Model Predictive Control of Bidirectional AC-DC Converter for Energy Storage System

Abstract

-Energy storage system has been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper presents a model predictive algorithm to control a bidirectional AC-DC converter, which is used in an energy storage system for power transferring between the three-phase AC voltage supply and energy storage devices. This model predictive control (MPC) algorithm utilizes the discrete behavior of the converter and predicts the future variables of the system by defining cost functions for all possible switching states. Subsequently, the switching state that corresponds to the minimum cost function is selected for the next sampling period for firing the switches of the AC-DC converter. The proposed model predictive control scheme of the AC-DC converter allows bidirectional power flow with instantaneous mode change capability and fast dynamic response. The performance of the MPC controlled bidirectional AC-DC converter is simulated with MATLAB/Simulink® and further verified with 3.0kW experimental prototypes. Both the simulation and experimental results show that, the AC-DC converter is operated with unity power factor, acceptable THD (3.3% during rectifier mode and 3.5% during inverter mode) level of AC current and very low DC voltage ripple. Moreover, an efficiency comparison is performed between the proposed MPC and conventional VOC-based PWM controller of the bidirectional AC-DC converter which ensures the effectiveness of MPC controller.

Experiment on Bidirectional Single Phase Converter Applying Model Predictive Current Controller

“…The controller schema is shown in Figure 2. The difference between nominal voltage value and measured voltage is fed to a PI controller, and the output is considered as the current reference, which is used as reference to the constant current controller of Equation (10). In order to have control over the absorbed current, PI (VB) output is limited with upper and lower limits.…”

“…Several reliable and effective control methods based on classical control algorithms with Pulse Width Modulation (PWM), like conventional Voltage Oriented Control (VOC), Direct Power Control (DPC) [10,11], deadbeat control [12,13], multiloop feedback control [14,15], adaptive control based on bank resonant filters [16], and repetitive-based controllers [17] have been introduced and implemented to industrial applications.…”

Application of Model Predictive Control to BESS for Microgrid Control

“…Therefore, MPC has been widely applied to drive applications [15][16][17][18] and power converters such as active front-end rectifiers [19], matrix converters [20], and multilevel converters [21]. Recently, it has been applied to a bidirectional AC-DC converter for use in BESSs [22][23][24].…”

A Robust Suboptimal Current Control of an Interlink Converter for a Hybrid AC/DC Microgrid

“…In [8], by employing an adaptive hysteresis control method, the switching loss of the traditional hysteresis control is reduced. Furthermore, a model predictive control (MPC) is proposed to optimize the control input [9]. However, those methods yield a variable switching frequency.…”

“…The filter parameters are essential for the design procedure. In such model-based control schemes [8][9][10], it is assumed that the parameters in the model are known. However, due to manufacturing and thermal effects, the inductors, resistors, and capacitors can be different from the designed values.…”