An apparatus includes an energy storage system electrically connected across a bus, the energy storage system comprising: a first energy storage element, and a second energy storage element electrically connected to the first energy storage element at an energy node that is between the first energy storage element and the second energy storage element; and an energy filter system electrically connected to the energy node. The energy filter system is configured to electrically connect to one phase of a multi-phase alternating current (AC) power system.