11-05-2012, 10:59 AM
POWER QUALITY IN ENERGY CONVERSION SYSTEMS.
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ABSTRACT
Power electronics and power quality are irrevocably linked together as we strive to advance both board areas. With the dramatic increases over the last20 years in energy conversion Systems utilizing power electronic devices, we have seen the emergence of “power quality” as a major field of power engineering. From a Power quality impact view point, applications such as Switched Mode Power Supplies, adjustable speed drives, and FACTS are often cause for concern. From utility supply system view point, these converter-based systems can lead to Operational and life expectancy problems for other equipment , possibly not owned or operated by the same party. It was from his initial perspective that the field of power quality emerged.
Introduction
The term “power quality “means different things to different people. To utility suppliers, power quality initially refers to quality of service delivered as measured by the consumer’s ability to use energy delivered desired manner. This conceptual definition included such conventional utility planning topics as voltage and frequency regulation and reliability.
The end-user’s definitions of Power quality also centers around their ability to use the delivered energy in the desired manner, but the topics considered can be much more specific and include magnitude and duration of different events as well as wave shape concerns.
I. Categories of power quality:-
1. Steady state voltage magnitude and frequency,
2. Voltage sag’s,
3. Grounding,
4. Harmonics,
5. Voltage fluctuations and flicker,
6. Transients and
7. Monitoring and measurement.
II.Reactive power and harmonic compensation:
1. Typical harmonics produced by equipments
2. Harmonic filters
1. STEADY STATE VOLTAGE FREQUENCY AND MAGNITUDE:-
Frequency deviations can affect power electronic equipment
that use controlled switching devices unless the controlled signals are derived from a signal that is phase-locked with the applied voltage. In most cases, phase-locks are used, or the converters consist of uncontrolled rectifiers. In either case, frequency deviations are not a measure cause of problems. Steady state voltage regulation is a much more pronounced issue that can impact a wide range of endues equipment in most cases, utility supply companies do a very effective job of providing carefully regulated voltage with in permissible ranges.