Dynamics of an ultra-fast Thomson actuated HVDC breaker

Abstract: High Voltage Direct Current (HVDC) is a rapidly growing form of power transmission that offers advantages with respect to conventional AC networks. One of the key elements that will allow the generalization of the HVDC grids is the Circuit Breaker (CB), which has to interrupt high DC currents in extremely short times. The use of a Thomson coil (TC) to generate high driving forces is being considered as a suitable working principle for the mechanical actuator inside the CB. This thesis presents the design of a concept of a mechanical actuator based on the Thomson coil for SCiBreak AB, a company whose final objective is to create a complete ultra-fast circuit breaker for HVDC lines. The design phase had to face challenges with the high forces required to open a gap between electrical contacts in just a few milliseconds. A detail design for the different components of the actuator was performed and analytical and CAD models of the system were generated. This thesis also included the construction and testing of a prototype at the company’s premises. The final output was the analysis and discussion of the experimental results of the prototype, as well as suggestions for the future development of the mechanical actuator.