UNINTERRUPTIBLE POWER SUPPLY SYSTEM

Each of n uninterruptible power supplies connected in parallel includes m uninterruptible power supply modules connected in parallel between an input terminal and an output terminal. In each uninterruptible power supply module, a controller controls an inverter so that the current value of AC power supplied from the inverter to a load matches a first instruction value. The n×m controllers are connected to one another to constitute an integrated controller. When a failure is detected in one of the m uninterruptible power supply modules in any one of the n uninterruptible power supplies, the integrated controller disconnects the failed uninterruptible power supply module and changes the first instruction value to a second instruction value so as to equalize the current values of AC power output from the inverters of the remaining normal uninterruptible power supply modules.