Simplified Four-Level Inverter-Based Single-Phase DSTATCOM Using Model Predictive Control

The conventional two-level inverter-based distribution static compensator (DSTATCOM) requires high switching frequency and fast digital signal processors (DSPs) to obtain smaller voltage/current ripples and low total harmonic distortion (THD). This increases the switching loss and computational burden. To solve such problems, this article proposes a simplified four-level (S4L) inverter-based DSTATCOM. The proposed inverter has a two-stage structure. The first stage produces three different voltage levels of full, two-thirds, and one-third of dc link voltage. These voltage levels are supplied to the second stage two-level inverter. Together with the zero voltage produced by the two-level inverter, the output of the proposed inverter can be four levels. With the same switching frequency and computational time, the S4L inverter-based DSTATCOM achieves much better performance than the conventional ones. Moreover, compared with the existing multilevel inverter-based DSTATCOMs, it is more cost-effective. To further enhance its performance, model predictive control (MPC) is employed. Experimental results are presented to verify the validity of the proposed system.