Modeling For Reduction Of Harmonics Using Inverters In Smart Grid System

Saeed, Ali Kareem (2016) Modeling For Reduction Of Harmonics Using Inverters In Smart Grid System. Masters thesis, Universiti Teknikal Malaysia Melaka.

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The rapid growth of grid-connected PY generation resulting in the total harmonic di tot1ions (THO) due to use of PV inverter is becoming a major concern. The output voltage of the inverter is a square or a nearly sinusoidal waveform, therefore, the output voltage contain the hannonic. Harmonic contents depend on the type and typology of the inverter. Use of multilevel inverter helps to solve this problem. Several converter topologie have been used in low-voltage applications; most of the topologies are not suitable in medium-voltage applications. CHB-MLI based on OHSW-SHE is a preferred choice to solve this problem. In this inverter, the THO depends on the switching angle and modulation index. The number of levels which can be synthesized in line voltage depends on MI ince the RMS line voltage depend on these number of levels. In this research, ewton Raphson iterative method is implemented for the computation of the optimal switching angles and total hannonic distortion (THO) in 5,7,9, 11 and 13-level inverter. The switching angle are calculated offline to eliminate lower order harmonic that are more hannful and difficult to remove without filter while the fundamental output voltage I obtained as desired. The simulation modeling for the single phase and the three-phase for 5.7,9,11 and 13-level CHB-MLI is done by u ing MATLAB Simulink . The THO for pha e voltage and line voltage for three-phase output inverter i obtained from the imulation for variou values of Modeling Index (MI). Computational THDs are validated with MA TLAB simulations, and both results are in close agreement. ln addition, the values of (MI) which achieve the maximum level in line to line voltage is also computed. In CHB-MLI, number of IGBT is proportional directly to number of level. One of the important features for CHB-MLl is the ability for this type to get a high AC voltage based on cascaded DC source. In addition, SHE technique helps to eliminate the lower order harmonics in the output voltage. This reduction in the THO value for the output voltage is below the limitation set in TEEE-519 without filtering y tem. Thu , it is nece ary to investigate the ability to produce 11 kv transformer less inverter to eliminate a bulk transformer in PV farm. Parameter identification is a vital part of the medium-voltage inverter de ign process. In this project, suitable IGBTs for 5, 7, 9, II , and 13 level II kYvoltage CHB-MLI for renewable generation ystem (PY) is selected accordingly. The availability of IGBT modules in the market is considered in the selection process. The result hows the line voltage THD for 13-level is below the limitation et in IEEE-519 without filtering system. [n addition, the IGBTs for 13 level II kV CHB-MLT inverter are costed a minimum total price of IGBTs when compared with IGBTs price for 5, 7, 9, and 11level. This means in transformer less CHB-MLI type, the I 3-levcl is more suitable for II kY medium application. However, this research i limited to harmonic reduction only using CHB-MLI based on OHSW-SHE, not including filter system. Also, the elimination ofhannonic is done by calculating the optimum switching angles by using equal SDCS.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Harmonics (Electric waves), Filters and filtration
Subjects: T Technology > T Technology (General)
T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Library > Tesis > FKE
Depositing User: Nor Aini Md. Jali
Date Deposited: 13 Jul 2017 07:42
Last Modified: 13 Jul 2017 07:42
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