统一潮流控制器的分析与控制策略

文中分析了统一潮流控制器（UPFC）系统的电压、无功功率和有功功率的平衡，得到了与UPFC控制相关的2个重要结论。首先，分析表明在UPFC输入端电压保持不变的情况下，线路无功潮流的变化实际上是由并联变换器提供的；其次，UPFC端电压既可以从发送端控制也可以从接收端控制。基于以上分析，提出了一种新颖的UPFC控制策略。在该策略中并联变换器控制UPFC直流母线电压和输电线无功潮流，而串联变换器控制UPFC输入端母线电压幅值和输电线有功潮流。同时，在控制系统中加入有功／无功功率协调控制，可在潮流调节中获得良好的静态、动态性能。最后，通过实验验证了所提出的控制策略的有效性。

Analysis and Study on Control Strategy for UPFC

Balance among real power, reactive power and voltage of the unified power flow controller (UPFC) system is analyzed. Two important conclusions related to UPFC are obtained. Firstly, it is found that the shunt converter provides all the required reactive power during the change of power flow if the UPFC bus voltage is constant. Secondly, the UPFC bus voltage can be controlled from both the sending side and the receiving side. Based on the analysis, a novel coordinated control strategy for UPFC is proposed. In the proposed strategy, the shunt converter of the UPFC controls the transmission line reactive power flow and the dc link capacitor voltage, and the series converter controls the transmission line real power flow and the UPFC bus voltage. The real/reactive power coordinated control in the UPFC control system can provide good performance during both transient and stable conditions. Experimental work has been carried out to verify the effectiveness of the proposed control strategy.