Design of a Short-Circuit Detection Intelligent Release Using Discrete Wavelet Algorithm

The short-circuit faults are one of the inevitable faults types in the power system. The frame circuit breaker can quickly break the transmission lines in case of the short-circuit faults to achieve the purpose of protecting the power system. At present, the method for detecting the short-circuit faults in the low-voltage distribution system by the intelligent release in the frame circuit breaker is mostly the rate of change of current or the effective value of current. Detection of the short-circuit faults by the rate of change of current has poor anti-interference ability. Detection of the short-circuit faults by the effective value will take a long time. In order to shorten the short-circuit fault detection time of the intelligent release, this paper proposes the wavelet packet decomposition as the short-circuit fault detection algorithm of the intelligent release. The multi-scale wavelet algorithm has a certain ability to filter white noise, and the singular value of the detail decomposition can be used to fast detection of the short-circuit faults when the short circuit occurs, which can shorten the detection time of the short-circuit faults. The results of the authoritative institutional tests prove that the intelligent release designed in this paper can detect the fault characteristics and send out the tripping signal within 0.5 ms after the short-circuit faults occur. The method proposed in this paper can be used in the low-voltage distribution system, as well as in medium-voltage and high-voltage situations to detect the short-circuit faults.