Patent ID: 8829716

Claim:
An energy storage device for a power compensator comprising: a battery stack including a plurality of battery units connected in series, each of the battery units comprising at least two parallel-connected battery modules including a plurality of battery cells, each battery unit further comprises a bypass switch connected in parallel with the battery modules; a control unit which is operatively connected to the bypass switches, said control unit receiving information on a failure in any of the battery modules and closing the bypass switch on a respective battery unit in order to bypass the battery unit in the event of a failure in any of the battery modules of the respective battery unit; wherein each battery unit comprises a battery module supervision unit communicating with the control unit via a communication link, said battery module supervision units detecting a failure in their respective battery modules; and a communication management module detecting a loss of communication between any of the battery module supervision units and the control unit and upon detecting a loss of communication, said communication management module closes the bypass switch in order to bypass the battery unit corresponding to the loss of communication.