222 results about "Capacitor voltage transformer" patented technology

The invention relates to a capacitor voltage transformer suitable for high-voltage harmonic measurement and a measurement method. The capacitor voltage transformer is characterized in that a current transformer is respectively connected into a low-voltage capacitance branch and an intermediate transformer branch of a capacitive voltage divider of the capacitor voltage transformer in series, two conventional current transformers are additionally arranged in a conventional capacitor voltage transformer, and the size and the phase position of harmonic voltage of a high-voltage system can be worked out by using electric currents measured by the two current transformers. Therefore, the capacitor voltage transformer has the advantages of being simple in structure and convenient to realize, having high measurement accuracy of voltage harmonics, being free of influence of the size of a load of the capacitor voltage transformer and having very high application value and market promotion prospect in occasions where high-voltage harmonics are measured.

The invention relates to an on-site calibrating method and an on-site calibrating device of a capacitor voltage transformer. The invention directly measures voltage and current signals at the primary side and the secondary side of the measured capacitor voltage transformer and calculates the ratio and angular differences of the measured capacitor voltage transformer by utilizing the measured result, so that the invention can realize separately measuring the error of the measured capacitor voltage transformer only by the on-site calibrating device of the capacitor voltage transformer and does not need equipment such as a standard transformer, a voltage regulator, a voltage booster, a reactor and the like, thus saving calibrating time, lowering labor intensity of workers and resolving the difficulty of difficult implementation for error test of the on-site capacitor voltage transformer.

The invention provides an on-site CVT integrated verification system, which comprises a test power supply, a standard appliance, a measuring apparatus and a vehicle-mounted test platform. The test power supply consists of a series reactor, an exciting transformer and a voltage regulator; the standard appliance comprises a high-tension bushing, a standard voltage transformer and a standard capacitor, wherein the high-tension bushing, the standard voltage transformer, the standard capacitor and the series reactor are designed into an integrated sulfur hexafluoride SF6 closed combined electrical apparatus (GIS); and the standard voltage transformer is designed into an SF6 gas insulated reclining posture type structure. The system of the invention can conveniently, accurately and reliably verify the ratio error of on-site 220Kv to 500 Kv CVT (capacitor voltage transformer), the capacitance of a capacitive divider, the medium loss, and the like without unloading from a vehicle. The additional error guided by the measuring system is relatively fixed and is easy to measure, wherein the variation thereof is less than or equal to 0.02 percent.

The invention relates to a method for measuring the electric capacity and the dielectric loss of a capacitance type voltage transformer, comprising the following steps of: disassembling primary and secondary lead wires of a tested article, and connecting a secondary winding of the tested article to the ground in a short circuit way by a fuse wire; disassembling a lower-voltage terminal X point ofa compensation reactor of the tested article and an end shield to connect to the ground, wherein the end shield and the X point are both suspended in midair; connecting a measuring ground point of a full-automatic digital electrical bridge AI-6000 E to the ground; connecting a high-voltage line and a measuring line to the full-automatic digital electrical bridge AI-6000 E; switching on a main power switch, then switching on an inner high-voltage permitting switch, selecting positive connection wire, inner standard, frequency conversion and testing voltage 10 kV, and finally pressing a starting/pausing key to carry out measurement for more than 1 second; and after the measurement is finished, pressing an up arrow key and a down arrow key to look up data. The invention can effectively reduce measurement errors and is beneficial to objectively and accurately analyzing and evaluating the insulating conditions of equipment.

The invention brings forward a harmonic wave measuring and correcting method for capacitor voltage transformers through transformation ratio fitting. The method includes the steps: establishing a consistent equivalent circuit for capacitor voltage transformers with the same voltage level, conducting fitting according to equivalent circuit component parameters of a preset model, obtaining a transformation ratio amplitude-frequency response curve and a phase frequency response characteristic curve, adjusting the curves through a translation method or the like on the basis of a fitting result for different equivalent circuit component parameters of other models, and finally realizing correction. The wideband characteristics of capacitor voltage transformers are taken as standards for the actual transformation ratio of the capacitor voltage transformers, a measurement result of the capacitor voltage transformers is corrected at the harmonic frequency, and the problem that capacitor voltage transformers cannot be applied to harmonic wave measurement is solved. The harmonic wave measuring and correcting method is simple in calculation, exhibits the real-time performance, and enables the application bandwidth of capacitor voltage transformers to be increased.

The invention provides an integrated standard device for field calibration of an extra/ultra high voltage capacitor voltage transformer (CVT). The device comprises a test power supply, a test lifting platform, a standard appliance, a measuring instrument and a vehicle platform, wherein the test power supply comprises cascade upper and lower level test transformers, a secondary compensating reactor and a voltage regulator; the standard appliance comprises cascade upper and lower level standard voltage transformers and a high voltage isolated transformer; the test lifting platform comprises a base, transmission mechanisms and insulating support members; the measuring instrument comprises a transformer calibrator and load boxes; all the equipment is fixedly installed on the vehicle platform;and the test lifting platform can lift in the vertical direction. The upper and lower level standard voltage transformers in the standard device can troubleshoot the standard device by way of mutual calibration in the field and complete field calibration of the extra/ultra high voltage CVT, without unloading.

The invention discloses a comprehensive operation state evaluation simulation system of a capacitor voltage transformer. The method comprises steps that: by establishing a CVT circuit model and a corresponding relation between an insulation parameter and each environmental parameter, the simulation error of the CVT under different environmental parameters is acquired, error data is recorded and stored, and is compared with the data measured by a on-site CVT error on-line monitoring device, and then a CVT error state is evaluated. According to the invention, influences of internal and externalinsulation factors on a CVT metering state in the actual operation of the CVT are considered, the comprehensive operation state evaluation simulation model of the capacitor voltage transformer is established, and influence rules of factors such as environmental temperature, secondary load, power supply frequency, external pollution and the like on the CVT metering performance can be acquired through simulation analysis, and a theoretical and practical basis for improving the operation stability of the CVT can be provided.

The invention relates to a device and method for measuring a bus voltage phase of a capacitor voltage transformer. The device comprises a first current transformer, a second current transformer and a current vector collection and computation unit. The method comprises the following steps: connecting the first current transformer and the second current transformer into a ground terminal of a middle voltage capacitor and a ground terminal of a middle transformer of the capacitor voltage transformer respectively, respectively feeding coupled current signals into the current vector collection and computation unit by the first current transformer and the second current transformer, conducting processing such as amplification and filtering on collected current signals, converting the current signals into digital signals, and computing the numerical value to obtain the instantaneous phase of the bus voltage of the capacitor voltage transformer. The device and method are accurate in measuring, good in real-time performance, simple in wiring, small in influence on the capacitor voltage transformer, safe and reliable.

The invention relates to an online calibration system for an electronic voltage transformer. The online calibration system comprises a standard channel voltage transformer on a high-voltage side, a receiving end on a low-voltage side and an upper computer. The online calibration system is characterized in that the receiving end on the low-voltage side is connected with the upper computer through a serial connecting line, the receiving end on the low-voltage side is connected with the standard voltage transformer wiring terminal of the standard channel voltage transformer on the high-voltage side through a signal transmission line and a grading ring of the standard channel voltage transformer on the high-voltage side is automatically overlapped with a primary bus bar through an automatic lifting device. By controlling the automatic lifting of the lifting device which is fixed on the standard voltage transformer through a remote controller, the automatic overlapping of the grading ring of the standard voltage transformer and the primary bus bar is realized, the controllability and the personal safety during field operation are guaranteed, the online calibration of the high-precision electronic voltage transformer is realized and the difficulty of field operation is greatly reduced.

The invention provides a method for testing wiring of secondary circuits of four-star voltage transformers. The method is implemented by the aid of a special tester. The tester comprises a primary-side device and a secondary-side device. The method for testing the wiring of the secondary circuits includes a three-phase voltage process and a single-phase voltage process, and mainly includes steps of selecting the testing processes; correspondingly applying three-phase asymmetric voltages or single-phase voltages to the voltage transformers according to the three-phase voltage process or the single-phase voltage process; acquiring secondary-side voltage parameters of the voltage transformers; automatically judging the sampled secondary-side voltage parameters of the voltage transformers by the aid of built-in programs and criteria of an information processor of the secondary-side device and displaying test results via a liquid crystal display. The method has the advantages that whether wiring of the secondary circuits of the voltage transformers is correct or not and error types of wiring of the secondary circuits of the voltage transformers can be automatically judged by the aid of the method and can be tested and judged quickly and accurately, the accuracy is high, and the work efficiency can be improved; the test results are verified by one another by the aid of the three-phase voltage process and the single-phase voltage process and accordingly are reliable.

The invention discloses a test method without disconnection of a capacitor voltage transformer. The capacitor voltage transformer comprises a capacitor C11, a capacitor C12, a capacitor C2, a reactor L and an intermediate transformer XT, wherein the primary capacitors (C11 and C12) and the voltage-dividing capacitor C2 constitute a capacity divider; a point A is arranged between C11 and C12, a point B is arranged between C12 and C2, a point delta is arranged on the other end of the capacitor C2; when C12 is tested, the reverse wiring method and the high voltage shielding method are used for measurement, namely the point A is connected with the high-voltage end, one end of C11 is earthed, the measuring voltage is 2kV and the point delta and a point X at the tail end of the intermediate transformer XT are connected with the shielding end; and when C12 and C2 are tested, the self-excitation method is used for measurement, namely one end of C11 is earthed, the secondary winding ax of the intermediate transformer XT is used to apply a voltage and the intermediate transformer XT is used to transform the voltage and provide a voltage. By using the test method of the invention, the testing sequences are greatly reduced, the operation procedure is simple, the test data are accurate and the reading error is small.

The invention relates to a transient overvoltage on-line monitoring system based on a CVT and provided with a built-in low-voltage capacitor. The transient overvoltage on-line monitoring system is connected with a power grid and comprises a partial pressure sensor, a protector, a transient voltage collector and an industrial personal computer. The partial pressure sensor is a capacitor voltage transformer provided with a built-in non-inductive capacitor. The partial pressure sensor is connected with a power transmission line or a bus. The partial pressure sensor monitors voltage disturbance of the power grid in real time; the magnitude of voltages of all phases is transmits to the transient voltage collector through the protector; the magnitude of voltages of all the phases when a transient overvoltage occurs and waveforms and parameters before and after a failure are collected and saved by the transient voltage collector, and the transient voltage collector transmits collected signals to the industrial personal computer. The industrial personal computer gives out an alarm according to the collected signals and displays monitoring results. Compared with the prior art, the transient overvoltage on-line monitoring system based on the CVT and provided with the built-in low-voltage capacitor has the advantages of being high in stability and monitoring accuracy and beneficial to the improvement of the operational stability of the power grid.

The invention discloses a detection method for disconnection of voltage transformers. Two voltage transformers are applied to generator protection in a pumped-storage power station, and include a first voltage transformer in a power generation direction and a second voltage transformer in a pumping direction. The detection method for disconnection of the voltage transformers comprises the following steps of: collecting voltage signals from the first and second voltage transformers; working out voltages U1AB, U1BC, U1CA, U2AB, U2BC and U2CA; working out voltage amplitude differences of lines of the two voltage transformers [delta]UAB, [delta]UBC and [delta]UCA, and judging whether the voltage transformers are in disconnection. The detection method can be applied to various connection modes at the generator end of the pumped-storage power station, and is simplified in detection on disconnection of the voltage transformers in various connection modes, wide in application range, high in reliability, and convenient to implement general microcomputer protection.

The invention discloses a method for testing the broadband characteristic of a CVT (capacitor voltage transformer) by a high voltage harmonic in the technical field of electric power. The method has the technical scheme that a high voltage harmonic source of U1 (j omega) is applied between a high voltage end of the CVT and the ground, and the voltage U2 (j omega) of each frequency point at a secondary side and the input voltage U1 (j omega) at a primary side are tested to obtain the broadband transmission characteristic of the CVT through computation. The method disclosed by the invention has the beneficial effects that components of a higher harmonic can be accurately obtained, harmonic interference can be effectively inhibited through harmonic treatment guiding measures, and the quality of electric energy is improved.

The invention discloses a wholly shielded capacitor voltage transformer which comprises a capacitor divider part and an electromagnetism device positioned in the sealed casing of filling with the insulating medium. The capacitor divider part is the high-voltage electrode and the medium-voltage electrode positioned in the wholly shielded capacitor voltage transformer, the high-voltage electrode is an electrode at the center, the medium-voltage electrode is a cylinder-shaped electrode with the same shaft of the high-voltage electrode and surrounds the high-voltage electrode. The wholly shielded casing of the capacitor divider part is a cylinder with the same shaft of the high-voltage electrode and surrounds the medium-voltage electrode. The medium-voltage electrode, the high-voltage electrode and the casing are of the structure of the same shaft, the electric field force generated between them evenly distributes at the circumference and offsets mutually under the role of the voltage, the relative position between the electrodes does not shift, the capacitor between the electrodes is extremely stable, thereby promoting the precision of the transformer.

The invention discloses a power system computer aided design (PSCAD) based running fault simulation method of a capacitor voltage transformer (CVT). The PSCAD based running fault simulation method comprises the following steps of sorting device parameters of a 500-kV CVT in a site during actual running; building a system model of a CVT equivalent circuit, setting device parameters for the system model, and simultaneously configuring a secondary voltage monitor for the system model of the CVT equivalent circuit; building an adjustable AC power module, an adjustable capacitor component module and a module controller; performing breakdown fault analogue simulation of a capacitor component in the CVT; and acquiring a correlation between a breakdown fault of the capacitor component in the CVT and secondary voltage change before and after performing breakdown fault analogue simulation of the capacitor component in the CVT. The PSCAD based running fault simulation method has the advantages of flexibility, high efficiency, simplicity, feasibility, accuracy, fineness, no safety risk and no test cost, various running faults of the CVT can be simulated, a basis is provided for research on state monitoring and fault diagnosis of the CVT, and the PSCAD based running fault simulation method has favorable application prospect.

The invention relates to a new type high voltage converter low energy consumption loading test method that includes the following steps: connects power network bus to converter through transformer, and the output end of converter connecting to bus after connecting inductive load, connecting voltage transformer and current transformer between converter and inductive load; adjusting the output amplitude and phase of converter, testing the voltage of resistance from inductive load to find the minimum, altering output pulse or modulation signal of PLC to control system current and realizing working state test in different current working state unit, the system current would be sent to PLC through current transformer. The invention has the following advantages and effects: it could be realized without motor; the control would be easy to realize; the test system is safe and reliable; and the power consumption of the entire system is low.

The invention relates to dry type capacitor voltage transformer utilized in AC high voltage power system and DC electrical power system with 110KV and higher voltage. The transformer comprises capacitor voltage divider utilized in circuit board for signal conversion and amplification treatment. The capacitor voltage divider in insulating sleeve comprises two pieces of cascaded capacitive components. Umbrella skirt covers the insulating sleeve. Based on need, voltage signal is picked out from a plate electrode in middle of the cascaded capacitive components. The said signal through the circuit board for signal conversion and amplification treatment is output to measuring and displaying device and protecting device. Advantages of the invention are dry type, free of maintenance, high insulating strength and small volume.

The invention discloses a capacitor voltage transformer (CVT) medium loss test method based on a resonance feature. The method comprises the following steps: establishing a resonance circuit model of a CVT; maintaining total currents of a circuit unchanged, and obtaining an active power increment and a reactive power increment of the resonance circuit model at a resonance state and disresonance state; and according to tg delta1=tg delta2=delta P/delta Q, obtaining medium loss of a high-voltage capacitor packaged with an intermediate-voltage capacitor and medium loss of the intermediate-voltage capacitor, wherein tg delta 1 is the medium loss of the high-voltage capacitor packaged with the intermediate-voltage capacitor, and tg delta 2 is the medium loss of the intermediate-voltage capacitor, delta P is the active power increment of the resonance circuit model at the resonance state and the disresonance state, and delta Q is the reactive power increment of the resonance circuit model at the resonance state and the disresonance state. According to the invention, by use of the resonance feature of a CVT circuit structure, an established CVT medium loss test model based on the resonance feature is more accurate compared to a conventional normal polarity method, reverse polarity method and self-excitation method test model.

The invention belongs to the field of power system transformer devices, and provides an extra-high-voltage capacitor voltage transformer with high precision, quick response and field validation avoidance. The extra-high-voltage capacitor voltage transformer comprises a capacitive divider with equal potential shielded double-layer coaxial capacitor assemblies and an electromagnetic unit with an energy storage element-free ferromagnetic resonance suppressor and a middle transformer, wherein the capacitive divider and the electromagnetic unit are connected in series to form the voltage transformer. The extra-high-voltage capacitor voltage transformer can meet the requirement of accurate measurement of power frequency alternating voltage of super-high-voltage to extra-high-voltage grade power grids and quick and reliable motion of relay protection. A measured main capacitor is in a good shielded state, and the capacitance can be greatly reduced, so the weight of the divider can be greatly reduced, and the shock-proof property of the thin and high divider is improved.

The invention provides a transmission line malfunction directional element, comprising a wavefront polarity acquisition unit 100, an initial polarity acquisition unit 200 and a comparison unit 300, wherein the wavefront polarity acquisition unit 100 is used for acquiring the wavefront polarity MMIalpha, MMIbeta and MMIgamma from three current modulus malfunction transient travelling wave of a transmission line; the initial polarity acquisition 200 unit is used for acquiring the initial polarity Salpha, Sbeta and Sgamma from power frequency components of the three current modulus malfunction transient travelling wave; and the comparison unit 300 is used for comparing the wavefront polarity MMIalpha, MMIbeta and MMIgamma of the three current modulus malfunction transient travelling waves with the initial polarity of the power frequency of the voltage malfunction transient travelling wave of the corresponding modulus respectively and determining the malfunction direction of the transmission line according to the judgment result, thus solving the problem that the travelling wave malfunction directional element and travelling wave directional protection capable of being applied in the actual power system can not be formed for a long time due to that the capacitor voltage transformer is unable to transmit the wavefront of the transient voltage malfunction travelling wave.

The invention discloses a capacitor voltage transformer error state evaluation method, which aims to acquire output voltage of a three-phase capacitor voltage transformer in a healthy state without depending on a standard voltage transformer. A high-dimensional random matrix analysis method is used to establish a statistical characteristic parameter representing the error state of the capacitor voltage transformer and a threshold value of a statistical characteristic quantity of a normal operation state; the output voltage of the three-phase capacitor voltage transformer after operation is acquired, the statistical characteristic quantity representing the error state of the three-phase capacitor voltage transformer is calculated, and the statistical characteristic quantity is compared witha statistical threshold value to judge whether the error state of the capacitor voltage transformer is normal or not. According to the method, the error state of the capacitor voltage transformer isevaluated on the premise of not cutting off power and not depending on a standard device and a physical model.

The invention discloses an on-line detection system for a field error of a capacitor type voltage transformer. The system is composed of a voltage transformer group, a secondary signal conversion unit, and an error online detection unit. The voltage transformer group consists of a plurality of to-be-tested capacitor type voltage transformers for measuring and outputting voltage signals. The secondary signal conversion unit connected to output terminals of secondary windings of the voltage transformers in the voltage transformer group and the error online detection unit is used for receiving output voltage signals of the plurality of voltage transformers, converting the output voltage signals into sampling data of the plurality of voltage transformers, and sending the sampling data to the error online detection unit. The error online detection unit is used for receiving the sampling data of the plurality of to-be-tested voltage transformers, analyzing the sampling data of the pluralityof to-be-tested voltage transformers, and acquiring errors of the sampling data of the plurality of to-be-tested capacitor type voltage transformers.