Phase-changing control for three-phase four-wire back-to-back VSC based soft open points

The increasing integration of intermittent single-phase distributed renewable generation (DRG) and varying single-phase loads exacerbates the issues of imbalance either between feeders or between three phases in the low-voltage active distribution networks (LV-ADNs). Soft open points (SOPs), which can be utilised to regulate power flow between the connected feeders, can be recognised as a solution to both unbalanced situations, as they can realise load balancing between feeders and have the potential to compensate for unbalanced phase power flows. In this paper, the three-phase four-wire back-to-back VSC (3P4WB2B- VSC) is applied as the topology of the SOPs. Based on this, a phase-changing (PC) control is proposed. It is designed for mitigating (1) the issue of load imbalance between feeders and (2) the phase imbalance in the heavily loaded feeder in LVADNs. The model of 3P4W-B2B-VSC based SOPs under the PC control is built and simulated in Matlab/Simulink. Presented results demonstrate the practicability of the 3P4W-B2B-VSC based SOP and the effectiveness of the phase-changing control in mitigating unbalanced network usage.