Capacitor Voltage Balancing in Two-Level Inverter with Split Capacitor Topology for DSTATCOM Application using Model Predictive Control

A Distribution Static Compensator (DSTATCOM) with split capacitor configuration is implemented in this paper to adjust reactive power requirements of various loads, harmonics, and unbalanced load factor compensation. The most serious issue with this structure is capacitor voltage imbalances, which cause the voltage source inverter (VSI) tracking performance to degrade. In the literature, the proportional integral (PI) controller and model predictive controller (MPC) are employed to suppress voltage divergence. However, the aforementioned controller is effective for three-phase diode bridge rectifier loads as well as unbalanced linear loads. Capacitor voltage balancing is not accomplished in half wave rectifier load because of the presence of its dc component. To provide capacitor voltage balancing for all combinations of loads such as linear unbalanced, half wave rectifier, and three phase diode bridge rectifier loads functioning alone or collectively, a two quadrant chopper circuit is employed across the split capacitors. The switching pulses of chopper switches conventionally generated using a hysteresis current controller, while the switching states of chopper and VSI switches are obtained purely using MPC in this paper. To validate the suggested control strategy, the generated model was studied and results were obtained using detailed simulation using MATLAB.