改善基于双馈感应发电机的并网风电场暂态电压稳定性研究

Study on Transient Voltage Stability Enhancement of Grid-connected Wind Farm With Doubly Fed Induction Generator Installations

提出了改善基于双馈感应发电机的并网风电场暂态电压稳定性的措施以实现风电场的低电压穿越(low voltage ride through,LVRT)功能。目前,大部分基于双馈感应发电机的变速风电机组不具有故障情况下的暂态电压支持能力,当电网侧发生严重短路故障时,风电场的暂态电压稳定能力会影响到电网安全稳定。该文在DIgSILENT/PowerFactory中建立了具有暂态电压支持能力的变速风电机组转子侧变频器控制模型及用于故障后稳定控制的桨距角控制模型,通过包含风电场的电力系统仿真计算验证了模型的有效性及其对风电机组和电网暂态电压稳定性的贡献。仿真结果表明,当电网侧发生三相短路故障时,风电机组转子侧变频器暂态电压控制能够控制风电机组发出无功功率支持电网电压;桨距角控制能有效降低变速风电机组机械转矩,避免出现风电机组超速及电压失稳。得出结论:采用变频器暂态电压控制及桨距角控制能够改善基于双馈感应发电机的并网风电场的暂态电压稳定性,确保风电机组低电压穿越(LVRT)功能的实现及电网安全稳定。

Measures to enhance transient voltage stability of grid-connected wind farm based on variable speed wind turbines equipped with doubly fed induction generator （DFIG） are presented to implement low voltage ride through （LVRT） characteristic. Because mostly used variable speed wind turbines based on DFIG do not provide with transient voltage support capability under fault conditions, the security and stability of grid is influenced by wind farms integration in the case of severe short circuit fault contingency occurred on the grid side. The power converter controller model with transient voltage support capability and pitch control model used for post-fault stability control are implemented in DIgSILENT/ PowerFactory. The models validation and the contribution to transient voltage stability enhancement are verified by power system simulation containing large wind farms. From simulation results, it can be illustrated that power converter controller with transient voltage support capability should provide dynamic reactive power to support grid voltage; the pitch control of variable speed wind turbines should effectively reduce mechanical power, preventing wind turbines from over-speeding in the duration of power system large disturbance. The conclusion is presented that adoption of power converter controller with transient voltage support capability and pitch control used for post-fault stability control enhances transient voltage stability of grid-connected wind farm, ensures low voltage ride through capability of variable speed wind turbines equipped with DFIG and the security of the grid.