基于改进控制策略与动态无功支撑相结合的高电压穿越方法研究

针对双馈风力发电机高电压穿越问题,利用Laplace变换对电网电压骤升时电磁暂态过渡过程进行分析,得出定子电流不仅含有直流分量,还包含有工频交流成分,并通过仿真频谱验证了理论分析的正确性。不同于常规研究中只在转子电压方程考虑定子磁链的动态变化,而忽略了其对功率外环的影响,分析了定子磁链动态变化对有功、无功解耦的影响,在此基础上对功率外环进行传统矢量控制策略的改进。此外,考虑并网规范对机组无功电流支撑的要求,控制换流器输出与电网电压骤升幅度相匹配的无功电流,帮助故障电网快速恢复。仿真结果表明,该方案不仅能够保证电网电压骤升时双馈机组不脱网运行,而且也满足并网规范对机组无功电流输出的要求,实现高电压穿越。

A HighVoltage RideThrough Control Method Study Based on ImprovedControl Strategy and Dynamic Reactive Power Support

The electromagnetic transient process under the grid voltage swell was analyzed by Laplace transform. The stator current contained not only the DC component but also the AC component. The results of simulations spectrum verified the correctness of the theoretical analysis. Different from the conventional research only on the rotor voltage equation considering the dynamic changes of stator flux, while ignoring the influence of the outer power, the stator flux dynamic changes of active and reactive power decoupling effect was analyzed. The improved control strategy considering the influence of stator flux linkage dynamics on the power output loop was proposed. And then, the requirement of reactive current support for unit considering the grid specifications, the grid side converter was controlled to output reactive current, which matches the surge margin and grid voltage quickly recovery. The simulation results showed that the proposed control scheme was capable of not only ensuring continuous operation of the DFIG system during the grid voltage swelling conditions, but also satisfying reactive current output requirement, which achieves the high voltage ride through.