Current Injection Circuit Breakers for HVDC: Overview on Improved Injection Circuits

HVDC circuit breakers are a key technology for the reliable and safe operation of multiterminal HVDC networks. Current injection topologies can perform this duty while offering advantages like low on-state losses and a robust and economical structure. The key component for its performance is the mechanical interrupter.In this paper, four improved injection circuits are proposed. These are designed to influence the injection current shape to facilitate interruption and reduce component cost. Based on a simulation study using synthetic fault cases, interruption performance and component use of the improved injection circuits are compared to a reference CI topology. The results promise that the same performance can be achieved with considerably scaled down components.