Uninterruptible power system with backfeed detection and method of operating the same

摘要

An uninterruptible power system and a method of operating the same are disclosed. The uninterruptible power system includes a power conversion apparatus, a switch unit, a first voltage detection unit, a second voltage detection unit, and a comparison unit. The power conversion apparatus receives an AC power source and converts the AC power source to supply an AC load. The first voltage detection unit detects an input voltage of the power conversion apparatus and produces a first voltage signal. The second voltage detection unit detects an output voltage of the switch unit and produces a second voltage signal. Under the AC power source is disabled and the power conversion apparatus provides a backup power to supply the AC load, the switch unit is detected in a fault operation when the first voltage signal is compared by the comparison unit to equal to the second voltage signal.

主权项

1. An uninterruptible power system, comprising:
a power conversion apparatus having an input terminal and an output terminal, the input terminal receiving an AC power source and converting the AC power source to supply an AC load; a switch unit having a first input terminal, a second input terminal, and an output terminal switchably connected to the first input terminal or the second input terminal, the output terminal directly connected to the AC load, the second input terminal directly connected to the output terminal of the power conversion apparatus and the first input terminal directly connected to the input terminal of the power conversion apparatus; a first voltage detection unit configured to detect an input voltage of the input terminal of the power conversion apparatus and configured to produce a first voltage signal, wherein the first voltage signal is an AC signal; a second voltage detection unit configured to detect an output voltage of the output terminal of the switch unit and configured to produce a second voltage signal, wherein the second voltage signal is an AC signal; and a comparison unit configured to receive the first voltage signal and the second voltage signal and configured to compare the first voltage signal and the second voltage signal; wherein when the AC power source is disabled, the switch unit output terminal is disconnected from the first input terminal and connected to the second input terminal, and the power conversion apparatus provides a backup power to supply the AC load, the switch unit is detected in a fault operation when the comparison unit determines that the first voltage signal is identical to the second voltage signal, the first and second voltage signals are determined to be identical when their frequency, phase, and magnitude are determined to be identical, and represents that the first input terminal and the second input terminal are shorted, whereas the switch unit is detected in a normal operation when the comparison unit determines that the first voltage signal is not identical to the second voltage signal;wherein the power conversion apparatus comprises:
an energy storage apparatus configured to receive energy from the AC power source, and configured to provide the backup power to supply the AC load.