current can easily cause the corrosion of carbon steel grounding devices,resulting in power ***,most carbon steel grounding devices in service are already corroded,and the accurate calculation of grounding parameters for corroded grounding devices is ***,most existing methods for calculating the grounding parameters of corroded grounding devices usually have the following disadvantages:1)They only consider whether the grounding devices are broken or not,and cannot analyze the grounding parameters of grounding devices with different corrosion degrees;2)They assume that the corroded grounding device is a conductor with a smaller diameter,and ignore the impact of the corrosion product layer,resulting in calculation *** solve the above problems,this paper establishes an accurate corrosion model for grounding devices based on the volume expansion coefficient of corrosion *** grounding parameters calculation method for corroded grounding devices is proposed based on the boundary element method(BEM)and Galerkin’s *** the grounding performance of tower grounding grids with different corrosion degrees in different soils(uniform and layered)is ***,some features of grounding parameters of corroded grounding devices are *** study can accurately calculate the grounding parameters of the corroded grounding devices and has far-reaching engineering significance for the safety of power equipment.

关键词： Corroded grounding devices corrosion product layer grounding parameters volume expansion coefficient

A comparison on the effects of coal fines and sand fouling on the shear behaviors of railway ballast using large scale direct shear tests

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Journal of Traffic and Transportation Engineering(English Edition) 2025年第1期 52-67页

作者： Xu Zhang Shunying Ji Yang Feng Yongjun Li Chunfa Zhao School of Civil and Transportation Engineering Guangdong University of Technology state key laboratory of Rail Transit Vehicle System Southwest Jiaotong University state key laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of Technology

Railway ballast is easily contaminated by different fouling material and the fouled ballast always causes the deterioration of railway track. Many previous studies focused on the effect of a certain kind of fouling material on ballast performance, but few studies compared the influence of different fouling material. This paper presents a series of direct shear tests on the clean ballast and the fouled ballast mixed with coal fines or sand to understand the effects of different fouling material. A unified empirical model is proposed to well capture the shear stress-displacement responses of the clean and fouled *** equations are also obtained to characterize the variation of the nonlinear shear strength envelope of the fouled ballast with the fouling content. Based on these equations,a simple method is proposed to predict the shear strength of the fouled ballast using the shear test results of clean ballast. The measured results demonstrate significant differences between the effects of coal fines and sand on the shear behaviors of ballast, to which particular attention should be paid in order to take targeted maintenance measures for the fouled ballast. The mechanisms for the different effects of coal fines and sand are also analyzed to understand the roles that various fouling material plays in the fouled ballast.

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Multi-stage Coordinated Robust Optimization for Soft Open Point Allocation in Active Distribution Networks with PV

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Journal of Modern power Systems and Clean Energy 2023年第5期11卷 1553-1563页

作者： Anqi Tao Niancheng Zhou Yuan Chi Qianggang Wang Guangde Dong state key laboratory of power transmission equipment and System Security and New technology Chongqing UniversityChongqing 400044China state Grid Chongqing Electric power Company Limited Chongqing 401123China

To optimize the placement of soft open points(SOPs)in active distribution networks(ADNs),many aspects should be considered,including the adjustment of transmission power,integration of distributed generations(DGs),coordination with conventional control methods,and maintenance of economic *** address this multi-objective planning problem,this study proposes a multi-stage coordinated robust optimization model for the SOP allocation in ADNs with photovoltaic(PV).First,two robust technical indices based on a robustness index are proposed to evaluate the operation conditions and robust optimality of the ***,the proposed coordinated allocation model aims to optimize the total cost,robust voltage offset index,robust utilization index,and voltage collapse proximity ***,the optimization methods of the multiand single-objective models are coordinated to solve the proposed multi-stage ***,the proposed model is implemented on an IEEE 33-node distribution system to verify its *** results show that the proposed index can better reveal voltage offset conditions as well as the SOP utilization,and the proposed model outperforms conventional ones in terms of robustness of placement plans and total cost.

关键词： Multi-stage coordinated optimization allocation robustness index soft open point(SOP) active distribution network

Design and Test of 1/5th Scale Horizontal Axis Tidal Current Turbine

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China Ocean Engineering 2016年第3期30卷 407-420页

作者：刘宏伟周宏宾林勇刚李伟顾海港 state key laboratory of Fluid power transmission and Control Zhejiang University

Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine （TCT） for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a l/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions.

关键词： tidal current energy horizontal axis turbine offshore test

Ultrahigh Performance Triboelectric Nanogenerator Enabled by Charge transmission in Interfacial Lubrication and Potential Decentralization Design

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Research 2022年第4期2022卷 519-529页

作者： Wencong He Wenlin Liu Shaoke Fu Huiyuan Wu Chuncai Shan Zhao Wang Yi Xi Xue Wang Hengyu Guo Hong Liu Chenguo Hu School of Physics State Key Laboratory of Power Transmission Equipment and System Security and New TechnologyChongqing UniversityChongqing 400044China state key laboratory of Crystal Materials Shandong UniversityJinan 250100China

Triboelectric nanogenerator (TENG) is a promising strategy for harvesting low frequency mechanical energy. However, the bottlenecks of limited electric output by air/dielectric breakdown and poor durability by material abrasion seriously restrict its further improvement. Herein, we propose a liquid lubrication promoted sliding mode TENG to address both issues. Liquid lubrication greatly reduces interface material abrasion, and its high breakdown strength and charge transmission effect further enhance device charge density. Besides, the potential decentralization design by the voltage balance bar effectively suppresses the dielectric breakdown. In this way, the average power density up to 87.26 W·m^(-2)·Hz^(-1), energy conversion efficiency of 48%, and retention output of 90% after 500,000 operation cycles are achieved, which is the highest average power density and durability currently. Finally, a cell phone is charged to turn on by a palm-sized TENG device at 2 Hz within 25 s. This work has a significance for the commercialization of TENG-based self-powered systems.

关键词： durability dielectric generator

Stability Comparison Between Grid-forming and Grid-following Based Wind Farms Integrated MMC-HVDC

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Journal of Modern power Systems and Clean Energy 2023年第4期11卷 1341-1355页

作者： Rongcai Pan Dong Liu Shan Liu Jie Yang Longze Kou Guangfu Tang China Electric power Research Institute Beijing 100192Chinaand he is also with the State Key Laboratory of Advanced Power Transmission Technology and Beijing Key Laboratory of DC Grid Technology&SimulationBeijing 102209China state key laboratory of Advanced power transmission technology and Beijing key laboratory of DC Grid technology&Simulation Beijing 102209China

Grid-forming(GFM)control based high-voltage DC(HVDC)systems and renewable energy sources(RESs)provide support for enhancing the stability of power ***,the interaction and coordination of frequency support between the GFM-based modular multilevel converter based HVDC(MMC-HVDC)and grid-following(GFL)based RESs or GFM-based RESs have not been fully investigated,which are examined in this ***,the detailed AC-and DC-side impedances of GFM-based MMC-HVDC are *** impedance characteristics of GFL-and GFM-based wind turbines are next ***,the influences of GFL-and GFM-based wind farms(WFs)on the DC-and AC-side stabilities of WF-integrated MMC-HVDC systems are compared and *** results show that the GFM-based wind turbine performs better than the GFL-based wind ***,to support a receiving-end AC system,the corresponding frequency supporting strategies are proposed based on the GFM control for WF-integrated MMC-HVDC *** GFM-based WF outperforms the GFL-based WF in terms of stability and response *** in PSCAD/EMTDC demonstrate the DC-and AC-side stability issues and seamless grid support from the RESs,i.e.,WFs,to the receiving-end AC system.

关键词： Renewable energy source(RES) modular multilevel converter(MMC) wind farm grid-forming(GFM) highvoltage direct current