Conversor Matricial para Interligação de Geradores Eólicos Residenciais

Abstract

The use of electronic converters and digital control in energy generation systems actively contribute to increasing the efficiency of the generated energy processing, which enables the delivery of levels of excitement and frequency suited to the norms and requirements for its loads. Many industrial processes that are powered by alternating current need specific voltage and phase levels for their activation and control, which imposes power quality criteria and can be provided by static converters. The generation of electricity from small wind turbines with synchronous generators, as they have voltage and frequency levels dependent on the speed of the wind, requires the conversion of these levels to fixed frequency and voltage compatible with the load or network, which the generator is connected. Wind energy is one of the fastest growing energy sources in the world, due to the increase in technologies that provide the processing of electrical energy generated at the terminals of its electric generator. Such processing, commonly done by back-to-back converters, can be performed by a pulse-width modulated matrix converter (direct AC/AC converter). Due to the fact that the matrix converter delivers voltage and frequency in only one stage, DC bus capacitors are not needed and may employ less robust switches compared to the back-to-back converter. Capacitors only will be needed in the input and output filters, also present in the back-to-back converter. The absence of the DC bus between the AC/AC conversion considerably increases the life expectancy of the system and reduces maintenance. Therefore, this work aims to study the interconnection of the synchronous generator of residential wind turbines by a feedback matrix converter, performing its mathematical modeling for the adequacy of the control. The methodology for this purpose includes writing the algorithm that governs the operation of the converter, initially on the Psim simulation platform and later on a digital platform with ESP-32 microcontroller. The algorithm was programmed using the Arduino development platform (IDE). A prototype of the proposed matrix converter was developed on a printed circuit board and interconnected to the microcontroller board, which made it possible to perform performance tests so that its behavior, during voltage and frequency delivery for single-phase load, could be observed. Such prototype tests reinforce the applicability of the algorithm used for voltage modulation, with a clear trend of the converter response compared to that predicted in the literature. However, during tests with different output loads and input frequencies, it was observed that the output presented considerable harmonic content and output voltage limitations. The implemented control loop could not act properly to guarantee the sinusoidal voltage of low harmonic distortion for the load, culminating in the low efficiency of the converter operation. Finally, it is concluded that the algorithm needs improvement, but the application of matrix converters in small wind turbines is fully possible.