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Science Letters:Multi-frequency proportional-resonant (MFPR) current controller for PWM VSC under unbalanced supply conditions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第10期8卷 1527-1531页

作者： HU jia-bing HE Yi-kang Sehool of Eleetrieal Engineering Zhejiang University Hangzhou 310027 China

This letter presents a multi-frequency proportional-resonant （MFPR） current controller developed for PWM voltage source converter （VSC） under the unbalanced supply voltage conditions. The delta operator is used in place of the shift operator for the implementation of MFPR by using a low-cost fixed-point DSE The experimental results with an alternative control strategy validated the feasibility of the proposed MFPR current controller for the PWM VSC during voltage unbalance.

关键词： PWM VSC Multi-frequency proportional-resonant (MFPR) Voltage unbalance

The nonlinear mechanism for the same responses of neuronal bursting to opposite self-feedback modulations of autapse

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Science China(Technological Sciences) 2021年第7期64卷 1459-1471页

作者： LI YuYe GU HuaGuang jia bing DING XueLi College of Mathematics and Computer Science Chifeng UniversityChifeng024000China School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai200092China Department of Physiology and Biophysics School of Life SciencesFudan UniversityShanghai200438China Department of Basic Education Fuyang Institute of TechnologyFuyang236031China

In the traditional viewpoint,inhibitory and excitatory effects always induce opposite *** the present study,the enhanced bursting activities induced by excitatory autapses,which are consistent with the recent experimental observations,and those induced by inhibitory autapses,which is a paradoxical phenomenon,were simulated using the Chay *** same bifurcations and different ionic currents for the same responses were acquired with fast-slow variable dissection and current decomposition,*** the inhibitory or excitatory autaptic conductance increased,the ending phase of the burst related to a homoclinic bifurcation of the fast subsystem changed to widen the burst duration to contain more spikes,which was induced by an elevated minimal potential(V_(min)) of spiking of the fast *** inhibitory and excitatory autaptic conductances induced smaller and larger maximal potentials(V_(max)) of spiking,*** the downstroke,a weaker potassium current induced by the smaller V_(max) played a dominant role for the inhibitory autapse,and the stronger potassium current induced by the larger V_(max) became weaker due to the opposite autaptic current of the excitatory autapse,which induced the V_(min) *** results present the nonlinear and biophysical mechanisms of the same responses to opposite effects,which extends nonlinear dynamics knowledge and provides potential modulation measures for the nervous system.

关键词： bifurcation bursting autapse inhibitory effect excitatory effect fast-slow variable dissection

Exact Solutions and Invariant Sets to General Reaction-Diffusion Equation

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Communications in Theoretical Physics 2008年第6期49卷 1389-1392页

作者： jia Hua-bing XU Wei Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China

In this paper, we introduce new invariant sets, and the invariant sets and exact solutions to general reactiondiffusion equation are discussed. It is shown that there exist a class of exact solutions to the equations ... 详细信息

关键词： invariant set exact solution general reaction-diffusion equation rotation group scaling group

Dynamic modelling and robust current control of wind-turbine driven DFIG during external AC voltage dip

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第10期7卷 1757-1764页

作者： HU jia-bing HE Yi-kang Department of Electrical Engineering Zhejiang University Hangzhou 310027 China

Doubly-Fed Induction Generator （DFIG）, with vector control applied, is widely used in Variable-Speed Constant- Frequency （VSCF） wind energy generation system and shows good performance in maximum wind energy capture. But in two traditional vector control schemes, the equivalent stator magnetizing current is considered invariant in order to simplify the rotor current inner-loop controller. The two schemes can perform very well when the grid is in normal condition. However, when grid disturbance such as grid voltage dip or swell fault occurs, the control performance worsens, the rotor over current occurs and the Fault Ride-Through （FRT） capability of the DFIG wind energy generation system gets seriously deteriorated. An accurate DFIG model was used to deeply investigate the deficiency of the traditional vector control. The improved control schemes of two typical traditional vector control schemes used in DFIG were proposed, and simulation study of the proposed and traditional control schemes, with robust rotor current control using Internal Model Control （IMC） method, was carded out. The validity of the proposed modified schemes to control the rotor current and to improve the FRT capability of the DFIG wind energy generation system was proved by the comparison study.

关键词： Wind energy generation Variable-Speed Constant-Frequency (VSCF) Doubly-Fed Induction Generator (DFIG) Fault Ride-Through (FRT) Internal Model Control (IMC)

Dynamic modeling and direct power control of wind turbine driven DFIG under unbalanced network voltage conditions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第12期9卷 1731-1740页

作者： jia-bing HU Yi-kang HE Lie XU School of Electrical Engineering Zhejiang University Hangzhou 310027 China Department of Electronics and Electrical Engineering University of Strathclyde Glasgow G40PG UK

This paper proposes an analysis and a direct power control (DPC) design of a wind turbine driven doubly-fed induction generator (DFIG) under unbalanced network voltage conditions. A DFIG model described in the positive and negative synchronous reference frames is presented. Variations of the stator output active and reactive powers are fully deduced in the presence of negative sequence supply voltage and rotor flux. An enhanced DPC scheme is proposed to eliminate stator active power oscillation during network unbalance. The proposed control scheme removes rotor current regulators and the decomposition processing of positive and negative sequence rotor currents. Simulation results using PSCAD/EMTDC are presented on a 2-MW DFIG wind power generation system to validate the feasibility of the proposed control scheme under balanced and unbalanced network conditions.

关键词： Doubly-fed induction generator (DFIG) Wind turbine Direct power control (DPC) Stator voltage oriented (SVO) Unbalanced network

Enhanced control of DFIG-used back-to-back PWM VSC under unbalanced grid voltage conditions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1330-1339页

作者： HU jia-bing HE Yi-kang NIAN Heng School of Electrical Engineering Zhejiang University Hangzhou 310027 China

This paper presents a unified positive-and negative-sequence dual-dq dynamic model of wind-turbine driven doubly-fed induction generator(DFIG) under unbalanced grid voltage conditions. Strategies for enhanced control and operation of a DFIG-used back-to-back(BTB) PWM voltage source converter(VSC) are proposed. The modified control design for the grid-side converter in the stationary αβ frames diminishes the amplitude of DC-link voltage ripples of twice the grid frequency,and the two proposed control targets for the rotor-side converter are alternatively achieved,which,as a result,improve the fault-ride through(FRT) capability of the DFIG based wind power generation systems during unbalanced network supply. A complete unbalanced control scheme with both grid-and rotor-side converters included is designed. Finally,simulation was carried out on a 1.5 MW wind-turbine driven DFIG system and the validity of the developed unified model and the feasibility of the proposed control strategies are all confirmed by the simulated results.

关键词： Unbalanced grid voltage Doubly-fed induction generator (DFIG) Back-to-back (BTB) Fault-ride through (FRT) Voltage source converter (VSC)

Adaptive rotor current control for wind-turbine driven DFIG using resonant controllers in a rotor rotating reference frame

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 149-155页

作者： jia-bing HU Yi-kang HE Hong-sheng WANG School of Electrical Engineering Zhejiang University Hangzhou 310027 China

This paper proposes an adaptive rotor current controller for doubly-fed induction generator (DFIG), which consists of a proportional (P) controller and two harmonic resonant (R) controllers implemented in the rotor rotating reference frame. The two resonant controllers are tuned at slip frequencies ωslip+ and ωslip-, respectively. As a result, the positive- and negative-sequence components of the rotor current are fully regulated by the PR controller without involving the positive- and negative-sequence decomposition, which in effect improves the fault ride-through (FRT) capability of the DFIG-based wind power generation system during the period of large transient grid voltage unbalance. Correctness of the theoretical analysis and feasibility of the proposed unbalanced control scheme are validated by simulation on a 1.5-MW DFIG wind power generation system.

关键词： Unbalanced grid voltage Doubly-fed induction generator (DFIG) Proportional plus Resonant (PR) controller Faultride-through (FRT)

Experiments on self-excited oscillation in a thin-walled collapsible tube

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Acta Mechanica Sinica 2015年第6期31卷 817-826页

作者： Hai-Jun Wu Lai-bing jia Xie-Zhen Yin Department of Modern Mechanics University of Science and Technology of China Department of Naval Architecture and Marine Engineering University of Strathclyde

Self-excited oscillation in a collapsible tube is an important phenomenon in physiology. An experimental approach on self-excited oscillation in a thin-walled collapsi- ble tube is developed by using a high transmittance and low Young＇s modulus silicone rubber tube. The elastic tube is manufactured by the method of centrifugal casting in our laboratory. An optical method for recording the evolution of the cross-sectional areas at a certain position along the longitudinal direction of the tube is developed based on the technology of refractive index matching. With the transparent tube, the tube law is measured under the static no-flow condition. The cross section at the middle position of the tube transfers from a quasi-circular configuration to an ellipse, and then to a dumbell-shape as the chamber pressure is increased. During the self-excited oscillation, two periodic self-excited oscillating states and one transitional oscillating state are identified. They all belong to the LU mode. These different oscillating states are related to the initial cross-sectional shape of the tube caused by the difference of the downstream transmural pressure.

关键词： Collapsible tube Refractive index matching ·Cross-sectional area measurement· Self-excited oscillatingstates LU mode

Effect of sintering temperature on the microstructure and thermal conductivity of Al/diamond composites prepared by spark plasma sintering

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International Journal of Minerals,Metallurgy and Materials 2010年第2期17卷 234-240页

作者： Ke Chu Cheng-chang jia Xue-bing Liang Hui Chen School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Spark plasma sintering was used to fabricate Al/diamond *** effect of sintering temperature on the microstructure and thermal conductivity（TC） of the composites was investigated with the combination of experimental results and theoretical *** composite sintered at 550℃shows high relative density and strong interfacial bonding,whereas the composites sintered at lower（520CC） and higher（580-600℃） temperatures indicate no interfacial bonding and poor interfacial bonding,*** relative density and strong interfacial bonding can maximize the thermal conductivity of Al/diamond composites,and taking both effects of particle shape and inhomogeneous interfacial thermal conductance into consideration can give a fairly good prediction of composites＇ thermal conduction properties.

关键词： metal matrix composites thermal properties spark plasma sintering interface