Research On Interface Characteristics Of Wind Power Generation System Based On Virtual Synchronous Generator

In order to study the new wind power generator units which can meet to the concept of "local autonomy and global coordination" and "grid-friendly", so that can support theoretic to develop the unit which will integrate into the smart grid. This paper will study the interface characteristics of full power converter wind generator and doubly fed induction generator (DFIG) systems. Based on the virtual synchronous generator (VSG), summarize the synchronization control model of the wind power generator appropriate to electric power system.Consider to the full power converter wind generator can be equivalent to a grid-connected inverter from the grid interface; based on the mathematical model of three-phase inverter, combine the droop characteristics, produce the droop control strategy of inverter. Based on droop control characteristic, the virtual governor and exciter are introduced, the mathematical model and control strategy of VSG is produced, so the power source have frequency inertia and voltage inertia and have similar dynamic characteristics to a synchronous generator. Synchronously controlled strategy of full power full power converter wind generator is achieved.Based on droop characteristic pre-synchronized control, this paper focuses on the research of the grid-connection pre-synchronized dynamic process of the inverter power sources based on droop control and virtual synchronous generator control in the non-ideal condition. The VSG can be paralleled in, loaded and parallel-connected operation by control the droop curve line, and the steady-state characteristic is well. According to the analysis of the voltage vector, proportional power sharing is achieved through inversely proportional adjust the virtual reactance values when the VSG with the different capacity parallel-connected. The control strategy can also eliminate reactive circulating in the inverters in steady state and suppress over-current of inverters in dynamic process.To control the inverter of rotor side in DFIG, based on virtual synchronous generator, this paper combine the real shaft with virtual synchronize shaft, draw the synchronization control model of DFIG. And draw the mathematical model oriented by the virtual rotor flux of that. Synchronously controlled strategy of DFIG is achieved. Make it have the similar characteristics to a synchronous generator.