Combined DC/AC supply on a single distribution cable

A commonly used low voltage power cable in The Netherlands has four main conductors for distribution and additionally four smaller sized conductors for powering public lighting or other services. This cable is called the combined-cable. In practice, two AC distribution grids are in parallel in a single distribution cable.The four additional conductors can also be applied for a separate DC distribution grid for public LED street lighting. Cost reduction thanks to a reduced number of feed-in points, extension of life span by reusing existing cables and reduced cable power loss are the main arguments for a combined DC/AC distribution on a single cable. Increased reliability and safer earth-leakage detection and safer short-circuit detection are important aspects of a DC distribution for public lighting.The research question is if the 400V, 3-phase AC grid can be combined into a single cable with regards to cross-talk and safety. A 2D electromagnetic model is set up to model the electromagnetic interactions in the cable. A circuit model based on the outcome of the electromagnetic model is set up and used in circuit simulation to test various conditions and behavior. For example, do AC disturbances and AC load steps in the AC grid influence the power electronics safety components in the DC grid. The simulation and measurement results indicate that the power electronics safety components in the DC grid are largely unaffected by transients in the AC grid. Simulation results are confirmed by the outcomes of first measurements.