Research On Control Strategy Of Circulating Current Suppression In Three-Phase Inverter Parallel System

Energy crisis and environmental pollution are key factors hindering the rapid development of society and economy,and the use of renewable energy is an important means to solve the problem.However,the output power of renewable energy is unstable and intermittent.In order to improve the stability of the system,it is an effective way to connect distributed power generation units to the main grid in the form of a microgrid.Three-phase inverter parallel circulating current suppression and power sharing control strategy are the primary issues to ensure the efficient and stable operation of the microgrid.This article is based on the three-phase inverter in the microgrid,focusing on its parallel operation circulating current suppression and power sharing Research on control strategies.First,the three-phase inverter is mathematically modeled and the main circuit parameters are designed,the control strategy of the three-phase inverter in island operation mode is given,and the current inner loop and voltage outer loop proportional integral regulator are designed.,And use simulation to verify the double closed-loop control model of a single three-phase inverter.Secondly,the mathematical model of the three-phase inverter parallel system is established,the circulation generation mechanism of the parallel system is analyzed,and the traditional droop control strategy of the parallel system is given through the basic principle of droop control.In order to reduce the circulation problem caused by the inconsistent line impedance,a droop control strategy based on the additional virtual impedance is proposed,and the influence of the voltage and current double loop control parameters and the virtual impedance on the output impedance of the three-phase inverter is analyzed.In order to avoid the problem of incomplete reactive power sharing caused by the addition of virtual impedance,the reactive power-voltage improved droop control is further proposed.Finally,the traditional droop control with virtual impedance and the improved droop control are simulated and verified by physical experiments through simulation software and physical experiment platform,which proves the effectiveness of the proposed control strategy.