This paper presents a compact Ultra-Wideband （UWB） band-pass filter using a high-pass filter and a low-pass one, and the resonator with lumped elements. The structure of our proposed bandpass filter is very simple a...This paper presents a compact Ultra-Wideband （UWB） band-pass filter using a high-pass filter and a low-pass one, and the resonator with lumped elements. The structure of our proposed bandpass filter is very simple and the Defected Ground Structure（DGS） structure is used to get the low-pass filter characteristics. This proposed band-pass filter can be much smaller than a cascaded type filter. As a result of simulation, the insertion loss is less than 0.3 dB throughout the pass-band of 2.2 GHz- 10.6 GHz, while the return loss is more than 18 dB. And it has rejection level of 36 dB at GPS band.展开更多
Power electronic interface of dispersed generation plays a very important role in connecting a dispersed generation with utility grids. A power electronic interface not only adjusts the amount of active and reactive p...Power electronic interface of dispersed generation plays a very important role in connecting a dispersed generation with utility grids. A power electronic interface not only adjusts the amount of active and reactive power injecting into a grid but also implements other importance duties as well. In this study, negative-sequence current injection has been fulfilled in three-phase power electronic interface for two important duties besides injecting reference power into utility grids. The first one is for islanding detection, and the other one is to enhance unbalance-fault ride-through capability of dispersed generation. This paper introduces a mechanism of negative-sequence injection based on controlling two separate coordinates of dq-control and explains the effect of negative-sequence injection in limiting the unbalanced currents generated from a dispersed generation. Using adaptive notch filter as a signal processing unit for the three-phase system, negative-sequence components are observed. The performance of entire control system is evaluated by time domain simulations, PSCAD/EMTDC （power systems computer aided design/electromagnetic transients including DC）.展开更多
Based on digital signal processing theory,a novel method of designing optical notch filter is proposed for Mach-Zehnder interferometer with cascaded optical fiber rings coupled structure.The method is simple and effec...Based on digital signal processing theory,a novel method of designing optical notch filter is proposed for Mach-Zehnder interferometer with cascaded optical fiber rings coupled structure.The method is simple and effective,and it can be used to implement the designing of the optical notch filter which has arbitrary number of notch points in one free spectrum range(FSR).A design example of notch filter based on cascaded single-fiber-rings is given.On this basis,an improved cascaded double-fiber-rings structure is presented to eliminate the effect of phase shift caused by the single-fiber-ring structure.This new structure can improve the stability and applicability of system.The change of output intensity spectrum is finally investigated for each design parameter and the tuning characteristics of the notch filter are also discussed.展开更多
基金supported by the IT R&D program of MKE/ⅡTA:Study of technologies for improvingthe RF spectrum characteristics by using the meta-electromagnetic structure[2009-F-033-01]
文摘This paper presents a compact Ultra-Wideband （UWB） band-pass filter using a high-pass filter and a low-pass one, and the resonator with lumped elements. The structure of our proposed bandpass filter is very simple and the Defected Ground Structure（DGS） structure is used to get the low-pass filter characteristics. This proposed band-pass filter can be much smaller than a cascaded type filter. As a result of simulation, the insertion loss is less than 0.3 dB throughout the pass-band of 2.2 GHz- 10.6 GHz, while the return loss is more than 18 dB. And it has rejection level of 36 dB at GPS band.
文摘Power electronic interface of dispersed generation plays a very important role in connecting a dispersed generation with utility grids. A power electronic interface not only adjusts the amount of active and reactive power injecting into a grid but also implements other importance duties as well. In this study, negative-sequence current injection has been fulfilled in three-phase power electronic interface for two important duties besides injecting reference power into utility grids. The first one is for islanding detection, and the other one is to enhance unbalance-fault ride-through capability of dispersed generation. This paper introduces a mechanism of negative-sequence injection based on controlling two separate coordinates of dq-control and explains the effect of negative-sequence injection in limiting the unbalanced currents generated from a dispersed generation. Using adaptive notch filter as a signal processing unit for the three-phase system, negative-sequence components are observed. The performance of entire control system is evaluated by time domain simulations, PSCAD/EMTDC （power systems computer aided design/electromagnetic transients including DC）.
基金supported by the National Natural Science Foundation of China (No.10804070)the Innovation Program of Shanghai Municipal Education Commission (No.09YZ06)Shanghai Leading Academic Discipline Project (No.S30108)
文摘Based on digital signal processing theory,a novel method of designing optical notch filter is proposed for Mach-Zehnder interferometer with cascaded optical fiber rings coupled structure.The method is simple and effective,and it can be used to implement the designing of the optical notch filter which has arbitrary number of notch points in one free spectrum range(FSR).A design example of notch filter based on cascaded single-fiber-rings is given.On this basis,an improved cascaded double-fiber-rings structure is presented to eliminate the effect of phase shift caused by the single-fiber-ring structure.This new structure can improve the stability and applicability of system.The change of output intensity spectrum is finally investigated for each design parameter and the tuning characteristics of the notch filter are also discussed.
