This paper addresses the problem of intelligent power management for the more electric aircraft framework. The main objective is to regulate the power flow between a low voltage and a high voltage busses through contr...This paper addresses the problem of intelligent power management for the more electric aircraft framework. The main objective is to regulate the power flow between a low voltage and a high voltage busses through control of a Buck-Boost converter unit. This approach allows the battery to help the generator when an overload scenario occurs, keeping at the same time the battery state of charge above a prescribed threshold. Moreover, in case a continued severe overload causes the battery state of charge to drop below a prescribed threshold, partial shedding of(noncritical) loads occurs. The control objectives are achieved through the design of a hierarchical control strategy based on high gain control for the low level and a finite state automaton for the high level control. Rigorous mathematical proofs of stability are provided for both low level and high level control and a detailed simulator with accurate model of the battery is presented in order to demonstrate the correctness and effectiveness of the proposed approach.展开更多
This paper proposes fuzzy model predictive control(FMPC)strategies for nonlinear interconnected systems based mainly on a system decomposition approach.First,the Takagi-Sugeno(TS)fuzzy model is formulated in such a wa...This paper proposes fuzzy model predictive control(FMPC)strategies for nonlinear interconnected systems based mainly on a system decomposition approach.First,the Takagi-Sugeno(TS)fuzzy model is formulated in such a way to describe the behavior of the nonlinear system.Based on that description,a fuzzy model predictive control is determined.The system under consideration is decomposed into several subsystems.For each subsystem,the main idea consists of the decomposition of the control action into two parts:The decentralized part contains the parameters of the subsystem and the centralized part contains the elements of other subsystems.According to such decomposition,two strategies are defined aiming to circumvent the problems caused by interconnection bet ween subsystems.The feasibility and efficiency of the proposed method are illustrated through numerical examples.展开更多
This paper presents a new Long-range generalized predictive controller in the synchronous reference frame for a wind energy system doubly-fed induction generator based. This controller uses the state space equations t...This paper presents a new Long-range generalized predictive controller in the synchronous reference frame for a wind energy system doubly-fed induction generator based. This controller uses the state space equations that consider the rotor current and voltage as state and control variables, to execute the predictive control action. Therefore, the model of the plant must be transformed into two discrete transference functions, by means of an auto-regressive moving average model, in order to attain a discrete and decoupled controller, which makes it possible to treat it as two independent single-input single-output systems instead of a magnetic coupled multiple-input multiple-output system. For achieving that, a direct power control strategy is used, based on the past and future rotor currents and voltages estimation. The algorithm evaluates the rotor current predictors for a defined prediction horizon and computes the new rotor voltages that must be injected to controlling the stator active and reactive powers. To evaluate the controller performance, some simulations were made using Matlab/Simulink. Experimental tests were carried out with a small-scale prototype assuming normal operating conditions with constant and variable wind speed profiles. Finally, some conclusions respect to the dynamic performance of this new controller are summarized.展开更多
There exists a gap between control theory and control practice,i.e.,all control methods suggested by researchers are not implemented in real systems and,on the other hand,many important in dustrial problems are not st...There exists a gap between control theory and control practice,i.e.,all control methods suggested by researchers are not implemented in real systems and,on the other hand,many important in dustrial problems are not studied in the academic research.Benchmark problems can help close this gap and provide many opportunities for members in both the controls theory and application communities.The goal is to survey and give pointers to different general controls and modeling related benchmark problems that can serve as inspiration for future benchmarks and then specifically focus the benchmark coverage on automotive control engineering application.In the paper reflections are given on how different categories of benchmark designers,benchmark solvers and third part users can benefit from providing,solving,and studying benchmark problems.The paper also collects information about several benchmark problems and gives pointers to papers than give more detailed information about different problems that have been presented.展开更多
In this paper,a model predictive control(MPC)solution,assisted by extended state observer(ESO),is proposed for the common rail pressure control in gasoline engines.The rail pressure dynamic,nonlinear with large uncert...In this paper,a model predictive control(MPC)solution,assisted by extended state observer(ESO),is proposed for the common rail pressure control in gasoline engines.The rail pressure dynamic,nonlinear with large uncertainty,is modeled as a simple first order system.The discrepancy of the model from the real plant is lumped as"total disturbance",to be estimated in real-time by ESO and the n mitigated in the nonlin ear MPC,assuming the total disturbance does not change in the prediction horiz on.The non linear MPC problem is solved using the Newton/generalized minimum residual(GMRES)algorithm.The proposed ESO-MPC solution,is compared with the conventional proportional-integral-differential(PID)controller,based on the high-fidelity model provided in the benchmark problem in IFAC-E-CoSM.Results show the following benefits from using ESO-MPC relative to PID(benchmark):1)the disturbance rejection capability to fuel inject pulse step is improved by 12%in terms of recovery time;2)the transient response of rail pressure is improved by 5%in terms of the integrated absolute tracking error;and 3)the robustness is improved without n eed for gain scheduling,which is required in PID.Additionally,in creasing the ban dwidth of ESO allows reducing the complexity of the model implemented in MPC,while maintaining the disturbance rejection performance at the cost of high noise-sensitivity.Therefore,the ESO-MPC combination offers a simpler and more practical solution for common rail pressure control,relative to the standard MPC,which is consistent with the findings in simulation.展开更多
Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling...Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control(MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control(DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods.展开更多
Enhancing traffic efficiency and alleviating (even circumventing) traffic congestion with advanced traffic signal control (TSC) strategies are always the main issues to be addressed in urban transportation systems. Si...Enhancing traffic efficiency and alleviating (even circumventing) traffic congestion with advanced traffic signal control (TSC) strategies are always the main issues to be addressed in urban transportation systems. Since model predictive control (MPC) has a lot of advantages in modeling complex dynamic systems, it has been widely studied in traffic signal control over the past 20 years. There is a need for an in-depth understanding of MPC-based TSC methods for traffic networks. Therefore, this paper presents the motivation of using MPC for TSC and how MPC-based TSC approaches are implemented to manage and control the dynamics of traffic flows both in urban road networks and freeway networks. Meanwhile, typical performance evaluation metrics, solution methods, examples of simulations, and applications related to MPC-based TSC approaches are reported. More importantly, this paper summarizes the recent developments and the research trends in coordination and control of traffic networks with MPC-based TSC approaches. Remaining challenges and open issues are discussed towards the end of this paper to discover potential future research directions.展开更多
The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator cont...The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator control scheme. To this end, we consider a nonlinear interconnected model for multiarea power systems which also include uncertainties and timevarying communication delays. The design procedure is formulated using semi-definite programming and linear matrix inequality(LMI) method. The solution of the proposed LMIs returns necessary parameters for the tracking controllers such that the impact of model uncertainty and load disturbances are minimized. The proposed controllers are capable of receiving all or part of subsystems information, whereas the outputs of each controller are local. These controllers are designed such that the resilient stability of the overall closed-loop system is guaranteed. Simulation results are provided to verify the effectiveness of the proposed scheme. Simulation results quantify that the distributed(and decentralized) controlled system behaves well in presence of large parameter perturbations and random disturbances on the power system.展开更多
In this paper, we propose an adaptive fuzzy dynamic surface control(DSC) scheme for single-link flexible-joint robotic systems with input saturation. A smooth function is utilized with the mean-value theorem to deal w...In this paper, we propose an adaptive fuzzy dynamic surface control(DSC) scheme for single-link flexible-joint robotic systems with input saturation. A smooth function is utilized with the mean-value theorem to deal with the difficulties associated with input saturation. An adaptive DSC design with an auxiliary first-order filter is used to solve the 'explosion of complexity'problem. It is proved that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded, and the tracking error eventually converges to a small neighborhood around zero. The main advantage of the proposed method is that only one adaptation parameter needs to be updated,which reduces the computational burden significantly. Simulation results demonstrate the feasibility of the proposed scheme and the comparison results show that the improved DSC method can reduce the computational burden by almost two thirds in comparison with the standard DSC method.展开更多
The rapid development of renewable energy sources such as wind power has brought great challenges to the power grid. Wind power penetration can be improved by using hybrid energy storage(ES) to mitigate wind power flu...The rapid development of renewable energy sources such as wind power has brought great challenges to the power grid. Wind power penetration can be improved by using hybrid energy storage(ES) to mitigate wind power fluctuation. We studied the strategy of smoothing wind power fluctuation and the strategy of hybrid ES power distribution. Firstly, an effective control strategy can be extracted by comparing constant-time low-pass filtering(CLF), variable-time low-pass filtering(VLF), wavelet packet decomposition(WPD), empirical mode decomposition(EMD) and model predictive control algorithms with fluctuation rate constraints of the identical grid-connected wind power. Moreover, the mean frequency of ES as the cutoff frequency can be acquired by the Hilbert Huang transform(HHT), and the time constant of filtering algorithm can be obtained. Then, an improved low-pass filtering algorithm(ILFA) is proposed to achieve the power allocation between lithium battery(LB) and supercapacitor(SC), which can overcome the over-charge and over-discharge of ES in the traditional low-pass filtering algorithm(TLFA). In addition, the optimized LB and SC power are further obtained based on the SC priority control strategy combined with the fuzzy control(FC) method. Finally, simulation results show that wind power fluctuation can be effectively suppressed by LB and SC based on the proposed control strategies, which is beneficial to the development of wind and storage system.展开更多
Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and alu...Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and aluminum in in got.The thermodynamic model based on ion and molecule coexistence theory and conservation law of element atoms was established to analyze the change in aluminum and titanium along the height of ingot.The results show that low CaO slag is suitable for electroslag remelting of metal containing high titanium-to-aluminum ratio.As electroslag remelting process consists of slag temperature-rising and temperature-stable periods,TiO2 should be added into water-cooled copper mold during temperature-rising period in order to keep the thermodynamic equilibrium between titanium and aluminum,and the amount of TiO2 is the difference value calculated by the reaction between titanium and alumina at 1477 and 1677℃.展开更多
This paper investigates the necessity of feasibility considerations in a fault tolerant control system using the constrained control allocation methodology where both static and dynamic actuator constraints are consid...This paper investigates the necessity of feasibility considerations in a fault tolerant control system using the constrained control allocation methodology where both static and dynamic actuator constraints are considered. In the proposed feasible control allocation scheme, the constrained model predictive control(MPC) is employed as the main controller. This considers the admissible region of the control allocation problem as its constraints. Using the feasibility notion in the control allocation problem provides the main controller with information regarding the actuator′s status, which leads to closed loop system performance improvement. Several simulation examples under normal and faulty conditions are employed to illustrate the effectiveness of the proposed methodology. The main results clearly indicate that closed loop performance and stability characteristics can be significantly degraded by neglecting the actuator constraints in the main controller. Also, it is shown that the proposed strategy substantially enlarges the domain of attraction of the MPC combined with the control allocation as compared to the conventional MPC.展开更多
Gasoline direct injection(GDI)is a pivotal technique for a highly efficient engine.However,how to maintain a stable rail pressure which offers good fuel economy and low emissions,is still a challengeable work.In this ...Gasoline direct injection(GDI)is a pivotal technique for a highly efficient engine.However,how to maintain a stable rail pressure which offers good fuel economy and low emissions,is still a challengeable work.In this paper,a rail pressure controller is designed basing on predictive functional control(PFC),a model predictive control(MPC)method,to surmount the nonlinearity and disc on tinuity brought by the common rail pressure system(CRPS).A control-oriented piecewise linear model is prese nted to simplify the CRPS.The simulation results on a benchmark show that rail pressure tracks the setpoint accurately even with some perturbations.Profiting from the conciseness of PFC algorithm,the controller can compute the online solution in a short time,which makes it possible to realize the strategy on a fast response system.展开更多
With the rapid development of power electronics technology, microgrid(MG) concept has been widely accepted in the field of electrical engineering. Due to the advantages of direct current(DC)distribution systems such a...With the rapid development of power electronics technology, microgrid(MG) concept has been widely accepted in the field of electrical engineering. Due to the advantages of direct current(DC)distribution systems such as reduced losses and easy integration with energy storage resources, DC MGs have drawn increasing attentions nowadays. With the increase of distributed generation, a DC MG consisting of multiple sources is a hot research topic. The challenge in such a multi-source DC MG is to provide voltage support and good power sharing performance. As the control strategy plays an important role in ensuring MG’s power quality and efficiency, a comprehensive review of the state-of-art control approaches in DC MGs is necessary. This paper provides an overview of the primary and secondary control methods under the hierarchical control architecture for DC MGs. Specifically,inner loop and droop control approaches in primary control are reviewed. Centralized, distributed and decentralized approach based secondary control is discussed in details.Key findings and future trends are also presented at last.展开更多
We review the controllability research on spacecraft attitude based on nonlinear geometry control theory.The existing studies on attitude controllability are mostly concerning the global controllability and small time...We review the controllability research on spacecraft attitude based on nonlinear geometry control theory.The existing studies on attitude controllability are mostly concerning the global controllability and small time local controllability(STLC).A presentation of study methods and connotation in both aspects is briefly carried out.As a necessary condition of reconfigurability,the controllability of the faulty attitude control system is studied.Moreover,two reconfigurability conditions based on controllability results that consider the actuator faults for a pyramid configuration spacecraft are provided.展开更多
This paper proposes a guaranteed feasible control allocation method based on the model predictive control. Feasible region is considered to guarantee the determination of the desired virtual control signal using the p...This paper proposes a guaranteed feasible control allocation method based on the model predictive control. Feasible region is considered to guarantee the determination of the desired virtual control signal using the pseudo inverse methodology and is described as a set of constraints of an MPC problem. With linear models and the given constraints, feasible region defines a convex polyhedral in the virtual control space. In order to reduce the computational time, the polyhedral can be approximated by a few axis alig ned hypercubes. Employing the MPC with rectangular constraints substantially reduces the computational complexity .In two dimensions, the feasible region can be approximated by a few rectangles of the maximum area using numerical geometry techniques which are considered as the constraints of the MPC problem. Also, an active MPC is defined as the controller to minimize the cost function in the control horizon. Finally, several simulation examples are employed to illustrate the effectiveness of the proposed techniques.展开更多
A microgrid is hard to control due to its reduced inertia and increased uncertainties. To overcome the challenges of microgrid control, advanced controllers need to be developed. In this paper, a distributed, two-leve...A microgrid is hard to control due to its reduced inertia and increased uncertainties. To overcome the challenges of microgrid control, advanced controllers need to be developed. In this paper, a distributed, two-level, communication-economic control scheme is presented for multiple-bus microgrids with each bus having multiple distributed generators (DGs) connected in parallel. The control objective of the upper level is to calculate the voltage references for one-bus subsystems. The objectives of the lower control level are to make the subsystems’ bus voltages track the voltage references and to enhance load current sharing accuracy among the local DGs. Firstly, a distributed consensusbased power sharing algorithm is introduced to determine the power generations of the subsystems. Secondly, a discrete-time droop equation is used to adjust subsystem frequencies for voltage reference calculations. Finally, a Lyapunov-based decentralized control algorithm is designed for bus voltage regulation and proportional load current sharing. Extensive simulation studies with microgrid models of different levels of detail are performed to demonstrate the merits of the proposed control scheme.展开更多
Plug-and-play technology is an important direction for future development of spacecraft and how to design controllers with less communication burden and satisfactory performance is of great importance for plug-and-pla...Plug-and-play technology is an important direction for future development of spacecraft and how to design controllers with less communication burden and satisfactory performance is of great importance for plug-and-play spacecraft. Considering attitude tracking of such spacecraft with unknown inertial parameters and unknown disturbances, an event-triggered adaptive backstepping controller is designed in this paper. Particularly, a switching threshold strategy is employed to design the event-triggering mechanism. By introducing a new linear time-varying model, a smooth function, an integrable auxiliary signal and a bound estimation approach, the impacts of the network-induced error and the disturbances are effectively compensated for and Zeno phenomenon is successfully avoided. It is shown that all signals of the closed-loop system are globally uniformly bounded and both the attitude tracking error and the angular velocity tracking error converge to zero. Compared with conventional control schemes, the proposed scheme significantly reduces the communication burden while providing stable and accurate response for attitude maneuvers. Simulation results are presented to illustrate the effectiveness of the proposed scheme.展开更多
文摘This paper addresses the problem of intelligent power management for the more electric aircraft framework. The main objective is to regulate the power flow between a low voltage and a high voltage busses through control of a Buck-Boost converter unit. This approach allows the battery to help the generator when an overload scenario occurs, keeping at the same time the battery state of charge above a prescribed threshold. Moreover, in case a continued severe overload causes the battery state of charge to drop below a prescribed threshold, partial shedding of(noncritical) loads occurs. The control objectives are achieved through the design of a hierarchical control strategy based on high gain control for the low level and a finite state automaton for the high level control. Rigorous mathematical proofs of stability are provided for both low level and high level control and a detailed simulator with accurate model of the battery is presented in order to demonstrate the correctness and effectiveness of the proposed approach.
文摘This paper proposes fuzzy model predictive control(FMPC)strategies for nonlinear interconnected systems based mainly on a system decomposition approach.First,the Takagi-Sugeno(TS)fuzzy model is formulated in such a way to describe the behavior of the nonlinear system.Based on that description,a fuzzy model predictive control is determined.The system under consideration is decomposed into several subsystems.For each subsystem,the main idea consists of the decomposition of the control action into two parts:The decentralized part contains the parameters of the subsystem and the centralized part contains the elements of other subsystems.According to such decomposition,two strategies are defined aiming to circumvent the problems caused by interconnection bet ween subsystems.The feasibility and efficiency of the proposed method are illustrated through numerical examples.
文摘This paper presents a new Long-range generalized predictive controller in the synchronous reference frame for a wind energy system doubly-fed induction generator based. This controller uses the state space equations that consider the rotor current and voltage as state and control variables, to execute the predictive control action. Therefore, the model of the plant must be transformed into two discrete transference functions, by means of an auto-regressive moving average model, in order to attain a discrete and decoupled controller, which makes it possible to treat it as two independent single-input single-output systems instead of a magnetic coupled multiple-input multiple-output system. For achieving that, a direct power control strategy is used, based on the past and future rotor currents and voltages estimation. The algorithm evaluates the rotor current predictors for a defined prediction horizon and computes the new rotor voltages that must be injected to controlling the stator active and reactive powers. To evaluate the controller performance, some simulations were made using Matlab/Simulink. Experimental tests were carried out with a small-scale prototype assuming normal operating conditions with constant and variable wind speed profiles. Finally, some conclusions respect to the dynamic performance of this new controller are summarized.
基金the Vin nova's Compete nee Centre Linkoping Center for Sensor Informatics and Control(LINK-SIC).
文摘There exists a gap between control theory and control practice,i.e.,all control methods suggested by researchers are not implemented in real systems and,on the other hand,many important in dustrial problems are not studied in the academic research.Benchmark problems can help close this gap and provide many opportunities for members in both the controls theory and application communities.The goal is to survey and give pointers to different general controls and modeling related benchmark problems that can serve as inspiration for future benchmarks and then specifically focus the benchmark coverage on automotive control engineering application.In the paper reflections are given on how different categories of benchmark designers,benchmark solvers and third part users can benefit from providing,solving,and studying benchmark problems.The paper also collects information about several benchmark problems and gives pointers to papers than give more detailed information about different problems that have been presented.
基金the Joint Research on Key Technologies of Energy Efficiency for Medium and Heavy-duty Trucks(No.2017YFE0102800).
文摘In this paper,a model predictive control(MPC)solution,assisted by extended state observer(ESO),is proposed for the common rail pressure control in gasoline engines.The rail pressure dynamic,nonlinear with large uncertainty,is modeled as a simple first order system.The discrepancy of the model from the real plant is lumped as"total disturbance",to be estimated in real-time by ESO and the n mitigated in the nonlin ear MPC,assuming the total disturbance does not change in the prediction horiz on.The non linear MPC problem is solved using the Newton/generalized minimum residual(GMRES)algorithm.The proposed ESO-MPC solution,is compared with the conventional proportional-integral-differential(PID)controller,based on the high-fidelity model provided in the benchmark problem in IFAC-E-CoSM.Results show the following benefits from using ESO-MPC relative to PID(benchmark):1)the disturbance rejection capability to fuel inject pulse step is improved by 12%in terms of recovery time;2)the transient response of rail pressure is improved by 5%in terms of the integrated absolute tracking error;and 3)the robustness is improved without n eed for gain scheduling,which is required in PID.Additionally,in creasing the ban dwidth of ESO allows reducing the complexity of the model implemented in MPC,while maintaining the disturbance rejection performance at the cost of high noise-sensitivity.Therefore,the ESO-MPC combination offers a simpler and more practical solution for common rail pressure control,relative to the standard MPC,which is consistent with the findings in simulation.
基金the National Nature Science Foundation of China(No.60974119)the Subject Construction of Shanghai University of Engineering Science(No.2018xk-B-09)the Young Teacher Training Scheme of Shanghai Universities(No.ZZGCD15007).
文摘Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control(MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control(DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods.
基金supported in part by the National Natural Science Foundation of China (61603154, 61773343, 61621002, 61703217)the Natural Science Foundation of Zhejiang Province (LY15F030021, LY19F030014)Open Research Project of the State Key Laboratory of Industrial Control Technology, Zhejiang University, China (ICT1800407).
文摘Enhancing traffic efficiency and alleviating (even circumventing) traffic congestion with advanced traffic signal control (TSC) strategies are always the main issues to be addressed in urban transportation systems. Since model predictive control (MPC) has a lot of advantages in modeling complex dynamic systems, it has been widely studied in traffic signal control over the past 20 years. There is a need for an in-depth understanding of MPC-based TSC methods for traffic networks. Therefore, this paper presents the motivation of using MPC for TSC and how MPC-based TSC approaches are implemented to manage and control the dynamics of traffic flows both in urban road networks and freeway networks. Meanwhile, typical performance evaluation metrics, solution methods, examples of simulations, and applications related to MPC-based TSC approaches are reported. More importantly, this paper summarizes the recent developments and the research trends in coordination and control of traffic networks with MPC-based TSC approaches. Remaining challenges and open issues are discussed towards the end of this paper to discover potential future research directions.
文摘The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator control scheme. To this end, we consider a nonlinear interconnected model for multiarea power systems which also include uncertainties and timevarying communication delays. The design procedure is formulated using semi-definite programming and linear matrix inequality(LMI) method. The solution of the proposed LMIs returns necessary parameters for the tracking controllers such that the impact of model uncertainty and load disturbances are minimized. The proposed controllers are capable of receiving all or part of subsystems information, whereas the outputs of each controller are local. These controllers are designed such that the resilient stability of the overall closed-loop system is guaranteed. Simulation results are provided to verify the effectiveness of the proposed scheme. Simulation results quantify that the distributed(and decentralized) controlled system behaves well in presence of large parameter perturbations and random disturbances on the power system.
基金the National Natural Science Foundation of China (61773051,61773072,61761166011)the Fundamental Research Fund for the Central Universities (2016RC021,2017JBZ003).
文摘In this paper, we propose an adaptive fuzzy dynamic surface control(DSC) scheme for single-link flexible-joint robotic systems with input saturation. A smooth function is utilized with the mean-value theorem to deal with the difficulties associated with input saturation. An adaptive DSC design with an auxiliary first-order filter is used to solve the 'explosion of complexity'problem. It is proved that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded, and the tracking error eventually converges to a small neighborhood around zero. The main advantage of the proposed method is that only one adaptation parameter needs to be updated,which reduces the computational burden significantly. Simulation results demonstrate the feasibility of the proposed scheme and the comparison results show that the improved DSC method can reduce the computational burden by almost two thirds in comparison with the standard DSC method.
基金supported by National Key Research and Development Program of China(No.2016YFB0900400)Foundation of Director of Institute of Electrical Engineering,Chinese Academy of Sciences(No.Y760141CSA)Jiangsu Province 2016 Innovation Ability Construction Special Funds(No.BM2016027).
文摘The rapid development of renewable energy sources such as wind power has brought great challenges to the power grid. Wind power penetration can be improved by using hybrid energy storage(ES) to mitigate wind power fluctuation. We studied the strategy of smoothing wind power fluctuation and the strategy of hybrid ES power distribution. Firstly, an effective control strategy can be extracted by comparing constant-time low-pass filtering(CLF), variable-time low-pass filtering(VLF), wavelet packet decomposition(WPD), empirical mode decomposition(EMD) and model predictive control algorithms with fluctuation rate constraints of the identical grid-connected wind power. Moreover, the mean frequency of ES as the cutoff frequency can be acquired by the Hilbert Huang transform(HHT), and the time constant of filtering algorithm can be obtained. Then, an improved low-pass filtering algorithm(ILFA) is proposed to achieve the power allocation between lithium battery(LB) and supercapacitor(SC), which can overcome the over-charge and over-discharge of ES in the traditional low-pass filtering algorithm(TLFA). In addition, the optimized LB and SC power are further obtained based on the SC priority control strategy combined with the fuzzy control(FC) method. Finally, simulation results show that wind power fluctuation can be effectively suppressed by LB and SC based on the proposed control strategies, which is beneficial to the development of wind and storage system.
基金the National Natural Science Foundation of China(Grant Nos.51674070,U1560203 and 51674172)Natural Science Foundation of Jiangsu Province(Grant Nos.BK20150334 and 20150336)the Open Foundation of The State Key Laboratory of Refractories and Metallurgy(Grant No.G201607).
文摘Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and aluminum in in got.The thermodynamic model based on ion and molecule coexistence theory and conservation law of element atoms was established to analyze the change in aluminum and titanium along the height of ingot.The results show that low CaO slag is suitable for electroslag remelting of metal containing high titanium-to-aluminum ratio.As electroslag remelting process consists of slag temperature-rising and temperature-stable periods,TiO2 should be added into water-cooled copper mold during temperature-rising period in order to keep the thermodynamic equilibrium between titanium and aluminum,and the amount of TiO2 is the difference value calculated by the reaction between titanium and alumina at 1477 and 1677℃.
基金supported by Research Council of Norway through the Centres of Excellence(No.223254 NTNU-AMOS).
文摘This paper investigates the necessity of feasibility considerations in a fault tolerant control system using the constrained control allocation methodology where both static and dynamic actuator constraints are considered. In the proposed feasible control allocation scheme, the constrained model predictive control(MPC) is employed as the main controller. This considers the admissible region of the control allocation problem as its constraints. Using the feasibility notion in the control allocation problem provides the main controller with information regarding the actuator′s status, which leads to closed loop system performance improvement. Several simulation examples under normal and faulty conditions are employed to illustrate the effectiveness of the proposed methodology. The main results clearly indicate that closed loop performance and stability characteristics can be significantly degraded by neglecting the actuator constraints in the main controller. Also, it is shown that the proposed strategy substantially enlarges the domain of attraction of the MPC combined with the control allocation as compared to the conventional MPC.
基金the National Key R&D Program of China(No.2018YFB1701102)the Natural Science Foundation of Zhejiang,China(No.LR17F030002).
文摘Gasoline direct injection(GDI)is a pivotal technique for a highly efficient engine.However,how to maintain a stable rail pressure which offers good fuel economy and low emissions,is still a challengeable work.In this paper,a rail pressure controller is designed basing on predictive functional control(PFC),a model predictive control(MPC)method,to surmount the nonlinearity and disc on tinuity brought by the common rail pressure system(CRPS).A control-oriented piecewise linear model is prese nted to simplify the CRPS.The simulation results on a benchmark show that rail pressure tracks the setpoint accurately even with some perturbations.Profiting from the conciseness of PFC algorithm,the controller can compute the online solution in a short time,which makes it possible to realize the strategy on a fast response system.
文摘With the rapid development of power electronics technology, microgrid(MG) concept has been widely accepted in the field of electrical engineering. Due to the advantages of direct current(DC)distribution systems such as reduced losses and easy integration with energy storage resources, DC MGs have drawn increasing attentions nowadays. With the increase of distributed generation, a DC MG consisting of multiple sources is a hot research topic. The challenge in such a multi-source DC MG is to provide voltage support and good power sharing performance. As the control strategy plays an important role in ensuring MG’s power quality and efficiency, a comprehensive review of the state-of-art control approaches in DC MGs is necessary. This paper provides an overview of the primary and secondary control methods under the hierarchical control architecture for DC MGs. Specifically,inner loop and droop control approaches in primary control are reviewed. Centralized, distributed and decentralized approach based secondary control is discussed in details.Key findings and future trends are also presented at last.
基金the National Natural Science Foundation of China(Nos.61622304,61773201)the Natural Science Foundation of Jiangsu Province(No.BK20160035)the Fundamental Research Funds for the Central Universities(Nos.NE2014202,NE2015002).
文摘We review the controllability research on spacecraft attitude based on nonlinear geometry control theory.The existing studies on attitude controllability are mostly concerning the global controllability and small time local controllability(STLC).A presentation of study methods and connotation in both aspects is briefly carried out.As a necessary condition of reconfigurability,the controllability of the faulty attitude control system is studied.Moreover,two reconfigurability conditions based on controllability results that consider the actuator faults for a pyramid configuration spacecraft are provided.
基金Research Council of Norway through the Centres of Excellence fun ding scheme (No. 223254-NTNUAMOS).
文摘This paper proposes a guaranteed feasible control allocation method based on the model predictive control. Feasible region is considered to guarantee the determination of the desired virtual control signal using the pseudo inverse methodology and is described as a set of constraints of an MPC problem. With linear models and the given constraints, feasible region defines a convex polyhedral in the virtual control space. In order to reduce the computational time, the polyhedral can be approximated by a few axis alig ned hypercubes. Employing the MPC with rectangular constraints substantially reduces the computational complexity .In two dimensions, the feasible region can be approximated by a few rectangles of the maximum area using numerical geometry techniques which are considered as the constraints of the MPC problem. Also, an active MPC is defined as the controller to minimize the cost function in the control horizon. Finally, several simulation examples are employed to illustrate the effectiveness of the proposed techniques.
基金US Office of NavalResearch (N00014-16-1-312, N00014-18-1-2185)in part by the NationalNatural Science Foundation of China (61673347, U1609214, 61751205).
文摘A microgrid is hard to control due to its reduced inertia and increased uncertainties. To overcome the challenges of microgrid control, advanced controllers need to be developed. In this paper, a distributed, two-level, communication-economic control scheme is presented for multiple-bus microgrids with each bus having multiple distributed generators (DGs) connected in parallel. The control objective of the upper level is to calculate the voltage references for one-bus subsystems. The objectives of the lower control level are to make the subsystems’ bus voltages track the voltage references and to enhance load current sharing accuracy among the local DGs. Firstly, a distributed consensusbased power sharing algorithm is introduced to determine the power generations of the subsystems. Secondly, a discrete-time droop equation is used to adjust subsystem frequencies for voltage reference calculations. Finally, a Lyapunov-based decentralized control algorithm is designed for bus voltage regulation and proportional load current sharing. Extensive simulation studies with microgrid models of different levels of detail are performed to demonstrate the merits of the proposed control scheme.
基金the National Natural Science Foundation of China(Nos.61673036,61661136007 and 51777013)the Beijing Natural Science Foundation of China(No.4182036).
文摘Plug-and-play technology is an important direction for future development of spacecraft and how to design controllers with less communication burden and satisfactory performance is of great importance for plug-and-play spacecraft. Considering attitude tracking of such spacecraft with unknown inertial parameters and unknown disturbances, an event-triggered adaptive backstepping controller is designed in this paper. Particularly, a switching threshold strategy is employed to design the event-triggering mechanism. By introducing a new linear time-varying model, a smooth function, an integrable auxiliary signal and a bound estimation approach, the impacts of the network-induced error and the disturbances are effectively compensated for and Zeno phenomenon is successfully avoided. It is shown that all signals of the closed-loop system are globally uniformly bounded and both the attitude tracking error and the angular velocity tracking error converge to zero. Compared with conventional control schemes, the proposed scheme significantly reduces the communication burden while providing stable and accurate response for attitude maneuvers. Simulation results are presented to illustrate the effectiveness of the proposed scheme.