TECHNICAL FIELD

The present invention relates to a DC electrical circuit protection apparatus which, in order to protect DC electrical circuits from a DC arc, carries out a detection of an arc which has occurred in an DC electrical circuit and thus carries out a protection of the DC electrical circuit, and to an arc detection method.

BACKGROUND ART

Owing to the dissemination and expansion of the use of information terminals, to the IT modernization of equipment, and to the rise of cloud computing technology, the amount of data to be processed by a network server, or the like, has increased significantly in recent years. The larger the amount of data processed, the larger a power load applied on information and communication equipment. In general, these processes are carried out by the information and communication equipment of a data center, and approximately one third of power consumption is said to derive from the information and communication equipment. Because of this, a power-efficient, high-voltage DC feed system is being widely used in order to realize energy saving. With the system, it is reported that as it is possible to reduce a loss caused when converting DC to AC, power consumption can be reduced by 20% as compared with the current one.

However, as the high-voltage DC feed system feeds a DC voltage/current, as the name indicates, there exists the risk of damage from an electrical fire triggered by a DC arc fault. In the case of an AC electrical circuit, there always exists current zero, and so it is easy to extinguish an arc. On the other hand, in the case of a DC electrical circuit, a constant current continues to flow, and so no current zero exists, making it difficult to extinguish an arc which has once occurred. Also, when this kind of fault occurs, a current at which a breaker trips is not reached, and so it is difficult to detect an arc occurrence. Furthermore, a huge electrical circuit system, such as a data center, is largely affected, and it is necessary to identify the fault part, disconnect a portion having the fault, and avoid a halt of the entire system. For this reason, in such a case that an arc occurs in the DC electrical circuit, leading to a fault, it is necessary to establish a DC electrical circuit protection system which can detect the arc occurrence quickly and identify a fault part.

As a DC generation system which has been highly improved in the protection against the arc occurrence, PTL 1 proposes one including an arc detection device which has an arc noise analysis unit which, based on the noises of signals from current sensors, detects an arc which occurs in the DC generation system based on the noises of signals from current sensors; a current fluctuation analysis unit which, when the arc is detected in the arc noise analysis unit, analyzes output current fluctuations of individual strings (a series of module circuits connected in series) based on the signals from the current sensors, and based on the fluctuations of current values before and after the arc has been detected, identifies an arc occurrence part; and a switch control unit which controls opening and closing of switches based on a result of the arc identification in the current fluctuation analysis unit.

CITATION LIST

Patent Literature

PTL 1: JP-A-2015-211606

SUMMARY OF INVENTION

Technical Problem

The arc detection device proposed in PTL 1, as it utilizes the property specific to a solar power system, has a problem in that in a common DC electrical circuit, it is not possible to identify a DC arc occurrence part, and that in the case of a system, such as a DC feed system for a data center, which is configured by combining a plurality of DC electrical circuits, it is net possible to identity a DC electrical circuit in which an arc has occurred from among the plurality of DC electrical circuits.

The invention, having been made in order to solve the heretofore described problem, has for its object to identify a DC electrical circuit in which an arc has occurred from in a complex configuration configured of a plurality of DC electrical circuits, and disconnect the circuit in which the arc has occurred from the entire system, thus enabling an operation by a sound circuit.

Solution to Problem

In a DC feed system where a plurality of DC electrical circuits are connected to a common main line, there is provided a DC electrical circuit protection apparatus which includes a plurality of current sensors which are each provided in at least one of a positive or a negative electrical path in each of at least two of the plurality of DC electrical circuits; a plurality of arc noise absorber which are provided one on the upstream side of each of the plurality of current sensors and which each absorb an arc noise, which has occurred in one of the DC electrical circuits and flows in from the upstream side, so as not to cause the arc noise to propagate to any other DC electrical circuit; and an arc detection device which compares respective arc noise signal strengths of the DC electrical circuits from current signals detected by the plurality of current sensors of the DC electrical circuits, and based on the arc noise signal strengths, identifies a circuit in which an arc has occurred from among the plurality of DC electrical circuits.

Advantageous Effects of Invention

According to the invention, with respect to an arc fault which has occurred in a DC feed system in which a plurality of DC electrical circuits are connected to a common main line and which is provided with means which absorb arc noises so as not to cause an arc noise having occurred in one of the DC electrical circuits to propagate to any other DC electrical circuit, it is possible to identify an arc occurrence part and disconnect only an arc fault segment.

