causing a voltage sag with duration of more than 1 cycle occurs within the area of vulnerability. However, faults outside this area will not cause the voltage to drop below 0.5 pu. The same discussion applies to the area of vulnerability for ASD loads. The less sensitive the equipment, the smaller the area of vulnerability will be (and the fewer times sags will cause the equipment to misoperate).
The voltage sag performance for a given customer facility will depend on whether the customer is supplied from the transmission system or from the distribution system.
There is an upward trend that human activities involve more electric power nowadays
and for years to come. And we will soon be facing shortage of electricity supply if we
rely solely on non-renewable power generation from fossil fuels such as coals.
Renewable energy generation has proven effective in meeting the demand.
With technology advancements in semiconductor devices such as insulated gate
bipolar transistors (IGBTs) and gate commutated thyristors (GCTs), modern highpower
medium voltage (MV) drives are increasingly used in petrochemical, mining,
steel and metals, transportation and other industries to conserve electric energy,
increase productivity and improve product quality.
Although research and development of the medium voltage (2.3 KV to 13.8 KV)
drive in the 1-MW to 100-MW range are continuously growing, books dedicated to
this technology seem unavailable.
It is my privilege to do my Masters in Electrical Engineering Department at Boise
State University. I would like to take this opportunity to thank my Professors for
providing me with quality and technical education, guidance and motivation. The special
courses and the research have induced valuable concepts and good understanding of the
I would like to thank MURI (Multidisciplinary University Research Initiative
Program) for funding this project. Very special thanks to my advisor, Dr.
Motivated by the need of energy-efficiency improvements, process optimization, soft-start capability and numerous other environmental benefits, it may be desirable to operate induction motors for many applications at continuously adjustable speeds. The induction motor drives can provide high productivity with energy efficiency in different industrial applications and are the basis for modern automation. This book provides an account of this developing subject through such topics as modelling, noise, control techniques used for high-performance applications and diagnostics....
Power quality has become an important issue in recent times when many utilities
around the world find very difficult to meet energy demands which leads to load
shedding and power quality problems. This book on power quality written by experts
in their fields will be of great benefit to professionals, engineers and researchers. This
book comprises of 16 chapters which are arranged in two sections. Section one covers
power quality monitoring, classification, and analysis aspects.
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Detection of Disturbances in Voltage Signals for Power Quality Analysis Using HOS
Nowadays, the rapid growth of power electronics in industry and the presence of
products based on electronic components in enterprises, institutions, shops, small
businesses, residences, etc. and transport systems has been welcomed by the people
who already use it due to its increased productivity within all areas.
This is a simple unipolar stepper board that can control stepper motors rated to 30VDC. The FET drivers are
rated at 50A, but in practicality this board should not be used with motors anywhere near that current for several
reasons. The power supply voltage, heat sinks and cooling used for the FET’s of your own application play an
extremely important part in making that determination. The FET package is designed for 50 Watts of dissipative
power. If you’re not wise in electronics, the board should be built in stages and tested during each stage to
Power Quality Considerations
Harmonics • What Are Harmonics? • Harmonic Sequence • Where Do Harmonics Come From? • Effects of Harmonics on the System Voltage • Notching • Effects of Harmonics on Power System Components • Conductors • Three-Phase Neutral Conductors • Transformers • Effects of Harmonics on System Power Factor • Power Factor Correction Capacitors • IEEE Standard 519
Badrul H. Chowdhury
University of Missouri–Rolla
Tokyo Institute of Technology
Arizona State University
ul Hasan et al. Nanoscale Research Letters 2011, 6:348 http://www.nanoscalereslett.com/content/6/1/348
Single nanowire-based UV photodetectors for fast switching
Kamran ul Hasan1*, N H Alvi1, Jun Lu2, O Nur1 and Magnus Willander1
Abstract Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison.
In this paper we present the implementation of a digital lock-in amplifier (LIA) completely based on Labview with a general-purpose data acquisition board (or a high quality sound card) and a high-gain low-noise amplifier. The signal analysis is processed by the software. We describe some characteristics of the LIA including output voltage vs. frequency and output phase vs. noise. The LIA can be used to measure the small signals, even in presence of broadband noise which is several times greater than the signal itself. Since the signal processing takes place on the computer, ...