Use of a Tubular Linear Induction Motor in a HVDC Breaker

The increasing development of the energy harvesting from remote renewable resources (solar cells in deserts or off-shore wind plants) is producing a great interest in multi-terminal high voltage direct current (HVDC) grids. The adoption of this technology relies on the existence of efficient and robust breakers. As known, the interruption of a direct current is harder than an alternate one, because of the absence of a natural zero of the current and because of the typical low impedance of DC systems. This requires the development of ad hoc designs of ultra-fast actuators capable to interrupt direct currents at high values of voltage. The aim of this work is to investigate the use of a tubular linear induction motor for this purpose.

I. Introduction

Several reasons are at the basis of the recent new interest in High Voltage Direct Current (HVDC) systems; the Renewable Energy Sources integration, the connection between asynchronous AC systems, as well as the transition between point-to-point to multiterminal HVDC systems are only few examples [1], [2]. The fast development of power electronic devices allows to foresee an increasing employment of HVDC systems. However, one of the main drawbacks of these systems is the difficulty to interrupt the fault currents, due to the absence of a natural zero-crossing and to the low impedance characteristic of DC systems [3].