With the significant improvement of microgrid technology, microgrid has gained large-scale application.However, the existence of intermittent distributed generations, nonlinear loads and various electrical and electro...With the significant improvement of microgrid technology, microgrid has gained large-scale application.However, the existence of intermittent distributed generations, nonlinear loads and various electrical and electronic devices causes power quality problem in microgrid, especially in islanding mode. An accurate and fast disturbance detection method which is the premise of power quality control is necessary. Aiming at the end effect and the mode mixing of original Hilbert-Huang transform(HHT), an improved HHT with adaptive waveform matching extension is proposed in this paper. The innovative waveform matching extension method considers not only the depth of waveform, but also the rise time and fall time. Both simulations and field experiments have verified the correctness and validity of the improved HHT for power quality disturbance detection in microgrid.展开更多
In view of the variable parameters that affect the transient stability of electromagnetic torque and mechanical torque balance in AC-DC system,and the uncertainty of wind power in large-scale interconnection of wind f...In view of the variable parameters that affect the transient stability of electromagnetic torque and mechanical torque balance in AC-DC system,and the uncertainty of wind power in large-scale interconnection of wind farm.This paper proposes a linear parameter varying(LPV)robust feedback control method for transient stability of interconnected systems.The proposed LPV robust feedback control method uses the DC channel power control and the mechanical power in the interconnected system as the control target to improve the transient stability of the interconnected system with wind farm channel.Firstly,aiming at the strong nonlinear characteristics of the interconnected system,the power balance and the wind power output uncertainty in the transient process,the transient process is designed as a linear model of variable parameters.Then,the H∞robust output feedback controller is designed according to the LPV model.The transient stability control strategy topology and transfer function of the interconnected system are proposed.Finally,the proposed scheme is verified by an interconnected system formed by four equal-value grids through AC and DC lines in a digital simulation platform.The results show that the LPV robust feedback control model proposed in this paper has better response characteristics and transient stability control effects for interconnected systems with wind power weak sendingend system.展开更多
An analog front-end of HF passive RFID transponders compatible with ISO/IEC 18000-3 is presented.Design considerations, especially the power transmission in the RFID transponder, are analyzed. Based on these considera...An analog front-end of HF passive RFID transponders compatible with ISO/IEC 18000-3 is presented.Design considerations, especially the power transmission in the RFID transponder, are analyzed. Based on these considerations,an analog front-end is presented with novel architecture, high power conversion efficiency, low voltage, low power consumption, and high performance in an environment of noise and power fluctuation. The circuit is implemented in a Chartered 0.35μm standard CMOS process. The experimental results show that the chip can satisfy the design target well.展开更多
This paper introduces a high-performance analog front end for a passive UHF RFID transponder IC, which is compatible with the ISO/IEC 18000-6B standard,operating at the 915MHz ISM band with a total supply current cons...This paper introduces a high-performance analog front end for a passive UHF RFID transponder IC, which is compatible with the ISO/IEC 18000-6B standard,operating at the 915MHz ISM band with a total supply current consumption less than 8μA. There are no external components, except for the antenna. The passive IC＇s power supply is taken from the energy of the received RF electromagnetic field with the help of a Schottky diode rectifier. The RFID analog front end includes a local oscillator, clock generator, power on reset circuit, matching network and backscatter,rectifier,regulator, and AM demodulator. The IC, whose reading distance is more than 3m,is fabricated with a Chartered 0.35μm two-poly four-metal CMOS process with Schottky diodes and is EEPROM supported. The core size is 300μm × 720μm.展开更多
A new,low-cost RFID tag analog front-end compatible with ISO 14443A and ISO 14443B is presented. By substituting conventional multi-circle antenna with single-circle antenna, the package cost of the tag is greatly red...A new,low-cost RFID tag analog front-end compatible with ISO 14443A and ISO 14443B is presented. By substituting conventional multi-circle antenna with single-circle antenna, the package cost of the tag is greatly reduced. Based on this exasperate antenna performance,a new rectifier with high power conversion efficiency and low turn-on voltage is presented. The circuit is implemented in an SMIC 0.18μm EEPROM process. Measurement results show that with a 120kΩ load,the power conversion efficiency reaches as high as 36%. For a sinusoidal wave with magnitude of 0. 5V, the output DC voltage reaches IV,which is high enough for RFID tags. The read distance is as far as 22cm.展开更多
Fiber gas lasers based on gas-filled hollow-core fibers(HCFs)perfectly combine the advantages of fiber lasers and gas lasers and have obtained fast development in the past years.However,stable and efficient coupling o...Fiber gas lasers based on gas-filled hollow-core fibers(HCFs)perfectly combine the advantages of fiber lasers and gas lasers and have obtained fast development in the past years.However,stable and efficient coupling of high-power pump lasers into the HCFs is one of the key problems to be solved.In this paper,we study the coupling of high-power continuous wave fiber lasers into anti-resonant HCFs through an end-cap.By optimizing the splicing parameters,a maximum laser power of 1167 W was injected into the 1-m-long HCFs,and 1021W was obtained at the output end,giving a total transmission efficiency of〜87.5%.A more than 1 h test showed the stability of such a coupling method.Meanwhile,the laser beam quality was well maintained.This work opens new opportunities for stable and highly efficient coupling of high-power lasers into HCFs,which is significant for its applications in many other fields besides high-power fiber gas lasers,such as high-power laser delivering.展开更多
This paper describes the implementation ofan RF receiver front-end for the 2.4 GHz industrial scientific medical band under TSMC 0.13 μm CMOS technology; it comprises a low noise amplifier （LNA） which uses an added...This paper describes the implementation ofan RF receiver front-end for the 2.4 GHz industrial scientific medical band under TSMC 0.13 μm CMOS technology; it comprises a low noise amplifier （LNA） which uses an added gate-source capacitor for low power performance and a dual-converter composed of a single-balanced active RF mixer and double-balanced passive IF mixer. Dual-down-conversion technique is used for reducing power. A 2.4 GHz low power low-IF RF receiver front-end is proposed. An LNA for rejecting image signal, an inductor- capacitor （LC） tank is used in series with source of input-stage transistor of the RF mixer, and combined with the LC load of the LNA, 30-dB image rejection is realized. Fabricated in a 0.13 μm CMOS process, the proposed chip occupies 0.42 mm2 area, achieves 4 dB noise figure, -22 dBm IIP3 and 37 dB voltage gain dissipating only 4.2-mW under 1.2-V supply.展开更多
This paper analyzes the power markets both in northwest sending end and, east receiving ends, points out the favorable and unfavorable conditions for power development In, the northwest area, brings forward,the develo...This paper analyzes the power markets both in northwest sending end and, east receiving ends, points out the favorable and unfavorable conditions for power development In, the northwest area, brings forward,the development planning of power sources and power network constructions, and presents the benefit estimation of sending power from northwest to east.展开更多
Egypt has been facing a vast power crisis in the past few years. A dilemma is projected to surge on the long run if not properly dealt with. The power sector is totally dependent on fuel, which is a primary source of ...Egypt has been facing a vast power crisis in the past few years. A dilemma is projected to surge on the long run if not properly dealt with. The power sector is totally dependent on fuel, which is a primary source of energy in Egypt, and since the production of energy is not equivalent to the rising demand, so it becomes a major cause behind the power crisis. Efforts so far had been concentrating on the supply side, while neglecting an equally important part of the equation presumed by the demand side. On the other hand, energy efficiency is fast becoming an integral part of the demand, where the residential sector in Egypt plays a very important part with around 47% of power consumption, making it the highest sector consuming energy from the demand side, and hence presents a good opportunity to investigate in term of energy efficiency and the promotion of its applications in order to solve the energy problem, so that later the same concept can be applied in other sectors for a holistic solution to the both the power and the energy problem in Egypt. This study will focus on generating a political framework to promote energy efficiency as a solution to the energy problem in Egypt at end-user’s level.展开更多
After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV in...After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.展开更多
基金supported by National High Technology Research and Development Program of China(863 Program)(No.2015AA050104)National Natural Science Foundation of China(No.51577068)
文摘With the significant improvement of microgrid technology, microgrid has gained large-scale application.However, the existence of intermittent distributed generations, nonlinear loads and various electrical and electronic devices causes power quality problem in microgrid, especially in islanding mode. An accurate and fast disturbance detection method which is the premise of power quality control is necessary. Aiming at the end effect and the mode mixing of original Hilbert-Huang transform(HHT), an improved HHT with adaptive waveform matching extension is proposed in this paper. The innovative waveform matching extension method considers not only the depth of waveform, but also the rise time and fall time. Both simulations and field experiments have verified the correctness and validity of the improved HHT for power quality disturbance detection in microgrid.
基金This study was supported in part by the National Key R&D Program of China(2017YFB0902100).
文摘In view of the variable parameters that affect the transient stability of electromagnetic torque and mechanical torque balance in AC-DC system,and the uncertainty of wind power in large-scale interconnection of wind farm.This paper proposes a linear parameter varying(LPV)robust feedback control method for transient stability of interconnected systems.The proposed LPV robust feedback control method uses the DC channel power control and the mechanical power in the interconnected system as the control target to improve the transient stability of the interconnected system with wind farm channel.Firstly,aiming at the strong nonlinear characteristics of the interconnected system,the power balance and the wind power output uncertainty in the transient process,the transient process is designed as a linear model of variable parameters.Then,the H∞robust output feedback controller is designed according to the LPV model.The transient stability control strategy topology and transfer function of the interconnected system are proposed.Finally,the proposed scheme is verified by an interconnected system formed by four equal-value grids through AC and DC lines in a digital simulation platform.The results show that the LPV robust feedback control model proposed in this paper has better response characteristics and transient stability control effects for interconnected systems with wind power weak sendingend system.
文摘An analog front-end of HF passive RFID transponders compatible with ISO/IEC 18000-3 is presented.Design considerations, especially the power transmission in the RFID transponder, are analyzed. Based on these considerations,an analog front-end is presented with novel architecture, high power conversion efficiency, low voltage, low power consumption, and high performance in an environment of noise and power fluctuation. The circuit is implemented in a Chartered 0.35μm standard CMOS process. The experimental results show that the chip can satisfy the design target well.
文摘This paper introduces a high-performance analog front end for a passive UHF RFID transponder IC, which is compatible with the ISO/IEC 18000-6B standard,operating at the 915MHz ISM band with a total supply current consumption less than 8μA. There are no external components, except for the antenna. The passive IC＇s power supply is taken from the energy of the received RF electromagnetic field with the help of a Schottky diode rectifier. The RFID analog front end includes a local oscillator, clock generator, power on reset circuit, matching network and backscatter,rectifier,regulator, and AM demodulator. The IC, whose reading distance is more than 3m,is fabricated with a Chartered 0.35μm two-poly four-metal CMOS process with Schottky diodes and is EEPROM supported. The core size is 300μm × 720μm.
文摘A new,low-cost RFID tag analog front-end compatible with ISO 14443A and ISO 14443B is presented. By substituting conventional multi-circle antenna with single-circle antenna, the package cost of the tag is greatly reduced. Based on this exasperate antenna performance,a new rectifier with high power conversion efficiency and low turn-on voltage is presented. The circuit is implemented in an SMIC 0.18μm EEPROM process. Measurement results show that with a 120kΩ load,the power conversion efficiency reaches as high as 36%. For a sinusoidal wave with magnitude of 0. 5V, the output DC voltage reaches IV,which is high enough for RFID tags. The read distance is as far as 22cm.
基金This work was supported by the Outstanding Youth Science Fund of Hunan Provincial Natural Science Foundation(No.2019JJ20023)National Natural Science Foundation of China(NSFC)(Nos.11974427 and 12004431)+2 种基金State Key Laboratory of Pulsed Power Laser(Nos.SKL2020ZR05 and SKL2021ZR01)Science and Technology Innovation Program of Hunan Province(No.2021RC4027)Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20200017).
文摘Fiber gas lasers based on gas-filled hollow-core fibers(HCFs)perfectly combine the advantages of fiber lasers and gas lasers and have obtained fast development in the past years.However,stable and efficient coupling of high-power pump lasers into the HCFs is one of the key problems to be solved.In this paper,we study the coupling of high-power continuous wave fiber lasers into anti-resonant HCFs through an end-cap.By optimizing the splicing parameters,a maximum laser power of 1167 W was injected into the 1-m-long HCFs,and 1021W was obtained at the output end,giving a total transmission efficiency of〜87.5%.A more than 1 h test showed the stability of such a coupling method.Meanwhile,the laser beam quality was well maintained.This work opens new opportunities for stable and highly efficient coupling of high-power lasers into HCFs,which is significant for its applications in many other fields besides high-power fiber gas lasers,such as high-power laser delivering.
文摘This paper describes the implementation ofan RF receiver front-end for the 2.4 GHz industrial scientific medical band under TSMC 0.13 μm CMOS technology; it comprises a low noise amplifier （LNA） which uses an added gate-source capacitor for low power performance and a dual-converter composed of a single-balanced active RF mixer and double-balanced passive IF mixer. Dual-down-conversion technique is used for reducing power. A 2.4 GHz low power low-IF RF receiver front-end is proposed. An LNA for rejecting image signal, an inductor- capacitor （LC） tank is used in series with source of input-stage transistor of the RF mixer, and combined with the LC load of the LNA, 30-dB image rejection is realized. Fabricated in a 0.13 μm CMOS process, the proposed chip occupies 0.42 mm2 area, achieves 4 dB noise figure, -22 dBm IIP3 and 37 dB voltage gain dissipating only 4.2-mW under 1.2-V supply.
文摘This paper analyzes the power markets both in northwest sending end and, east receiving ends, points out the favorable and unfavorable conditions for power development In, the northwest area, brings forward,the development planning of power sources and power network constructions, and presents the benefit estimation of sending power from northwest to east.
文摘Egypt has been facing a vast power crisis in the past few years. A dilemma is projected to surge on the long run if not properly dealt with. The power sector is totally dependent on fuel, which is a primary source of energy in Egypt, and since the production of energy is not equivalent to the rising demand, so it becomes a major cause behind the power crisis. Efforts so far had been concentrating on the supply side, while neglecting an equally important part of the equation presumed by the demand side. On the other hand, energy efficiency is fast becoming an integral part of the demand, where the residential sector in Egypt plays a very important part with around 47% of power consumption, making it the highest sector consuming energy from the demand side, and hence presents a good opportunity to investigate in term of energy efficiency and the promotion of its applications in order to solve the energy problem, so that later the same concept can be applied in other sectors for a holistic solution to the both the power and the energy problem in Egypt. This study will focus on generating a political framework to promote energy efficiency as a solution to the energy problem in Egypt at end-user’s level.
文摘After the North China grid and the Central China grid get into connection with the UHVAC demonstration, a new phenomenon is discovered according to some simulations. That is, the faults at the remote end of the UHV interconnected grid will result in significant power fluctuation and voltage drop on the UHV transmission line and even system splitting. But the faults near the UHV line only have marginal effects. Further, the simulation results also indicate that the short-circuit current of the buses near the UHV line is larger than that of the buses far away from the UHV line. This phenomenon is divergent from the traditional view. In this paper, the detail will be introduced, and the factors influencing the system stability after faults are presented and analyzed. The results indicate that transmission power of the UHV line and of the lines between the remote end and the major grid influence the fluctuation on UHV line. The load model and the grid structure of the remote end also have effect on it. Finally, corresponding control scheme is presented to improve the operation conditions of the UHV interconnected grid and ensure its security and stability.
