Peak Shaving in a Common DC-Grid by Synchronization of High-Load Machine Operations

In the past decades, machine tools have been optimized for productivity, which has led to high feed rates and accelerations of drives. These high accelerations cause peak loads in the power grid. The electrical infrastructure for the machine supply must be designed to handle these peak loads even if peak loads occur simultaneously on several machines working in parallel. By reducing the resulting overall peak loads in the grid, components can be designed for lower currents and thus more resource-efficiently. In this study we investigated how total peak loads in a shared DC-grid can be lowered by synchronizing high-load-operations. It is possible to slightly delay individual load-intensive NC steps via OPC UA so peak loads of the individual machines no longer occur simultaneously. The approach is implemented on two machine tools. In a field test we achieve a peak load reduction of up to 8.3%. In a simulation, we show that a reduction of almost 20% can be achieved by extending the approach to a network of six machine tools.