e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:12/December -2020
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SYNCHRONOUS REFERENCE FRAME THEORY BASED CONTROL OF SERIES ACTIVE POWER FILTER Faliqa Mushtaq *1 *1Bachelor
of Technology, Department of Electrical Engineering, Baba Ghulam Shah Badshah University, India.
ABSTRACT Presence of power electronic devices in the power system has created a number of power quality problems such as voltage sags, interruptions, voltage swells, harmonics. Of all these problems, presence of harmonics is the most troublesome for consumers as it causes malfunctioning of all the electrical equipments connected to the supply among other bunch of power quality problems. Solution to this problem is to connect a device named filter with the electrical system. Of all the existing filters, active power filter is the most efficient in filtering out harmonics. In this paper it is planned to present the simulation model and performance of synchronous reference theory controlled series active power filter. It can be concluded that synchronous reference theory is effective in filtering out voltage harmonics from a three phase electrical system. Keywords: Harmonic, Total Harmonic Distortion (THD), Synchronous reference frame theory (SRF), Series APF, Hysteresis Controller, Pulse width modulation (PWM),
I.
INTRODUCTION
Power quality is said to be poor when there is a change in supply voltage, current or frequency beyond permissible limits. It causes a range of power quality problems such as voltage sag, swell, inter harmonic, harmonics, interruption, blackout etc. The presence of harmonics in an electrical system is of grave concern as it causes malfunctioning of the electrical equipments connected to the supply, overheating of underground cables, insulation failure etc. [1] Solution to this problem is to connect filters to remove harmonics from the supply. There are two types of filters: passive and active. Passive filters do selective filtering and suffer from other drawbacks as well such as ageing, resonance etc. To overcome these limitations, active power filters were introduced. Active power filters(APF) have proved to be most efficient in harmonic and reactive power compensation. APF are of two major types: shunt and series. APFs injects harmonics into the supply at the point of common coupling. The harmonics produced by APF are the same as produced by loads but displaced by 180 degrees. Thus, it cancels out the effect of the harmonic generated by loads smoothening the supply waveform. Shunt APFs inject current harmonics into the supply system while as series APF inject voltage harmonics. Shunt APF is used for harmonic current compensation while as series APF is used for harmonic voltage compensation.[2]
II.
METHODOLOGY
Basic configuration of series APF Figure 1.1 shows a series APF connected to mains circuit which consists of supply and non-linear load. APFs are constructed with either a voltage source inverter or current source inverter, a reference generator and a control circuit. The series APF used for the power quality mitigation is realized as a six legged VSI which consists of IGBTs. The VSI is connected in series with the source impedance through a transformer. A capacitor is used at the input side of VSI to provide constant input to the VSI.
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