Voltage Open-Loop Control of Modular Multilevel Matrix Converter for Flexible Low-Frequency AC System Under Open-Phase

Flexible low-frequency AC transmission technology combines the advantages of high-voltage AC transmission and DC transmission, and has good development prospects. For transmission lines, single-phase grounding is the most common type of fault, and configuring single-phase reclosing can improve system stability. In view of this, a control strategy suitable for low-frequency transmission lines in open phase operation is proposed to ensure the stable operation of the converter valve during single-phase tripping. The article first introduces the structure of a dual ended flexible low-frequency AC system, and then analyzes the fault characteristics after single-phase tripping of low-frequency lines. Based on the fault characteristics, a voltage open-loop control strategy without voltage feedback is proposed. Finally, a dual ended low-frequency AC transmission system model based on M3C is constructed, and the effectiveness and feasibility of the proposed method are verified through simulation.