Studies on fault characteristics and protection strategies of MTDC system with DC hub

Abstract

Renewable energy power generation is developing fast in recent years, thereinto wind power generation is one of the most mature and feasible technologies, especially the offshore wind power is the future trend of wind power development. However, the integration of large-scale wind power will bring various challenges and affect the safe operation of power grids. Compared to AC system, multi-terminal DC (MTDC) system can solve these problems better and is more suitable for this application. Thus, the integration of wind power through MTDC system is considered as one of effective technical solutions. Accordingly, the studies on fault characteristics and protection strategies of MTDC system are becoming urgent and important. This paper presents a topology of MTDC system with DC hub which is suitable for wind power collection and transmission of large offshore wind farms, and the fault characteristics of this MTDC system against open-circuit faults are analysed in detail. Furthermore, the corresponding fault protection strategies for the MTDC system are proposed, and the simulations of the MTDC system with DC hub are carried out using the PSCAD/EMTDC simulation tool to verify the feasibility and validity of the above protection strategies.