不平衡情况下LCL型PWM整流器准直接功率控制

Quasi Direct Power Control for LCL based PWM Rectifier under Unbalanced Conditions

直接功率控制的PWM整流器系统具有结构和算法简单,动态响应快等优点,但无法直接应用于电网电压不平衡情况下的LCL型PWM整流器。针对上述情况,提出一种LCL滤波PWM整流器的准直接功率控制策略。首先将正负序分量分解;然后将交流侧控制系统设计为正序功率环和正序电流环的双环结构,功率环为电流环提供电流指令;最后电流环引入电容电流反馈,实现有源阻尼。介绍了控制系统的结构,给出了控制器的设计过程。所提方法具有原理清晰,简单易实现的优点。仿真结果表明系统稳定,未发生谐振,交流侧电流的负序分量得到抑制,网侧电流正弦度高,稳态和暂态性能优良。

The pulse width modulation（PWM） rectifier system based on direct power control has the advantages of simple structure, simple algorithm and fast dynamic response. But the direct power control can not be directly applied to the LCL-based PWM rectifier under unbalanced grid voltage conditions. A quasi direct power control scheme for LCL- based PWM rectifier was proposed for these conditions. The positive and negative sequence components are decomposed at first. Then the AC-side control system are designed as a two-loop structure composed of a positive sequence power loop and a positive sequence current loop, the power loop provides current commands for the current loop. Finally the capacitor currents feedback is introduced to the current loop for active damping. The control system structure was introduced and the design procedure of the controller was described. The proposed method has the advantage of simplicity and easy to implement. The simulation results show that the system is stable without the occurrence of resonance; the negative components of the AC-side currents are suppressed, the grid side currents are highly sinusoidal, and the system has excellent stable and transient performance.