Research on Modeling of Multi-terminal LCC-UHVDC Transmission System

Ningxia-Hunan ±800 kV HVDC transmission project was approved in June 2023, marking that Multi-infeed UHVDC transmission system will be formed in Hunan Power Grid. Due to the UHVDC transmission project can only realize the power transmission of point to point, and the power conveying method of the multi-terminal HVDC (MTDC) transmission system is more flexible. Based on 2 HVDC transmission projects in Hunan province, China. This article considers three configurations of 4-terminal LCC-MTDC transmission systems, and analyzes its advantages and disadvantages. Subsequently, combined with the practical engineering parameters, a simulation model included main circuit, DC circuit breaker, and control system are established. Finally, the DC line ground fault condition, the start-up of the parallel-type mesh topology MTDC transmission system, the steady-state characteristics, the opening characteristics of DC circuit breakers are studied. This research provides theoretical basis for the subsequent MTDC transmission system that may be constructed in the Hunan province in the future. It has a certain reference value.