直驱式风电场对电力系统的暂态稳定性影响分析

为研究大容量直驱式风电场并入对电力系统暂态稳定性的影响,建立了风速、风力机、轴系、直驱永磁同步发电机、全功率变流器的数学模型;研究了变流器控制策略和桨距角控制策略;并搭建直驱式风电场并网的仿真模型.以风电场并网点电压为研究对象,用电压跌落深度、电压冲击幅值、暂态电压恢复时间三个指标,对风电场出口故障、风电场突然切出、在同一点发生三相短路故障时不同风电场容量及三相短路故障发生在线路不同位置时对系统暂态稳定性的影响进行了分析.仿真结果表明直驱式风电场具有一定的低电压穿越能力;风电场突然切出时,并网点电压有小额增幅;风电场接入会改善系统的暂态电压稳定性,但当容量增大到一定程度时系统稳定性下降;随着故障点与风电场电气距离的增大,系统的暂态电压稳定性逐渐改善.

Analysis of transient stability of power system for direct drive wind farm

The characteristic of transient stability was investigated when large capacity direct-drive wind farms were connected to the grid,set up the mathematical model of wind speed,wind turbine,shaft,direct drive permanent magnet synchronous generator,full power converter model;the converter control strategies and the pitch angle control strategy were studied.Take the PCC point voltage as the research object,put forward three indicators:voltage drop depth、peak voltage surge、transient voltage recovery time.The wind farm exports fault,suddenly cut out wind farm,the three-phase short circuit fault occurs at the same point in different wind farm capacity and the three-phase short circuit fault in different location impact on system transient stability have are analyzed.Simulation results show that direct drive wind farm has a low voltage ride-through capability;when the wind farm was cut out suddenly,node voltage increases slightly;wind farms will improve the transient stability of the system,but the stability will decline when the capacity increases to a certain degree;the transient stability is gradually improved with the electric distance of fault point farther from the wind farm.