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There are two commonly used 3-phase configurations in power grid applications, the 3-phase 3-wire, and 3-phase 4-wire configurations. The 3-phase 4-wire power converter systems is necessary to supply single-phase loads but at the expense of higher output harmonics and losses, as compared to 3-phase 3-wire systems. The neutral inductor is added to reduce the neutral line harmonics and a LCL+ L filter...
A tubular flux-switching permanent-magnet linear machine (PMLM) is proposed and designed for free-piston energy converter. The influences of several main structure parameters on the machine performances are investigated. The power, power density and efficiency are improved by optimizing the structure parameters. Further, characteristic of the detent force is studied and the detent force is reduced...
The high power density converter (HPDC) in more electric aircraft gains more and more attention. However, HPDC is one of the main harmonics and electromagnetic influence (EMI) sources in aircraft network. To improve power density of HPDC, different levels with power converter includes 2-level, 3-level, and 5-level configurations will be investigated. Besides, two 3-phase power grids such as 3-phase...
A novel broadband linearization scheme for time-stretch analog-to-digital converters employing an asymmetrical dual-parallel Mach-Zehnder modulator and a balanced detector is presented. The theoretical and simulation results show that the proposed scheme can effectively suppress the even-order distortions and the third-order spurs even under a large modulation depth. The carrier to third-order intermodulation...
Noise and vibration is one of key issues in the development of the direct drive wind power generator. The exciting radial forces can cause unwanted noise/vibration. In this paper, the influence of generator parameters on exciting radial forces is studied. A noise and vibration reduction method based on harmonic current injection is evaluated. The side band vibration phenomenon is found and discussed.
This paper promotes a better understanding of the power grid quality and dynamics through the introduction of a newly developed Universal Grid Analyzer (UGA). The UGA is a real-time, highly accurate, and GPS synchronized power grid monitoring device used at distribution level. They can function as a power quality analyzer by performing harmonics measurement along with voltage sag and swell detection...
Calculating additional losses of the transformer driven by load harmonics is very significant to economic, safe and efficient operation of transformer. Based on the transditional model of additional losses driven by load harmonics, the simplified model is put forward, as well as the calculation equation. According to the simplified model, a method to monitor the transformer harmonic losses online...
In this paper, internal fault protective relay maloperation of assembling capacitor bank caused by switching-on transient harmonics is analyzed. Mathematical expressions describing the adaptive settings of single-wye, dual-wye and bridge connections are given. The realistic action of internal fault protections under high amplitude harmonic conditions is possibly very different from theoretic setting...
An improved adaptive harmonic detector based on adaptive control theory was presented, and analyzed systematically. The proposed method conquers the limitation of the average adaptive harmonic detection methods and is able to detect harmonic as well as extract distortion of currents. The transient speed of the novel adaptive is improved through chose of learning rate. Due to its excellent tracking...
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