Reactive Power Control for Grid-Connected Inverters with PPWM at a Constant Modulation Index

The article is devoted to the development of a method for controlling reactive power of grid-connected inverters (GCIs) with pre-programmable pulse width modulation (PPWM) at a constant modulation index. The paper describes the GCI reactive power control modes, mathematical expressions for relationship between the reactive power level, DC link voltage, and modulation index. It allows us to determine the required voltage in the GCI DC link that provides a required level of reactive power generation or consumption at a constant modulation index. The article presents the experimental results of laboratory studies to confirm the operability of the proposed GCI control method for reactive power control. The oscillograms demonstrate reactive power compensation modes at a level of 10 kvar. The developed method can be used to compensate reactive power by GCI with PPWM.