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

The invention provides an online low-current earth fault positioning method and positioning device based on a BP neural network and by means of a multi-source data fusion algorithm. Due to the fact that terminals arranged on different positions on a circuit accurately catch zero-sequence current transient signals of zero-sequence currents which exceed a starting value before a previous period of a starting value and after four periods of the starting value, signal characteristics of a fault transient signals are extracted by means of a Prony algorithm, a wavelet packet algorithm, an HHT algorithm and a fractal algorithm, the characteristics extracted by the algorithms are analyzed by means of the BP neural network, and a zone where a fault occurs is determined. The positioning device comprises a terminal and a main station, wherein the terminal is arranged on an overhead line tower or in a cable ring main unit, the input end of the terminal receives a zero-sequence current signal synthetized by a phase current signal of a CT secondary side of a power distribution circuit including an overhead line and a cable, the terminal is connected with the main station through optical cable communication or mobile communication, and the main station is arranged in a transformer substation or a dispatch center, comprises an optical cable communication module and a mobile communication module and receives a signal sent by the terminal. The method and the device are mature in technology and high in reliability.

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 application provides a positioning method and a positioning device for a single-phase ground fault section of a power distribution network based on a transient signal prony algorithm. The positioning method comprises the following steps in sequence: accurately capturing zero-sequence current transient signals of the zero-sequence current in one cycle before exceeding the starting value and in four cycles after exceeding the starting value through terminals in different positions on a circuit; extracting the transient high-frequency component signal which plays a lead role in the fault transient signals through the prony algorithm; and analyzing the section of the fault point according to the transient high-frequency component signals. The positioning device comprises terminals and a master station, wherein the terminals are arranged on overhead line poles and towers or cable ring main units; the input ends of the terminals are used for receiving phase current signals from the CT (Computed Tomography) secondary sides of power distribution lines (including overhead lines and cables) and combining the phase current signals into the zero-sequence current signals; the input ends of the terminals are connected with the master station in an optical fiber communication way or a mobile communication way; the master station is built in a transformer substation or a control center and comprises an optical fiber communication module and a mobile communication module; and the master station is used for receiving the signals transmitted by the terminals. The method and device provided by the application are mature in technology and high in reliability.

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.