双馈电机风力发电柔性并网方式的分析与比较

Analysis and Comparison on Soft Grid-Connection for Doubly Fed Wind Power Generation

随着风力发电机组单机容量的增大,并网技术越来越受到重视.传统的风力发电并网技术在并网瞬间会产生很大的冲击电流,威胁发电机及电力系统的安全.近年来变速恒频双馈风力发电系统逐渐成为风力发电的主流,针对该系统的特点,分析比较了空载并网、负载并网这两种适合双馈电机的柔性并网方式,建立了并网前数学模型,并基于电网电压定向分别设计了并网控制策略.仿真和试验结果表明,这两种方法都能在变风速条件下实现无冲击电流并网,并网后切换到最大功率点跟踪控制过渡平稳,是双馈电机风力发电系统理想的并网方式.

With growing capacity of wind power generator, the grid-connection technology increasingly attracts attention. Traditional methods can produce high impact current therefore threaten safety of generators and the power system. In recent years, variable speed, constant frequency and doubly fed wind power generation system gradually becomes the mainstream technology. Based on the system＇s characteristics, two methods of soft grid-connection with doubly-fed generator are analyzed and compared. The mathematical model for prior grid-connection is established. A strategy for grid-connection control is proposed based on the grid voltage orientation. Simulation and experiments show that both methods can realize non-impact grid-connection and smoothly transition in the maximum power point tracking （MPPT） control, even under changeable wind speeds. Both are ideal for doubly-fed wind power generation.