Abstract: A software upgrade system includes a control apparatus and M control units, where M is a positive integer. The M control units include a first control unit. The control apparatus includes a first partition and a second partition. The first control unit includes a first storage area. A second software version is deployed in the first partition. A first software version is deployed in the second partition. The control apparatus is configured to: receive a third software version; update the first software version in the second partition to the third software version; and send the third software version to the first control unit. The first control unit is configured to update the second software version deployed in the first storage area to the third software version, where the first software version, the second software version, and the third software version are different versions.

Abstract: A detection system of distributed generation islanding based on power frequency carrier, the detection system comprising: a power frequency carrier signal generating device; a power frequency carrier signal detection device; a signal coupling transformer; a substation bus; a distribution power generator (DG); and a safety isolation breaker, wherein the power frequency carrier signal generating device comprises a voltage and current monitor circuit, the power frequency carrier signal generating device is connected with the signal coupling transformer through four three phase four line power cables, and the signal coupling transformer is connected with substation bus through 3 power cables.

Abstract: This present inversion relates to a detection system and detection method of distributed generation islanding based on power frequency carrier. The system includes a power frequency carrier signal generating device near the terminal power distribution substation, a power frequency carrier signal detection device in distributed power grid; the power frequency carrier signal generating device is connected to the substation bus through a signal coupling transformer; the power frequency carrier signal generating device is connected with signal coupling transformer though phase A, B C live wires and the N middle wire, that results in the signal can be send by anyone signal phase, any two phases parallel way or three phases parallel way. The power frequency carrier signal detection device is connected with the low voltage power network though phase A, B and C live wires and the N middle wire.