Developing and Testing Model Predictive Control to Minimize Ground Potentials in Transformerless Interconnected Five-Level Power Electronic Converters

This article presents the implementation and performance evaluation of a model predictive control (MPC) for three-phase (3Ψ) transformerless interconnected five-level power electronic converters (PECs). The proposed MPC employs a discrete-time model of five-level PECs to predict future values of the grid-injected currents and ground potential. Predicted values of the grid-injected currents and ground potential are used to set the reference signals to minimize a cost function, which is formulated in terms of the command and actual values of grid-injected current and ground potential. The proposed MPC is implemented for transformerless interconnected diode-clamped and flying-capacitor five-level PECs under different conditions. Test results show that the developed MPC can operate transformerless interconnected PECs to ensure accurate, dynamic, and fast responses to changes in the power delivered to the host grid. Furthermore, the MPC demonstrates a good ability to minimize ground potentials during steady state and step changes in the power delivered to the host grid.