1328results about "Transformers testing" patented technology

A method for fault detection in a power transformer/autotransformer and/or interconnected power lines, which are within the zone protected by the differential protection, and particularly suitable for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e. the fault position, is within the protected zone or outside of the protected zone, delimited with current transformer locations, the protected object is disconnected if determined that the source of the negative sequence currents is within the protected zone.

The invention relates to a transformer internal insulation aging diagnosis method based on a multi-feature information fusion technology, which comprises the following steps: 1) selecting feature quantities and obtaining feature quantity values; 2) normalizing the feature quantities by adopting a calculation method with relative impairment grade; 3) determining a weighted value of each feature quantity; 4) obtaining a relative impairment grade value of transformer whole internal insulation; and 5) judging the aging degree of a transformer according to the relative impairment grade value of the transformer whole inner insulation. Through the transformer internal insulation aging diagnosis method, the same type of information is fused together, and a technology of useful information with more features or more accurate useful information is obtained from the same type of information to accurately judge the transformer internal insulation aging degree. The transformer internal insulation aging diagnosis method has the beneficial effects that the utilization rate of the information can be increased, the credibility and the accuracy of the infused information are improved, the different feature quantities can be selected as required, and the various feature quantities are endowed with the corresponding weighted values; and the applicability is strong, and the judgment accuracy is high.

A method for measuring partial discharges in windings of electrical devices comprised by the following steps: Applying voltages having high frequency components to the winding of the electrical device, detecting partial discharge signals by means of a tuned VHF and/or UHF electromagnetic sensor located close to the electrical device and evaluating the detected sensor signals by means of electrical hardware or software. Further, a VHF and/or UHF electromagnetic sensor for measuring partial discharges in windings of electrical devices is described wherein an antenna made of a coaxial cable is provided as electromagnetic sensor. The present invention provides an improved measuring method and sensor device, which avoid the drawbacks of the prior art. The improved measuring method provides more detailed information about the status of the insulation system and clear short-circuits during the testing are not necessary any more. The proposed sensor provides a surprisingly simple and inexpensive solution.

The invention relates to system and method for detecting the transformer winding state by using constant-current sweep frequency power source excitation. A measurement and control analysis module controls sweep frequency power source and applies output constant-current sweep frequency excitation signals by an exciting transformer at a high-voltage side of the transformer to be detected; a vibration sensor measures vibration response signals of a transformer winding to be detected at different excitation frequencies; a vibration signal collector collects and preprocesses the signals measured by the vibration sensor; and the measurement and control analysis nodule carries out spectrum analysis to the received and processed vibration response signal data, displays and records a resonant frequency curve of the transformer winding on a frequency domain, compares with the resonant frequency curve previously measured and recorded as well as the vibration frequency curve of a transformer three-phase coil, and judges the state of the transformer winding to obtain the measuring result. The invention can effectively and sensitively detect the states of looseness or deformation of the transformer winding for prompt repair or replacement so as to avoid a fault of abrupt short circuit of the transformer caused by damage of the winding structure.

The invention relates to a method of utilizing the vibration waveform for detecting the state of the transformer winding. A transformer winding is viewed as a mechanical system; and if the winding is loosened or deformed, the mechanical characteristics of the winding changes, thus the corresponding mechanical characteristics of the transformer winding under the action of the impulse current are detected and the loosening and deforming condition of the transformer winding can be detected sensitively.

Certain embodiments may generally relate to a smart fault detection device for power grids, and a method of fault detection for power grids. A method may include receiving raw data samples of currents in grounding conductors and line conductors. The method may also include processing the raw data samples under at least one of a plurality of system operating modes. The method may also include monitoring normal operation and anticipating an impending fault while operating under at least one of the system operating modes. The method may further include extracting fault information based on the monitoring. The method may also include reporting the fault information to a supervisory control and data acquisition system human-machine interface. The method may further include anticipating faults based on an analysis of the raw data samples.

The present invention is a method of and an apparatus for measuring resistances of at least one transformer winding (109) in configurations of connected transformers windings. The method is based on increasing driving power from the source of electrical energy (12, 102) until the current reaches a predetermined level, which is below the core saturation current level of the measured transformer or the measuring device current limit, and then controls the power of the source of the electrical energy to maintain predetermined current flowing through the at least one winding over a time period sufficient to cause a L di/dt contribution to a voltage drop across the at least one winding to decrease below a threshold level. The apparatus measures simultaneously the constant current flowing in the at least one winding and the voltage drop over the at least one winding after the predetermined time period has elapsed. The resistance of the at least one winding is calculated from the voltage drop over the at least one winding and the current flowing in the at least one winding.

The disclosure discloses a fault locating method based on a multi-layer evaluation model. Firstly, determine a fault type to be inspected and a fault symptom which able to accurately and effectively reflect a power transformer operation status and determine a weight of each fault type by using an association rule and a set pair analysis. Then, establish a DBN model to perform feature extraction and classification on multi-dimensional data of a fault. Finally, perform a comprehensive evaluation on an existing diagnosis result by using the D-S evidence theory. Accordingly, the supporting strength of the common target is reinforced, while the influence of divergent targets is reduced. As a result, the uncertainty in the diagnosis result is significantly reduced. The disclosure is mainly used to monitor and diagnose a status variable of the power transformer in a real-time manner, and treats power transformer status evaluation as a multi-property decision issue.

The invention provides a method of carrying out transformer fault identification based on a BP neural network algorithm. The method comprises the following steps of step S1, through a partial discharge test system, collecting discharge pulse graphs of different transformer faults; step S2, carrying out power graph analysis on discharge pulses acquired through the step S1; step S3, extracting a training sample and a test sample from characteristic quantities acquired through the power graph analysis obtained from the step S2; step S4, constructing a BP network nerve; step S5, carrying out BP network nerve training; step S6, carrying out BP network nerve testing. By using the method of carrying out transformer fault identification based on the BP neural network algorithm, a fault type of a transformer can be accurately identified. And the method plays an important role in transformer fault diagnosis and a state assessment and the method is convenient.

The invention provides a property monitoring apparatus comprising a test current output circuit capable of varying an output current, a test current value computing means for computing a current value of a test current output from the test current output circuit, a test current control means for performing feedback control of the test current value computed via the test current value computing means to a target value, a measurement current detection circuit for measuring an output current value of the current transformer or the voltage transformer when the test current controlled to the target value via the test current control means is supplied, for storing a relationship between the output current value of the current transformer or the voltage transformer and the test current value for each target value by varying the target value of the test current via a predetermined pattern, and computing a correction coefficient for correcting a property of the current transformer or the voltage transformer based on the stored relationship.

The invention discloses a system and method for judging interior looseness of a power transformer. The system for judging and initially positioning interior looseness of the power transformer comprises a signal conditioning circuit, a data acquisition instrument, a data analysis module and three vibration sensors, wherein the signal conditioning circuit, the data acquisition instrument and the data analysis module are sequentially connected. The three vibration sensors are connected with the data acquisition instrument through the signal conditioning circuit and measure vibration signals of three phases of the power transformer correspondingly, the vibration signals are amplified, filtered and denoised by the signal conditioning circuit and then transmitted to the data acquisition instrument, the data acquisition instrument transmits the acquired vibration signals to the data analysis module, and the data analysis module stores and processes the vibration signals and carries out fault judgment. The looseness fault of the transformer is judged through 100 Hz signals in the vibration signals according to the characteristic of change of the vibration signals along with the looseness degree.

A method for calculating a primary time constant of a power grid. It comprises the steps of: establishing an electromechanical transient model of the power grid using the widely used power system analysis software package (PSASP) according to the actual power grid parameters and network topology; establishing an electromagnetic transient model under PASAP using the actual power grid parameters for a site which requires the calculation of the primary time constant of the power grid, and setting a ground short circuit fault at the site; obtaining a transient short circuit current of the short circuit point of the power grid using a hybrid simulation method of the electromechanical and electromagnetic transient models; filtering out a periodic component in the transient short circuit current to obtain a non-periodic component attenuated with time, and finding the attenuation time constant of the non-periodic component which is the primary time constant of the power grid.

A preferred method for identifying a type of abnormality in an insulation system of a power transformer comprises measuring dielectric losses in a section of the insulation system, calculating theoretical dielectric losses for the section based on the material properties, geometry, and temperature of the section, and generating a graphical representation of a percent difference between the measured and calculated dielectric losses. The preferred method also comprises comparing a shape of the graphical representation with a shape of one or more graphical representations of a percent difference between measured and theoretical dielectric losses in one or more other sections of insulation each known to have a specific type of abnormality.

A method of measuring the characteristics of a transformer comprises the steps of determining the transformer turns ratio, switching the load tap changer from the current tap position to a subsequent tap position while determining a primary current and measuring the secondary voltage across the secondary side, determining the primary voltage across the primary side, and determining the characteristics of the transformer based on the determined transformer turns ratio, the determined primary current and the measured secondary voltage. Thereby, the static and dynamic characteristics of the transformer including a load tap changer can be determined.

The invention provides a method for simulating a gas insulated switchgear (GIS) transformer substation to produce very fast transient overvoltage (VFTO) by a test circuit and the test circuit. The test circuit comprises a first isolating switch gear, a second isolating switch gear, a first isolating pipe sleeve, a second isolating pipe sleeve and a branch bus, wherein one end of the first isolating switch gear is connected with one end of the second isolating switch gear via a pipeline; and the other end of the first isolating switch gear is connected with one end of th first isolating pipe sleeve via a pipeline; the other end of the second isolating switch gear is connected with one end of the second isolating pipe sleeve; one end of the branch bus is connected with the pipeline between the first isolating switch gear and the first isolating pipe sleeve and the other end thereof is overhung; and VTTO waveforms occurring on isolating switch fractures and GIS pipelines in the GIS transformer substation are simulated by changing the length of the branch bus under different GIS connection modes.

The invention discloses a transformer fault diagnosis method based on feature information quantization and weighted KNN, comprising the following steps: S1, dividing sample data into a training set and a test set; S2, inputting the training set, and performing preprocessing on the sample data; S3, based on principal component analysis (PCA) and grey relational analysis (GRA), performing quantization on fault feature information; S4, introducing a particle swarm optimization algorithm for optimizing a weighted KNN categorization algorithm, according to a true fault category, training a sample in a standardized fault feature matrix, and obtaining a power transformer fault diagnosis model, thus categorization on a power transformer fault is realized; and S5, inputting the test set into the power transformer fault diagnosis model, and obtaining a diagnosis result, thus diagnosis on the power transformer fault is realized. The transformer fault diagnosis method disclosed by the invention solves the problems that processing efficiency is low, model training is difficult and limitation exists in the prior art.

The invention relates to a health state early warning method and device of a distribution transformer. The method comprises the following steps: collecting the load current of the distribution transformer and an ambient temperature of the environment in which the distribution transformer is located; determining a winding hot-spot temperature of the distribution transformer according to the load current of the distribution transformer and the ambient temperature of the environment in which the distribution transformer is located; and performing health state early warning of the distribution transformer according to the winding hot-spot temperature of the distribution transformer. According to the health state early warning method and device provided by the invention, the accurate real-timemonitoring of the winding hot-spot temperature of the distribution transformer is achieved by measuring the external temperature, and the voltage and the current of the distribution transformer, and the operation state of the distribution transformer is estimated to provide an important support for the overload control of the distribution transformer, the use efficiency of the distribution transformer and the safe and stable operation of the distribution transformer.

A method for recognizing a transformer partial discharge pattern based on a singular value decomposition (SVD) algorithm includes a training model and a classification recognizing process, comprising: firstly setting up an experimental environment having artificial defects, collecting at least one datum sample, and calculating statistical feature parameters of each datum sample to form a datum sample matrix; performing singular value decomposition on the datum sample matrix and determining an order of an optimal retention matrix by judging whether a feature of a retention matrix is clear, so as to obtain a type feature description matrix and a class-center description vector group after dimensionality reduction; preprocessing samples to be recognized to obtain a sample vector, and performing linear transformation on the sample vector utilizing a type space description matrix.

The invention discloses a system for testing a GIS electronic transformer based on a small connecting and disconnecting capacity current of a disconnecting switch. The system comprises a high-voltage testing transformer connected to a BSG sleeve, a capacitive voltage divider, a load capacitor arranged on the other BSG sleeve, the disconnecting switch arranged between the two sleeves, a calibration primary transient state testing system and the electronic transformer to be tested, one end of a secondary converter is connected with the electronic transformer to be tested, the other end of the secondary converter is connected with a merging unit, and the other end of the merging unit is connected with a fault recorder. When the disconnecting switch is connected or disconnected, voltage values and current values of a high-voltage bus are tested and compared with the output values of the electronic transformer to be tested. According to the testing system, the electromagnetic environment at the voltage levels of 110KV, 220KV, 500KV and the like in the process of electricity connection and electricity disconnection can be simulated, the site disconnecting switch connecting and disconnecting hollow conducting wire and capacity small current loading process is simulated, similar site transient sate strong-interference is generated, and the electromagnetic protective performance of the electronic transformer under the condition is examined.

A transformer diagnosis apparatus and method which can advantageously be used for on-line diagnosis of a transformer, and by which transformer properties may be monitored and/or determined. The diagnosis method includes collecting, for at least two different transformer loads, measurements of a current being indicative of the transformer load, as well as measurements of at least one further transformer AC signal. The method further includes deriving, from the collected measurements, at least two values of a quantity which depends on a transformer property as well as on transformer load; and determining, from the derived values, a set of coefficient(s) of a relation for how the quantity is expected to vary with transformer load. The method further includes using the determined coefficient(s) in performing a diagnosis of the transformer.