Comprehensive performance analysis of model predictive current control based on-grid photovoltaic inverters

Abstract

A considerable amount of energy is lost by utilizing the traditional pulse width modulation (PWM) based inverters in an on-grid PV system. Therefore, a model predictive current control (MPCC) based control strategy is proposed in this research work. The controller works based on a predefined cost function. The cost function includes deviation of current from its reference and a switching frequency term to reduce the average switching frequency. All the possible control actions i.e. inverter switching states are tested against the cost function. The state which yields minimum cost is selected as an optimal control action for the inverter. Simulation results show that the proposed controller tracks the reference current accurately with a mean absolute error of 2.5% which is 30% for the PI-PWM based controller. The MPCC based inverter yields low current THD of 2.07%, whereas in traditional PI-PWM based inverter the current THD is 7.26%. The energy efficient operation of the MPCC based inverter is also verified by doing loss analysis. It is shown that conduction, switching, and harmonic losses of the inverter are reduced by 36.8%, 50%, and 91.9%, respectively, in comparison with the PIP-WM based inverter.