35results about How to "Obvious fault features" patented technology

The invention discloses a method for detecting winding deformation faults of a power transformer. The method includes that different vibration characteristics of the transformer in a normal state and a fault state are combined according to running characteristics of the transformer, vibration signals are monitored by a vibration sensor mounted on the surface of the transformer, frequency spectrums of the vibration signals are analyzed, and the transformer is judged to have winding deformation faults if the ratio of 50Hz energy sum and 150Hz energy sum to (50+150Hz) energy sum to (100+200Hz) energy sum which are actually measured is obvious increased as compared with that of the transformer in the normal state and an actually measured 100Hz energy value is hardly changed or even reduced as compared with that of the transformer in the normal state. The invention further discloses a system for detecting the winding deformation faults of the power transformer. The method and the system have the advantages of obvious fault characteristics and good repeatability, and are universal for power transformers of the same type, engineering implementation is simple, and diagnosis is intuitive.

A distribution network phase-to-earth fault section location method and location device. By terminals mounted in different positions on a line, zero sequence current transient signals of 2 periods before a zero sequence current exceeds a startup value and of 2 periods after exceeding the startup value are accurately caught, and the terminals perform wavelet transformation and reconstruction on the zero sequence current transient signals, and analyse a section where a fault point is located according to the approximation coefficient integral value of a reconstructed precise component.The location device is composed of two parts; terminals and a main station. The terminals are mounted on an aerial line pole or in a cable ring main unit, the input ends of which receive phase current signals of a distribution line CT secondary side which are combined to obtain a zero sequence current signal, and are connected to the main station by optical fibre communication or mobile communication. The main station is mounted in a transformer station or at a scheduling centre, includes an optical fibre communication module and a mobile communication module, and receives signals transmitted from the terminals.

The invention relates to a series arc detection method for a low-voltage distribution network, which belongs to the field of electrical engineering measurement. It is characterized in that it includes the following steps: step a, setting a monitoring node in the line to be tested; step b, synchronously looking at the line to be tested and collecting the voltage at both ends; step c, performing filtering processing on Uo; step d, obtaining Us- The waveform of Uo; step e, if a series arc fault occurs, go to the next step, if no series arc fault occurs, return to step b; step f, count the number of faults; if it exceeds the preset threshold, cut off the line or send an alarm signal. If the preset threshold value is not exceeded, return to step f; in the series arc detection method for low-voltage distribution network, the detection of series fault arc is realized by measuring the voltage difference between the head end and the end of the line, and the voltage information is used to judge the series fault The existence of arc has the advantage of being less affected by load type and load power, and its fault characteristics are more obvious, so its judgment accuracy is higher.

The invention provides a method for the early failure detection of a motor using current characteristic enhancement transformation, which comprises (1) real-time collecting three-phase current of an induction machine ia, ib, and ic, and calculating a transformation matrix K based on a current power frequency fe; (2) demodulating via the following formula to obtain a torque current iq and a magnetizing current id, wherein iqd0 is equal to Kiabc; (3) performing fast Fourier transformation of torque current iq and the magnetizing current to obtain a subtle current characteristic spectrum; and (4) comparing with the failure characteristic frequency of the induction machine, and determining the failure types of the induction machine. The method has the advantages of simple principle, simple operation, and high measuring accuracy, and can extract failure characteristic component in severe power frequency background using the current characteristic enhancement transformation to detect the early failure of the induction machine.

The invention provides a fault diagnosis method for a rolling bearing based on an enhanced Mel linear frequency cepstral coefficient, belonging to the technical field of rolling bearing fault diagnosis. The method includes: acquiring a time domain vibration signal of the rolling bearing; using a preset Mel linear frequency filter The feature extraction is performed on the time-domain vibration signal to obtain a two-dimensional feature map of the enhanced Mel linear frequency cepstral coefficients; the final diagnosis result is obtained according to the two-dimensional feature map of the enhanced Mel linear frequency cepstral coefficients and a preset Transformer model; the present invention Accurate and rapid diagnosis of rolling bearing faults can be achieved under the condition of data distribution offset.

The invention discloses a current second-order gradient-based single-ended data protection method for a high-voltage direct-current transmission line. The method comprises the steps of measuring the current at each end of the line, calculating the second-order gradient integral value of the current, and recognizing troubles inside the sample space through comparing the second-order gradient integral value of the current with a starting threshold. The method is simple in principle, and can be realized only by adopting the whole content of a single-ended current. Meanwhile, the filtering is not needed, and the method is easy in implementation. In viewing from the principle, a most serious external fault is guaranteed. That means, the method is free of maloperation and good in selectively during the external metallic grounding fault of a smoothing reactor. Based on the cooperation of existing fault pole selection elements, the correct pole selection action can be achieved. The method is fast in action speed and realizes the complete setting principle. The full-line high speed can be realized. Compared with traveling wave protection, the method is not influenced by noises and is high in reliability. Compared with break variable protection, the method is not influenced by the most serious external fault and is good in selectively. The method can be used for the main protection of the high-voltage direct-current transmission line.