PSCAD Based Research On Operation Characteristics Of Grid-Connected Doubly Fed Induction Generator

As an important kind of generating form,wind power has many advantages such as improving the energy structure,economic and environmental protection.At resent,wind power generation has been paid more attention by governments all around the world.With the continued growth of wind power installed capacity, as well as the continual emergence of large-capacity wind farm,the impact of wind power on the grid will not be ignored. Studying on the performance characteristics of wind turbine and analyzing the effects on grid and the generators are of great significance to ensure the grid-connected wind turbine safe and reliable operation.And the doubly fed induction generator(DFIG) based on wind turbine is one of the main stream machine type.Therefore,to study its running characteristic connected in the grid that has been paid growing attation.Basic structure and working principle of the doubly fed VSCF wind turbine are described in this paper.And on this basis,the mathematical models of doubly fed VSCF wind power generator in the dq synchronous rotating coordinate system and other part of the wind power generation system are established in the PSCAD.Based on these,simulation analysis is made for the dynamic characteristics of grid connected double fed wind turbine in the mode of ramdom wind.Simulation results demonstrate the doubly-fed wind turbine unit model is correct and rational design of control objectives.Then taking a wind farm and the power system for example,in conditions of the wind disturbance and the grid-side fault,the operating characteristics of VSCF doubly fed wind turbine and conventional CSCF wind turbine are compared by simulation.The simulation results show that double fed VSCF wind turbine has more advantages than the traditional constant-speed asynchronous wind turbine,and the former has a fast dynamic response characteristics and a good ability to regulate the reactive power.At last,the low voltage ride-through characteristic of doubly fed induction wind turbine is simulated by using the method of crowbar protection circuit,which verifies the effectiveness of protection of the crowbar and achieves the low voltage ride-though of the double fed VSCF wind turbine with crowbar during grid fault.Good dynamic performance and stability of VSCF doubly fed wind power generator system are showed through research,which provides a reliable theoretical basis for VSCF wind power generation system for further applied research and a reference of the application for the doubly fed VSCF wind turbine wind farm in a large grid.