提高直驱永磁风机低电压穿越能力的控制策略

为提高直驱风电机组低电压穿越能力和改善故障穿越后风电机组的稳定运行能力，提出了一种基于变阻值和变功率因数无功控制的直驱风电机组低电压穿越综合控制策略(the comprehensive control strategy, CCS)。在直流侧采用IGBT与变阻值卸荷电阻串联构成变阻值卸荷电路，且在长时故障时引入磁控型动态无功补偿装置进行无功补偿，根据实际电压值与预设电压阈值的比较结果动态投切卸荷电路。在网侧根据电压跌落程度所处的阶梯范围，动态调整直驱风电机组发出的无功功率。在PSCAD/EMTDC中搭建了直驱风电场的仿真模型，应用某实际运行的1.5 MW直驱风机参数，在卸荷电阻值、无功功率因数分别不同时仿真验证了该控制策略的有效性。结果表明:该控制策略不仅能够提升机组的LVRT能力，而且可以改善故障穿越结束后机组的稳定运行特性。

Comprehensive control strategy for improving low voltage ride through capability of permanent magnet synchronous generator

In order to improve permanent magnet synchronous generators (PMSGs) low voltage ride through (LVRT) capability and operation stability after LVRT, a comprehensive control strategy (CCS) of PMSG based on variable resistance and power factor is proposed, which can be described as that, a series circuit of IGBT and variable-value unloading resistor is utilized in the DC side, a dynamic reactive power compensation device based Magnetically Controlled Reactor (MSVC) is utilized under long period faults, the series circuit and MSVC device are accessed according to the comparison of actual voltage value and preset limit voltage. According to the voltage drop level, the reactive power generated by PMSG is adjusted. A simulation model is established in PSCAD/EMTDC, based on parameters of an actual operational PMSG with the output power of 1.5 MW, the efficiency of the proposed control strategy is verified under different unloading resistances and power factors. The results shown that, not only the LVRT capability of PMSG can be enhanced, but also the operation stability after LVRT can be improved. This work is supported by National Natural Science Foundation of China (No. 51267019 and No. 51467019).