Analysis of stable operation region of the hybrid AC/DC distribution systems

Abstract

Hybrid alternating current (AC)/direct current (DC) distribution is a promising technology emerging for future power systems owing to its advantages, such as high controllability and compatibility. The stability of grid-connected converters is essential for the operation of an AC/DC distribution system. This study analyses the stable operation requirements of converters under different control modes based on the short-circuit ratio (SCR). Then, a method to calculate the critical SCR (CSCR) of a specified converter is proposed. Based on the CSCR of each converter, the stability criterion to judge the stability of multi-terminal DC (MTDC) distribution networks is proposed. To verify the accuracy and effectiveness of the proposed method and criterion, detailed electromagnetic simulations using PSCAD are conducted. The simulations indicate that the analysis results obtained using the proposed method and criterion are accurate, and the presented stable operation requirements of the converters can help to enhance the controllability of hybrid AC/DC distribution systems.

Keywords

• power convertors
• hvdc power transmission
• hvdc power convertors
• distribution networks
• power grids
• stable operation region
• future power systems
• grid-connected converters
• different control modes
• specified converter
• multiterminal dc distribution networks
• presented stable operation requirements