多功能柔性功率调节器的矢量励磁控制

AC excitation control of multi-function flexible power conditioner

作为大容量低速飞轮储能系统,多功能柔性功率调节器(FPC)由双馈电机(DFIM)和作为交流励磁电源的电压源型双脉宽调制(PWM)变换器组成,具有独立的有功和无功调节能力,能提高电力系统稳定和改善电能质量。FPC采用改进型定子磁链定向控制策略。该策略利用电压控制代替无功控制,同时分别对定子q轴和d轴电压进行反馈和补偿控制,从而对电网电压波动具有较好的鲁棒性。由于FPC主要工作在电网扰动时,为了避免机端电压突然跌落引发变频器不能承受的转子过电流而导致装置跳闸,采用了专门的转子过电流快速限制措施和控制策略。此外,还附加了转速反馈控制,使FPC转速在其待机时总是能保持在稳态给定转速。

As a large-capacity low-speed flywheel energy storage system,the multi-functional FPC （Flexible Power Conditioner） consists of a DFIM（Doubly Fed Induction Machine） and an AC exciter, i.e. voltage-source PWM（Pulse Width Modulation） rectifier-inverter. With the ability of independent active and reactive power control ,it is used to improve the stability of power system as well as the quality of power supply. An improved stator flux linkage orientated control strategy is proposed for FPC ,which uses voltage control instead of reactive power control ,feedbacks the stator q- axis voltage and compensates the stator d-axis voltage to obtain better robustness against the grid voltage fluctuation. During grid disturbance,terminal voltage dip may induce over- current in rotor windings ,which leads to equipment trip for converter protection. Special fast rotor over -current restriction technique is adopted. In addition,the rotation feedback control is added to keep the practical rotation speed at setting value when FPC stands by.