|Title:||Harmonics control of lift in high-rise building|
|Subject:||Harmonics (Electric waves)|
Electric power systems -- Control.
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Building Services Engineering|
|Pages:||75 pages : color illustrations|
|Abstract:||With the increasing use of electronic equipment like computers, fluorescent lightings, and variable speed motors in modern building, the problem caused by harmonics is getting serious, and draws more attention than before to control the harmonics. Such equipment generates large harmonic currents in power distribution system of the buildings, and may cause malfunction or failure of sensitive equipment. In high rise buildings, the harmonics situation is more serious because the high rise nature. The long feeder or raising mains as well as the distribution transformers cause significant harmonic voltage drops along those circuits, and distort the power supply especially on upper floors in the buildings. This paper discusses sizing filter for harmonics generated by lift in a more economical way. Normally for mitigation of harmonics there are several effective way, when planning the installation of large nonlinear plant components the decision has to be made between designing the nonlinear devices for low levels of waveform distortion or installing harmonic compensation equipment at the terminal. Passive or active filter are often used for mitigate the harmonics. Nowadays sizing filter for lift is based on the worst case in order to comply the harmonics limits, which is estimate the maximum harmonics generated by single lift and multiply the number of lift installed together. This is an effective way of sizing, but it may over sizing the filter for the situation. Because when lift work on different loads and different stage (accelerate, decelerate, constant speed), it can generate different harmonic current, Irms value may not always constant be maximum, the maximum value actually only appears very short time in extreme situation. Furthermore different lift also work in different situation, phase harmonic current might effected by this. As long as comply the regulations, we can sizing filter in a more economical way.|
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