Electromagnetic Transient Modeling and Analysis of Soft Open Point

The soft open point (SOP) can replace the interconnection switch on several key nodes of the distribution network, which can improve the flexibility of the distribution network. However, the circuit structure in SOP is complex. Although the accuracy of electromagnetic transient simulation is high, the difficulty of modeling restricts the operation optimization of SOP. In this paper, a simplified model of SOP based on voltage source converter (VSC) is proposed by using the Thevenin equivalent method, and the importance of SOP in power flow reversal of distribution network is proved. Firstly, the equivalent circuit composed of controlled source is established for the AC/DC side of VSC; Then, the expression of the transient effect of power between converters on DC voltage is given; Next, the control equations of double closed loops with different VSCs are derived; Finally, using IEEE34 node parameters, a simplified SOP is built on the ADPSS platform, and the waveforms of various electrical quantities are given when the power changes. The correctness is proved by the PSCAD.