Pusat Pengajian Kejuruteraaan Elektrik dan Elektronik - Tesis

Browse

Browsing Pusat Pengajian Kejuruteraaan Elektrik dan Elektronik - Tesis by Author "Al-Maryam, Taha Ahmed Husain"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Publication
    Integrated optimization-based technique incorporating multilevel inverter for minimization of total harmonic distortion.
    (2025-06)
    Al-Maryam, Taha Ahmed Husain
    The primary aim of employing multi-level inverter (MLI) is to obtain an output of sine wave that contains the lowest level of unwanted harmonics. This increases the electrical power efficiency by reducing the distortion in the electrical network. MLI is used in many applications that require medium voltages and high power, and it is chosen as an ideal choice in the fields of clean energy source industry, such as photovoltaic cells, wind energy, UPS, and variable frequency drives, as well as in electrical power transmission and numerous other uses. Two important factors contribute to diminishing the harmonic components in MLI. The first one is to decrease the number of switches for certain levels. The second is to eliminate selected numbers of harmonics by using intelligent algorithms. This contributes to reducing the total harmonic distortion (THD) ratio and enhancing the system’s efficiency and reducing the costs of manufacturing the MLI. In this research work, the staircase-like sine waveform of MLI is fabricated through selective harmonic elimination techniques (SHE) based on intelligent algorithms. When examining many algorithms for different values of the modulation index, they produce different values for the THD. To achieve this objective, five optimization algorithms have been developed. It is worth emphasizing that no individual algorithm is capable of efficiently minimizing THDs across all modulation index values. Therefore, the hybridization of these five algorithms becomes essential. The lowest values of THD are selected from each algorithm and compiled into a hybrid algorithm capable of giving the lowest values of THD for each modulation index range. This criterion is adopted for operating the MLI switches. A thirty-one level 3-phase 50Hz MLI is engineered and implemented using a minimum number of switches, incorporating 30 switches and 12 DC sources in total, i.e., 10 switches and 4 DC sources per phase. The Spartan3E board with 50MHz clock frequency is used as the controller kit. VHDL (Very High-Speed Integrated Circuit Hardware Description Language) programming is employed to code the hybrid algorithm. In the test and measurements, resistors were used as static loads and a 3-phase induction motor as dynamic load. Simulation of the 31-level MLI is conducted using MATLAB Simulink software. Simulated results show a distinct agreement with the results of the experimental prototype. This research presents practical and simulated results for the voltages and currents associated with different loads, as well as frequency analysis and THD ratios for each case. The THD did not exceed 5% for the output voltages and a lower THD value for the output currents for all operating conditions is detected. The phase difference between the three phases did not exceed 0.4% due to the high accuracy provided by the SPARTAN35 controller.