A Low Voltage Ride-Through Control Strategy for Multi-Ports Energy Router Based on Positive and Negative Sequence Composite Limiting

Distribution network is gradually transformed from the power network that merely accepts and distributes electric energy to users to the power network that integrates and interacts, and flexibly couples with the upper power network. The function of promoting nearby consumption of distributed power sources and carrying new loads is becoming increasingly significant. In view of the trends of diversified power demand, large-scale distributed access, and complicated power flow control, this paper proposes a county-level high proportion of energy router. Router has characteristics of large capacity(>50MW),many ports (more than 5 ports),and rich voltage levels <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(110\text{kVAC},\ 10\text{kVAC},\ \pm 20\text{kV},\ \pm 375\mathrm{V})$</tex>. In addition, for the problem that the fault through requires long time testing due to the overall overcurrent that may occur during the process of separately limiting the positive or negative sequence current during the low-voltage through, this paper proposes an additional composite limiting strategy design. Finally, the designed large capacity multi-port energy router is applied in the county 100% new energy distribution network, and the effectiveness of low-voltage through control strategy is verified.