Walking is the most basic and essential part of the activities of daily living. To enable the elderly and non-ambulatory gait-impaired patients, the repetitive practice of this task, a novel gait training robot(GTR) w...Walking is the most basic and essential part of the activities of daily living. To enable the elderly and non-ambulatory gait-impaired patients, the repetitive practice of this task, a novel gait training robot(GTR) was designed followed the end-effector principle, and an active partial body weight support(PBWS) system was introduced to facilitate successful gait training. For successful establishment of a walking gait on the GTR with PBWS, the motion laws of the GTR were planned to enable the phase distribution relationships of the cycle step, and the center of gravity(COG) trajectory of the human body during gait training on the GTR was measured. A coordinated control strategy was proposed based on the impedance control principle. A robotic prototype was developed as a platform for evaluating the design concepts and control strategies. Preliminary gait training with a healthy subject was implemented by the robotic-assisted gait training system and the experimental results are encouraging.展开更多
As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated syst...As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated system operation. This paper analyzes the power grid side and unit side influence factors on the isolated power system. The dynamic models which are suitable for islanding operation are applied to simulate and analyze the stability and dynamic characteristics of the isolated power system under the conditions of different load disturbances and governor parameters. With considering the differences of frequency characteristics between the interconnected and isolated power system, the adjusting and optimization methods of under frequency load shedding are proposed to meet the frequency stability requirements simultaneously in the two cases. Not only proper control strategies of the power plant but the settings of their parameters are suggested to improve the operation stability of the isolated power system. To confirm the correctness and effectiveness of the method mentioned above, the isolated system operation test was conducted under the real power system condition, and the results show that the proposed coordinated control strategies can greatly improve stability of the isolated power system.展开更多
Starting from the historical evolution of China s regional coordinated development policy and practice,three stages of"enlightenment stage","development stage"and"maturity stage",as well ...Starting from the historical evolution of China s regional coordinated development policy and practice,three stages of"enlightenment stage","development stage"and"maturity stage",as well as the connotation,characteristics and content of implementing regional coordinated development strategy were analyzed.On this basis,from different aspects of industrial distribution,pollutant characteristics and regional environmental protection policy,the existing ecological and environmental protection problems in China s regional coordinated development in the new era were analyzed,and some suggestions for the next step were put forward.It is necessary to follow the"four ones"concept from the overall point of view,implement"three lines and one list"from the perspective of the width of the access red line,strengthen"joint prevention and control"from the perspective of the depth of regional regulation,deepen the"planning environmental impact assessment"from the perspective of the breadth of industrial distribution,and promote the"green-way model"from the perspective of ecological low carbon.展开更多
An improved automatic voltage coordination control strategy(AVCCS) based on automatic voltage control(AVC) and battery energy storage control(BESC) is proposed for photovoltaic grid-connected system(PVGS) to mitigate ...An improved automatic voltage coordination control strategy(AVCCS) based on automatic voltage control(AVC) and battery energy storage control(BESC) is proposed for photovoltaic grid-connected system(PVGS) to mitigate the voltage fluctuations caused by environmental disturbances.Only AVC is used when small environmental disturbances happen,while BESC is incorporated with AVC to restrain the voltage fluctuations when large disturbances happen.An adjustable parameter determining the allowed amplitudes of voltage fluctuations is introduced to realize the above switching process.A benchmark low voltage distribution system including PVGS is established by using the commercial software DIg SILENT.Simulation results show that the voltage under AVCCS satisfies the IEEE Standard 1547,and the installed battery capacity is also reduced.Meanwhile,the battery's service life is extended by avoiding frequent charges/discharges in the control process.展开更多
This paper presents a novel design procedure for optimizing the power distribution strategy in distributed generation system. A coordinating controller, responsible to distribute the total load power request among mul...This paper presents a novel design procedure for optimizing the power distribution strategy in distributed generation system. A coordinating controller, responsible to distribute the total load power request among multiple DG units, is suggested based on the conception of hierarchical control structure in the dynamic system. The optimal control problem was formulated as a nonlinear optimization problem subject to set of constraints. The resulting problem was solved using the Kuhn-Tucker method. Computer simulation results demonstrate that the proposed method can provide better efficiency in terms of reducing total costs compared to existing methods. In addition, the proposed optimal load distribution strategy can be easily implemented in real-time thanks to the simplicity of closed-form solutions.展开更多
More and more attention has been paid to the high penetration of renewable energy in recent years.The randomness and intermittency of solar and wind energy make it an inevitable trend that renewables are coupled with ...More and more attention has been paid to the high penetration of renewable energy in recent years.The randomness and intermittency of solar and wind energy make it an inevitable trend that renewables are coupled with energy storage technologies.Pumped hydro storage(PHS)is the most widelyused storage form in the power grid but the capacity is limited by geographic conditions.The concentrated solar power(CSP)plant with a thermal energy storage(TES)system can realize easier grid connections and effective peak shaving.Therefore,this paper proposes a solar-wind-hydro hybrid power system with PHS-TES double energy storages,and investigates the optimal coordinated operational strategy and multi-objective sizing.The optimal sizing problem which considers the minimum levelized cost of energy(LCOE)and loss of power supply probability(LPSP)as objectives is solved by multi-objective particle swarm optimization.Moreover,the seasonal uncertainties of renewables are considered by applying a scenario-based analysis using Kmeans clustering.Finally,a case study reveals the effectiveness of the coordinated operational strategy and double energy storages from the perspectives of economy and reliability.The comparisons of optimal sizing results show that the PV-WindCSP-PHS system decreases the LCOE by 19.1%compared to a PV-Wind-CSP system under the same LPSP,and reduces the LPSP compared to PV-Wind-PHS systems with limited reservoir capacity,which indicates that the proposed system with double energy storages has better economy and reliability performance compared to single storage.展开更多
In this paper,distributed power flow controller(DPFC)constraints are analyzed.The energy balance relationship between fundamental wave and third harmonic in series and shunt-side converter is deduced.A proportional in...In this paper,distributed power flow controller(DPFC)constraints are analyzed.The energy balance relationship between fundamental wave and third harmonic in series and shunt-side converter is deduced.A proportional integral(PI)controller of the DPFC is constructed.The PI controller uses the voltage amplitude and phase angle injected into the system in the series side,along with the modulation ratio of the three-phase converter on the shunt side as the control variables.A multiobjective coordinated control equation is proposed,which factors the constraints of the energy balance between series and shunt side,device capacity limit,safe operation limit,fundamental component,as well as third harmonic component of the injection voltage at the series side.The equation minimizes the variance between the actual value of the control target and its given value to ensure that the DC capacitor voltage,both in the series and shunt side,is stable at target value.Simulations are conducted to verify correctness and effectiveness of the proposed control method.展开更多
This paper addresses the problem of coordinating multiple mobile robots in searching for and capturing a mobile target,with the aim of reducing the capture time.Compared with the previous algorithms,we assume that the...This paper addresses the problem of coordinating multiple mobile robots in searching for and capturing a mobile target,with the aim of reducing the capture time.Compared with the previous algorithms,we assume that the target can be detected by any robot and captured successfully by two or more robots.In this paper,we assume that each robot has a limited communication range.We maintain the robots within a mobile network to guarantee the successful capture.In addition,the motion of the target is modeled and incorporated into directing the motion of the robots to reduce the capture time.A coordination algorithm considering both aspects is proposed.This algorithm can greatly reduce the expected time of capturing the mobile target.Finally,we validate the algorithm by the simulations and experiments.展开更多
基金Project(61175128) supported by the National Natural Science Foundation of ChinaProject(2008AA040203) supported by the National High Technology Research and Development Program of China
文摘Walking is the most basic and essential part of the activities of daily living. To enable the elderly and non-ambulatory gait-impaired patients, the repetitive practice of this task, a novel gait training robot(GTR) was designed followed the end-effector principle, and an active partial body weight support(PBWS) system was introduced to facilitate successful gait training. For successful establishment of a walking gait on the GTR with PBWS, the motion laws of the GTR were planned to enable the phase distribution relationships of the cycle step, and the center of gravity(COG) trajectory of the human body during gait training on the GTR was measured. A coordinated control strategy was proposed based on the impedance control principle. A robotic prototype was developed as a platform for evaluating the design concepts and control strategies. Preliminary gait training with a healthy subject was implemented by the robotic-assisted gait training system and the experimental results are encouraging.
文摘As the existing coordinated control strategies between grid and unit have limitations in isolated power system, this paper introduces new coordinated control strategies which can improve the stability of isolated system operation. This paper analyzes the power grid side and unit side influence factors on the isolated power system. The dynamic models which are suitable for islanding operation are applied to simulate and analyze the stability and dynamic characteristics of the isolated power system under the conditions of different load disturbances and governor parameters. With considering the differences of frequency characteristics between the interconnected and isolated power system, the adjusting and optimization methods of under frequency load shedding are proposed to meet the frequency stability requirements simultaneously in the two cases. Not only proper control strategies of the power plant but the settings of their parameters are suggested to improve the operation stability of the isolated power system. To confirm the correctness and effectiveness of the method mentioned above, the isolated system operation test was conducted under the real power system condition, and the results show that the proposed coordinated control strategies can greatly improve stability of the isolated power system.
基金Supported by Special Project for Prevention and Control of Air Pollution from Fixed Sources of Ministry of Ecology and Environment,China(2020A060).
文摘Starting from the historical evolution of China s regional coordinated development policy and practice,three stages of"enlightenment stage","development stage"and"maturity stage",as well as the connotation,characteristics and content of implementing regional coordinated development strategy were analyzed.On this basis,from different aspects of industrial distribution,pollutant characteristics and regional environmental protection policy,the existing ecological and environmental protection problems in China s regional coordinated development in the new era were analyzed,and some suggestions for the next step were put forward.It is necessary to follow the"four ones"concept from the overall point of view,implement"three lines and one list"from the perspective of the width of the access red line,strengthen"joint prevention and control"from the perspective of the depth of regional regulation,deepen the"planning environmental impact assessment"from the perspective of the breadth of industrial distribution,and promote the"green-way model"from the perspective of ecological low carbon.
基金Supported by National Basic Research Program of China ("973" Program,No. 2009CB219701 and No. 2010CB234608)Tianjin Municipal Science and Technology Development Program (No. 09JCZDJC25000)Specialized Research Fund for Doctor Discipline of Ministry of Education of China (No. 20090032110064)
文摘An improved automatic voltage coordination control strategy(AVCCS) based on automatic voltage control(AVC) and battery energy storage control(BESC) is proposed for photovoltaic grid-connected system(PVGS) to mitigate the voltage fluctuations caused by environmental disturbances.Only AVC is used when small environmental disturbances happen,while BESC is incorporated with AVC to restrain the voltage fluctuations when large disturbances happen.An adjustable parameter determining the allowed amplitudes of voltage fluctuations is introduced to realize the above switching process.A benchmark low voltage distribution system including PVGS is established by using the commercial software DIg SILENT.Simulation results show that the voltage under AVCCS satisfies the IEEE Standard 1547,and the installed battery capacity is also reduced.Meanwhile,the battery's service life is extended by avoiding frequent charges/discharges in the control process.
基金Sponsored by the Indiana 21stCentury Research and Technology Fund
文摘This paper presents a novel design procedure for optimizing the power distribution strategy in distributed generation system. A coordinating controller, responsible to distribute the total load power request among multiple DG units, is suggested based on the conception of hierarchical control structure in the dynamic system. The optimal control problem was formulated as a nonlinear optimization problem subject to set of constraints. The resulting problem was solved using the Kuhn-Tucker method. Computer simulation results demonstrate that the proposed method can provide better efficiency in terms of reducing total costs compared to existing methods. In addition, the proposed optimal load distribution strategy can be easily implemented in real-time thanks to the simplicity of closed-form solutions.
基金the National Key Research and Development Program of China 2018YFE0128500the Fundamental Research Funds for the Central Universities of China under Grant B210202069.
文摘More and more attention has been paid to the high penetration of renewable energy in recent years.The randomness and intermittency of solar and wind energy make it an inevitable trend that renewables are coupled with energy storage technologies.Pumped hydro storage(PHS)is the most widelyused storage form in the power grid but the capacity is limited by geographic conditions.The concentrated solar power(CSP)plant with a thermal energy storage(TES)system can realize easier grid connections and effective peak shaving.Therefore,this paper proposes a solar-wind-hydro hybrid power system with PHS-TES double energy storages,and investigates the optimal coordinated operational strategy and multi-objective sizing.The optimal sizing problem which considers the minimum levelized cost of energy(LCOE)and loss of power supply probability(LPSP)as objectives is solved by multi-objective particle swarm optimization.Moreover,the seasonal uncertainties of renewables are considered by applying a scenario-based analysis using Kmeans clustering.Finally,a case study reveals the effectiveness of the coordinated operational strategy and double energy storages from the perspectives of economy and reliability.The comparisons of optimal sizing results show that the PV-WindCSP-PHS system decreases the LCOE by 19.1%compared to a PV-Wind-CSP system under the same LPSP,and reduces the LPSP compared to PV-Wind-PHS systems with limited reservoir capacity,which indicates that the proposed system with double energy storages has better economy and reliability performance compared to single storage.
基金This work was supported in part by the State Grid Corporation of China(Grant No.52150016000Y)in part by the State Key Laboratory of Power Grid Safety and Energy Conservation(China Electric Power Research Institute)Open Fund,the Major Projects of Technical Innovation in Hubei(Grant No.2018AAA050)the Major Projects of Technical Innovation in Hubei(Grant No.2019AAA016).
文摘In this paper,distributed power flow controller(DPFC)constraints are analyzed.The energy balance relationship between fundamental wave and third harmonic in series and shunt-side converter is deduced.A proportional integral(PI)controller of the DPFC is constructed.The PI controller uses the voltage amplitude and phase angle injected into the system in the series side,along with the modulation ratio of the three-phase converter on the shunt side as the control variables.A multiobjective coordinated control equation is proposed,which factors the constraints of the energy balance between series and shunt side,device capacity limit,safe operation limit,fundamental component,as well as third harmonic component of the injection voltage at the series side.The equation minimizes the variance between the actual value of the control target and its given value to ensure that the DC capacitor voltage,both in the series and shunt side,is stable at target value.Simulations are conducted to verify correctness and effectiveness of the proposed control method.
基金supported by the National Natural Science Foundation of China(No.60434030)
文摘This paper addresses the problem of coordinating multiple mobile robots in searching for and capturing a mobile target,with the aim of reducing the capture time.Compared with the previous algorithms,we assume that the target can be detected by any robot and captured successfully by two or more robots.In this paper,we assume that each robot has a limited communication range.We maintain the robots within a mobile network to guarantee the successful capture.In addition,the motion of the target is modeled and incorporated into directing the motion of the robots to reduce the capture time.A coordination algorithm considering both aspects is proposed.This algorithm can greatly reduce the expected time of capturing the mobile target.Finally,we validate the algorithm by the simulations and experiments.