Power supply optimization for the superconducting coil system of HELIAS fusion reactor

A power supply system for feeding the superconducting coils of the Helias reactor, an upgraded system of Wendelstein 7X, has been investigated. These investigations on operation of the power supply of the fusion power plant were made using the SIMPLORER, EFFI and NEPLAN codes. This multiconverter supply system has been optimized, in view of low losses in the components and only little negative impact to the power grid. The design of the optimized multiconverter supply system was studied by means of computer simulations. The influence of the passive structures on operation of the power supply system was taken into account. The computation of induced eddy currents in the coil structure during transient processes are transformed into electric network analyses using the inductance and resistance data of the nonplanar coils and their coil housings, by means of the Finite Element Network (FEN) method. This approximation allows the investigation of the whole coil system including power supplies and passive structures. The new approach was to use an additional 80MW, 1.2GJ energy storage unit with the magnetic confinement system as a SMES in order to reduce network loadings to 80MW instead of 160MW in the power plant start-up phase during plasma heating. The reduction of the active power pulse loads reduces the risk of oscillating power frequency changes. These oscillations produce transient power flows which can danger the grid stability