Simulation And Research On Characteristics Of Large Grid-connected Wind Farm

The growing demand for energy, combined with increasingly limited natural resourcesare challenging energy suppliers, industry decision-makers as well as consumers to userenewable energy as more as possible. China is the world’s fastest-growing wind market, andits installed wind energy capacity has doubled each year since2005. However, thefluctuations and intermittency of wind power output will exert great influence on the securityand stability of power system.It is also of great significance to choose suitable cut-in methodsof wind power integrating into the existing electric power grid.Firstly, in this paper, the author studies the statistics of wind farm accidents in recentyears, and analyzes the causes of wind farms off-grid.Secondly, the author describes different methods of different wind turbine cut-in. Then,the author establishes detailed electromagnetic transient models of three kinds of typicalWTGs integrating into the existing electric power grid by PSCAD/EMTDC and confirmstheir validity respectively by way of the simulation analysis so that the operationcharacteristics of WTGs are obtained. The author introduces the working principle and startmode of the thyristor soft starter, compared the thyristor soft start with the traditionaldepressed start. The simulation and experimental results validate the grid-connection mode isan ideal approach for variable speed constant frequency wind power generation.Finally, the operation properties of the constant speed constant frequency wind turbineand doubly-fed wind turbine when the wind speed changes and the grid voltage drops arestudied. A new low voltage ride through control strategy based pitch control is proposed. Thesimulation results show that this method is effective.