Multivariable Sequential Model Predictive Control of LCL-type Grid Connected Inverter

Abstract

The traditional single variable indirect model predictive control (SIMPC) of LCL-type three-level grid connected inverter (GCI) indirectly controls grid current by controlling the output current of the inverter, which usually produces large errors and reduces the anti-disturbance performance of the system. Although the existing multivariable weighted model predictive control (MWMPC) method can realize the direct control of multiple variables such as grid current and filter capacitor voltage, it needs to set the weight coefficient of variables, and the calculation of prediction and evaluation is large. In view of the above problems, a multivariable sequential model predictive control (MSMPC) method for LCL-type three-level GCI is presented in this paper. According to the sequence of variable control in the mathematical model of LCL-type GCI, inverter output current, filter capacitor voltage and grid current are predicted and evaluated one by one. Under the premise of realizing the direct control of the above variables, this method omits the setting of weight coefficient, and gradually shrinks the solution space to reduce the calculation amount of multivariable control. In this paper, the LCL-type three-level GCI system is built in the simulation environment to verify the effectiveness of the proposed algorithm.