Stochastic planning location selection method for DC intertie in urban distribution network

The increasing integration of renewable energy sources and new types of loads is driving a fundamental shift from conventional AC to AC/DC hybrid systems in urban distribution networks (UDN). This transition highlights the inefficiency of traditional AC distribution technology, which requires additional conversion steps to interconnect DC generation and loads. Therefore, a direct and promising solution for future UDN upgrades is the installation of new DC interties or the replacement of existing AC lines with DC interties to meet the growing demand for DC interconnection. However, the critical issue for the DC intertie application in UDN is lacking reliable quantitative index system for control performance assessment to determine best siting location, especially for the embedded DC intertie. Poorly chosen locations can prevent these interties from achieving their full potential in terms of increased power delivery capacity and enhanced active/reactive power regulation, thus diminishing their significance in the network. To address this, this paper proposed a novel index system for embedding DC interties in UDN. This system guides the selection of optimal locations for new Voltage Source Converter (VSC)-DC interties between two regions or for replacing existing AC lines, aiming to maximize the functionality of the DC intertie. Compared to conventional index system for AC lines, the proposed system incorporates additional factors, such as DC utilization rate and short-circuit current optimization, to quantify the improvement in control performance. To implement location selection using the proposed index system, a method for embedded DC intertie is proposed based on a stochastic selection strategy in conjunction with integer programming. The efficacy and precision of this VSC-DC location method are validated through case studies on a standard IEEE 33-bus system and a real-world UDN in China.