Abstract:
The typical PI controller for a hybrid energy storage system (HESS) includes shortcomings including difficult parameter tweaking and the need for filters to apportion high- and low-frequency power variations.
Model predictive control (MPC) is proposed to control three-level bidirectional DC/DC converters for grid-connections to a HESS in a DC microgrid. First, the mathematical model of a HESS with a battery and ultra capacitor (UC) is constructed, and the neutral point voltage imbalance of a three-level converter is solved by studying its operating modes.
Second, an MPC approach is proposed for calculating steady-state reference values in the outer layer and dynamic rolling optimization in the inner layer to regulate grid-connected converters. The outer layer regulates voltage and establishes the current predictive model, while the inner layer uses model predictive current control to reduce system current ripple by following the predictive value.
HESS high- and low-frequency power distribution is achieved with two separate controllers and no filters in this cascaded topology. Thus, two types of energy storage devices can separately regulate voltage and allocate battery and UC power. Finally, PSCAD/EMTDC simulations verify the HESS control strategy’s effectiveness in a controller comparison and fault scenario.
Note: Please discuss with our team before submitting this abstract to the college. This Abstract or Synopsis varies based on student project requirements.