Study on AC and DC side grounding method of DC distribution system based on modular series two-level converter

With the rapid development of renewable energy, new types of loads and power electronic technology, the construction of DC distribution system on the basis of AC distribution network is becoming the future trend in distribution network development. The choice of grounding method significantly impacts the system’s security, reliability and economy. The grounding method for DC system is influenced by many factors, such as converter topology. Currently, there is no unified method for the grounding design of DC system, and the grounding methods of various demonstration projects in China differ. The purpose of this paper is to study the grounding methods of DC power distribution systems based on modular series two-level converters, including AC-side grounding and DC-side grounding. By constructing a system model and combining with simulation analysis, this study explores the impact of different grounding methods on harmonic voltage, current, and fault conditions of the system to provide a reference for designers.