137 results about "Power transformer windings" patented technology

The invention discloses a detection method of the looseness fault vibration of a power transformer winding, comprising the following steps of: gathering the original vibration signal of the power transformer winding and carrying out normalization processing by taking the large-sized power transformer winding as a monitoring object, and judging a special vibration state, the light looseness, the moderate looseness and serious looseness of the winding by calculating the Fourier frequency spectrum, the peak value, six time scale sampling entropies and a second-order sampling entropy. In the invention, the vibration signal which is sensitive to the change of the mechanical structure of the winding is adopted to make analysis to detect different degrees of looseness of the winding, and particularly, the invention can well detect the light looseness.

The invention discloses a power transformer winding fault simulation test method and belongs to the field of power transformer winding fault simulation test. The method comprises the following steps that: the high-voltage side of a universal power transformer is connected with an alternating current power supply through a voltage regulator, a resistor for limiting magnetizing rush current is connected in series between the voltage regulator and an electric switch; a bypass switch is connected in parallel at two ends of the resistor; the low-voltage side of the universal power transformer is connected with the low-voltage side of a tested power transformer provided with a winding fault; the high-voltage side of the tested power transformer is in short circuit; the voltage regulator is regulated, so that the tested power transformer acquires different required testing current; and a vibration signal on the surface of an oil tank of the tested transformer is acquired through a vibration sensor, and a current signal which reflects load of the tested transformer is measured through a current sensor so as to be processed and analyzed by a computer. The requirement of the power transformer winding fault simulation test on the power capacity is reduced, the method is easy in operation and readily available in parameters and has universality on similar transformers.

The invention relates to a power transformer winding deformation state multi-information detection method and device, and belongs to the technical field of power equipment fault diagnosis. The method comprises the steps of detecting current, voltage and a phase angle at a high voltage side and a low voltage side, detecting ultrasonic signals, detecting vibration signals, thereby realizing online detection, fault phase detection, fault position detection and fault type detection for the winding deformation state, and effectively solving a problem that the running state, the fault position and the fault type of a power transformer winding cannot be effectively detected because of the simplified detection signals. The device comprises a voltage transformer, a current transformer, an ultrasonic probe, a vibration sensor, a signal conditioning circuit, an AD conversion circuit and a central processing unit, wherein the output ends of the voltage transformer, the current transformer, the ultrasonic probe and the vibration sensor are connected with the input end of the signal conditioning circuit, the output end of the signal conditioning circuit is connected with the input end of the central processing unit through the AD conversion circuit, and the output end of the central processing unit is connected with a communication bus.

The invention discloses a power transformer winding deformation detection method based on vibration analysis. The method comprises the following steps of: (1) arranging vibration detection points, and monitoring load current and a vibration signal of each detection point in real time; (2) acquiring an impact hopping vibration signal, and judging a tripping form of a power transformer; (3) performing winding deformation diagnosis on a first power transformer according to an extracted fixed frequency; and (4) performing winding deformation diagnosis on a second power transformer according to change of a nonlinear degree. By the detection method, the vibration signals are processed and judged, so that electric connection with the power transformer is not needed, and influence on the running of the whole power system is avoided; due to the method, real-time and on-line detection is realized, and detection can be performed without stopping the power transformer, so that the influence on the running of the whole power system is avoided; small and intermediate deformation of a winding of the power transformation can be detected; and moreover, the method is easily integrated into a transformer fault diagnosis instrument and is easy to operate and favorable for popularization.

The invention relates to a winding temperature measuring method of an oil-immersed power transformer. A thermal simulation experiment principle is utilized, actual heating current is obtained after the steps of acquiring related parameters of the transformer, inquiring a thermal simulation features-temperature rise and current mapping table, computing and the like, actual copper oil temperature difference is obtained according to an actual heating current lock-up table, and top oil level temperature is superposed to obtain the winding temperature. The method has the advantages that a winding temperature meter used by the transformer in field can be replaced completely, and economic cost and maintenance cost for purchasing the winding temperature meter are saved greatly; the effect as same as that of measurement by the winding temperature meter can be achieved, and the temperature of a transformer winding can be uploaded to a monitoring data network accurately and inerrably; the problem of inaccuracy of winding temperature measurement caused by influences of the environmental temperature or self defects of the winding temperature meter can be solved completely, and operation and maintenance level of a transformer substation can be increased.

The invention provides a power transformer winding fault diagnosing method, by which winding deformation fault diagnosis is performed through combination of frequency response analysis (FRA) and empirical mode decomposition (EMD). According to the power transformer winding fault diagnosing method, on the basis of energy change information in each interval during a winding deformation fault as well as the adaptive decomposing capacity of the empirical mode decomposition (EMD), a fault energy characteristic quantity of a winding is extracted to establish a fault energy database; the fault energy characteristic quantity is compared with an energy curve of a transformer winding without a fault; the change trend of the characteristic energy shows the working state of the transformer; and the method is used for establishing a mapping relationship between an intrinsic mode function of the winding deformation and an intrinsic mode function of an FRA signal and establishing an integrated fault diagnosis analysis system based on characteristic energy information of the EMD. The integrated fault diagnosis analysis system can accurately know a basic rule of the change of the transformer winding deformation energy and provides a new research way for determining the type and the degree of a transformer fault and estimating the developmental trend of the fault.

The invention discloses a method for detecting deformation of power transformer windings. The method includes the following steps that the short-circuit impedance relative change rate, the overall correlation coefficients of amplitude-frequency curves, the amplitude-frequency curves of a low frequency band, a medium frequency band and a high frequency band, the local correlation coefficients of the amplitude-frequency curves of all the frequency bands, the voltage ratio deviation and the capacitance relative change rate are acquired; the deformed windings and phase results are acquired according to the short-circuit impedance relative change rate and the overall correlation coefficients of the amplitude-frequency curves; according to the correlation coefficient of the amplitude-frequency curve of the low frequency band and the voltage ratio deviation, turn-to-turn or cake-to-cake short circuit detection results are acquired; according to the correlation coefficient of the amplitude-frequency curve of the medium frequency band and the capacitive relative change rates between the windings, local deformation results are acquired; according to the correlation coefficient of the amplitude-frequency curve of the high frequency band and the ground capacitance relative change rates of the windings, whole displacement or lead displacement deformation detection results of winding coils are acquired; the results are logically processed, and a comprehensive detection result is acquired. According to the method, reliability of the deformation detection result of the power transformer windings is greatly improved.

A method for judging a fault type of a winding based on a power transformer includes the following steps of collecting frequency response data of the transformer to be detected, drawing a frequency response curve according to the frequency response data, setting up a KLC model and selecting all parameters of the KLC model according to the type of the transformer to be detected, simulating the KLC model, obtaining changes, corresponding to the changes of different types of parameters, of the frequency response curve by changing the parameters of the KLC model, setting up the corresponding relationship between deformation of the winding of the transformer to be detected and the parameter changes of the KLC model, obtaining the parameter changes, corresponding to the frequency response curve, of the KLC model according to a frequency response curve chart of the transformer to be detected, and obtaining deformation of the winding of the transformer to be detected according to the parameter changes, corresponding to the frequency response curve chart of the transformer to be measured, of the KLC model. The KLC model of the winding of the transformer is set up according to the specific characteristics of the transformer to be detected so that the fault type of the winding of the transformer to be detected can be judged, the result is more accurate and more reliable, and the method is easy and convenient to operate.

The invention discloses a power transformer winding turn-to-turn short circuit failure detecting method based on a resistance frequency curve. The method comprises the steps that all the non-tested windings of a detected power transformer are made to be in a short circuit; the frequency sweeping signals of the preset frequency and amplitude are linearly applied to the head end of a detected winding, meanwhile, voltage signals on non-inductive resistors connected at the head end and the tail end of the detected winding are measured, and per unit values of the impedance of the detected winding under different frequencies are calculated through a computational formula; the trend curve of the impedance per unit values, changing along with the frequency, of the detected winding is drawn according to all the impedance per unit values obtained under the preset frequency, the trend curve is compared with a historical trend curve, and whether the winding turn-to-turn short circuit failure exists or not is detected according to the comparative result. The power transformer winding turn-to-turn short circuit failure detecting method based on the resistance frequency curve can overcome the defects that in the prior art, measuring difficulty is large, the accuracy degree is low and the misjudgment rate is high so as to achieve the advantages of being small in measuring difficulty, high in accuracy degree and low in misjudgment rate.

The invention relates to a power transformer winding fault online monitoring device and a diagnosis method, and belongs to the technical field of power transformer fault diagnosis. The power transformer winding fault online monitoring device is characterized in that the output end of a voltage sensor and the output end of a current sensor are connected to the input end of a synchronous signal sampling circuit, the output end of the synchronous signal sampling circuit and the output end of an ultrahigh frequency sensor are connected to the input end of a signal conditioning circuit, the output end of the signal conditioning circuit is connected to the input end of a DSP (Digital Signal Processor) through an A/D conversion circuit, the output end of the DSP is connected with a PC (Personal Computer) through a CPLD (Complex Programmable Logic Device), and the PC is connected with an alarm. The diagnosis method comprises the steps of acquiring ultrasonic signals at the wall of a transformer oil tank, and finally acquiring coordinates of partial discharge through signal conditioning and A/D conversion and through DSP denoising; acquiring voltage signals and current signals, processing the signals, building an online short-circuit reactance model, acquiring a short-circuit reactance value of each phase winding, comparing the acquired short-circuit reactance value with a corresponding historical fault-free short-circuit reactance value so as to acquire the short-circuit reactance change rate, judging a range, in which the change rate is located, of an upper limit threshold and a lower limit threshold, and judging the winding operating state.

The invention discloses a simulation calculation method for temperature rise characteristics of transformer windings, which is based on finite element method, fluid mechanics and computational heat transfer, and adopts ANSYS Fluent software to realize temperature rise of transformer windings. Based on the fluid-field coupling numerical model, a simulation method of temperature rise of oil-immersedpower transformer winding hot spots is proposed.

The present invention relates to a transformer dynamic stability condition parameter testing apparatus and its diagnosis software. Said product is composed of testing apparatus and diagnosis software, and said invention is characterized by that it adopts a low-voltage reactance method to diagnose the winding deformation of power transformer and changed condition of iron-core looseness in the place so as to create a set of complete high-effective detection and diagnosis method, its detection accuracy is high, can be up to 0.2 grade.

The invention provides an online monitoring system for power transformer winding vibration signals. The online monitoring system comprises a signal amplifying circuit, an A/D (analog-digital) conversion circuit, a level conversion circuit and a signal processing module which are sequentially connected with a vibration acquisition module, the signal processing module and a man-machine interaction unit are connected with each other and then respectively connected with a PC (personal computer) through a communication module, the signal processing module computes vibration energy of different frequency bands of the power transformer winding vibration signals, the vibration energy of the frequency bands is compared with an energy threshold value by the PC, and a failure winding phase in a power transformer is judged. Compared with the prior art, the online monitoring system for the power transformer winding vibration signals can online monitor the vibration signals when the transformer is short-circuited in real time, acquired data are synchronously uploaded to the PC, a diagnosis result is displayed through a display module, and the online monitoring system gives the alarm in real time to explain the running state of a transformer.

The invention provides a power frequency freewheeling test device and its use method, wherein the device includes: a power transformer used to convert the grid voltage into a power frequency voltage, the inter-turn insulation material of the winding of the power transformer is yellow wax silk, The interlayer insulating material is made of glass fiber-wrapped flat wire; the impulse voltage generator with the capacitance of the charging capacitor of 0.05μF, the resistance of the wave head resistance of 80Ω and the resistance of the wave tail resistance of 2100Ω; the impulse voltage generator and the protection of the impact side The output terminal after the circuit is connected in series is connected in parallel with the product to be tested; the output terminal after the parallel connection of the power transformer and the protection circuit on the power frequency side is connected in parallel with the product to be tested; and the control measurement circuit is used to judge whether to trigger the impulse voltage according to the phase of the power frequency voltage . The invention can better simulate the situation that the lightning arrester encounters lightning waves during the operation of hanging on the grid, and can withstand higher overvoltage and overcurrent, and does not need too many protection circuits under the premise of ensuring high reliability.

The present invention discloses an on-line monitoring method and an on-line monitoring system for an axial pressing state of an electric power transformer winding. A natural frequency of an upper layer wire cake of the winding is extracted from vibration signals of an upper surface of a transformer oil tank according to a characteristic that the natural frequency of the upper layer wire cake of the winding reduces under the action of a stable component of an axial Ampere force, a degradation of the axial pressing state of the winding, namely the reduction of a pre-tightening force, results in the reduction of the natural frequency of the wire cake of the winding, and thereby on-line monitoring the axial pressing state of the large power transformer winding by following and observing a variation trend of the natural frequency. The on-line monitoring system includes a vibration signal acquisition module, a load current acquisition module, an analysis control module, a storage module, an output display module and a sound alarm module, wherein, the vibration signal acquisition module, the load current acquisition module, the storage module, the output display module and the sound alarm module are connected to the analysis control module respectively. The on-line monitoring method and the on-line monitoring system have the advantages of a distinct physical significance and a simple realization way.

A power transformer winding deformation reverse acquisition method based on topological optimization includes the steps of building an equivalent circuit model of a transformer winding and acquiring afrequency response function of the equivalent circuit model of the transformer winding, calculating flexibility of the frequency response function of the equivalent circuit model to element parameters, correcting parameter of a simulated equivalent circuit model according to the frequency response function obtained through test, and performing reverse acquisition on deformation status of the transformer winding by a topological optimization method based on a flexible deformation unit. High calculated amount generated in the process of directly utilizing electromagnetic field finite elements to calculate the frequency response function is avoided and correction efficiency is improved; besides, the topological optimization method is introduced to perform visual reduction on the deformed winding, and thus the winding deformation acquisition precision is improved.