The H_∞ performance analysis and controller design for linear networked control systems(NCSs) are presented.The NCSs are considered a linear continuous system with time-varying interval input delay by assuming that t...The H_∞ performance analysis and controller design for linear networked control systems(NCSs) are presented.The NCSs are considered a linear continuous system with time-varying interval input delay by assuming that the sensor is time-driven and the logic Zero-order-holder(ZOH) and controller are event-driven.Based on this model,the delay interval is divided into two equal subintervals for H_∞ performance analysis.An improved H_∞ stabilization condition is obtained in linear matrix inequalities(LMIs) framework by adequately considering the information about the bounds of the input delay to construct novel Lyapunov–Krasovskii functionals(LKFs).For the purpose of reducing the conservatism of the proposed results,the bounds of the LKFs differential cross terms are properly estimated without introducing any slack matrix variables.Moreover,the H_∞ controller is reasonably designed to guarantee the robust asymptotic stability for the linear NCSs with an H_∞ performance level γ.Numerical simulation examples are included to validate the reduced conservatism and effectiveness of our proposed method.展开更多
Based on the analysis of a specific relay model and an HVAC （high voltage alternating current） cable system, a detailed approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to cr...Based on the analysis of a specific relay model and an HVAC （high voltage alternating current） cable system, a detailed approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay models can be applied with various systems, allowing to obtain the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC 4 7SD522/610. Relay model was verified experimentally with its real equivalent by both EMTP-simulated and real world generated current signals connected to the relay.展开更多
Based on the data from the Medium-Energy Proton and Electron Detector （MEPED） onboard NOAA-17, 141 anomalies of a Chinese Sun-Synchronous satellite （SSO-X） that occurred between 02/01/2010 and 09/31/2012 were stud...Based on the data from the Medium-Energy Proton and Electron Detector （MEPED） onboard NOAA-17, 141 anomalies of a Chinese Sun-Synchronous satellite （SSO-X） that occurred between 02/01/2010 and 09/31/2012 were studied statistically. About 26 out of the 52 anomalies that occurred outside the South Atlantic Anomaly （SAA） were accompanied by energetic electron storms. Superposed Epoch Analysis （SEA） was used to analyze the properties of the anomalies and the dynamics of the space environments during these 26 events. Then, a Monte Carlo method was utilized to simulate the electron deposition and the interactions of the injected electrons with an aluminum shield and polyethylene dielectric. The average, median, and 75tb percentile values of the maximum electric field strength inside the dielectric were calculated. The results showed the tbl- lowing. （1） SSO-X anomalies are more likely to occur within the SAA, as 89 out of 141 anomalies （63%） occurred there. （2） Twenty-six of the anomalies that occurred outside the SAA during energetic electron storms were located near the outer boundaries of the outer radiation belts, and these were more frequent in the Southern Hemisphere than in the Northern Hemi- sphere. （3） Electron flux enhancements occurred around the failure time at all energy levels but were more profound in the lower energy channels. The maximum fluxes of electrons 〉30 keV, 〉100 keV, and 〉300 keV were 106, 3.5x10s, and 1.2×10^6 cm 2 s^-1 · sr ^-1, respectively. （4） The average, median, and 75th percentile values of the maximum electric field strengths inside the dielectric for the aforementioned 26 events remained in the range from 106 to 107 V/m for long time periods, which sug- gests that the ＇potential hazards＇ of internal discharges cause SSO-X anomalies. The above results can provide useful infor- mation for the design and protection of sun-synchronous spacecraft.展开更多
基金Project (61304046) supported by the National Natural Science Funds for Young Scholar of ChinaProject (F201242) supported by Natural Science Foundation of Heilongjiang Province,China
文摘The H_∞ performance analysis and controller design for linear networked control systems(NCSs) are presented.The NCSs are considered a linear continuous system with time-varying interval input delay by assuming that the sensor is time-driven and the logic Zero-order-holder(ZOH) and controller are event-driven.Based on this model,the delay interval is divided into two equal subintervals for H_∞ performance analysis.An improved H_∞ stabilization condition is obtained in linear matrix inequalities(LMIs) framework by adequately considering the information about the bounds of the input delay to construct novel Lyapunov–Krasovskii functionals(LKFs).For the purpose of reducing the conservatism of the proposed results,the bounds of the LKFs differential cross terms are properly estimated without introducing any slack matrix variables.Moreover,the H_∞ controller is reasonably designed to guarantee the robust asymptotic stability for the linear NCSs with an H_∞ performance level γ.Numerical simulation examples are included to validate the reduced conservatism and effectiveness of our proposed method.
文摘Based on the analysis of a specific relay model and an HVAC （high voltage alternating current） cable system, a detailed approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay models can be applied with various systems, allowing to obtain the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC 4 7SD522/610. Relay model was verified experimentally with its real equivalent by both EMTP-simulated and real world generated current signals connected to the relay.
基金supported by the National Natural Science Foundation of China(Grant No.41421003)the Major Project of Chinese National Programs for Fundamental Research and Development(Grant No.2012CB825603)
文摘Based on the data from the Medium-Energy Proton and Electron Detector （MEPED） onboard NOAA-17, 141 anomalies of a Chinese Sun-Synchronous satellite （SSO-X） that occurred between 02/01/2010 and 09/31/2012 were studied statistically. About 26 out of the 52 anomalies that occurred outside the South Atlantic Anomaly （SAA） were accompanied by energetic electron storms. Superposed Epoch Analysis （SEA） was used to analyze the properties of the anomalies and the dynamics of the space environments during these 26 events. Then, a Monte Carlo method was utilized to simulate the electron deposition and the interactions of the injected electrons with an aluminum shield and polyethylene dielectric. The average, median, and 75tb percentile values of the maximum electric field strength inside the dielectric were calculated. The results showed the tbl- lowing. （1） SSO-X anomalies are more likely to occur within the SAA, as 89 out of 141 anomalies （63%） occurred there. （2） Twenty-six of the anomalies that occurred outside the SAA during energetic electron storms were located near the outer boundaries of the outer radiation belts, and these were more frequent in the Southern Hemisphere than in the Northern Hemi- sphere. （3） Electron flux enhancements occurred around the failure time at all energy levels but were more profound in the lower energy channels. The maximum fluxes of electrons 〉30 keV, 〉100 keV, and 〉300 keV were 106, 3.5x10s, and 1.2×10^6 cm 2 s^-1 · sr ^-1, respectively. （4） The average, median, and 75th percentile values of the maximum electric field strengths inside the dielectric for the aforementioned 26 events remained in the range from 106 to 107 V/m for long time periods, which sug- gests that the ＇potential hazards＇ of internal discharges cause SSO-X anomalies. The above results can provide useful infor- mation for the design and protection of sun-synchronous spacecraft.
