Design of Intelligent Controller Based Facts Devices for Voltage Fluctuation

Abstract

ABSTRACT newlinePower Quality is the term used to describe how closely the electrical power delivered to customers conforms to the appropriate standards in operating their end-use equipment correctly. Therefore it is essentially to have a customer-focused measure that is greatly affected by the operation of the distribution and transmission network. There are number of ways in which the electric supply can deviate from the specified measures. These range from transients and short duration variations to long-term waveform distortions. Sustained complete interruptions of supply are generally considered as an issue of network reliability rather than power quality. The growing importance of power quality is due to the increasing use of sensitive load equipment including computer-based controllers and power electronic converters. Besides, the customers are well aware of the commercial consequences of disturbances originating on the power system. Any problem associated with voltage, current or frequency deviation that causes failure or mal-operation of customer equipment is termed as a power quality problem. For quality power, voltage and current should be purely sinusoidal with a specified magnitude and frequency. Hence power quality is the combination voltage quality and current quality. Voltage quality involves the performance of the power system towards the load, while current quality involves the behavior of the load towards the power system. Voltage quality issues may arise in the form of voltage harmonics, over-voltage, under- voltage, voltage sag, voltage swell and voltage fluctuations. Change in wave shape of voltage is termed as voltage harmonics. Decrease in RMS voltage from 10% to 90% of rated value for more than one minute is termed as under voltage. Decrease in RMS voltage from 10% to 90% of rated value for a period less than one minute is termed as voltage sag. Increase in RMS voltage from 10% to 80% of rated value for more than one minute is termed as over voltage. Increase in RMS voltage from 10% to 80% of ra