scispace - formally typeset
Search or ask a question
Topic

Harmonic

About: Harmonic is a research topic. Over the lifetime, 44833 publications have been published within this topic receiving 495922 citations. The topic is also known as: overtone & partial.


Papers
More filters
Journal ArticleDOI
TL;DR: It is shown that, in the case of machines with one or several broken bars, the IF of the LSHst exhibits a very characteristic and easy to identify pattern, which is physically justified, and a universal fault indicator can be defined.
Abstract: In this paper, a new method for detecting the presence of broken rotor bars is presented. The proposed approach is valid for induction machines started at constant frequency and consists of extracting the instantaneous frequency (IF) of the left sideband harmonic (LSH) from the start-up current (LSHst), via the Hilbert transform. It is shown that, in the case of machines with one or several broken bars, the IF of the LSHst exhibits a very characteristic and easy to identify pattern, which is physically justified. This paper also shows that, if the IF of the LSHst is represented against the slip, a universal fault indicator (nondependent neither on the machine characteristics nor on the starting conditions) can be defined. This fault indicator consists of the correlation between the experimental IF of the LSHst and its theoretical evolution. This approach is theoretically introduced and experimentally validated by testing a commercial motor in faulty and healthy conditions, under different operating conditions.

105 citations

Journal ArticleDOI
11 May 2006
TL;DR: In this paper, the authors investigated the use of ancillary services from inverter-interfaced distributed generators (DGs) to achieve harmonic mitigation across a network, including the functionality of a resistive active-power filter (R-APF) within several DGs.
Abstract: The paper investigates the use of ancillary services from inverter-interfaced distributed generators (DGs) to achieve harmonic mitigation across a network. The approach is to include the functionality of a resistive active-power filter (R-APF) within several DGs. The R-APF provides adjustable damping at harmonic frequencies. In a realistic network, which has feeder sections of different characteristic impedances, it is impractical to damp with a single value of resistance. Instead, feeders are split into harmonic sections based on the standing waves of the highest-order harmonic, and DG ancillary services are called up for each section. Co-ordination of services from each DG is arranged through adaptation of the harmonic resistance according to target THD levels. The primary purpose of each DG is the supply of real power and this is respected through a further aspect of the resistance adaptation which reduces the harmonic duty of an individual DG if it approaches the apparent-power rating of the inverter. The harmonic VA required of the inverter is dependent on both the chosen harmonic resistance and the harmonic-voltage component present at the connection bus. The system is demonstrated through a simulation of an irregular feeder using Simulink and PLECS.

105 citations

Journal ArticleDOI
TL;DR: In this paper, the harmonic analysis of systems containing nonlinear dynamic components in periodic steady state was formulated in the complex conjugate multiharmonic space that inherently represents the harmonic coupling between the different harmonic frequencies.
Abstract: Computer algorithms of the Newton-Raphson type are derived for the harmonic analysis of systems containing nonlinear dynamic components in periodic steady state. The problem is formulated in the complex conjugate multiharmonic space that inherently represents the harmonic coupling between the different harmonic frequencies. The theory is applied to single-phase systems, including magnetic nonlinearities. >

105 citations

Proceedings ArticleDOI
21 Feb 1995
TL;DR: In this article, an analysis and design method of the output LC filter of single-phase PWM inverters is presented, where analytical expressions for the total harmonics of the inductor current and capacitor voltage of the LC filter are derived.
Abstract: In this paper, an analysis and design method of the output LC filter of single-phase PWM inverters is presented. At first, the analytical expressions for the total harmonics of the inductor current and capacitor voltage of the LC filter are derived. As the unique values of the parameters of the LC filter cannot be specified based on the total harmonic of the capacitor voltage alone an additional criterion based on the minimum reactive power of the LC filter is used to specify these parameters. Experimental results are included to verify the derived expressions. >

105 citations

Dissertation
01 Jan 1998
TL;DR: In this paper, the authors investigated the differences between human induced loading on floors and that on stairs, and showed that loading data from floors is highly inappropriate for staircase design, and they used Monte Carlo simulation techniques to model the effects of group loading on stairs.
Abstract: Over the last decade it has become increasingly popular to provide large public areas with gracefully designed 'flexible' staircases. One inherent characteristic of this type of construction is a low stiffness to mass ratio and hence a low natural frequency when compared to more traditional designs. A number of staircases have been found to be dynamically responsive to pedestrian traffic resulting in costly repairs. The objective of this thesis was to investigate the differences between human induced loading on floors with that on stairs. Experimental work carried out on a purpose built staircase showed that forces up to 3 times the static body weight were generated during fast descents while forces up to 2.5 times the static body weight were generated during fast ascents. The work also showed that first harmonic values generated while ascending were slightly higher than for descending whilst second harmonic values were up to 3 times greater for fast descents than for fast ascents. When compared with floor testing, stair testing produced first harmonic values nearly 2.5 times greater with second, third and fourth harmonic values nearly 3 times greater. The harmonic results for the flat testing were also incorporated into a new mathematical expression to predict peak accelerations on simply supported floors and footbridges. The experimental results were duplicated analytically by developing a computer program to calculate the vertical ground reaction forces from body segment positional data. Following a Newtonian approach, the predicted first harmonic values were 20% to 30% lower than actual while the second harmonic values were approximately the same. Monte Carlo simulation techniques were also used to model the effects of group loading on stairs. The simulations predicted enhancement factors (a multiplier on single subject loading) of 3 to 6 for smaller groups( 25 people). If the experimental/analytical results are combined with the group loading predictions, the harmonic values for groups ascending or descending flexible staircase could be substantially increased. These results demonstrate that loading data from floors is highly inappropriate for staircase design.

105 citations


Network Information
Related Topics (5)
Nonlinear system
208.1K papers, 4M citations
86% related
Voltage
296.3K papers, 1.7M citations
85% related
Boundary value problem
145.3K papers, 2.7M citations
81% related
Matrix (mathematics)
105.5K papers, 1.9M citations
79% related
Magnetic field
167.5K papers, 2.3M citations
79% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,223
20222,724
20211,878
20202,330
20192,612
20182,495