A robust control strategy using the second-order integral sliding mode control(SOISMC)based on the variable speed grey wolf optimization(VGWO)is proposed.The aim is to maximize the wind power extraction of wind turbin...A robust control strategy using the second-order integral sliding mode control(SOISMC)based on the variable speed grey wolf optimization(VGWO)is proposed.The aim is to maximize the wind power extraction of wind turbine.Firstly,according to the uncertainty model of wind turbine,a SOISMC torque controller with fast convergence speed,strong robustness and effective chattering reduction is designed,which ensures that the torque controller can effectively track the reference speed.Secondly,given the strong local search ability of the grey wolf optimization(GWO)and the fast convergence speed and strong global search ability of the particle swarm optimization(PSO),the speed component of PSO is introduced into GWO,and VGWO with fast convergence speed,high solution accuracy and strong global search ability is used to optimize the parameters of wind turbine torque controller.Finally,the simulation is implemented based on Simulink/SimPowerSystem.The results demonstrate the effectiveness of the proposed strategy under both external disturbance and model uncertainty.展开更多
In predictive direct power control(PDPC)system of three-phase pulse width modulation(PWM)rectifier,grid voltage sensor makes the whole system more complex and costly.Therefore,third-order generalized integrator(TOGI)i...In predictive direct power control(PDPC)system of three-phase pulse width modulation(PWM)rectifier,grid voltage sensor makes the whole system more complex and costly.Therefore,third-order generalized integrator(TOGI)is used to generate orthogonal signals with the same frequency to estimate the grid voltage.In addition,in view of the deviation between actual and reference power in the three-phase PWM rectifier traditional PDPC strategy,a power correction link is designed to correct the power reference value.The grid voltage sensor free algorithm based on TOGI and the corrected PDPC strategy are applied to three-phase PWM rectifier and simulated on the simulation platform.Simulation results show that the proposed method can effectively eliminate the power tracking deviation and the grid voltage.The effectiveness of the proposed method is verified by comparing the simulation results.展开更多
This paper presents an improved Voice Activity Detection （VAD） algorithm which uses the Signal-to-Noise Ratio （SNR） measure. We assume that noise Power Spectral Density （PSD） in each spectral bin follows a Rayle...This paper presents an improved Voice Activity Detection （VAD） algorithm which uses the Signal-to-Noise Ratio （SNR） measure. We assume that noise Power Spectral Density （PSD） in each spectral bin follows a Rayleigh distribution. Rayleigh distributions with its asymmetric tail characteristics give a better description of the noise PSD distribution than Gaussian distribution. Under this asstlmption, a new threshold updating expression is derived. Since the analytical integral of the false alarm probability, the threshold updating expression can be represented without the inverse complementary error function and low computational complexity is achieved in our system. Experimental results show that the proposed VAD outperforms or at least is comparable with the VAD scheme presented by Davis under several noise environments and has a lower computational complexity.展开更多
The verifi cation of nuclear test ban necessitates the classifi cation and identifi cation of infrasound events.The accurate and eff ective classifi cation of seismic and chemical explosion infrasounds can promote the...The verifi cation of nuclear test ban necessitates the classifi cation and identifi cation of infrasound events.The accurate and eff ective classifi cation of seismic and chemical explosion infrasounds can promote the classifi cation and identifi cation of infrasound events.However,overfi tting of the signals of seismic and chemical explosion infrasounds easily occurs during training due to the limited amount of data.Thus,to solve this problem,this paper proposes a classifi cation method based on the mixed virtual infrasound data augmentation(MVIDA)algorithm and multiscale squeeze-and-excitation ResNet(MS-SE-ResNet).In this study,the eff ectiveness of the proposed method is verifi ed through simulation and comparison experiments.The simulation results reveal that the MS-SE-ResNet network can eff ectively determine the separability of chemical explosion and seismic infrasounds in the frequency domain,and the average classifi cation accuracy on the dataset enhanced by the MVIDA algorithm reaches 81.12%.This value is higher than those of the other four types of comparative classifi cation methods.This work also demonstrates the eff ectiveness and stability of the augmentation algorithm and classifi cation network in the classifi cation of few-shot infrasound events.展开更多
Wind speed and direction data during typhoon Meari were obtained from eight anemometers installed at heights of 10, 20, 30, and 40 m on a 40-m tower built in the Pudong area of Shanghai. Wind-turbulence characteristic...Wind speed and direction data during typhoon Meari were obtained from eight anemometers installed at heights of 10, 20, 30, and 40 m on a 40-m tower built in the Pudong area of Shanghai. Wind-turbulence characteristics, including wind-speed profile, turbulence integral scale, power spectra, correlations, and coherences were analyzed. Wind-speed profiles varied with time during the passage of Meari. Measured wind-speed profiles could be expressed well by both a power law and a log law. Turbulence integral scales for u, v, and w components all increased with wind speed. The ratios of the turbulence scales among the turbulence components averaged for all 10-min data were 1：0.69：0.08 at 10 m, 1：0.61：0.09 at 20 m, and 1：0.65：0.13 at 40 m. The turbulence integral scales for the u and v components increased with average gust time, but the turbulence integral scale for the w component remained almost constant when the gust duration was greater than 10 min. The decay factor of the coherence function increased slightly with wind speed, with average values for longitudinal and lateral dimensions of 14.3 and 11.3, respectively. The slope rates of the turbulence spectra in the inertial range were less than -5/3 at first, but gradually satisfied the Kolmogorov 5/3 law. The longitudinal wind-power fluctuation spectrum roughly fitted the von Karman spectrum, but slight deviations occurred in the high-frequency band for lateral and vertical wind-power fluctuation spectra.展开更多
This paper presents limit theorems for realized power variation of processes of the form Xt=t0φsdGs+ξt as the sampling frequency within a fixed interval increases to infinity.Here G is a Gaussian process with statio...This paper presents limit theorems for realized power variation of processes of the form Xt=t0φsdGs+ξt as the sampling frequency within a fixed interval increases to infinity.Here G is a Gaussian process with stationary increments,ξis a purely non-Gaussian L′evy process independent from G,andφis a stochastic process ensuring that the integral is well defined as a pathwise Riemann-Stieltjes integral.We obtain the central limit theorems for the case that both the continuous term and the jump term are presented simultaneously in the law of large numbers.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.51876089)the Fundamental Research Funds for the Central Universities(No.kfjj20190205).
文摘A robust control strategy using the second-order integral sliding mode control(SOISMC)based on the variable speed grey wolf optimization(VGWO)is proposed.The aim is to maximize the wind power extraction of wind turbine.Firstly,according to the uncertainty model of wind turbine,a SOISMC torque controller with fast convergence speed,strong robustness and effective chattering reduction is designed,which ensures that the torque controller can effectively track the reference speed.Secondly,given the strong local search ability of the grey wolf optimization(GWO)and the fast convergence speed and strong global search ability of the particle swarm optimization(PSO),the speed component of PSO is introduced into GWO,and VGWO with fast convergence speed,high solution accuracy and strong global search ability is used to optimize the parameters of wind turbine torque controller.Finally,the simulation is implemented based on Simulink/SimPowerSystem.The results demonstrate the effectiveness of the proposed strategy under both external disturbance and model uncertainty.
基金National Natural Science Foundation of China(Nos.51767013,52067013)。
文摘In predictive direct power control(PDPC)system of three-phase pulse width modulation(PWM)rectifier,grid voltage sensor makes the whole system more complex and costly.Therefore,third-order generalized integrator(TOGI)is used to generate orthogonal signals with the same frequency to estimate the grid voltage.In addition,in view of the deviation between actual and reference power in the three-phase PWM rectifier traditional PDPC strategy,a power correction link is designed to correct the power reference value.The grid voltage sensor free algorithm based on TOGI and the corrected PDPC strategy are applied to three-phase PWM rectifier and simulated on the simulation platform.Simulation results show that the proposed method can effectively eliminate the power tracking deviation and the grid voltage.The effectiveness of the proposed method is verified by comparing the simulation results.
基金Supported by the National Natural Science Foundation of China (No. 60874060)
文摘This paper presents an improved Voice Activity Detection （VAD） algorithm which uses the Signal-to-Noise Ratio （SNR） measure. We assume that noise Power Spectral Density （PSD） in each spectral bin follows a Rayleigh distribution. Rayleigh distributions with its asymmetric tail characteristics give a better description of the noise PSD distribution than Gaussian distribution. Under this asstlmption, a new threshold updating expression is derived. Since the analytical integral of the false alarm probability, the threshold updating expression can be represented without the inverse complementary error function and low computational complexity is achieved in our system. Experimental results show that the proposed VAD outperforms or at least is comparable with the VAD scheme presented by Davis under several noise environments and has a lower computational complexity.
基金supported by the Natural Science Foundation of Shaanxi Province(2023-JC-YB-221).
文摘The verifi cation of nuclear test ban necessitates the classifi cation and identifi cation of infrasound events.The accurate and eff ective classifi cation of seismic and chemical explosion infrasounds can promote the classifi cation and identifi cation of infrasound events.However,overfi tting of the signals of seismic and chemical explosion infrasounds easily occurs during training due to the limited amount of data.Thus,to solve this problem,this paper proposes a classifi cation method based on the mixed virtual infrasound data augmentation(MVIDA)algorithm and multiscale squeeze-and-excitation ResNet(MS-SE-ResNet).In this study,the eff ectiveness of the proposed method is verifi ed through simulation and comparison experiments.The simulation results reveal that the MS-SE-ResNet network can eff ectively determine the separability of chemical explosion and seismic infrasounds in the frequency domain,and the average classifi cation accuracy on the dataset enhanced by the MVIDA algorithm reaches 81.12%.This value is higher than those of the other four types of comparative classifi cation methods.This work also demonstrates the eff ectiveness and stability of the augmentation algorithm and classifi cation network in the classifi cation of few-shot infrasound events.
基金Project supported by the National Natural Science Foundation of China （No. 51378396）, the Open Project of Guangxi Key Laboratory of Disaster Prevention and Structural Safety （No. 2014ZDK005）, and the Chongqing Postdoctoral Science Foundation （No. Xm2015066）, China
文摘Wind speed and direction data during typhoon Meari were obtained from eight anemometers installed at heights of 10, 20, 30, and 40 m on a 40-m tower built in the Pudong area of Shanghai. Wind-turbulence characteristics, including wind-speed profile, turbulence integral scale, power spectra, correlations, and coherences were analyzed. Wind-speed profiles varied with time during the passage of Meari. Measured wind-speed profiles could be expressed well by both a power law and a log law. Turbulence integral scales for u, v, and w components all increased with wind speed. The ratios of the turbulence scales among the turbulence components averaged for all 10-min data were 1：0.69：0.08 at 10 m, 1：0.61：0.09 at 20 m, and 1：0.65：0.13 at 40 m. The turbulence integral scales for the u and v components increased with average gust time, but the turbulence integral scale for the w component remained almost constant when the gust duration was greater than 10 min. The decay factor of the coherence function increased slightly with wind speed, with average values for longitudinal and lateral dimensions of 14.3 and 11.3, respectively. The slope rates of the turbulence spectra in the inertial range were less than -5/3 at first, but gradually satisfied the Kolmogorov 5/3 law. The longitudinal wind-power fluctuation spectrum roughly fitted the von Karman spectrum, but slight deviations occurred in the high-frequency band for lateral and vertical wind-power fluctuation spectra.
基金supported by National Natural Science Foundation of China(Grant Nos.11071045 and 11226201)Natural Science Foundation of Jiangsu Province of China(Grant No.BK20131340)+1 种基金Social Science Foundation of Chinese Ministry of Education(Grant No.12YJCZH128)QingLan Project ofthe Priority Academic Program Development of Jiangsu Higher Education Institutions(Auditing Science and Technology)
文摘This paper presents limit theorems for realized power variation of processes of the form Xt=t0φsdGs+ξt as the sampling frequency within a fixed interval increases to infinity.Here G is a Gaussian process with stationary increments,ξis a purely non-Gaussian L′evy process independent from G,andφis a stochastic process ensuring that the integral is well defined as a pathwise Riemann-Stieltjes integral.We obtain the central limit theorems for the case that both the continuous term and the jump term are presented simultaneously in the law of large numbers.
