基于交叉耦合与交叉解耦的UPFC控制性能对比

Comparison of UPFC performance betweencross coupling and decoupling controls

交叉耦合与交叉解耦控制是统一潮流控制器(UPFC)的2种主要控制策略,两者内环相同而外环有显著差异。交叉耦合以线路潮流为控制对象,控制结构简单易于实现,属于直接控制方式;交叉解耦的外环控制由电流反馈环与比例积分(PI)控制相结合,以线路电流为控制对象,具有快速调节潮流的能力,属于间接控制方式。交叉耦合不依赖于电流反馈,通过外环PI调节器对线路潮流进行独立调节,因此具有较好的鲁棒性;交叉解耦通过电流环解耦,具有解耦完全的特点。单相接地短路实验体现出交叉解耦控制在三相不平衡状态下迅速限制潮流冲击分量的特点。通过实验波形和仿真分析,对交叉耦合与交叉解耦的控制性能特点予以了证实,并针对交叉解耦控制鲁棒性较差的缺陷,提出了PI控制器的智能化和线路参数在线辨识2条改进途径。

Cross coupling and decoupling controls are two main UPFC（Unified Power Flow Controller） control schemes,which have same inner control loop and different outer control loop. Taking power flow as the control object,the cross coupling control is ascribing to the direct control scheme,which is simple and easy to be implemented. Taking line current as the control object,the cross decoupling control is ascribing to the indirect control scheme,which combines PI controller with current feedback loop and has the ability of fast power regulation. The cross coupling control is independent of the current feedback and uses PI controller alone to adjust the power flow,s0 it has better robustness. The cross decoupling control decouples completely using current feedback,which quickly restricts the concussion current under 3-phase unbalanced condition caused by single-phase grounding fault. The performance of cross coupling and decoupling controls are validated with simulations and experiments. Two methods are proposed to improve the robustness of cross decoupling control：the intelligent PI controller and the online identification of line parameters.