Research On Control Method Of Three-phase Dual-mode Inverter

The distribute generation system, the bridge between power system and renewableenergy, is the crossing between power grid technology and power electronic energy. In thispaper, based on the dual-mode inverter, the control strategies, anti-islanding strategies andmode switch are detailed analyzed.Firstly, the main topology of the three phase dual-mode inverter is presented. Theoutput filter adopt LCL filter in grid on mode and LC filter in stand-alone mode. The mathmodel of the grid-on mode and stand-alone mode is established.Secondly, the control strategy of the inverter is designed. The strategy based on theinner loop with capacitor current and out loop with grid current is adopted in grid-on mode,the strategy based on inner loop with capacitor current and out loop with capacitor voltageis adopted in stand-alone mode. The optimum control parameters is choose after thediscussing of the influence on system characteristic of the parameters.Thirdly, An anti-islanding strategy is designed. An anti-islanding strategy based on Q-fcharacteristic curve is designed to avoid the none detected zone. After the testing withsimulation, the effectiveness is proofed.Fourthly, the switch flow for mode switch is designed. The voltage difference betweenthe grid and the inverter would cause the leap of grid current or voltage. An improve phaselock is designed to decrease the voltage difference. The effectiveness of the switch flow isproof by simulation.At last, based on an available three phase dual-mode inverter, experiments have beentaken to test the control strategies above. The experimental and simulation results areaccord with the theoretical analysis, the correctness of the controller is verified.