Filter Design for DC Grids with Distributed Link Capacitors

Inhalt:
DC conductor rails are an attractive choice for many conveyor systems as commonly used in car factories. One advantage is that the DC link capacitance of the moving conveyors and the DC supply can be replaced by distributed capacitors along the conductor rail. This leads to a reduction in mass and size of the moving conveyors. Due to the distributed capacitors, the conductor rail exhibits now a transmission line behavior, which cannot be neglected anymore because the distributed capacitors reduce the propagation velocity drastically. To regulate the power flow in the DC grid, droop control can be used. Employing droop control in DC grids leads to several advantages, namely ease of implementation and lack of an additional communication bus. However, the impact of the transmission line behavior on droop control has to be investigated to ensure safe operation. In this paper, simulations are conducted for this purpose. The stability of the proposed system greatly depend on the propagation delay. By adjusting the control system and attenuating the resonance frequency, stability is achieved.