Analysis and control of multilevel converters connected to the distribution grid for photovoltaic arrays and storage energy devices

Author(s)

Giovani Guarienti Pozzebon

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2013-05-10

Examining board members

José Carlos de Melo Vieira Júnior; Carlos Alberto Canesin; José Roberto Boffino de Almeida Monteiro; Sérgio Pires Pimentel; José Antenor Pomilio

• Advisor: Ricardo Quadros Machado

Abstract

The utilization of multilevel converters has been an important alternative for medium voltage applications with high power and power quality demand, thanks to the high power levels achievable for this kind of structure. Recently, this converter topology was proposed as a new possibility in renewable energy source applications, mainly in system delivering power to the grid, where different renewable energy resources may be used. Based on the characteristics of multilevel converters, and their potential applicability in distributed generation systems, this study aims to build a multilevel system that could be powered by renewable energy sources as primary sources and then connect them to a distribution grid. However, considering the energy produced by alternative sources can vary, it is analyzed the integration of a storage energy system in this multilevel topology. Taking into account this ends, the main concern of this study is related to the development of a control strategy to maximize the active power transferred to the grid. The multilevel topology employed in this study has two H-bridge inverter modules connected in series forming a cascaded configuration. Therefore, it is possible that at least one of these inverters, operating with a low frequency of modulation, process the majority of power with lower amount of losses. On this way, two control strategies for power transfer are analyzed. The advantages and disadvantages of each method are presented, and the most appropriated strategy is used in the operation of the multilevel converter system. In addition, it has been presented the design criteria for each controller and finally the validation of the proposed approach is done by mains of simulations and experimental results which show the ability of the converter to transfer constant active power to the grid and keep the grid current in phase with the grid voltage. (AU)

• FAPESP's process: 08/10451-1 - Analysis and Control of Multilevel Converters Connected to the Distribution Grid for Photovoltaic Arrays and Storage Energy Devices
• Grantee: Giovani Guarienti Pozzebon
• Support Opportunities: Scholarships in Brazil - Doctorate