Modeling of energy saving in substations feeding DC metro systems based on appropriate location of energy storage elements

Energy storage elements based on lithium-ion batteries became a part of new generation of power systems. One of the most efficient places of energy storage elements implementation is DC traction system because of train regenerative breaking mode. The experiment made in 2012 in Moscow metro shows advantages of energy storage elements installation at 2 substations even at the worst conditions for regenerative breaking. Authors extended that experiment to digital simulation to show the potential advantages of energy saving in ideal conditions. Authors considered two different locations of energy storage element. The first location is DC bus of the first substation. The second location is the point in the middle between the first and the second substations. The results show the significant advantages of its connection to the point in the middle between substations and provides better operation conditions.