基于模糊切换的DFIG转子串联双动态电阻LVRT优化控制

LVRT optimal control of DFIG using rotor series double dynamic resistance based on fuzzy switching

针对双馈感应风力发电机(DFIG)转子串联单电阻不能满足高性能低电压穿越(LVRT)需求的问题,提出了基于模糊切换的DFIG转子串联双动态电阻LVRT优化控制策略。建立LVRT期间DFIG转子串联阻尼电阻的数学模型,剖析串联电阻对转子磁链、电流、电压及温度的影响机理。根据实际中不同电网电压跌落深度和转子电流大小的逻辑关系,设计转子串联双动态电阻开关信号模糊控制器,对其切换状态进行全面、详细、精确的控制。仿真和实验结果表明,所提控制策略可根据电网电压跌落深度和转子电流幅值的不同,快速、准确地选择相应电阻值,在有效抑制LVRT期间转子过流、直流母线过压的同时,减小了转子串联电阻消耗的有功功率,促进了电网跌落电压的快速恢复,提高了LVRT期间机组整体安全性能。

Aiming at the problem that the rotor series single resistance of DFIG(Doubly-Fed Induction wind Generator)cannot meet the demand of high performance LVRT(Low-Voltage Ride-Through).A LVRT optimal control of DFIG using rotor series double dynamic resistance based on fuzzy switching is proposed.A mathematical model for the rotor series damping resistance is established during LVRT period.The relationships between the series resistance and rotor flux linkage,current,voltage and temperature are analyzed.According to the logical relationship between different voltage sag depths and rotor currents,the fuzzy controller of rotor series double dynamic switching signal is designed to control its switching state comprehensively,in detail and precisely.Simulative and experimental results demonstrate that the proposed control strategy can quickly and accurately select corresponding series resistance according to different voltage sag depths and rotor current amplitudes,effectively suppress rotor over-current and DC bus over-voltage during LVRT period and reduce the active power consumed by the rotor series resistances,which promotes quick recovery of power grid voltage sag and enhances the overall unit security during LVRT period.