The transient synchronization stability of grid-forming converters(GFMCs)is significantly challenged under grid voltage sags.Continuous efforts have been devoted to analyzing the GFMC transient stability,with limited ...The transient synchronization stability of grid-forming converters(GFMCs)is significantly challenged under grid voltage sags.Continuous efforts have been devoted to analyzing the GFMC transient stability,with limited attention paid to the impacts of control loop dynamics.However,the complex control dynamics,especially the interactions between the active/reactive power control loops and the current saturation process(CSP),are crucial for accurately describing the transient behavior and evaluating the stability.Thus,in this study,a new large-signal GFMC model is established,considering the reactive power control(RPC)with different kinds of controllers and the CSP simultaneously.It is revealed that GFMC does not switch to the current-limited mode immediately,and the dynamics of RPC further affect the transient behavior before the current limiting significantly.Hence,the complex control dynamics can alter the mode switching point of current saturation,thereby increasing the risk of loss of synchronization(LOS).Based on the above findings,comprehensive comparisons of typical RPC controllers are presented to facilitate practical engineering applications.A unified stability enhancement method is proposed for solving the problem of LOS.Finally,experiments validate the correctness of the analysis and the effectiveness of the proposed control strategy.展开更多
The wide-area damping controllers(WADCs),which are essential for mitigating regional low-frequency oscillations,face cyber-physical security threats due to the vulnerability of wide-area measurement system to cyber at...The wide-area damping controllers(WADCs),which are essential for mitigating regional low-frequency oscillations,face cyber-physical security threats due to the vulnerability of wide-area measurement system to cyber attacks and wind power uncertainties.This paper introduces reachability analysis method to quantify the impact of varying-amplitude attacks and uncertain wind fluctuations on the performance of WADC.Firstly,considering wind farm integration and attack injection,a nonlinear power system model with multiple buses is constructed based on Kron reduction method to improve computational efficiency and mitigate the constraints imposed by algebraic constraints.Then,a zonotope-based polytope construction method is employed to effectively model the range of attack amplitudes and wind uncertainties.By conducting reachability analysis,the reachable set preserving the nonlinear characteristics of studied system is computed,which enables the quantification of the maximum fluctuation range of regional oscillations under the dual disturbances.Case studies are undertaken on two multi-machine power systems with wind farm integration.The obtained results emphasize the efficacy of designed method,providing valuable insights into the magnitude of the impact that attacks exert on the operational characteristics of power system under various uncertain factors.展开更多
Inertial response control(IRC)makes variable-speed wind turbine generators(WTGs)provide short-term frequency support during contingencies by releasing the kinetic energy stored in wind turbine rotors.When frequency su...Inertial response control(IRC)makes variable-speed wind turbine generators(WTGs)provide short-term frequency support during contingencies by releasing the kinetic energy stored in wind turbine rotors.When frequency support is terminated,the rotor speed should be restored to optimum for maximum power point tracking(MPPT).Existing IRCs utilize rotor speed recovery(RSR)strategies with a consistent power reference function.However,under real turbulent wind with alternate gusts and lulls,the consistent power reference function may fail to restore rotor speed or cause unexpected secondary frequency drop(SFD).In this regard,this paper proposes a novel adaptive RSR strategy that not only restores rotor speed via the aerodynamic power enhanced by wind gusts,but also stabilizes the turbine at wind lulls by tracking a suboptimal power curve.Experiments on a wind power-integrated power system testbed validate the proposed RSR strategy can successfully restore rotor speed while attenuating SFD under turbulent wind.展开更多
This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance ...This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.展开更多
Unmanned Aerial Vehicle(UAV)swarm collaboration enhances mission effectiveness.However,fixed-wing UAV swarm flights face collaborative safety control problems within a limited airspace in complex environments.Aimed at...Unmanned Aerial Vehicle(UAV)swarm collaboration enhances mission effectiveness.However,fixed-wing UAV swarm flights face collaborative safety control problems within a limited airspace in complex environments.Aimed at the cooperative control problem of fixed-wing UAV swarm flights under the airspace constraints of a virtual tube in a complex environment,this paper proposes a behavior-based distributed control method for fixed-wing UAV swarm considering flight safety constraints.Considering the fixed-wing UAV swarm flight problem in complex environment,a virtual tube model based on generator curve is established.The tube keeping,centerline tracking and flight safety behavioral control strategies of the UAV swarm are designed to ensure that the UAV swarm flies along the inside of the virtual tube safety and does not go beyond its boundary.On this basis,a maneuvering decision-making method based on behavioral fusion is proposed to ensure the safe flight of UAV swarm in the restricted airspace.This cooperative control method eliminates the need for respective pre-planned trajectories,reduces communication requirements,and achieves a high level of intelligence.Simulation results show that the proposed behaviorbased UAV swarm cooperative control method is able to make the fixed-wing UAV swarm,which is faster and unable to hover,fly along the virtual tube airspace under various virtual tube shapes and different swarm sizes,and the spacing between the UAVs is larger than the minimum safe distance during the flight.展开更多
The high proportion of uncertain distributed power sources and the access to large-scale random electric vehicle(EV)charging resources further aggravate the voltage fluctuation of the distribution network,and the exis...The high proportion of uncertain distributed power sources and the access to large-scale random electric vehicle(EV)charging resources further aggravate the voltage fluctuation of the distribution network,and the existing research has not deeply explored the EV active-reactive synergistic regulating characteristics,and failed to realize themulti-timescale synergistic control with other regulatingmeans,For this reason,this paper proposes amultilevel linkage coordinated optimization strategy to reduce the voltage deviation of the distribution network.Firstly,a capacitor bank reactive power compensation voltage control model and a distributed photovoltaic(PV)activereactive power regulationmodel are established.Additionally,an external characteristicmodel of EVactive-reactive power regulation is developed considering the four-quadrant operational characteristics of the EVcharger.Amultiobjective optimization model of the distribution network is then constructed considering the time-series coupling constraints of multiple types of voltage regulators.A multi-timescale control strategy is proposed by considering the impact of voltage regulators on active-reactive EV energy consumption and PV energy consumption.Then,a four-stage voltage control optimization strategy is proposed for various types of voltage regulators with multiple time scales.Themulti-objective optimization is solved with the improvedDrosophila algorithmto realize the power fluctuation control of the distribution network and themulti-stage voltage control optimization.Simulation results validate that the proposed voltage control optimization strategy achieves the coordinated control of decentralized voltage control resources in the distribution network.It effectively reduces the voltage deviation of the distribution network while ensuring the energy demand of EV users and enhancing the stability and economic efficiency of the distribution network.展开更多
This paper solves the problem of model-free dual-arm space robot maneuvering after non-cooperative target capture under high control quality requirements.The explicit system model is unavailable,and the maneuvering mi...This paper solves the problem of model-free dual-arm space robot maneuvering after non-cooperative target capture under high control quality requirements.The explicit system model is unavailable,and the maneuvering mission is disturbed by the measurement noise and the target adversarial behavior.To address these problems,a model-free Combined Adaptive-length Datadriven Predictive Controller(CADPC)is proposed.It consists of a separated subsystem identification method and a combined predictive control strategy.The subsystem identification method is composed of an adaptive data length,thereby reducing sensitivity to undetermined measurement noises and disturbances.Based on the subsystem identification,the combined predictive controller is established,reducing calculating resource.The stability of the CADPC is rigorously proven using the Input-to-State Stable(ISS)theorem and the small-gain theorem.Simulations demonstrate that CADPC effectively handles the model-free space robot post operation in the presence of significant disturbances,state measurement noise,and control input errors.It achieves improved steady-state accuracy,reduced steady-state control consumption,and minimized control input chattering.展开更多
Mosquito-borne diseases pose a significant global health threat,necessitating the development of innovative vector control strategies.In this study,we investigated the potential of harnessing host immunity against mos...Mosquito-borne diseases pose a significant global health threat,necessitating the development of innovative vector control strategies.In this study,we investigated the potential of harnessing host immunity against mosquitoes through vaccination.Using Culex pipiens(C.pipiens)as a model,we demonstrated that polyclonal antibodies against C.pipiens abdominal protein extracts significantly impaired oviposition and increased mosquito mortality,primarily through the classical complement activation pathways.However,repeated exposure led to resistance,indicating potential adaptation.Proteomic analysis identified metabolic proteins as key targets,with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses highlighting their roles in carboxylic acid metabolism,tyrosine degradation,and the proteasome pathways.Notably,cross-species reactivity was revealed by Western blotting,showing strong binding of Culex-specific antibodies to Anopheles and Aedes abdominal proteins.This study provides mechanistic insights into antibody-based mosquito suppression,highlighting its potential as an innovative vector control strategy while underscoring the need for further research on resistance management and ecological impacts.展开更多
This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow con...This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.展开更多
Feedforward control is one of the most effective control techniques to increase the robot’s tracking accuracy.However,most of the dynamic models used in the feedforward controllers are linearly simplified such that t...Feedforward control is one of the most effective control techniques to increase the robot’s tracking accuracy.However,most of the dynamic models used in the feedforward controllers are linearly simplified such that the nonlinear and time-varying characteristics of dynamics in the workspace are ignored.In this paper,an iterative tuning method for feedforward control of parallel manipulators by taking nonlinear dynamics into account is proposed.Based on the robot rigid-body dynamic model,a feedforward controller considering the dynamic nonlinearity is presented.An iterative tuning method is given to iteratively update the feedforward controller by minimizing the root mean square(RMS)of the joint errors at each cycle.The effectiveness and extrapolation capability of the proposed method are validated through the experiments on a 2-DOF parallel manipulator.This research proposes an iterative tuning method for feedforward control of parallel manipulators considering nonlinear dynamics,which has better extrapolation capability in the whole workspace of manipulators.展开更多
Vehicle collision avoidance(CA)has been widely studied to improve road traffic safety.However,most evasion assistance control methods face challenges in effectively coordinating collision avoidance safety and human-ma...Vehicle collision avoidance(CA)has been widely studied to improve road traffic safety.However,most evasion assistance control methods face challenges in effectively coordinating collision avoidance safety and human-machine interaction conflict.This paper introduces a novel multi-mode evasion assistance control(MEAC)method for intelligent distributed-drive electric vehicles.A reference safety area is established considering the vehicle safety and stability requirements,which serves as a guiding principle for evading obstacles.The proposed method includes two control modes:Shared-EAC(S-EAC)and Emergency-EAC(E-EAC).In S-EAC,an integrated human-machine authority allocation mechanism is designed to mitigate conflicts between human drivers and the control system during collision avoidance.The E-EAC mode is tailored for situations where the driver has no collision avoidance behavior and utilizes model predictive control to generate additional yaw moments for collision avoidance.Simulation and experimental results indicate that the proposed method reduces human-machine conflict and assists the driver in safe collision avoidance in the S-EAC mode under various driver conditions.In addition,it enhances the vehicle responsiveness and reduces the extent of emergency steering in the E-EAC mode while improving the safety and stability during the collision avoidance process.展开更多
In the aerospace industry,double-sided friction stir welding has gradually become a crucial solid-state welding technology for rocket manufacturing.During the welding process,the welding equipment on both sides may en...In the aerospace industry,double-sided friction stir welding has gradually become a crucial solid-state welding technology for rocket manufacturing.During the welding process,the welding equipment on both sides may encounter complex conditions involving unsynchronized collaborative movements.The resulting bending stress and destructive vibration affect workpiece processing quality.Therefore,this study proposes an adaptive admittance-based dual-robot collaborative forging force control method for double-sided friction stir welding.Specifically,the following steps are required:First,we analyzed the mechanism model of the hybrid robot and indirectly estimated the forging force value of friction stir welding using the Jacobian matrix of the hybrid robot.Second,an adaptive variable admittance controller was designed based on the reference admittance model with ideal stiffness.Subsequently,an adaptive variable admittance controller was applied to the dual-machine hybrid robot.By adjusting the welding trajectory and correcting the position error,the forging force was corrected,allowing adaptive tracking control of the forging force in complex environments.Finally,we conducted double-sided friction stir welding experiments to compare and verify the effectiveness of the adaptive tracking control algorithm for the forging force.展开更多
Aiming at the challenge of complex load balancing coordination for a three-phase four-leg(3P4L)based multi-ended low voltage flexible DC distribution system(M-LVDC)considering unbalanced power compensation,this paper ...Aiming at the challenge of complex load balancing coordination for a three-phase four-leg(3P4L)based multi-ended low voltage flexible DC distribution system(M-LVDC)considering unbalanced power compensation,this paper proposes a phase-split power decoupling unbalanced compensation strategy based load balancing strategy for 3P4L based M-LVDC.Firstly,the topology and operation principle of the 3P4L-based M-LVDC system is introduced,and quasi-proportional resonant(QPR)based phase-split power current control for the 3P4L converter is proposed.Secondly,a load-balancing control strategy considering unbalanced compensation for 3P4L-based MLVDC is presented,in which the control diagrams for each 3P4L-based converter are detailed.The core idea of the proposed strategy is to comprehensively consider the imbalance compensation and load rate balancing between the two areas to calculate the split-phase power and current reference values of each 3P4L converter and achieve the static error-free tracking of the reference values through the QPR current inner-loop control.These reference values are then tracked with zero steady-state error using QPR current inner-loop control.Finally,the effectiveness of the proposed control strategy is verified through a 3P4L M-LVDC case study conducted on the PSCAD/EMTDC software.Theresults indicate that the proposed method not only can reduce the three-phase imbalance degrees from>20% to<0.5%,but also achieve excellent balanced load rates,with the load-rate difference smaller than 1.5%.展开更多
The wireless intelligent water distributor is an emerging technology increasingly applied in oilfields to enhance oil recovery.Although the system has many advantages,the high energy consumption of its integrated cont...The wireless intelligent water distributor is an emerging technology increasingly applied in oilfields to enhance oil recovery.Although the system has many advantages,the high energy consumption of its integrated control valve hinders its adoption in long-term applications.However,existing studies have not sufficiently captured the mechanical characteristics of forces acting on the spool,particularly under the influence of multiple coupled factors,such as fit clearance,deflection,and fluid-structure interaction,which limit the ability to accurately assess energy consumption.To address this gap,this study develops a comprehensive energy consumption model of the control valve,specifically addressing the design of fit clearance,a critical factor influencing energy efficiency.Utilizing a loosely coupled fluid-structure interaction algorithm,we established a mechanical model of the spool to investigate the fluid-solid interaction mechanisms within the fit clearance.For the first time,the effects of contact friction on energy consumption are incorporated.An optimization algorithm was then applied to determine the optimal fit clearance by balancing low friction and minimal leakage.The validity of our numerical model was confirmed through comparison with both theoretical and experimental results.Our results demonstrate that the fit clearance has a pronounced impact on the valve's energy usage:the total maximum energy consumption for one full stroke with a 0.05 mm clearance is 3.33%higher than with a 0.25 mm clearance.When the spool is independently driven,this value is 7.21%.The optimal fit clearance is determined to be 0.127 mm.These results can improve the overall performance and extend the service life of intelligent water distributors.The findings and models developed in this study provide essential theoretical support and practical strategies for optimizing control valve energy consumption.展开更多
The integrated energy systems(IESs)offer a practical solution for achieving low-carbon targets in residential buildings.However,IES encounters several challenges related to increased energy consumption and costs due t...The integrated energy systems(IESs)offer a practical solution for achieving low-carbon targets in residential buildings.However,IES encounters several challenges related to increased energy consumption and costs due to fluctuations in renewable energy generation.Leveraging building flexibility to address these power fluctuations within IES is a promising strategy,which requires coordinated control between air-conditioning systems and other IES components.This study proposes a cross-time-scale control framework that contains optimal scheduling and on-the-fly flexible control to reduce the cost impacts of a residential IES system equipped with photovoltaic(PV)panels,batteries,a heat pump,and a domestic hot water tank.The method involves three key steps:solar irradiance prediction,day-ahead optimal scheduling of energy storage,and intra-day flexible control of the heat pump.The method is validated through a high-fidelity residential building model with actual weather and energy usage data in Frankfurt,Germany.Results reveal that the proposed method limits the cost increase to just 2.67% compared to the day-ahead schedule,whereas the cost could increase by 7.39% without the flexible control.Additionally,computational efficiency is enhanced by transforming the mixed-integer programming(MIP)into nonlinear programming(NLP)problem via introducing action-exclusive constraints.This approach offers valuable support for residential IES operations.展开更多
The 110-mining method,a rising and revolutionary non-pillar longwall mining method,can obviously expand coal extraction ratio and minimize roadway incidents.However,in case of composite hard roof,problems such as diff...The 110-mining method,a rising and revolutionary non-pillar longwall mining method,can obviously expand coal extraction ratio and minimize roadway incidents.However,in case of composite hard roof,problems such as difficulty in commanding the entry steadiness and insufficient fragmentation and bulking of the goaf gangue are prevalent.In this study,a 110-mining method for roadway surrounding rock stability control technology based on a compensation mechanism was proposed.First,the composite hard roof cutting short cantilever beam(SCB)model was built and the compensation mechanism including stress and space dual compensation was studied.Subsequently,the controllable elements influencing the roadway steadiness were confirmed to consequently put forward a control technology based on stress compensation for entry support and space compensation for the fragmentation and bulking of goaf gangue.The control technology was finally verified through onsite engineering experiments in terms of composite hard roof.The adoption of the 110-mining method with compensation control technology indicated good support effect on the roadway.The initial and residual expansion coefficients of the goaf gangue increased by 0.6 and 0.6,respectively,and the maximum and average working resistances of the working face support decreased by 10.9%and 13.8%,respectively.Consequently,the deformations of reserved entry decreased,and entry steadiness was enhanced.The presented technique and effects got probably have practical values for non-pillar mining functions in comparable field.展开更多
Innovating distillation technology to improve the efficiency of distillation equipment,reduce energy consumption,and increase product purity is an important challenge for the rapid development of the distillation indu...Innovating distillation technology to improve the efficiency of distillation equipment,reduce energy consumption,and increase product purity is an important challenge for the rapid development of the distillation industry.In this paper,steady-state simulations are developed for the separated isopropanol and water systems,and the sensitive temperature stage locations are determined using sensitivity and singular value decomposition(SVD).An open-loop steady-state gain analysis of the isopropanol/water system was performed,and a series of dynamic control schemes were designed and optimized to resist±10% feed flow disturbances and ±5% feed composition disturbances,comparing the performance of the control schemes one by one through IAE error analysis.The results show that the side-stream extractive distillation separation of isopropanol and water system using a single temperature fixed reflux ratio control loop suffers from a large product shift problem.One of the key control loops is to control the isopropanol purity by controlling the bottom of the column flow rate,and the scheme performs well under both single-temperature control and dual-temperature control,effectively resisting ±10% feed flow disturbances and ±5% feed composition disturbances.The improvement of product purity can be seen from the compone nt controllers play an important role,while the feed-fo rward effect under certain conditions can also enable the system to quickly restore stability and improve the system response speed.展开更多
Voltage source converters(VSCs),equipped with Pf and Q-U droop characteristics,can support a power system from both frequency and voltage.Unfortunately,overcurrent and power angle instability are still challenging asp...Voltage source converters(VSCs),equipped with Pf and Q-U droop characteristics,can support a power system from both frequency and voltage.Unfortunately,overcurrent and power angle instability are still challenging aspects of VSCs under fault conditions.Therefore,fault current limitation and power angle stability are essential conditions for the safe operation of a VSC.Thus,the transient characteristics of a VSC are analyzed to guide transient control.Then,a transient control method for a VSC,considering both fault current limitation and power angle stability,is proposed.With the proposed method,power angle stability is realized by optimizing the P-f controller.On the basis of power angle control,the Q-U controller and inner current controller are improved to effectively suppress the fault current.Finally,relevant tests are performed to verify the proposed method.展开更多
A drag-free satellite is an important platform for space-borne gravitational wave(GW)observation.To achieve the high-precision control of a drag-free satellite in practical engineering,an accurate dynamic model is ess...A drag-free satellite is an important platform for space-borne gravitational wave(GW)observation.To achieve the high-precision control of a drag-free satellite in practical engineering,an accurate dynamic model is essential.This paper presents a nonlinear model of the electrostatic effect between a satellite and a test mass(TM),and designs a model predictive controller based on the drag-free satellite model with the nonlinear electrostatic effect.To determine the analytical form of the electrostatic effect,a comprehensive theoretical analysis is performed for gravitational reference sensors(GRSs).An electrostatic force and a torque are simulated with the displacement as a varying parameter through a commercial software.Then,the results are fitted to derive the nonlinear expressions of the electrostatic effect.The model predictive controllers based on the models with the nonlinear and linear electrostatic effects are designed in the capture mode.Finally,the control results are given to show the advantages of the nonlinear electrostatic effect.展开更多
In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-...In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-view (FOV) constraints based on biased proportional navigation guidance (PNG) is developed in this paper. The remaining flight time (time-to-go) estimation method is derived considering aerodynamic force and gravity. The number of differential equations is reduced and the integration step is increased by changing the integral variable, which makes it possible to obtain time-to-go through integration. An impact time controller with FOV constraints is proposed by analyzing the influence of the biased term on time-to-go and FOV constraint. Then, numerical simulations are performed to verify the correctness and superiority of the method.展开更多
基金supported by the National Natural Science Foundation of China under Grant 52277184 and Grant 52277183.
文摘The transient synchronization stability of grid-forming converters(GFMCs)is significantly challenged under grid voltage sags.Continuous efforts have been devoted to analyzing the GFMC transient stability,with limited attention paid to the impacts of control loop dynamics.However,the complex control dynamics,especially the interactions between the active/reactive power control loops and the current saturation process(CSP),are crucial for accurately describing the transient behavior and evaluating the stability.Thus,in this study,a new large-signal GFMC model is established,considering the reactive power control(RPC)with different kinds of controllers and the CSP simultaneously.It is revealed that GFMC does not switch to the current-limited mode immediately,and the dynamics of RPC further affect the transient behavior before the current limiting significantly.Hence,the complex control dynamics can alter the mode switching point of current saturation,thereby increasing the risk of loss of synchronization(LOS).Based on the above findings,comprehensive comparisons of typical RPC controllers are presented to facilitate practical engineering applications.A unified stability enhancement method is proposed for solving the problem of LOS.Finally,experiments validate the correctness of the analysis and the effectiveness of the proposed control strategy.
基金supported in part by the Young Elite Scientists Sponsorship Program by the Chinese Society for Electrical Engineering under Grant CSEE-YESS-2022019in part by the Guangzhou Basic and Applied Basic Research Foundation under Grand 2024A04J3672in part by the National Natural Science Foundation of China under Grant 52207106.
文摘The wide-area damping controllers(WADCs),which are essential for mitigating regional low-frequency oscillations,face cyber-physical security threats due to the vulnerability of wide-area measurement system to cyber attacks and wind power uncertainties.This paper introduces reachability analysis method to quantify the impact of varying-amplitude attacks and uncertain wind fluctuations on the performance of WADC.Firstly,considering wind farm integration and attack injection,a nonlinear power system model with multiple buses is constructed based on Kron reduction method to improve computational efficiency and mitigate the constraints imposed by algebraic constraints.Then,a zonotope-based polytope construction method is employed to effectively model the range of attack amplitudes and wind uncertainties.By conducting reachability analysis,the reachable set preserving the nonlinear characteristics of studied system is computed,which enables the quantification of the maximum fluctuation range of regional oscillations under the dual disturbances.Case studies are undertaken on two multi-machine power systems with wind farm integration.The obtained results emphasize the efficacy of designed method,providing valuable insights into the magnitude of the impact that attacks exert on the operational characteristics of power system under various uncertain factors.
基金supported by National Natural Science Foundation of China(51977111)the Six Talent Peaks High-level Talent Project in Jiangsu Province(XNY-025)the Special Fund of Jiangsu Province for Transformation of Scientific and Technological Achievements(BA2019045).
文摘Inertial response control(IRC)makes variable-speed wind turbine generators(WTGs)provide short-term frequency support during contingencies by releasing the kinetic energy stored in wind turbine rotors.When frequency support is terminated,the rotor speed should be restored to optimum for maximum power point tracking(MPPT).Existing IRCs utilize rotor speed recovery(RSR)strategies with a consistent power reference function.However,under real turbulent wind with alternate gusts and lulls,the consistent power reference function may fail to restore rotor speed or cause unexpected secondary frequency drop(SFD).In this regard,this paper proposes a novel adaptive RSR strategy that not only restores rotor speed via the aerodynamic power enhanced by wind gusts,but also stabilizes the turbine at wind lulls by tracking a suboptimal power curve.Experiments on a wind power-integrated power system testbed validate the proposed RSR strategy can successfully restore rotor speed while attenuating SFD under turbulent wind.
基金supported in part by the National Key Research and Development Program of China under Grant 2023YFA1011803in part by Natural Science Foundation of Chongqing,China under Grant CSTB2023NSCQ-MSX0588+2 种基金in part by the Fundamental Research Funds for the Central Universities,China under Grant 2023CDJKYJH047in part by the National Natural Science Foundation of China under Grant 62273064,Grant 61991400,Grant 61991403,Grant 61933012,Grant 62250710167,Grant 62203078in part by Innovation Support Program for International Students Returning to China under Grant cx2022016.
文摘This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.
基金co-supported by the National Natural Science Foundation of China(No.61903350)the Ministry of Education industry-university-research innovation project,China(No.2021ZYA02002)the Beijing Institute of Technology Research Fund Program for Young Scholars,China(No.3010011182130)。
文摘Unmanned Aerial Vehicle(UAV)swarm collaboration enhances mission effectiveness.However,fixed-wing UAV swarm flights face collaborative safety control problems within a limited airspace in complex environments.Aimed at the cooperative control problem of fixed-wing UAV swarm flights under the airspace constraints of a virtual tube in a complex environment,this paper proposes a behavior-based distributed control method for fixed-wing UAV swarm considering flight safety constraints.Considering the fixed-wing UAV swarm flight problem in complex environment,a virtual tube model based on generator curve is established.The tube keeping,centerline tracking and flight safety behavioral control strategies of the UAV swarm are designed to ensure that the UAV swarm flies along the inside of the virtual tube safety and does not go beyond its boundary.On this basis,a maneuvering decision-making method based on behavioral fusion is proposed to ensure the safe flight of UAV swarm in the restricted airspace.This cooperative control method eliminates the need for respective pre-planned trajectories,reduces communication requirements,and achieves a high level of intelligence.Simulation results show that the proposed behaviorbased UAV swarm cooperative control method is able to make the fixed-wing UAV swarm,which is faster and unable to hover,fly along the virtual tube airspace under various virtual tube shapes and different swarm sizes,and the spacing between the UAVs is larger than the minimum safe distance during the flight.
基金funded by the State Grid Corporation Science and Technology Project(5108-202218280A-2-391-XG).
文摘The high proportion of uncertain distributed power sources and the access to large-scale random electric vehicle(EV)charging resources further aggravate the voltage fluctuation of the distribution network,and the existing research has not deeply explored the EV active-reactive synergistic regulating characteristics,and failed to realize themulti-timescale synergistic control with other regulatingmeans,For this reason,this paper proposes amultilevel linkage coordinated optimization strategy to reduce the voltage deviation of the distribution network.Firstly,a capacitor bank reactive power compensation voltage control model and a distributed photovoltaic(PV)activereactive power regulationmodel are established.Additionally,an external characteristicmodel of EVactive-reactive power regulation is developed considering the four-quadrant operational characteristics of the EVcharger.Amultiobjective optimization model of the distribution network is then constructed considering the time-series coupling constraints of multiple types of voltage regulators.A multi-timescale control strategy is proposed by considering the impact of voltage regulators on active-reactive EV energy consumption and PV energy consumption.Then,a four-stage voltage control optimization strategy is proposed for various types of voltage regulators with multiple time scales.Themulti-objective optimization is solved with the improvedDrosophila algorithmto realize the power fluctuation control of the distribution network and themulti-stage voltage control optimization.Simulation results validate that the proposed voltage control optimization strategy achieves the coordinated control of decentralized voltage control resources in the distribution network.It effectively reduces the voltage deviation of the distribution network while ensuring the energy demand of EV users and enhancing the stability and economic efficiency of the distribution network.
基金supported by the National Natural Science Foundation of China(No.12372045)the National Key Research and the Development Program of China(Nos.2023YFC2205900,2023YFC2205901)。
文摘This paper solves the problem of model-free dual-arm space robot maneuvering after non-cooperative target capture under high control quality requirements.The explicit system model is unavailable,and the maneuvering mission is disturbed by the measurement noise and the target adversarial behavior.To address these problems,a model-free Combined Adaptive-length Datadriven Predictive Controller(CADPC)is proposed.It consists of a separated subsystem identification method and a combined predictive control strategy.The subsystem identification method is composed of an adaptive data length,thereby reducing sensitivity to undetermined measurement noises and disturbances.Based on the subsystem identification,the combined predictive controller is established,reducing calculating resource.The stability of the CADPC is rigorously proven using the Input-to-State Stable(ISS)theorem and the small-gain theorem.Simulations demonstrate that CADPC effectively handles the model-free space robot post operation in the presence of significant disturbances,state measurement noise,and control input errors.It achieves improved steady-state accuracy,reduced steady-state control consumption,and minimized control input chattering.
基金supported by the National Natural Science Foundation of China(Grant No.82472312).
文摘Mosquito-borne diseases pose a significant global health threat,necessitating the development of innovative vector control strategies.In this study,we investigated the potential of harnessing host immunity against mosquitoes through vaccination.Using Culex pipiens(C.pipiens)as a model,we demonstrated that polyclonal antibodies against C.pipiens abdominal protein extracts significantly impaired oviposition and increased mosquito mortality,primarily through the classical complement activation pathways.However,repeated exposure led to resistance,indicating potential adaptation.Proteomic analysis identified metabolic proteins as key targets,with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses highlighting their roles in carboxylic acid metabolism,tyrosine degradation,and the proteasome pathways.Notably,cross-species reactivity was revealed by Western blotting,showing strong binding of Culex-specific antibodies to Anopheles and Aedes abdominal proteins.This study provides mechanistic insights into antibody-based mosquito suppression,highlighting its potential as an innovative vector control strategy while underscoring the need for further research on resistance management and ecological impacts.
基金the Scientific Research Projects Unit of Erciyes University under contract no:FDS-2022-11532 and FOA-2025-14773.
文摘This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.
基金Supported by National Natural Science Foundation of China(Grant No.52375502)EU H2020 MSCA R&I Programme(Grant No.101022696).
文摘Feedforward control is one of the most effective control techniques to increase the robot’s tracking accuracy.However,most of the dynamic models used in the feedforward controllers are linearly simplified such that the nonlinear and time-varying characteristics of dynamics in the workspace are ignored.In this paper,an iterative tuning method for feedforward control of parallel manipulators by taking nonlinear dynamics into account is proposed.Based on the robot rigid-body dynamic model,a feedforward controller considering the dynamic nonlinearity is presented.An iterative tuning method is given to iteratively update the feedforward controller by minimizing the root mean square(RMS)of the joint errors at each cycle.The effectiveness and extrapolation capability of the proposed method are validated through the experiments on a 2-DOF parallel manipulator.This research proposes an iterative tuning method for feedforward control of parallel manipulators considering nonlinear dynamics,which has better extrapolation capability in the whole workspace of manipulators.
基金Supported by National Key Research and Development Program of China(Grant Nos.2022YFE0117100 and 2021YFB250120101)National Natural Science Foundation of China(Grant No.52325212)+1 种基金Shanghai Municipal Automotive Industry Science,Technology Development Foundation(Grant No.2203)the SAIC Motor Corporation Limited(Grant No.2023023).
文摘Vehicle collision avoidance(CA)has been widely studied to improve road traffic safety.However,most evasion assistance control methods face challenges in effectively coordinating collision avoidance safety and human-machine interaction conflict.This paper introduces a novel multi-mode evasion assistance control(MEAC)method for intelligent distributed-drive electric vehicles.A reference safety area is established considering the vehicle safety and stability requirements,which serves as a guiding principle for evading obstacles.The proposed method includes two control modes:Shared-EAC(S-EAC)and Emergency-EAC(E-EAC).In S-EAC,an integrated human-machine authority allocation mechanism is designed to mitigate conflicts between human drivers and the control system during collision avoidance.The E-EAC mode is tailored for situations where the driver has no collision avoidance behavior and utilizes model predictive control to generate additional yaw moments for collision avoidance.Simulation and experimental results indicate that the proposed method reduces human-machine conflict and assists the driver in safe collision avoidance in the S-EAC mode under various driver conditions.In addition,it enhances the vehicle responsiveness and reduces the extent of emergency steering in the E-EAC mode while improving the safety and stability during the collision avoidance process.
基金Supported by National Key R&D program of China(Grant No.2019YFA0709004)National Natural Science Foundation of China(Grant Nos.52325501,52175025).
文摘In the aerospace industry,double-sided friction stir welding has gradually become a crucial solid-state welding technology for rocket manufacturing.During the welding process,the welding equipment on both sides may encounter complex conditions involving unsynchronized collaborative movements.The resulting bending stress and destructive vibration affect workpiece processing quality.Therefore,this study proposes an adaptive admittance-based dual-robot collaborative forging force control method for double-sided friction stir welding.Specifically,the following steps are required:First,we analyzed the mechanism model of the hybrid robot and indirectly estimated the forging force value of friction stir welding using the Jacobian matrix of the hybrid robot.Second,an adaptive variable admittance controller was designed based on the reference admittance model with ideal stiffness.Subsequently,an adaptive variable admittance controller was applied to the dual-machine hybrid robot.By adjusting the welding trajectory and correcting the position error,the forging force was corrected,allowing adaptive tracking control of the forging force in complex environments.Finally,we conducted double-sided friction stir welding experiments to compare and verify the effectiveness of the adaptive tracking control algorithm for the forging force.
基金supported by the key technology project of China Southern Power Grid Corporation(GZKJXM20220041)partly by theNational Key Research and Development Plan(2022YFE0205300).
文摘Aiming at the challenge of complex load balancing coordination for a three-phase four-leg(3P4L)based multi-ended low voltage flexible DC distribution system(M-LVDC)considering unbalanced power compensation,this paper proposes a phase-split power decoupling unbalanced compensation strategy based load balancing strategy for 3P4L based M-LVDC.Firstly,the topology and operation principle of the 3P4L-based M-LVDC system is introduced,and quasi-proportional resonant(QPR)based phase-split power current control for the 3P4L converter is proposed.Secondly,a load-balancing control strategy considering unbalanced compensation for 3P4L-based MLVDC is presented,in which the control diagrams for each 3P4L-based converter are detailed.The core idea of the proposed strategy is to comprehensively consider the imbalance compensation and load rate balancing between the two areas to calculate the split-phase power and current reference values of each 3P4L converter and achieve the static error-free tracking of the reference values through the QPR current inner-loop control.These reference values are then tracked with zero steady-state error using QPR current inner-loop control.Finally,the effectiveness of the proposed control strategy is verified through a 3P4L M-LVDC case study conducted on the PSCAD/EMTDC software.Theresults indicate that the proposed method not only can reduce the three-phase imbalance degrees from>20% to<0.5%,but also achieve excellent balanced load rates,with the load-rate difference smaller than 1.5%.
基金supported by China Scholarship Council(CSC)(No.202306440123).
文摘The wireless intelligent water distributor is an emerging technology increasingly applied in oilfields to enhance oil recovery.Although the system has many advantages,the high energy consumption of its integrated control valve hinders its adoption in long-term applications.However,existing studies have not sufficiently captured the mechanical characteristics of forces acting on the spool,particularly under the influence of multiple coupled factors,such as fit clearance,deflection,and fluid-structure interaction,which limit the ability to accurately assess energy consumption.To address this gap,this study develops a comprehensive energy consumption model of the control valve,specifically addressing the design of fit clearance,a critical factor influencing energy efficiency.Utilizing a loosely coupled fluid-structure interaction algorithm,we established a mechanical model of the spool to investigate the fluid-solid interaction mechanisms within the fit clearance.For the first time,the effects of contact friction on energy consumption are incorporated.An optimization algorithm was then applied to determine the optimal fit clearance by balancing low friction and minimal leakage.The validity of our numerical model was confirmed through comparison with both theoretical and experimental results.Our results demonstrate that the fit clearance has a pronounced impact on the valve's energy usage:the total maximum energy consumption for one full stroke with a 0.05 mm clearance is 3.33%higher than with a 0.25 mm clearance.When the spool is independently driven,this value is 7.21%.The optimal fit clearance is determined to be 0.127 mm.These results can improve the overall performance and extend the service life of intelligent water distributors.The findings and models developed in this study provide essential theoretical support and practical strategies for optimizing control valve energy consumption.
基金supported by the National Key Research and Development Program of China(2022YFB4200902)。
文摘The integrated energy systems(IESs)offer a practical solution for achieving low-carbon targets in residential buildings.However,IES encounters several challenges related to increased energy consumption and costs due to fluctuations in renewable energy generation.Leveraging building flexibility to address these power fluctuations within IES is a promising strategy,which requires coordinated control between air-conditioning systems and other IES components.This study proposes a cross-time-scale control framework that contains optimal scheduling and on-the-fly flexible control to reduce the cost impacts of a residential IES system equipped with photovoltaic(PV)panels,batteries,a heat pump,and a domestic hot water tank.The method involves three key steps:solar irradiance prediction,day-ahead optimal scheduling of energy storage,and intra-day flexible control of the heat pump.The method is validated through a high-fidelity residential building model with actual weather and energy usage data in Frankfurt,Germany.Results reveal that the proposed method limits the cost increase to just 2.67% compared to the day-ahead schedule,whereas the cost could increase by 7.39% without the flexible control.Additionally,computational efficiency is enhanced by transforming the mixed-integer programming(MIP)into nonlinear programming(NLP)problem via introducing action-exclusive constraints.This approach offers valuable support for residential IES operations.
基金This work described herein was supported by the Program of China Scholarship Council(202206430008)the National Natural Science Foundation of China(NSFC)(52074300 and 52304111)+1 种基金the Yueqi Young Scholars Project of China University of Mining and Technology Beijing(2602021RC84)the Guizhou province science and technology planning project([2020]3007 and[2020]2Y019).
文摘The 110-mining method,a rising and revolutionary non-pillar longwall mining method,can obviously expand coal extraction ratio and minimize roadway incidents.However,in case of composite hard roof,problems such as difficulty in commanding the entry steadiness and insufficient fragmentation and bulking of the goaf gangue are prevalent.In this study,a 110-mining method for roadway surrounding rock stability control technology based on a compensation mechanism was proposed.First,the composite hard roof cutting short cantilever beam(SCB)model was built and the compensation mechanism including stress and space dual compensation was studied.Subsequently,the controllable elements influencing the roadway steadiness were confirmed to consequently put forward a control technology based on stress compensation for entry support and space compensation for the fragmentation and bulking of goaf gangue.The control technology was finally verified through onsite engineering experiments in terms of composite hard roof.The adoption of the 110-mining method with compensation control technology indicated good support effect on the roadway.The initial and residual expansion coefficients of the goaf gangue increased by 0.6 and 0.6,respectively,and the maximum and average working resistances of the working face support decreased by 10.9%and 13.8%,respectively.Consequently,the deformations of reserved entry decreased,and entry steadiness was enhanced.The presented technique and effects got probably have practical values for non-pillar mining functions in comparable field.
基金the Key Research and Development Plan of Shandong Province (Major Scientific and Technological Innovation Project) (2021ZDSYS24)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing (Yantai) (AMGM2023A09)the Open Project Program of Fujian Universities Engineering Research Center of Reactive Distillation Technology (RDRC202204), Fuzhou University。
文摘Innovating distillation technology to improve the efficiency of distillation equipment,reduce energy consumption,and increase product purity is an important challenge for the rapid development of the distillation industry.In this paper,steady-state simulations are developed for the separated isopropanol and water systems,and the sensitive temperature stage locations are determined using sensitivity and singular value decomposition(SVD).An open-loop steady-state gain analysis of the isopropanol/water system was performed,and a series of dynamic control schemes were designed and optimized to resist±10% feed flow disturbances and ±5% feed composition disturbances,comparing the performance of the control schemes one by one through IAE error analysis.The results show that the side-stream extractive distillation separation of isopropanol and water system using a single temperature fixed reflux ratio control loop suffers from a large product shift problem.One of the key control loops is to control the isopropanol purity by controlling the bottom of the column flow rate,and the scheme performs well under both single-temperature control and dual-temperature control,effectively resisting ±10% feed flow disturbances and ±5% feed composition disturbances.The improvement of product purity can be seen from the compone nt controllers play an important role,while the feed-fo rward effect under certain conditions can also enable the system to quickly restore stability and improve the system response speed.
基金supported in part by the National Natural Science Foundation of China(51907057 and 52077072)Technological Leading Talent of Hunan province(2019RS3014).
文摘Voltage source converters(VSCs),equipped with Pf and Q-U droop characteristics,can support a power system from both frequency and voltage.Unfortunately,overcurrent and power angle instability are still challenging aspects of VSCs under fault conditions.Therefore,fault current limitation and power angle stability are essential conditions for the safe operation of a VSC.Thus,the transient characteristics of a VSC are analyzed to guide transient control.Then,a transient control method for a VSC,considering both fault current limitation and power angle stability,is proposed.With the proposed method,power angle stability is realized by optimizing the P-f controller.On the basis of power angle control,the Q-U controller and inner current controller are improved to effectively suppress the fault current.Finally,relevant tests are performed to verify the proposed method.
基金supported by the National Key Research and Development Program of China(No.2022YFC2204800)the National Natural Science Foundation of China(No.W2433004)the Jiangsu Funding Program for Excellent Postdoctoral Talent of China(No.2024ZB114)。
文摘A drag-free satellite is an important platform for space-borne gravitational wave(GW)observation.To achieve the high-precision control of a drag-free satellite in practical engineering,an accurate dynamic model is essential.This paper presents a nonlinear model of the electrostatic effect between a satellite and a test mass(TM),and designs a model predictive controller based on the drag-free satellite model with the nonlinear electrostatic effect.To determine the analytical form of the electrostatic effect,a comprehensive theoretical analysis is performed for gravitational reference sensors(GRSs).An electrostatic force and a torque are simulated with the displacement as a varying parameter through a commercial software.Then,the results are fitted to derive the nonlinear expressions of the electrostatic effect.The model predictive controllers based on the models with the nonlinear and linear electrostatic effects are designed in the capture mode.Finally,the control results are given to show the advantages of the nonlinear electrostatic effect.
基金supported by the National Natural Science Foundation of China(U21B2028).
文摘In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-view (FOV) constraints based on biased proportional navigation guidance (PNG) is developed in this paper. The remaining flight time (time-to-go) estimation method is derived considering aerodynamic force and gravity. The number of differential equations is reduced and the integration step is increased by changing the integral variable, which makes it possible to obtain time-to-go through integration. An impact time controller with FOV constraints is proposed by analyzing the influence of the biased term on time-to-go and FOV constraint. Then, numerical simulations are performed to verify the correctness and superiority of the method.
