As power system interconnections become more prevalent, there has been an increase in use of thyristor controlled shunt connected compensation devices for dynamic power compensation and enhancement of real power trans...As power system interconnections become more prevalent, there has been an increase in use of thyristor controlled shunt connected compensation devices for dynamic power compensation and enhancement of real power transmission capacity. In this paper, an enhancement technique of real power transfer capacity of transmission lines is presented. A SVC （static var compensator） is designed and applied to a simple power system for this purpose. Increase in power flow and improvement in bus voltage profile are observed after using the SVC. Stability analysis of the system after experiencing fault as well as consequent fault clearance by time domain analysis has also beeu performed and satisfactory results are obtained.展开更多
A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gol...A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gold platinum contact is used to get a stable and little insert loss.From DC to 5GHz,0 6dB insertion loss,30dB isolation,and 30μs delay are demonstrated.Thermal effect of the switch is tested in 85℃ and -55℃ atmosphere separately.From DC to 4GHz,the insert loss of the switch increases 0 2dB in 85℃ and 0 4dB in -55℃,while the isolation holds the same value as that in room temperature.To measure the power handling capability of the switch,we applied a continuous RF power increasing from 10dBm to 35 1dBm with the step of 1 0dBm across the switch at 4GHz.The switch keeps working and shows a decrease of the insert loss for 0 1～0 6dB.The maximum continuous power handling (35 1dBm,about 3 24W) is higer than the reported value of shunt switch (about 420mW),which implies series switches have much better power handling capability.展开更多
The maximum power transfer capability(MPTC)of phase-locked loop(PLL)-based grid-following inverters is often limited under weak-grid conditions due to passivity violations caused by operating-point-dependent control l...The maximum power transfer capability(MPTC)of phase-locked loop(PLL)-based grid-following inverters is often limited under weak-grid conditions due to passivity violations caused by operating-point-dependent control loops.This paper reveals and compares the mechanisms of these violations across different control strategies.Using admittance decomposition and full-order state-space models for eigenvalue analysis,MPTC limitations from control loops and their interactions are identified.The small-signal stabilities of different control loops are compared under varying grid strength,and both static and dynamic MPTCs for each control mode are examined.This paper also explores how control loop interactions impact the MPTC,offering insights for tuning control loops to enhance stability in weak grids.For example,fast power control improves the MPTC when paired with a slow PLL,while power control has minimal effect when the PLL is sufficiently fast.The findings are validated through frequency scanning,eigenvalue analysis,simulations,and experiments.展开更多
Global demand for power has significantly increased, but power generation and transmission capacities have not increased proportionally with this demand. As a result, power consumers suffer from various problems, such...Global demand for power has significantly increased, but power generation and transmission capacities have not increased proportionally with this demand. As a result, power consumers suffer from various problems, such as voltage and frequency instability and power quality issues. To overcome these problems, the capacity for available power transfer of a transmission network should be enhanced. Researchers worldwide have addressed this issue by using flexible AC transmission system （FACTS） devices. We have conducted a comprehensive review of how FACTS controllers are used to enhance the avail- able transfer capability （ATC） and power transfer capability （PTC） of power system networks. This review includes a discussion of the classification of different FACTS devices according to different factors. The popularity and applications of these devices are discussed together with relevant statistics. The operating principles of six major FACTS devices and their application in increasing ATC and PTC are also presented. Finally, we evaluate the performance of FACTS devices in ATC and PTC improvement with respect to different control algorithms.展开更多
This paper studies an electronic counter-counter measures（ECCM） scheme combating against deceptive electronic counter measure（ECM） techniques. An adaptive detector exploiting generalized likelihood ratio test（GRL...This paper studies an electronic counter-counter measures（ECCM） scheme combating against deceptive electronic counter measure（ECM） techniques. An adaptive detector exploiting generalized likelihood ratio test（GRLT） criterion is applied to detect the presence of deceptive jamming in fractional Fourier transform（Fr FT） domain. First, the generating mechanism of spurious frequencies is analyzed based on the Volterra serial. The proposed nonlinear distortion model based on power amplifier behavior is robust in distortion analysis when the memory effect is considered.Second, a modified adaptive beamformer orthogonal rejection test（ABORT） like detector in closed form is built. The proposed detector can discriminate the echo and deceptive jamming adaptively by exploiting primary data and secondary data. This ECCM scheme is capable of guaranteeing the performance without the restriction of orthogonality, which is essential for the ABORT detectors. The expansion to radar network is discussed as a special case at the final part of this paper. Numerical simulations demonstrate the effectiveness of the proposed method.展开更多
We report on a high-efficiency,high-power tandem Ho:YAG single-crystal fiber(SCF)laser in-band pumped by a Tm-doped fiber laser at 1907 nm.In addition to the uniform heat distribution resulting from the large surface-...We report on a high-efficiency,high-power tandem Ho:YAG single-crystal fiber(SCF)laser in-band pumped by a Tm-doped fiber laser at 1907 nm.In addition to the uniform heat distribution resulting from the large surface-to-volume ratio of this fiber-like thin-crystal rod,the long gain region provided by the tandem layout of two SCFs enables high lasing efficiency and power handling capability.More than 100 W output power is achieved at 2.1μm,corresponding to a slope efficiency of 70.5%and an optical-to-optical efficiency of 67.6%.To the best of our knowledge,this is the highest output power and efficiency ever reported from SCF lasers in the 2-μm spectral range.展开更多
文摘As power system interconnections become more prevalent, there has been an increase in use of thyristor controlled shunt connected compensation devices for dynamic power compensation and enhancement of real power transmission capacity. In this paper, an enhancement technique of real power transfer capacity of transmission lines is presented. A SVC （static var compensator） is designed and applied to a simple power system for this purpose. Increase in power flow and improvement in bus voltage profile are observed after using the SVC. Stability analysis of the system after experiencing fault as well as consequent fault clearance by time domain analysis has also beeu performed and satisfactory results are obtained.
文摘A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gold platinum contact is used to get a stable and little insert loss.From DC to 5GHz,0 6dB insertion loss,30dB isolation,and 30μs delay are demonstrated.Thermal effect of the switch is tested in 85℃ and -55℃ atmosphere separately.From DC to 4GHz,the insert loss of the switch increases 0 2dB in 85℃ and 0 4dB in -55℃,while the isolation holds the same value as that in room temperature.To measure the power handling capability of the switch,we applied a continuous RF power increasing from 10dBm to 35 1dBm with the step of 1 0dBm across the switch at 4GHz.The switch keeps working and shows a decrease of the insert loss for 0 1～0 6dB.The maximum continuous power handling (35 1dBm,about 3 24W) is higer than the reported value of shunt switch (about 420mW),which implies series switches have much better power handling capability.
基金funded by the Australian Renewable Energy Agency(No.2023/ARP010).
文摘The maximum power transfer capability(MPTC)of phase-locked loop(PLL)-based grid-following inverters is often limited under weak-grid conditions due to passivity violations caused by operating-point-dependent control loops.This paper reveals and compares the mechanisms of these violations across different control strategies.Using admittance decomposition and full-order state-space models for eigenvalue analysis,MPTC limitations from control loops and their interactions are identified.The small-signal stabilities of different control loops are compared under varying grid strength,and both static and dynamic MPTCs for each control mode are examined.This paper also explores how control loop interactions impact the MPTC,offering insights for tuning control loops to enhance stability in weak grids.For example,fast power control improves the MPTC when paired with a slow PLL,while power control has minimal effect when the PLL is sufficiently fast.The findings are validated through frequency scanning,eigenvalue analysis,simulations,and experiments.
基金supported by the Ministry of Higher Education of Malaysia and University of Malaya under the E-Science Fund Research Grant(No.SF005-2013)the UMRG Project RP015D-13AET
文摘Global demand for power has significantly increased, but power generation and transmission capacities have not increased proportionally with this demand. As a result, power consumers suffer from various problems, such as voltage and frequency instability and power quality issues. To overcome these problems, the capacity for available power transfer of a transmission network should be enhanced. Researchers worldwide have addressed this issue by using flexible AC transmission system （FACTS） devices. We have conducted a comprehensive review of how FACTS controllers are used to enhance the avail- able transfer capability （ATC） and power transfer capability （PTC） of power system networks. This review includes a discussion of the classification of different FACTS devices according to different factors. The popularity and applications of these devices are discussed together with relevant statistics. The operating principles of six major FACTS devices and their application in increasing ATC and PTC are also presented. Finally, we evaluate the performance of FACTS devices in ATC and PTC improvement with respect to different control algorithms.
文摘This paper studies an electronic counter-counter measures（ECCM） scheme combating against deceptive electronic counter measure（ECM） techniques. An adaptive detector exploiting generalized likelihood ratio test（GRLT） criterion is applied to detect the presence of deceptive jamming in fractional Fourier transform（Fr FT） domain. First, the generating mechanism of spurious frequencies is analyzed based on the Volterra serial. The proposed nonlinear distortion model based on power amplifier behavior is robust in distortion analysis when the memory effect is considered.Second, a modified adaptive beamformer orthogonal rejection test（ABORT） like detector in closed form is built. The proposed detector can discriminate the echo and deceptive jamming adaptively by exploiting primary data and secondary data. This ECCM scheme is capable of guaranteeing the performance without the restriction of orthogonality, which is essential for the ABORT detectors. The expansion to radar network is discussed as a special case at the final part of this paper. Numerical simulations demonstrate the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(Nos.62075090 and 52032009)。
文摘We report on a high-efficiency,high-power tandem Ho:YAG single-crystal fiber(SCF)laser in-band pumped by a Tm-doped fiber laser at 1907 nm.In addition to the uniform heat distribution resulting from the large surface-to-volume ratio of this fiber-like thin-crystal rod,the long gain region provided by the tandem layout of two SCFs enables high lasing efficiency and power handling capability.More than 100 W output power is achieved at 2.1μm,corresponding to a slope efficiency of 70.5%and an optical-to-optical efficiency of 67.6%.To the best of our knowledge,this is the highest output power and efficiency ever reported from SCF lasers in the 2-μm spectral range.
