Power Quality Improvement Using Shunt Active FilterWith Fuzzy Logics

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International Journal of Engineering, Management & Sciences (IJEMS) ISSN-2348 –3733, Volume-2, Issue-1, January 2015

Power Quality Improvement Using Shunt Active FilterWith Fuzzy Logics Kamalesh sharma, Sunil kumar goyal, Nagendra kumar swarnkar  Abstract— Power quality is a very important issue. Non-linear loads and semi-conductor devices connected to AC electric mains generate unwanted signals (harmonics) in the dynamics of current which are responsible for additional power losses in heat loss and the risk of equipment damage or malfunctioning. In the simulink model of shunt active filter fuzzy logic controller and hysteresis current controller for reducing the harmonic distortion. Powergui tool of mat lab provides the function of FFT analysis which is very important to calculate total harmonic distortion in source current. By taking various firing angles the total harmonic distortion is calculated by FFT analysis. Index Terms—Shunt Active Filter, Fuzzy Logics, FFT analysis, Harmonic Distortion

I. POWER QUALITY IN POWER SYSTEMS Power quality is a phrase that means different things to different consumers. Power quality is defined in Institute of Electrical and Electronic Engineers (IEEE) Standard IEEE1100 as “This is the method of power supply and grounding sensitive electronic equipment and other nonlinear equipment in amanner such that is suitable for the equipment.” As appropriate as this description might seem,the limitation of power quality to “sensitive electronic equipment and nonlinear equipment” might be subjectto disagreement. Electrical equipment susceptible to power quality or more suitableto lack of power quality would fall within a seemingly boundless domain.All electrical devices are prone to failure or malfunction when exposed to one ormore than one power quality problems. Examples of poor power quality A. VOLTAGE SAG Voltage sag (also called a “dip”) is a slight decrease in the r.m.s value of line voltage of 10 to 90 percent of the nominal line-voltage. The duration of a sag is 0.5 cycle to 1 minute [1.44–1.50].

cycles to 1 minute. Sources of voltage swells are line faults and incorrect tap settings in tap changers in substations. C. Transient It is a brief, unidirectional variation in voltage and current, or both on a power line. The Most Common The most common causes of impulsive transients are lightning strikes on power line, switch on or off of inductive loads, or switching in the power distribution system. Interruption: Interruption is the reduction in line-voltage or line-current to less than 10% of the nominal, not exceeding 60 seconds in length. Voltage Imbalance: A voltage “imbalance” is defined as variation in the amplitudes of 3-phase voltages, relative to another. Flicker: Voltage fluctuations variations in the rms line-voltage are relatively small (less than 5 percent). II. POWER QUALITY INDICES UNDER HARMONIC DISTORTION There are some power quality indices those are comprehensibly described:  Total Harmonic Distortion: Total harmonic distortion (THD) is very important index. Which is widely used to describe power quality agenda in transmission and distribution networks. It considers the contribution of every individual harmonic component on the signal. THD is given for voltage and current signals, respectively, as given below:

(3.1) B. Voltage swell A voltage swell is the converse to the sag. A swell is a brief increase in the r.m.s of line-voltage of 110 to 180 percent of the nominal line-voltage for duration of 0.5 Manuscript received January 18, 2015 Kamalesh sharma, M.tech Scholar Apex Institute of Engineering College Jaipur Sunil kumar goyal, Assistant Professor ,Manipal University, Jaipur Nagendra kumar swarnkar, 3Associate Professor at Apex Institute of Engineering College, Jaipur

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 Telephone Influence Factor (TIF): This index is found in IEEE-5197 as a measure of audio circuit interference produced in electric power systems by harmonics. It will thus use the total harmonic distortion concept influenced by appropriate weighting factors, ωh, that establish the sensitivity of the human ear to noise from different frequencies:

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