Control of bidirectional power flow in a multi terminal DC transmission system based on modular multilevel converter

摘要

Multi terminal DC transmission system based on modular multilevel converter (MMC) is a promising and emerging development in HVDC applications. Here several converter stations, based on MMC topology is connected to the HVDC grid. Each of these stations can operate either in rectifier mode or in inverter mode allowing easy flexibility of bidirectional power flow. In this paper, a MMC based MTDC system is developed and its operation is analysed in details. A mathematical model of MTDC with two rectifier station and one inverter station has been developed. Control system for the MTDC system is proposed and explained. Several simulation results at steady state during load change and power flow reversal is illustrated. The proposed system shows easy integration of several converter stations in the MTDC grid and bidirectional power flow among the converters.