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Active filters are known as the best tools for harmonic mitigation as well as reactive power compensation, load balancing, voltage regulation, and voltage flicker regulation on the power lines. To introduce the operation of active filters in education, it is a good method to use a software, named SPICE. It is a good choice, because it has a high level of objects for simulation, and good presentation...
The distortion of a current-steering digital-to-analog converter (DAC) is often dominated by the signal-dependent output impedance. This has normally been analysed by assuming a purely resistive load. When a digital IF signal is generated, the different harmonic bands are separated and can also be filtered separately. This paper illustrates that linearity can be improved considerably by shorting the...
Ever more students start their master programme with a bachelor degree which does not provide the ideal background for their study. Such students benefit from dedicated help when they have to master advanced topics in automation, control and electrical engineering. Because individual help is adequate but too labour-intensive, a self-study package has been developed by which individual students can...
The arc furnace is an important load which affects the electrical energy quality of the electrical power system. High harmonic current and low power factor are in 20T arc furnace short net. Here we proposed a Mallat algorithm based on multi-resolution analysis of wavelet transform separating the fundamental current and harmonic current, to detect harmonic current in the short net current. Results...
Monitor and analysis of power system is very important to guarantee power quality. Accidents often occur because of bad power supply quality. So power department and user of electric power all want to improve power quality. Monitor and analysis System of power quality is widely used. The paper monitored fluctuated condition of power quality index by means of method of frequency spectrum analysis based...
Some methods of detecting harmonic current in the power system were analyzed in this paper, the models were built and simulated with Matlab simpowersystem module, result indicates ip-iq method can detect harmonic currents in the balanced power system and as long as doing an improvement slightly, can use single phase ip-iq to check the harmonic electric current in the single phase system, or to apply...
Nowadays, most of the electrical railway tractions, especially the high-speed tractions are using AC-DC-AC power driving system. The best choice for the AC-DC link is four-quadrant PWM rectifier, which can provide controllable DC link voltage and better power factor for the grid. In high power drive applications, the switch frequency of the power semiconductor device cannot be very high, usually less...
Harmonic detection based on Wavelet Transform is one of the hottest problems of the measurement of harmonics in power system. The paper introduces the selecting principle of wavelet function, and chooses the optimum wavelet function used for power harmonic detection, The MATLAB simulation testified that db20 to db30 wavelet are applicable to harmonic detection and we can get not only every harmonic...
To achieve the dimensional synthesis of planar four-bar linkages, it established the numerical atlases of coupler rotation-angle operator harmonic characteristic parameters and coupler rotation-angle function's harmonic components firstly. It achieved the basic dimension type of linkages and the mathematical model of coupler path based on complex-vector theory secondly, then acquired the formula of...
In the actual power system three-phase voltages are distorted and asymmetric and contain a large number of negative sequence components. Traditional ip-iq method which detect harmonic currents based on instantaneous reactive power theory will be inaccurate, so the positive sequence voltage component of A-phase need be extracted. Improved instantaneous symmetrical components structured a rotary phases...
In this paper is presented the structure and working principle of the cascaded H-bridge multilevel converter with PWM rectifier and phase-shift transformer. Using the leak inductance as the filter reactor of the PWM rectifier can reducing the volume and cost of the converter; the phase-shift secondary side of the transformer can eliminate the current harmonics caused by the single power unit, restraining...
Sensorless Brushless DC motors have been a research focus home and abroad, because their characteristics of small volume, high reliability, strong anti-interference and the ability to overcome inaccurate commutation caused by mechanical installation. This article will carry on a research on the operation principles and performance characteristics of sensorless DC motors and methods that terminal voltage...
We present an all-pairs shortest path algorithm whose running time on a complete directed graph on n vertices whose edge weights are chosen independently and uniformly at random from [0,1] is O(n2), in expectation and with high probability. This resolves a long standing open problem. The algorithm is a variant of the dynamic all-pairs shortest paths algorithm of Demetrescu and Italiano. The analysis...
The proposals for the “More Electric Aircraft” place a significant, increased demand on the electrical power distribution system. To increase safety and reduce aircraft maintenance times on the ground, there is a greater need to quickly identify and locate electrical faults within the electrical distribution system. The work presented in this paper forms an initial study into the use of power system...
A simple but powerful design method based on real-coded Genetic algorithms (GAs) to solve the minimization of the Total Harmonic Distortion (THD) criterion is obtained. GAs provides a much simpler approach to off-line tuning of Pulse width Modulation (PWM) switching angles than the rather complicated non-genetic optimization algorithms. Genetic algorithms are exploratory search and optimization procedures...
A small scale laboratory demonstrator has been constructed to represent a zonal DC distribution system as proposed for future naval vessels. This paper describes how the demonstrator has been used to validate a proposed fault location strategy - Active Impedance Estimation (AIE) - under experimental conditions. The practical processing algorithms required to reduce the effect of noise and the background...
A new method for calculation of first order sensitivity and sensitivity groups for Multiple FeedBack (MFB) filter in non-sinusoidal regime is presented. Such a group of linear dependent parameters is defined the relative input values of current and voltage harmonics. The interdependence of the various network sensitivities for a given network needs special consideration. Numerical example for Butterworth...
In this paper a stiffening technique for cage rotors of induction machines is proposed and analyzed, aimed at reducing the mechanical oscillations excited by the traction torque harmonics. The solution is simple, consisting of stiffening blocks inserted between couples of adjacent copper bars, overhanging from the rotor stack. The insertion of the stiffening blocks yields an increase of the lowest...
Wrist pulse-diagnosis has been used in traditional Chinese medicine for thousands of years, because pulse wave signal contains a large number of physiological and pathological information of people, the analysis on it is an important means to examine on people in sub-health status. In this research, a systematic approach was proposed to analyze the computerized wrist pulse signals, with the focus...
In a monaural polyphonic context, music transcription and specifically, multiple-F0 estimation systems have achieved promising results in the last decade. However, most of these systems present intermittent misses of pitch within a note or inaccurate definitions about onsets and offsets due to frame-by-frame analysis. In this paper, we propose a multiple-F0 estimation system which extracts a set of...
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