CN222926812U - High-voltage capacitor partial discharge oscillatory wave detection system - Google Patents
High-voltage capacitor partial discharge oscillatory wave detection system Download PDFInfo
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- CN222926812U CN222926812U CN202421468273.4U CN202421468273U CN222926812U CN 222926812 U CN222926812 U CN 222926812U CN 202421468273 U CN202421468273 U CN 202421468273U CN 222926812 U CN222926812 U CN 222926812U
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Abstract
The utility model discloses a high-voltage capacitor partial discharge oscillatory wave detection system, which belongs to the technical field of electric equipment detection and comprises an oscillatory wave power supply system and an oscillatory wave partial discharge detection system which are connected in series, wherein the oscillatory wave power supply system comprises a high-voltage direct current power supply, a resonant reactor and a switch, the positive electrode of the high-voltage direct current power supply is respectively connected with one end of the switch and the input end of the resonant reactor, the other end of the switch is grounded, the output end of the resonant reactor is connected with the input end of a sample capacitor, the negative electrode of the high-voltage direct current power supply is grounded, the oscillatory wave partial discharge detection system comprises a special impedance and a partial discharge detection system, the input end of the special impedance is connected with the output end of the sample capacitor, and the output end of the special impedance is connected with the partial discharge detection system and grounded. The high-voltage high-capacity capacitor insulation fault is detected by using the oscillation wave partial discharge detection technology, so that the problem that a high-power supply needs to be configured in a high-capacity capacitor boosting test is solved.
Description
Technical Field
The utility model belongs to the technical field of electrical equipment detection, and particularly relates to a partial discharge oscillatory wave detection system of a high-voltage capacitor.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The high-voltage high-capacity capacitor is an essential important electrical device in a power grid system, and the purpose of carrying out partial discharge detection on the high-voltage high-capacity capacitor is to detect the internal defect of the capacitor before the capacitor fails, know the insulation state of the operation of the device in time, monitor the degradation process of the device better, know the current real health state of the device effectively, and carry out effective early warning at the initial stage of the failure of the device so as to take measures in time.
At present, the partial discharge detection modes of the capacitor include a power frequency withstand voltage method, a direct current partial discharge detection method, an ultrasonic detection method and the like. The power frequency withstand voltage partial discharge measurement is mostly carried out on a small-capacitance sample, and the detection mode has the defects of huge test power supply, high input cost, insufficient test sensitivity, insufficient analysis means and the like for a large-capacity capacitor. The direct current partial discharge detection mode can not truly reflect the fault characteristics of the capacitor and can not accurately detect the insulation defects of the capacitor according to the signal excitation and detection modes. The ultrasonic method is the most commonly used method for partial discharge detection of a current large-capacity capacitor, and has the advantages that the power supply burden is not required to be increased, but the ultrasonic method also has the problems that 1) an ultrasonic sensor is used for coupling acoustic signals from the outer surface of the capacitor, the ultrasonic signals are transmitted through different mediums in the capacitor, the signal attenuation is large, the detection sensitivity is low, only larger discharge signals can be detected, 2) the ultrasonic sensor collects the attenuated signals, the actual discharge intensity is difficult to confirm, and the discharge capacity cannot be accurately measured, 3) the ultrasonic method cannot simplify the power supply configuration, and a set of conventional large-capacity capacitor power supply also needs higher cost.
Meanwhile, in the technology based on the partial discharge of the oscillation wave detection capacitor, most of cable oscillation wave power supplies cannot meet the detection requirement of a large-capacity capacitor, a switch module (semiconductor switch) in the oscillation wave power supply system can act under the alternation of voltage oscillation, and when the semiconductor switch acts, pulse interference with higher frequency and stronger amplitude is inevitably introduced.
Disclosure of utility model
In order to solve the technical problems in the prior art, the utility model provides a high-voltage capacitor partial discharge oscillatory wave detection system, which uses an oscillatory wave partial discharge detection technology to detect insulation faults of a high-voltage high-capacity capacitor, and compared with a conventional power frequency test power supply, the oscillatory wave power supply has the advantages that the volume, the weight and the input cost are greatly reduced, and the problem that a high-power supply needs to be configured in a high-capacity capacitor boosting test is solved.
In order to achieve the above purpose, the present utility model is realized by the following technical scheme:
The system comprises an oscillating wave power supply system and an oscillating wave partial discharge detection system which are connected in series;
The oscillating wave power supply system comprises a high-voltage direct current power supply, a resonant reactor and a switch, wherein the positive electrode of the high-voltage direct current power supply is connected with one end of the switch and the input end of the resonant reactor respectively, the other end of the switch is grounded, the output end of the resonant reactor is connected with the input end of a test sample capacitor, the negative electrode of the high-voltage direct current power supply is grounded, the oscillating wave partial discharge detection system comprises a special impedance and a partial discharge detection system, the input end of the special impedance is connected with the output end of the test sample capacitor, and the output end of the special impedance is connected with the partial discharge detection system and grounded.
According to a further technical scheme, the high-voltage direct-current power supply comprises a step-up transformer, a voltage doubling rectifying circuit and a control module, wherein the input end of the commercial power is connected with the input end of the control module, the output end of the control module is connected with the input end of the step-up transformer, the output end of the step-up transformer is connected with the input end of the voltage doubling rectifying circuit, and the output end of the voltage doubling rectifying circuit is connected with the input end of the resonant reactor.
According to a further technical scheme, the control module comprises a first control branch and a second control branch which are connected in parallel.
According to a further technical scheme, the output end of the first control branch is connected with the input end of the current sampling circuit, the output end of the current sampling circuit is connected with the input end of the PWM generator, the output end of the PWM generator is connected with the input end of the driving circuit, and the output end of the driving circuit is connected with the input end of the full-bridge inverter.
According to a further technical scheme, the output end of the second control branch is connected with the input end of the voltage sampling circuit, the output end of the voltage sampling circuit is connected with the input end of the error amplifier, the output end of the error amplifier is connected with the input end of the PWM controller, the output end of the PWM controller is connected with the input end of the driving circuit, the output end of the driving circuit is connected with the input end of the Buck circuit, and the output end of the Buck circuit is connected with the input end of the full-bridge inverter.
According to a further technical scheme, the switch adopts a power electronic switch and comprises a thyristor and a diode which are connected in parallel, wherein the anode of the thyristor is connected with the cathode of the diode, and the cathode of the thyristor is connected with the anode of the diode.
According to a further technical scheme, the resonant reactor is a high-voltage partial-discharge-free resonant reactor.
According to a further technical scheme, the special impedance comprises a transformer, the input end of a primary winding of the transformer is connected with the output end of the sample capacitor and is respectively connected with the graduation capacitor and the resistor in parallel, and the output end of a secondary winding of the transformer is connected with the input end of the partial discharge detection system.
According to a further technical scheme, one end of a primary winding of the transformer is connected with one end of the dividing capacitor and one end of the resistor respectively, the other end of the primary winding is connected with the other end of the dividing capacitor and the other end of the resistor respectively, and the other end of the dividing capacitor is grounded.
Further technical scheme, oscillatory wave power supply system still includes protection resistance and damping resistance of establishing ties, protection resistance's input is connected with high-voltage direct current power supply's output, and protection resistance's output is connected with the non-ground terminal of switch, damping resistance's input respectively, damping resistance's output is connected with the input of resonance reactor.
The utility model has the beneficial effects that:
The utility model designs an oscillating wave power supply system, which is characterized in that a step-up transformer is connected with a voltage doubling circuit in series, the step-up transformer is boosted by a method of firstly passing through the step-up transformer and then passing through the voltage doubling rectifying circuit, the voltage level which can be boosted is very high to meet the detection requirements of large-capacity capacitors with different capacities, meanwhile, the power electronic switch is designed by combining a thyristor with a diode on the basis of a common thyristor in an optimization way, the interference signal is small, and the influence on the detection sensitivity of partial discharge is small.
The utility model also develops a special impedance which can be directly connected to the tail end of the test article capacitor, and can detect the partial discharge signal generated by the insulation fault of the test article capacitor with high sensitivity without configuring a large-capacity coupling capacitor.
The utility model uses the oscillation wave partial discharge detection technology to detect the insulation fault of the high-voltage large-capacity capacitor, compared with the conventional power frequency test power supply, the oscillation wave power supply has greatly reduced volume, weight and input cost, and solves the problem that the large-capacity capacitor boosting test needs to be configured with a large-power supply.
Drawings
The accompanying drawings are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate the utility model and together with the embodiments of the utility model, serve to explain the utility model.
FIG. 1 is a schematic diagram of an oscillatory wave detection system according to an embodiment of the present utility model;
Fig. 2 is a schematic diagram of a high-voltage dc power supply in an oscillating wave power supply system according to an embodiment of the present utility model;
FIG. 3 is a diagram of a switch equivalent circuit in an oscillating wave power system according to an embodiment of the present utility model;
fig. 4 is an electrical schematic diagram of a specific impedance in an oscillating wave partial discharge detection system according to an embodiment of the present utility model.
The high-voltage direct current power supply is characterized in that HV DC is a high-voltage direct current power supply, R1 is a protection resistor, R2 is a damping resistor, L is a resonant reactor, C X is a sample capacitor, Z is a special impedance, and M is a partial discharge detection system.
Detailed Description
The utility model is further described below with reference to the drawings and specific embodiments.
Referring to fig. 1, an embodiment of the present utility model provides a high-voltage capacitor partial discharge oscillatory wave detection system, which includes an oscillatory wave power supply system and an oscillatory wave partial discharge detection system connected in series;
The oscillating wave power supply system comprises a high-voltage direct current power supply, a resonant reactor and a switch, wherein the positive electrode of the high-voltage direct current power supply is connected with one end of the switch and the input end of the resonant reactor respectively, the other end of the switch is grounded, the output end of the resonant reactor is connected with the input end of a test sample capacitor, the negative electrode of the high-voltage direct current power supply is grounded, the oscillating wave partial discharge detection system comprises a special impedance and a partial discharge detection system, the input end of the special impedance is connected with the output end of the test sample capacitor, and the output end of the special impedance is connected with the partial discharge detection system and grounded.
As shown in fig. 1, the oscillatory wave power supply system further includes a protection resistor R1 and a damping resistor R2 connected in series, the input end of the protection resistor R1 is connected with the output end of the high-voltage direct current power supply, the output end of the protection resistor R1 is respectively connected with the non-grounding end of the switch and the input end of the damping resistor R2, the output end of the damping resistor R2 is connected with the input end of the resonant reactor, the protection resistor has a proper resistance value, the current in the circuit is ensured not to exceed the safety range, the effect of the protection circuit is achieved, and the damping resistor is used for inhibiting high-frequency oscillation and improving the stability of the circuit.
Since the voltage level to which the oscillating wave power supply system needs to be raised is very high, the method of directly using the transformer to raise the target voltage and rectifying the target voltage into direct current and the method of directly outputting the commercial power through the voltage doubling rectifying circuit are not suitable, and the method of firstly boosting through the primary boosting transformer and then boosting through the voltage doubling rectifying circuit is adopted in the embodiment.
In this embodiment, as shown in fig. 2, the high-voltage dc power supply is configured to convert the utility power into the high-voltage dc power, and includes a step-up transformer, a voltage-multiplying rectifying circuit, and a control module, where an input end of the utility power is connected to an input end of the control module, an output end of the control module is connected to an input end of the step-up transformer, an output end of the step-up transformer is connected to an input end of the voltage-multiplying rectifying circuit, and an output end of the voltage-multiplying rectifying circuit is connected to an input end of the resonant reactor, and outputs the high-voltage dc power.
The control module is used for controlling and obtaining a preset and stable output voltage and comprises a first control branch and a second control branch which are connected in parallel; the output end of the voltage-doubling rectifying circuit is also connected with the input end of the voltage sampling circuit, the output end of the voltage sampling circuit is connected with the input end of an error amplifier (error amplifying circuit), the output end of the error amplifier is connected with the input end of a PWM (pulse width modulation) controller, the output end of the PWM controller is connected with the input end of a Buck circuit, the output end of the Buck circuit is connected with the input end of a full-bridge inverter, the output voltage of the voltage-doubling rectifying circuit is controlled to be the output voltage of the full-bridge inverter through pulse width modulation, the output end of the voltage-doubling rectifying circuit is also connected with the input end of the voltage sampling circuit, the output end of the voltage sampling circuit is connected with the input end of the error amplifier, the output end of the error amplifier is connected with the input end of the PWM controller, the output end of the PWM controller is connected with the input end of the Buck circuit, the output end of the Buck circuit is connected with the input end of the full-bridge inverter, the output voltage of the voltage-doubling rectifying circuit is compared with a given reference voltage (namely, the output voltage setting) and the comparison result is consistent, the stable voltage is transmitted to a subsequent circuit of the oscillating wave detecting system, the comparison result does not meet preset requirements, the Buck requirement is regulated by the voltage, the voltage is regulated by the voltage-doubling circuit, and the voltage is regulated again after the voltage is cycled, and the voltage is regulated until the voltage is regulated.
The input end of the mains supply is connected with the input end of the rectifying and filtering circuit, the output end of the rectifying and filtering circuit is connected with the BUCK circuit, and the mains supply is subjected to preliminary rectifying and filtering when the mains supply is just input, so that alternating current is converted into direct current and noise in the direct current is filtered.
It should be noted that, each circuit structure, full-bridge inverter, step-up transformer, PWM controller, PWM generator that adopt in the high-voltage direct current power supply are current circuit structure and electrical component, and PWM controller, PWM generator control analog circuit through pulse width modulation technique, adopt current PWM pulse width modulation mode control, carry out quick effectual control to the output voltage of power, power and frequency, do not relate to the improvement on the software program, and the realization method that the person skilled in the art can know is not repeated here.
In some embodiments, the ER49 ferrite core is selected as the booster core for a booster transformer with an operating frequency of 60kHz. During winding, the primary winding is a 0.55mm enameled wire, and the secondary winding is a 0.3mm enameled wire.
In this embodiment, as shown in fig. 3, the switch adopts a power electronic switch, which includes a thyristor and a diode connected in parallel, wherein the anode of the thyristor is connected with the cathode of the diode, and the cathode of the thyristor is connected with the anode of the diode, that is, the diode is connected in anti-parallel at two ends of the thyristor, so that the emission junction of the anode and the cathode is short-circuited. After test, the optimization is carried out on the basis of the common thyristor, the on-off time of the switch is only a few microseconds, the working frequency reaches tens of kilohertz, and the on-off performance is obviously superior to that of the fast thyristor, so that the thyristor is particularly suitable for being used as a power switch of an oscillating wave system, and has the advantages of high temperature and high pressure resistance, quick turn-off, low on-state voltage and the like.
In this embodiment, the resonant reactor is a high-voltage partial-discharge-free resonant reactor. In some embodiments, the detected capacitance value of the capacitor is between 1 and 100 μf, and the designed inductance of the reactor is 0.2H. At this time, for a capacitor having a capacitance in the range of 1 to 100uF, the resonant frequency is between 35 and 424Hz, and for most large-capacity capacitors, the resonant frequency can meet the requirements.
In some embodiments, if the dielectric medium of the resonant reactor is unevenly distributed, partial discharge phenomenon can be easily generated, and in this embodiment, in order to effectively ensure the insulation state, after comparing with various insulating materials, the epoxy resin has the characteristics of corrosion resistance, heat resistance, good electrical insulation performance and small shrinkage rate. The method of epoxy resin casting is used, and the conditions of vacuum degree, humidity, temperature, dust and the like of the casting environment are strictly controlled in the casting process, so that the effectiveness of insulation is greatly ensured. Meanwhile, after the manufacturing of the reactor is completed, the reactor is subjected to partial discharge detection, and the insulation performance of the reactor is tested.
When partial discharge detection is performed on a large-capacity capacitor, a coupling capacitor with a larger capacity than the capacitor is connected in parallel, and then the detection impedance of the detection signal is connected to the tail end of the coupling capacitor. The capacitance of the large-capacity capacitor is large, if a coupling capacitor larger than the capacitor is connected in parallel, the capacitance of the detection loop can be greatly increased, so that the requirements on a power supply system and the impedance through-current capacity are high, the construction investment equipment cost of the whole test platform is extremely high, and the test platform is not suitable for practical application. The embodiment researches that the coupling capacitor is removed, and the special impedance is directly connected to the tail end of the sample capacitor to detect the partial discharge signal of the large-capacity capacitor, so that the difficulty in constructing the coupling capacitor can be avoided without configuring the large-capacity coupling capacitor, and the requirement on a power supply system is reduced.
In this embodiment, the specific impedance adopts an RLC resonant circuit structure, and includes a transformer Lm, where an input end of a primary winding of the transformer is connected with an output end of a sample capacitor, and is respectively connected in parallel with a graduation capacitor Cm and a resistor Rm, where the graduation capacitor is connected in parallel with the resistor Rm, and an output end of a secondary winding of the transformer is connected with an input end of a partial discharge detection system. Specifically, one end of a primary winding of the transformer is connected with one end of the dividing capacitor and one end of the resistor respectively, and the other end of the primary winding is connected with the other end of the dividing capacitor and the other end of the resistor respectively, and the other end of the dividing capacitor is grounded.
In some embodiments, the special impedance uses a thickened hollow copper wire on the primary winding to improve the primary on-current, the special impedance uses a nickel-zinc ferrite material as a magnetic core to improve the impedance detection frequency, the number of turns of the winding can be increased to realize the function of improving the sensitivity of detection signals, and one end of the primary winding is connected in series with the graduation capacitor while the other end is grounded. Therefore, the ferrite core can transmit the partial discharge signal to the secondary winding, and the partial discharge signal received by the secondary winding can be connected to a partial discharge detection system for detection, so that the test requirement of a capacitor with the maximum capacitance of 100 mu F is met.
The special impedance is a special new structure impedance only aiming at the partial discharge detection of the high-capacity capacitor, and mainly starts from the improvement of impedance detection frequency to realize the acquisition of the partial discharge signal of the high-capacity capacitor.
In this embodiment, the partial discharge detection system adopts an existing integrated module to realize the partial discharge detection of the large-capacity capacitor, and a person skilled in the art can select the partial discharge detection system according to the function of the partial discharge detection system, which is not particularly limited in this embodiment.
Detailed description of working principle:
The whole detection process can be divided into two phases, namely a direct current charging phase. The high-voltage direct current power supply charges the sample capacitor until reaching the preset voltage, and then an alternating current discharging stage, which is also called an oscillation process, is adopted. At the moment, the switch is quickly closed, the action time is less than 1 mu s, the series resonance occurs between the test capacitor and the resonance reactor, the damped oscillation voltage is generated in the test loop, the partial discharge signal at the defect of the capacitor can be excited, the partial discharge signal is directly collected from the tail end of the capacitor through the special impedance, and the partial discharge signal is measured through the partial discharge detection system, so that the detection purpose is achieved.
While the foregoing description of the embodiments of the present utility model has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the utility model, but rather, it is intended to cover all modifications or variations within the scope of the utility model as defined by the claims of the present utility model.
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| CN202421468273.4U CN222926812U (en) | 2024-06-25 | 2024-06-25 | High-voltage capacitor partial discharge oscillatory wave detection system |
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| CN202421468273.4U CN222926812U (en) | 2024-06-25 | 2024-06-25 | High-voltage capacitor partial discharge oscillatory wave detection system |
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