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H_∞ output tracking control for flight control systems with time-varying delay

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Chinese Journal of Aeronautics 2013年第5期26卷 1251-1258页

作者： Zhang Yingxin Wang Qing Dong Chaoyang Jiang Yifan school of automation Science and electrical engineering Beihang University school of Aeronautic Science and engineering Beihang University

For flight control systems with time-varying delay, an H∞ output tracking controller is proposed. The controller is designed for the discrete-time state-space model of general aircraft to reduce the effects of uncertainties of the mathematical model, external disturbances, and bounded time-varying delay. It is assumed that the feedback-control loop is closed by the communication network, and the network-based control architecture induces time-delays in the feedback information. Suppose that the time delay has both an upper bound and a lower bound. By using the Lyapu- nov-Krasovskii function and the linear matrix inequality （LMI）, the delay-dependent stability criterion is derived for the time-delay system. Based on the criterion, a state-feedback H∞ output tracking controller for systems with norm-bounded uncertainties and time-varying delay is presented. The control scheme is applied to the high incidence research model （HIRM）, which shows the effectiveness of the proposed approach.

关键词： Discrete time control systems Flight control systems H∞ output tracking Time-varying delay Uncertainty

A systematic method of smooth switching LPV controllers design for a morphing aircraft

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Chinese Journal of Aeronautics 2015年第6期28卷 1640-1649页

作者： Jiang Weilai Dong Chaoyang Wang Qing school of Aeronautic Science and engineering Beihang University school of automation Science and electrical engineering Beihang University

This paper is concerned with a systematic method of smooth switching linear parameter- varying （LPV） controllers design for a morphing aircraft with a variable wing sweep angle. The morphing aircraft is modeled as an LPV system, whose scheduling parameter is the variation rate of the wing sweep angle. By dividing the scheduling parameter set into subsets with overlaps, output feedback controllers which consider smooth switching are designed and the controllers in over- lapped subsets are interpolated from two adjacent subsets. A switching law without constraint on the average dwell time is obtained which makes the conclusion less conservative. Furthermore, a systematic algorithm is developed to improve the efficiency of the controllers design process. The parameter set is divided into the fewest subsets on the premise that the closed-loop system has a desired performance. Simulation results demonstrate the effectiveness of this approach.

关键词： Morphing aircraft Parameter set division:Robust control Smooth switching Switched linear parameter-varying system

Improved Fractional-order Damping Method for Voltage-controlled DFIG System Under Weak Grid

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1531-1541页

作者： Zhen Xie Xiang Gao Shuying Yang Xing Zhang school of electrical engineering and automation Hefei University of TechnologyHefeiChina

When a doubly-fed induction generator(DFIG)is connected to a weak grid,the coupling between the grid and the DFIG itself will increase,which will cause stability *** is difficult to maintain the tracking accuracy and robustness of the phase-locked loop(PLL)in the weak grid,and the risk of instability of the current-controlled DFIG(CC-DFIG)system will *** this paper,a new type of voltage-controlled DFIG(VC-DFIG)mode is adopted,which is a grid-forming structure that can independently support the voltage and frequency with a certain adaptability in the weak grid.A small-signal impedance model of the VC-DFIG system is also *** impedance of DFIG inevitably generates coupling with the grid impedance in the weak grid,especially in parallel compensation grids,and results in *** the basis of the VC-DFIG,impedance stability analysis is performed to study the influences of the control structure and short-circuit ***,a feedforward damping method is proposed to modify the impedance of the VC-DFIG system at resonance *** proposed fractional order damping is utilized,which can enhance the robustness and rapidity of resonance suppression under parameter ***,the experimental results are presented to validate the effectiveness of the proposed control strategy.

关键词： Weak grid voltage-controlled doubly-fed induction generator(DFIG) resonance feedforward damping fractional-order damping

Backstepping design of missile guidance and control based on adaptive fuzzy sliding mode control

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Chinese Journal of Aeronautics 2014年第3期27卷 634-642页

作者： Ran Maopeng Wang Qing Hou Delong Dong Chaoyang school of automation Science and electrical engineering Beihang University school of Aeronautic Science and engineering Beihang University

This paper presents an integrated missile guidance and control law based on adaptive fuzzy sliding mode control. The integrated model is formulated as a block-strict-feedback nonlinear system, in which modeling errors, unmodeled nonlinearities, target maneuvers, etc. are viewed as unknown uncertainties. The adaptive nonlinear control law is designed based on backstepping and sliding mode control techniques. An adaptive fuzzy system is adopted to approximate the coupling nonlinear functions of the system, and for the uncertainties, we utilize an online-adaptive control law to estimate the unknown parameters. The stability analysis of the closed-loop system is also conducted. Simulation results show that, with the application of the adaptive fuzzy sliding mode control, small miss distances and smooth missile trajectories are achieved, and the system is robust against system uncertainties and external disturbances.

关键词： Adaptive fuzzy system Backstepping Integrated guidance and control Nonlinear Sliding mode control

Spectral-Energy Efficiency Tradeoff in Mixed-ADC Massive MIMO Uplink with Imperfect CSI

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Chinese Journal of Electronics 2019年第3期28卷 618-624页

作者： DING Qingfeng JING Yindi school of electrical and automation engineering East China Jiaotong University Department of electrical and Computer engineering University of Alberta

An uplink multi-user massive Multiinput multi-output(MIMO) system is considered with a mixed Analog-to-digital converter(ADC) architecture under imperfect Channel state information(CSI). A closed-form approximation for the Spectral efficiency(SE)is derived for a general mixed ADC structure with any resolution profile. To achieve a balance between the SE and receive Energy efficiency(EE) of the system, the ADC resolution profile optimization problem that maximizes a linear combination of the SE and the Base station(BS)receive power consumption is formulated. An algorithm based on gradient search is proposed whose complexity is linear in the number of BS antennas. Numerical results verify that the proposed ADC resolution design largely outperforms the two-level structure especially in the lower SE region and provides more choices than the uniformADC architecture for resolving the SE-EE tradeoff.

关键词： Massive MIMO Mixed-ADC receiver Spectral-energy efficiency tradeoff Gradient search Imperfect channel state information

Ground experimental investigations into an ejected spray cooling system for space closed-loop application

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Chinese Journal of Aeronautics 2016年第3期29卷 630-638页

作者： Zhang Hongsheng Li Yunze Wang Shengnan Liu Yang Zhong Mingliang school of Aeronautic Science and engineering Beihang University school of automation Science and electrical engineering Beihang University

Spray cooling has proved its superior heat transfer performance in removing high heat flux for ground applications. However, the dissipation of vapor liquid mixture from the heat sur- face and the closed-loop circulation of the coolant are two challenges in reduced or zero gravity space enviromnents. In this paper, an ejected spray cooling system for space closed-loop application was proposed and the negative pressure in the ejected condenser chamber was applied to sucking the two-phase mixture from the spray chamber. Its ground experimental setup was built and exper- imental investigations on the smooth circle heat surface with a diameter of 5 mm were conducted with distilled water as the coolant spraying from a nozzle of 0.51 mm orifice diameter at the inlet temperatures of 69.2 ℃ and 78.2 ℃ under the conditions of heat flux ranging from 69.76 W/cm2 to 311.45 W/cm2, volume flow through the spray nozzle varying from 11,22 L：h to 15.76 L·h. Work performance of the spray nozzle and heat transfer performance of the spray cooling system were analyzed; results show that this ejected spray cooling system has a good heat transfer performance and provides valid foundation for space closed-loop application in the near future.

关键词： Ejected spray cooling systemEvaluation models Ground experiment Heat transfer performance High heat flux Space closed-loop

Dynamic thermal rating assessment of oil-immersed power transformers for multiple operating conditions

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High Voltage 2024年第1期9卷 195-205页

作者： Chen Zhang Xuzhu Dong Jiangjun Ruan Yongqing Deng school of electrical engineering and automation Wuhan UniversityWuhanHubeiChina

In this article,the dynamic thermal rating assessment method of oil-immersed power transformer with multiple operating conditions is proposed,considering the constraints of hot spot temperature(HST),top oil temperature,losses of life and the maximum allowable current of on-load tap changer(OLTC)or bushing,which can determine the dynamic load curves under different operating conditions and give the most sensitive constraints to limit the dynamic load *** improve the accuracy of HST estimation,the temperature estimation model is also improved and the thermal parameters are optimised using the HST measured by optical ***,several application examples are studied for transformers in different *** results show that the normal cyclic dynamic transformer rating(DTR)is mainly limited by the losses of life when the ambient temperature is high,and the average load factor can be increased to 0.82 with a maximum load capacity of *** main limiting factor of short-term DTR is the OLTC or bushing current constraint,and the average load factor can be increased to *** maximum load capacity of the transformer under both operating conditions is 23%and 50%higher than its rated load capacity,indicating that the transformer still has a large load potential available.

关键词： load thermal power

Leader-follower Optimal Selection Method for Distributed Control System in Active Distribution Networks

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 314-323页

作者： Jian Le Liangang Zhao Cao Wang Qian Zhou Yang Wang school of electrical engineering and automation Wuhan UniversityWuhan 430072China

Aiming at the shortcomings of a traditional centralized control in an active distribution network(AND),this paper proposes a leader-follower distributed group cooperative control strategy to realize multiple operation and control tasks for an *** distributed information exchange protocols of the distributed generation(DG)group devoted to node voltage regulation or exchange power control are developed using a DG power utilization ratio as the consensus *** these bases,this study further investigates the leader optimal selection method for a DG group to improve the response speed of the distributed control ***,a single or multiple leader selection model is established to minimize the constraints of the one-step convergence factor and the number of leaders to improve the response speed of the distributed control *** simulation results of the IEEE 33 bus standard test system show the effectiveness of the proposed distributed control *** addition,the response speed of a DG control group can be improved effectively when the single or multiple leaders are selected optimally.

关键词： Active distribution1network consensus algorithm leader-follower system mixed-integer semidefinite programming optimal distributed control

Finite Time Consensus Problem for Multiple Non-Holonomic Agents with Communication Delay

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Journal of Systems Science & Complexity 2015年第3期28卷 559-569页

作者： WANG Jiankui FU Jiankuan ZHANG Guoshan school of Science Tianjin Polytechnic University school of electrical engineering & automation Tianjin University

In this paper, finite time consensus problem is discussed for multiple non-holonomic mobile agents with constant communication delay. The objective is to design non-smooth distributed control laws such that multiple non-holonomic mobile agents can be all in agreement within any given finite time larger than communication delay. The authors propose a novel switching control strategy with the help of Lyapunov-based method and graph theory.

关键词： Communication delay finite time consensus non-holonomic agent.