Optimal torque(OT)control is a widely used method for maximum power point tracking(MPPT)due to its simplicity.In order to overcome the adverse impacts of turbulent wind speed variations on MPPT,in several methods,modi...Optimal torque(OT)control is a widely used method for maximum power point tracking(MPPT)due to its simplicity.In order to overcome the adverse impacts of turbulent wind speed variations on MPPT,in several methods,modification factors have been proposed to dynamically modify the ideal power curve for OT control.However,this paper finds that the update cycles used in existing methods to adjust power curve modification factors are very long and hence these factors are difficult to be updated in a timely manner along with the wind speed variations.This thereby may deteriorate the effectiveness of wind energy extraction.Therefore,an optimal decreased torque gain(DTG)control method is proposed in this paper.Based on the persistence method,an offline mapping from the wind speed and rotor speed to optimal modification factors is established via optimal control theory.The power curve can be periodically modified online through the mapping relationship.In this method,the update cycles for these power curve modification factors are shortened from tens of minutes to seconds.The simulations and experiments show that the proposed method is more efficient than others in terms of energy extraction under varying wind speeds,especially for turbulent wind cases.展开更多
The optimal torque(OT)method,which is preferred for its simplicity,is widely employed in maximum power point tracking(MPPT)control strategies for wind energy capture in wind turbine generators(WTGs).Based on the OT me...The optimal torque(OT)method,which is preferred for its simplicity,is widely employed in maximum power point tracking(MPPT)control strategies for wind energy capture in wind turbine generators(WTGs).Based on the OT method,the decreased torque gain(DTG)method is developed to improve turbine acceleration through a reduction of the torque gain coefficient.However,the DTG method does not fully align with the acceleration performance required by wind turbines,which subsequently limits improvements in wind energy capture efficiency.To address these concerns,a novel MPPT control strategy is proposed,which introduces redefined torque curve and torque command conceptualized based on a higher-order function relative to rotor speed.Additionally,an adaptive algorithm for the periodic update of the torque command is suggested to better accommodate the variability of turbulent wind speeds,thus aiming to improve the wind energy capture efficiency.The effectiveness of the proposed MPPT control strategy is substantiated through the wind turbine simulator(WTS)-based experiments.展开更多
As the power control technology of wind farms develops,the output power of wind farms can be constant,which makes it possible for wind farms to participate in power system restoration.However,due to the uncertainty of...As the power control technology of wind farms develops,the output power of wind farms can be constant,which makes it possible for wind farms to participate in power system restoration.However,due to the uncertainty of wind energy,the actual output power can’t reach a constant dispatch power in all time intervals,resulting in uncertain power sags which may induce the frequency of the system being restored to go outside the security limits.Therefore,it is necessary to optimize the dispatch of wind farms participating in power system restoration.Considering that the probability distribution function(PDF)oftransient power sags is hard to obtain,a robust optimization model is proposed in this paper,which can maximize the output power of wind farms participating in power system restoration.Simulation results demonstrate that the security constraints of the restored system can be kept within security limits when wind farm dispatch is optimized by the proposed method.展开更多
Wind turbine simulator(WTS) is an important test rig for validating the control strategies of wind turbines(WT). Since the inertia of WTSs is much smaller than that of WTs, the inertia compensation scheme is usually e...Wind turbine simulator(WTS) is an important test rig for validating the control strategies of wind turbines(WT). Since the inertia of WTSs is much smaller than that of WTs, the inertia compensation scheme is usually employed in WTSs for replicating the slow mechanical behavior of WTs. In this paper, it is found that the instability of WTSs applying the inertia compensation scheme,characterized by the oscillation of compensation torque, is caused by the one-step time delay produced in the acceleration observation. Hence, a linear discrete model of WTS considering the time delay of acceleration observation is developed and its stability is analyzed. Moreover, in order to stably simulate WTs with large inertia, an improved inertia compensation scheme, applying a first-order digitalfilter to mitigate deviation response induced by the time delay, is proposed. And, the criterion for selecting the filter coefficients is established based on the stability condition analysis. Finally, the WTS with the proposed scheme is validated by simulations and experiments.展开更多
To avoid the secondary frequency dip caused by the steep drop of the electrical power of wind turbines(WTs)at the end of frequency support stage,the torque limit-based iner-tial control(TLIC)method sets the power refe...To avoid the secondary frequency dip caused by the steep drop of the electrical power of wind turbines(WTs)at the end of frequency support stage,the torque limit-based iner-tial control(TLIC)method sets the power reference as a linear function of rotor speed,rather than the step form for the step-wise inertial control.However,the compensation effect on the frequency nadir(FN)caused by the load surge is weakened as the TLIC power is no longer in the step form.Specifically,the maximum point of the frequency response component(FRC)contributed by TLIC occurs earlier than the minimum point of FRC corresponding to the load surge,so that the FN cannot be adequately raised.Therefore,this paper first investigates the relation between the peak and nadir times of FRCs stimulated by the TLIC and load power.On this basis,with the compensation principle of matching the peak and nadir times of FRCs,the improved TLIC method based on delayed support is proposed.Finally,the effectiveness of the proposed method is validated via the experiments on the test bench of wind-integrated power system.展开更多
In this paper,we apply a model predictive control based scheme to the energy management of networked microgrid,which is reformulated based on column generation.Although column generation is effective in alleviating th...In this paper,we apply a model predictive control based scheme to the energy management of networked microgrid,which is reformulated based on column generation.Although column generation is effective in alleviating the computational intractability of large-scale optimization problems,it still suffers from slow convergence issues,which hinders the direct real-time online implementation.To this end,we propose a graph neural network based framework to accelerate the convergence of the column generation model.The acceleration is achieved by selecting promising columns according to certain stabilization method of the dual variables that can be customized according to the characteristics of the microgrid.Moreover,a rigorous energy management method based on the graph neural network accelerated column generation model is developed,which is able to guarantee the optimality and feasibility of the dispatch results.The computational efficiency of the method is also very high,which is promising for real-time implementation.We conduct case studies to demonstrate the effectiveness of the proposed energy management method.展开更多
Carbon nanotube field-effect transistors(CNTFETs)are increasingly recognized as a viable option for creating high-performance,low-power,and densely integrated circuits(ICs).Advancements in carbon-based electronics,enc...Carbon nanotube field-effect transistors(CNTFETs)are increasingly recognized as a viable option for creating high-performance,low-power,and densely integrated circuits(ICs).Advancements in carbon-based electronics,encompassing materials and device technology,have enabled the fabrication of circuits with over 1000 gates,marking carbon-based integrated circuit design as a burgeoning field of research.A critical challenge in the realm of carbon-based very-large-scale integration(VLSI)is the lack of suitable automated design methodologies and infrastructure platforms.In this study,we present the development of a waferscale 3μm carbon-based complementary metal-oxide-semiconductor(CMOS)process design kit(PDK)(3μm-CNTFETs-PDK)compatible with silicon-based Electronic Design Automation(EDA)tools and VLSI circuit design flow.The proposed 3μm-CNTFETs-PDK features a contacted gate pitch(CGP)of 21μm,a gate density of 128 gates/mm^(2),and a transistor density of 554 transistors/mm^(2),with an intrinsic gate delay around 134 ns.Validation of the 3μm-CNTFETs-PDK was achieved through the successful design and tape-out of 153 standard cells and 333-stage ring oscillator circuits.Leveraging the carbon-based PDK and a silicon-based design platform,we successfully implemented a complete 64-bit static random-access memory(SRAM)circuit system for the first time,which exhibited timing,power,and area characteristics of clock@10 kHz,122.1μW,3795μm×2810μm.This research confirms that carbon-based IC design can be compatible with existing EDA tools and silicon-based VLSI design flow,thereby laying the groundwork for future carbon-based VLSI advancements.展开更多
基金supported by the National Natural Science Foundation of China(61203129,61174038,61473151,51507080)the Fundamental Research Funds for the Central Universities(30915011104,30920130121010,30920140112005)
基金supported by the National Natural Science Foundation of China(No.61773214).
文摘Optimal torque(OT)control is a widely used method for maximum power point tracking(MPPT)due to its simplicity.In order to overcome the adverse impacts of turbulent wind speed variations on MPPT,in several methods,modification factors have been proposed to dynamically modify the ideal power curve for OT control.However,this paper finds that the update cycles used in existing methods to adjust power curve modification factors are very long and hence these factors are difficult to be updated in a timely manner along with the wind speed variations.This thereby may deteriorate the effectiveness of wind energy extraction.Therefore,an optimal decreased torque gain(DTG)control method is proposed in this paper.Based on the persistence method,an offline mapping from the wind speed and rotor speed to optimal modification factors is established via optimal control theory.The power curve can be periodically modified online through the mapping relationship.In this method,the update cycles for these power curve modification factors are shortened from tens of minutes to seconds.The simulations and experiments show that the proposed method is more efficient than others in terms of energy extraction under varying wind speeds,especially for turbulent wind cases.
基金supported in part by the National Key R&D Program of China(No.2021YFB1506904)the National Natural Science Foundation of China(No.51977111).
文摘The optimal torque(OT)method,which is preferred for its simplicity,is widely employed in maximum power point tracking(MPPT)control strategies for wind energy capture in wind turbine generators(WTGs).Based on the OT method,the decreased torque gain(DTG)method is developed to improve turbine acceleration through a reduction of the torque gain coefficient.However,the DTG method does not fully align with the acceleration performance required by wind turbines,which subsequently limits improvements in wind energy capture efficiency.To address these concerns,a novel MPPT control strategy is proposed,which introduces redefined torque curve and torque command conceptualized based on a higher-order function relative to rotor speed.Additionally,an adaptive algorithm for the periodic update of the torque command is suggested to better accommodate the variability of turbulent wind speeds,thus aiming to improve the wind energy capture efficiency.The effectiveness of the proposed MPPT control strategy is substantiated through the wind turbine simulator(WTS)-based experiments.
基金supported by the National Natural Science Foundation of China(No.51507080)the Science and Technology Project of State Grid Corporation of China(5228001600DT)
文摘As the power control technology of wind farms develops,the output power of wind farms can be constant,which makes it possible for wind farms to participate in power system restoration.However,due to the uncertainty of wind energy,the actual output power can’t reach a constant dispatch power in all time intervals,resulting in uncertain power sags which may induce the frequency of the system being restored to go outside the security limits.Therefore,it is necessary to optimize the dispatch of wind farms participating in power system restoration.Considering that the probability distribution function(PDF)oftransient power sags is hard to obtain,a robust optimization model is proposed in this paper,which can maximize the output power of wind farms participating in power system restoration.Simulation results demonstrate that the security constraints of the restored system can be kept within security limits when wind farm dispatch is optimized by the proposed method.
基金supported by National Natural Sci-ence Foundation of China(No.61203129,No.61174038,No.51507080)Jiangsu Planned Projects for Postdoctoral Research Funds(No.1301014A)the Fundamental Research Funds for the Central Universities(30915011104)
文摘Wind turbine simulator(WTS) is an important test rig for validating the control strategies of wind turbines(WT). Since the inertia of WTSs is much smaller than that of WTs, the inertia compensation scheme is usually employed in WTSs for replicating the slow mechanical behavior of WTs. In this paper, it is found that the instability of WTSs applying the inertia compensation scheme,characterized by the oscillation of compensation torque, is caused by the one-step time delay produced in the acceleration observation. Hence, a linear discrete model of WTS considering the time delay of acceleration observation is developed and its stability is analyzed. Moreover, in order to stably simulate WTs with large inertia, an improved inertia compensation scheme, applying a first-order digitalfilter to mitigate deviation response induced by the time delay, is proposed. And, the criterion for selecting the filter coefficients is established based on the stability condition analysis. Finally, the WTS with the proposed scheme is validated by simulations and experiments.
基金supported by the National Natural Science Foundation of China(No.51977111)the“Six Talent Peaks”High-level Talent Project in Jiangsu Province(No.XNY-025)+1 种基金the Special Fund of Jiangsu Province for Transformation of Scientific and Technological Achievements(No.BA2019045)the Jiangsu Qinglan Project。
文摘To avoid the secondary frequency dip caused by the steep drop of the electrical power of wind turbines(WTs)at the end of frequency support stage,the torque limit-based iner-tial control(TLIC)method sets the power reference as a linear function of rotor speed,rather than the step form for the step-wise inertial control.However,the compensation effect on the frequency nadir(FN)caused by the load surge is weakened as the TLIC power is no longer in the step form.Specifically,the maximum point of the frequency response component(FRC)contributed by TLIC occurs earlier than the minimum point of FRC corresponding to the load surge,so that the FN cannot be adequately raised.Therefore,this paper first investigates the relation between the peak and nadir times of FRCs stimulated by the TLIC and load power.On this basis,with the compensation principle of matching the peak and nadir times of FRCs,the improved TLIC method based on delayed support is proposed.Finally,the effectiveness of the proposed method is validated via the experiments on the test bench of wind-integrated power system.
基金supported in part by the National Science Foundation of China(No.51977111)the Jiangsu Qinglan Projectthe State Grid Corporation Science and Technology Project“Key technologies of active frequency support for mid and long distance offshore wind farm with multiple grid-forming converter connected via VSC-HVDC”(No.5108-202218280A-2-241-XG)。
文摘In this paper,we apply a model predictive control based scheme to the energy management of networked microgrid,which is reformulated based on column generation.Although column generation is effective in alleviating the computational intractability of large-scale optimization problems,it still suffers from slow convergence issues,which hinders the direct real-time online implementation.To this end,we propose a graph neural network based framework to accelerate the convergence of the column generation model.The acceleration is achieved by selecting promising columns according to certain stabilization method of the dual variables that can be customized according to the characteristics of the microgrid.Moreover,a rigorous energy management method based on the graph neural network accelerated column generation model is developed,which is able to guarantee the optimality and feasibility of the dispatch results.The computational efficiency of the method is also very high,which is promising for real-time implementation.We conduct case studies to demonstrate the effectiveness of the proposed energy management method.
基金The authors gratefully acknowledge fundings from the Strategic Priority Research Program of Chinese Academy of Sciences(CAS)(No.XDA0330401)CAS Youth Interdisciplinary Team(No.JCTD-2022-07).
文摘Carbon nanotube field-effect transistors(CNTFETs)are increasingly recognized as a viable option for creating high-performance,low-power,and densely integrated circuits(ICs).Advancements in carbon-based electronics,encompassing materials and device technology,have enabled the fabrication of circuits with over 1000 gates,marking carbon-based integrated circuit design as a burgeoning field of research.A critical challenge in the realm of carbon-based very-large-scale integration(VLSI)is the lack of suitable automated design methodologies and infrastructure platforms.In this study,we present the development of a waferscale 3μm carbon-based complementary metal-oxide-semiconductor(CMOS)process design kit(PDK)(3μm-CNTFETs-PDK)compatible with silicon-based Electronic Design Automation(EDA)tools and VLSI circuit design flow.The proposed 3μm-CNTFETs-PDK features a contacted gate pitch(CGP)of 21μm,a gate density of 128 gates/mm^(2),and a transistor density of 554 transistors/mm^(2),with an intrinsic gate delay around 134 ns.Validation of the 3μm-CNTFETs-PDK was achieved through the successful design and tape-out of 153 standard cells and 333-stage ring oscillator circuits.Leveraging the carbon-based PDK and a silicon-based design platform,we successfully implemented a complete 64-bit static random-access memory(SRAM)circuit system for the first time,which exhibited timing,power,and area characteristics of clock@10 kHz,122.1μW,3795μm×2810μm.This research confirms that carbon-based IC design can be compatible with existing EDA tools and silicon-based VLSI design flow,thereby laying the groundwork for future carbon-based VLSI advancements.
