Cascaded push-pull and cascaded h-bridge inverter for total harmonic distortion reduction in stand-alone photovoltaic system

• Main Author: Saidatul Shema, Saad
• Format: Thesis
• Language: English
• Published: Universiti Malaysia Perlis (UniMAP) 2014
• Subjects: Inverter; Total harmonic distortion (THD); Photovoltaic (PV); Solar energy
• Online Access: http://dspace.unimap.edu.my:80/dspace/handle/123456789/32467

This thesis presents the cascaded Push-Pull and cascaded H-Bridge inverter for total harmonic distortion (THD) reduction in stand-alone photovoltaic (PV) system. This study involves the development of the proposed cascaded Push-Pull inverter and cascaded H-Bridge inverter for stand-alone PV system applications. This study also involves the data collection of solar irradiance, temperature and PV module electrical output. The output of PV module is in direct current (DC) form. However, the power utilisation in Malaysia is mostly in alternating current (AC) form. Therefore, a sophisticated conversion technique is required in converting the DC signal into AC signal which is known as inverter. The output voltage waveform of ideal inverters should be sinusoidal. However, the waveform of practical inverter is non-sinusoidal and contains harmonics. The aim of this research is mainly to study and develop the suitable inverter design that can be applied in stand-alone PV system. Therefore, three inverter designs which are Push-Pull inverter, cascaded Push-Pull inverter and cascaded H-Bridge inverter have been developed for stand-alone PV system and THD has been analyzed over these three inverters. The data collection of solar irradiance and temperature were analyzed in order to know the potential of solar energy application in Perlis. These data were measured using weather station at the Centre of Excellence for Renewable Energy (CERE), in Kangar, Perlis. Solar irradiance and temperature are two important variables to be considered in designing a PV system because these variables will affect the PV module electrical output. Based on the average monthly solar irradiance for the year 2011, the annual total solar irradiance in Perlis is 4715.95 W/m². This shows that solar irradiance intensity was very high and has a potential for PV power generation in Perlis. Meanwhile, the performances of the proposed inverters have been evaluated in terms of output waveform and THD. The Push-Pull inverter, cascaded Push-Pull inverter and cascaded H-Bridge inverter has been simulated using OrCAD software. These three inverter designs are modelled with the resistive load. Based on the simulation results, the performance of cascaded H-Bridge inverter is better compared to cascaded Push-Pull and Push-Pull inverters. The experiment also has been carried out using inductive load of 20 W AC water pump for Push-Pull and cascaded Push-Pull inverter while the cascaded H-Bridge inverter was tested with pure resistive load of 50 Ω. The experimental result shows that the output waveform of cascaded H-Bridge inverter is nearly to sinusoidal shape and the voltage THD is less than cascaded Push-Pull and Push-Pull inverter. A comparative study between output waveform and THD between simulation and experiment has been conducted and validated. The results obtained show that the experimental results are close enough to the simulation results. A comparative study of output waveform and THD between Push-Pull inverter and the proposed cascaded Push-Pull and cascaded H-bridge inverters has been also conducted. The result shows that the proposed cascaded H-Bridge inverter is better than cascaded Push-Pull inverter in terms of output waveform and THD. It also shows that the THD of proposed cascaded Push-Pull is better than Push-Pull inverter. Overall, these three inverter designs are basically suitable for DC source applications and can be applied for PV system applications which are dependent upon the load application.