不对称弱电网下双馈风机系统的稳定性评估及正负序虚拟转子电感控制策略

Stability evaluation and positive and negative sequence virtual rotor inductance control strategy of DFIG system in asymmetric weak grid

不对称弱电网下,双馈风机与电网之间存在着复杂且剧烈的交互作用,严重影响风机运行的稳定性以及向电网输送功率的能力。针对该问题,建立了双馈风机系统源荷耦合的单输入单输出(SISO)等效模型,分析了系统失稳机理,特别是探明了正序有功电流、电网不对称故障深度等因素对稳定性的作用规律。提出了正负序虚拟转子电感控制策略,厘清了虚拟转子电感参数对系统稳定性的作用机理,并据此给出了参数整定依据,有效提升了双馈风机系统在弱电网下的稳定运行能力。理论分析表明所提模型大幅减小了稳定性分析时间,仿真及实验验证了理论分析结果的正确性和正负序虚拟转子电感控制策略的有效性。

In the asymmetric weak grid,the complex and intense interaction between the doubly-fed induction generator(DFIG) and the power grid seriously affects the stability of DFIG operation and the ability to transmit power to the power grid. To address this issue,a single input single output(SISO) equivalent model that considers source-load coupling is established,the instability mechanism of the system is analyzed, especially the influence rules of positive sequence active current,grid asymmetric fault depth and other factors on stability are explored. A positive and negative sequence virtual rotor inductance control strategy is proposed,the mechanism of virtual rotor inductance parameters on system stability is clarified. And based on this,the parameter tuning basis is provided to enhance the stable operation ability of DFIG system in weak grid. The theoretical analysis results show that the proposed model significantly reduces stability analysis time. The correctness of the theoretical analysis and the effectiveness of the positive and negative sequence virtual rotor inductance control strategy are verified by simulations and experiments.