An energy storage apparatus, an energy storage system, and a redundant control method, where the energy storage apparatus includes a power module and a battery module; the power module includes a first switch and a first controller configured to control the first switch; the battery module includes a second switch and a second controller configured to control the second switch; the first controller is connected to both the first switch and the second controller, and the second controller is connected to the second switch.

A network unit may be operatively attached to power lines of an interconnected power system and/or a device such as a power module that may further include a communication interface. The network unit may be operable to superimpose a first signal representative of a sensed parameter of the power system onto the power lines, thereby to transmit the first signal to other power modules in the interconnected power system or to a power device in interconnected power system. The network unit may receive a second signal of the parameter superimposed onto the power lines from another network unit.

A solution is disclosed for providing fault-managed power systems using optical elements. The fault-managed power systems are able to provide safe and efficient power delivery utilizing optical fiber links to improve signal integrity, security, and reach of the system.