双馈风机串补输电系统次同步谐振影响因素及稳定区域分析

Impacting Factors and Stable Area Analysis of Subsynchronous Resonance in DFIG Based Wind Farms Connected to Series-Compensated Power System

以华北地区某风电场双馈风机串补输电系统为原型,首先通过特征值灵敏度分析得到影响风机次同步谐振的主导因素。然后研究了对包含最大功率跟踪在内的风机全运行区域的稳定性,说明了各种主导因素变化对风机稳定性和安全运行区的影响。结果表明:在相同的条件下,串补度越高,次同步谐振风险越大,稳定区面积越小。风机转子侧变流器电流环比例系数对次同步谐振起负阻尼,若将该系数降低会对次同步起到一定的抑制作用,该系数越小,稳定区的面积越大。研究还发现:在一定条件下,降低风机台数会消除次同步谐振风险并且谐振频率随着风机台数的变化而变化。在此基础上,给出了风机参数设置和风电场安全稳定运行建议。

Taking a certain doubly fed induction generators （DFIG） based wind farm located at North China, which is connected to the series-compensated power transmission system, as the prototype, firstly, through the eigenvalue sensitivity analysis the predominant factors influencing the subsynchronous resonance （SSR） of wind turbine are obtained; then the stability of the whole operating area of wind turbines, in which the maximum power point tracking （MPPT） is included, is researched to explain the influences of the change of various predominant factors on DFIG stability and secure operation area. Research results show that under the same conditions the higher the series compensation degree, the higher the risk of leading to SSR is and the small the stable area will be. The proportional gain if the current loop in rotor side converter of the wind turbine itself plays the role of negative damping, decreasing the gain may play a certain role to suppress SSR, the smaller this gain the larger the stable area will be. It is also found that under a certain condition decreasing the number of DFIG can eliminate the risk of occurring SSR and the SSR frequency varies with the number of DFIG. On this basis, some suggestions on the setting of DFIG control parameters and secure operation of wind farm are given.