A converter-assisting flexible switch topology and its control strategy

Abstract

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.

Keywords

• flexible switching
• integrated gate-commutated thyristor (igct)
• virtual synchronous generator (vsg)
• voltage support
• pre-synchronization grid-connection
• flexible grid-connection