Analysis of Low Voltage Ride Through Capability in Multiport Converters for Soft Open Point Applications

The growing power demand, combined with intermittent renewables, presents significant challenges for distribution networks. This paper focuses on multiport converters as key devices for enhancing flexibility and optimizing existing infrastructure. Multiport converters are designed to facilitate enhanced power flow control on meshed networks and extended operation in case of faults. As an example of multiport converters, traditional soft open points (SOPs) are explored in this study, configured in a back-to-back (B2B) circuit. SOPs are investigated for their vulnerabilities, particularly in fault scenarios disrupting the converter responsible for regulating the dc link voltage, so fault ride through (FRT) approach is required to handle this situation. Furthermore, low voltage ride through (LVRT) requirements mandate the converter to remain connected during voltage sags, to prevent undesired tripping and provide reactive power support to the grid. To address these challenges, a unified control logic is proposed, devised to handle both LVRT requirements and FRT conditions. This approach ensures system connection during voltage sags and provides reactive power support to the grid. Simulation results presented in this paper validate the effectiveness of the proposed unified control logic, discussing its significance in enhancing the reliability of distribution networks and meeting the LVRT requirements.