Control strategy for Modular Multilevel Converter applied to Active Power Injection and Reactive Power Compensation: Integration in PV Microgrids

This paper proposes a strategy for the active and reactive power flow control, applied to a three-phase power inverter connected to a microgrid. In recent years, smart grids have changed the energy distribution sector. The power quality is essential in the integration of renewable energy sources into small microgrids. These renewable microgrids can operate in stand-alone mode or connected to the utility grid. The continuous development of non-linear loads such as converters, fluorescent lamp, AC and DC-drives, switched mode and uninterruptable power supplies are producing harmonic pollution problems in the distribution grid. This way, the effective use of a small photovoltaic installation for the active power injection and reactive power compensation in a microgrid has been presented. As a technological innovation, a modular multilevel converter (MMC) is introduced, as well as the power flow control technique. The purpose is to improve the voltage unbalance and harmonic compensation in stand-alone grids. The model shown allows to control the power flows in microgrids and smartgrids; improving the power quality and the reliability of the distribution system. The grid-connected inverter has also ability harmonic current suppression generated by nonlinear loads. Advantages the developed model include: the cellular concept, easy thermal design, increased system efficiency, low overall cost as well as improvement in the system expansion capacity. The simulation model has been developed using the MATLAB/Simulink software. The results obtained have been satisfactory.