变流器辅助换流的柔性切换开关拓扑与控制

分布式新能源渗透率的快速提高，在提升配电网灵活性的同时也加大了其运行调控难度。为此，文中提出一种新型配电网柔性切换开关设备，开关由集成门极换流晶闸管(integrated gate-commutated thyristor，IGCT)与并联电压型变流器组成，其中针对并联电压型变流器采取虚拟同步发电机控制，可实现负载在不同馈线间的平稳切换。文中首先将所提柔性切换开关与柔性多状态开关及机械开关的主要特征进行比较；然后，分析柔性切换开关在故障前、故障中和故障后的工作模式，并研究在3种工作模式间进行柔性切换时的切换逻辑；最后，通过基于RT-Lab的控制在环实验模拟开关在不同馈线间切换的过程，获得不同工作模式下和柔性切换过程中的电压电流波形。实验结果表明柔性切换开关具有短时电压支撑能力，在不同馈线间切换的过程中不产生电压电流冲击。

A converter-assisting flexible switch topology and its control strategy

The rapid development of new energy in the distribution network increases its flexibility while making it more complicated to operate and manage the network. For this reason,a novel flexible switch,which is composed of integrated gate- commutated thyristors (IGCT) and parallel voltage converters,is proposed in this paper. Applying virtual synchronous generator (VSG) control on the parallel voltage converterensures smoothness and steadiness while switching from one feeder to another. Firstly,the proposed flexible switch is compared with the flexible multi-state switch and the mechanical switch on their main characteristics. Then,the operating features of the flexible switch before,during,and after feeder fault are analyzed,as well as its switching logic. Finally,the switching process between different feeders is simulated on a control in-the-loop experiment based on RT-Lab. The voltage and current waveforms are obtained under different operating modes and during flexible switching. The experiment resultsshow that the flexible switch has short-term voltage support capability and does not generate voltage and current impulses during the switching process.