Impact of MTDC Grid Reconfiguration and Control on the Dynamics of the GB System

Abstract

Multi-terminal DC (MTDC) grids are becoming increasingly popular for interconnecting non-synchronous generating resources such as offshore wind power plants (WPPs). The benefit of MTDC systems is that they can be reconfigured during contingencies to maintain the supply of power to the host AC systems. DC grid reconfiguration in MTDC systems will inevitably change the power injections to the host AC system, and will thus affect the dynamic behaviour of the AC system. This paper investigates the dynamic behaviour of the representative Great British (GB) transmission system (i.e. a reduced order dynamic model) for a series of reconfigurations in a meshed MTDC grid connecting offshore WPPs to the system. Hierarchical control strategies for the MTDC system including a DC power flow solver (PFS) and pilot voltage droop (PVD) are compared. From the analysis, it is observed that the reconfiguration of MTDC grid has a notable impact on large-disturbance dynamics of the GB transmission system.