Short circuit protection in DC ship grids based on MMC with full bridge modules
DC grids offer highly efficient distribution of electric energy, eliminating components and optimizing the use of cables. Efficient generation, however, is still based on AC generators. Power electronic devices link generators and grid and customize energy flow to the loads. Efficient distribution with low losses demands high voltage, e.g. in the range of 10 kV for ship size grids. Such voltages challenge power electronics as well as protective devices: Short circuit protection with fast auto reclosing in a context where fuses are not applicable has to be solved. This paper proposes modular multilevel converters (MMC) with full bride (4QC) modules and demonstrates fault mitigation in controlled MMC operation by measurement results. The associated control separates asset characteristic defining the steady state and transient behaviour and converter near control operating in the subtransient and transient regime. The feasibility of the approach is demonstrated by selected measurement results.
2015 International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles (ESARS)