CN111880064A - Cable voltage-withstanding partial discharge synchronous detection device - Google Patents
Cable voltage-withstanding partial discharge synchronous detection device Download PDFInfo
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- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
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Abstract
The invention discloses a cable voltage-withstanding partial discharge synchronous detection device, which comprises a high-voltage direct-current power supply unit, a polarity conversion unit and an oscillation wave generation unit, wherein the high-voltage direct-current power supply unit is connected with an alternating-current power supply and converts alternating current into high-voltage direct current; one end of the polarity conversion unit is connected with the high-voltage direct-current power supply unit and used for outputting ultralow-frequency cosine square waves as voltage-withstanding test waves, and the other end of the polarity conversion unit is connected with a cable to carry out voltage-withstanding detection on the cable; one end of the oscillation wave generating unit is connected with the high-voltage direct-current power supply unit, the other end of the oscillation wave generating unit is connected with the cable, an oscillation loop is formed by the oscillation wave generating unit and the cable to generate damping oscillation, and partial discharge detection is carried out on the cable. The cable voltage-withstanding partial discharge synchronous detection device disclosed by the invention can synchronously carry out voltage-withstanding detection and partial discharge detection on a cable, improves the detection efficiency, can also improve the voltage of partial discharge detection during synchronous detection, is easier to find the partial discharge phenomenon, and has strong practicability in the technical field of cable detection.
Description
Technical Field
The invention relates to the technical field of cable detection, in particular to a cable voltage-withstanding partial discharge synchronous detection device.
Background
The cable plays an important role in the power transmission and distribution system, in order to improve the operation reliability of cable equipment and avoid the cable from breaking down to influence the normal operation of the power transmission and distribution system, after the cable laying or the cable head manufacturing and maintenance are completed, a withstand voltage test and a partial discharge test need to be carried out on the cable to find out the fault and hidden danger of the cable.
At present, generally, a voltage withstand test is carried out before a cable is put into operation, and a partial discharge test is carried out after the cable is put into operation, so that the situation that partial discharge points on a body or accessories of the cable are not found although the cable passes the voltage withstand test can occur, and the potential safety hazard is inevitably caused when the cable is put into operation. In addition, the applied voltage is higher than the operating voltage during the withstand voltage test, which is more favorable for finding the partial discharge phenomenon that the initial voltage is higher than the operating voltage; signals measured by partial discharge testing under the power frequency of 50Hz are often easily interfered by signals of adjacent cables or other power equipment, and in the process of carrying out partial discharge testing in voltage-withstanding synchronization, the test frequency is different from the power frequency, and the partial discharge signals are easier to find due to the difference of the frequencies.
The Chinese patent with publication number CN106990341A discloses an ultralow frequency cosine square wave high voltage generator and method for insulation diagnosis of a distribution cable, the device consists of a positive and negative polarity high voltage source, a bidirectional high voltage power electronic switch, a polarity conversion device and a master control unit, and ultralow frequency cosine square wave high voltage with the peak value of 30kV at most and periodic variation of 0.1Hz can be applied to a test cable. When the waveform is in a positive and negative stable state, the direct current high voltage can be simulated to carry out a direct current withstand voltage test on the cable, so that the leakage current of a test article can be obtained, the concentrated defect of the test article can be effectively reflected, and the 50Hz alternating current high voltage can be simulated to carry out an alternating current test on the cable at the rising edge and the falling edge, so that the dielectric loss tangent value and the partial discharge defect of the test article can be detected, and the insulation state of the test article cable can be comprehensively evaluated. The device can simultaneously carry out voltage resistance and partial discharge detection. However, after the direct-current voltage withstand test is carried out on the cable, the residual space charge in the cable can generate an additional electric field, the electric field can be superposed at the tip of a water tree in actual operation, so that partial discharge occurs at the water tree of the cable, a large amount of high-energy particles are generated to continuously bombard the end part of the water tree and a water tree channel, the degradation of the insulation performance of the crosslinked polyethylene power cable is accelerated, the service life of the power cable is shortened, and the power supply reliability is reduced.
The chinese utility model patent with publication number CN206248767U discloses an ac damped oscillatory wave partial discharge test device, which comprises a frequency conversion source host, a resonant reactor, a special voltage divider and a data acquisition, processing and analysis unit, wherein the frequency conversion source host comprises an ac high voltage source, an excitation transformer and an electronic switch, wherein the input end of the excitation transformer is connected with the ac high voltage source, and the output end is respectively connected with the electronic switch and the resonant reactor; the resonance reactor is respectively connected with a cable to be tested and a special voltage divider, and the special voltage divider is connected to the data acquisition, processing and analysis unit through a filter; the alternating current attenuation damping oscillatory wave partial discharge testing device adopts an alternating current high voltage source, adds a peak value synchronous signal on an alternating current variable frequency series resonance voltage-withstanding device to enable a series resonance circuit to stop power output when the peak value is reached, and simultaneously closes a high-voltage electronic switch to form oscillatory wave damping oscillation to perform cable partial discharge testing. The alternating current attenuation damping oscillation wave partial discharge testing device utilizes oscillation wave damping oscillation to carry out partial discharge testing on a cable, and can not carry out withstand voltage testing while carrying out partial discharge testing.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a cable voltage-withstand partial discharge synchronous detection apparatus, which can perform voltage-withstand detection and partial discharge detection on a cable at the same time, and find faults and hidden dangers of the cable.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a cable withstand voltage partial discharge synchronous detection device which includes:
the high-voltage direct-current power supply unit is connected with an alternating-current power supply and converts alternating current into high-voltage direct current;
one end of the polarity conversion unit is connected with the high-voltage direct-current power supply unit and used for outputting the ultralow-frequency cosine square wave as a voltage-withstanding test wave, and the other end of the polarity conversion unit is connected with a cable to carry out voltage-withstanding detection on the cable; and
and one end of the oscillation wave generating unit is connected with the high-voltage direct-current power supply unit, the other end of the oscillation wave generating unit is connected with the cable, and the oscillation wave generating unit and the cable form an oscillation loop to generate damping oscillation so as to perform partial discharge detection on the cable.
Further, the high voltage dc power supply unit includes:
the voltage stabilizing module comprises a chopping voltage regulating circuit, is connected with an alternating current power supply and is used for outputting stable direct current; and
the boost module is connected with the chopping voltage regulating circuit and comprises a square wave inverter circuit, a high-frequency transformer and a voltage doubling rectifying circuit, the square wave inverter circuit is used for converting direct current into high-frequency square waves, the high-frequency transformer is used for boosting the high-frequency square waves for the first time, and the voltage doubling rectifying circuit is used for boosting the high-frequency square waves for the second time and rectifying the high-frequency square waves into high-voltage direct current.
Furthermore, the high-voltage direct-current power supply unit further comprises a feedback control module, the feedback control module is connected with the voltage-multiplying rectification circuit through a voltage divider, the feedback control module comprises a voltage conditioning circuit and a voltage-stabilizing control chip, and the voltage-stabilizing control chip is in driving connection with the chopping voltage-regulating circuit.
Further, the square wave inverter circuit further comprises a constant frequency inverter controller, the constant frequency inverter controller is used for outputting an inverter control signal for driving the square wave inverter circuit to perform constant frequency inversion, the square wave inverter circuit responds to the inverter control signal, and high frequency square waves are output after direct current voltage is inverted.
Further, the chopping voltage regulating circuit is a Boost-PFC circuit.
Furthermore, the polarity conversion unit comprises a polarity conversion circuit, a current and voltage sampling circuit and a digital time sequence controller, wherein the polarity conversion circuit is an LC oscillation circuit, the current and voltage sampling circuit collects voltage and current information in the circuit and transmits the voltage and current information to the digital time sequence controller, and the digital time sequence controller is in driving connection with the polarity conversion circuit and used for sending out a pulse control signal to control the on-off of the circuit.
Furthermore, the polarity conversion circuit adopts a reverse feedable polarity conversion circuit.
Furthermore, the oscillatory wave generating unit comprises an oscillatory wave generating circuit and a monitoring display unit, the oscillatory wave generating circuit comprises a current-limiting resistor, a damping resistor, an oscillatory inductor, a high-voltage switch and a resistance-capacitance voltage divider, the cable is connected with the oscillatory wave generating circuit to form an oscillatory circuit to generate damping oscillation, the damped oscillatory wave signal is obtained to carry out partial discharge detection on the cable, and the monitoring display unit is connected with the resistance-capacitance voltage divider.
Generally, a cable is subjected to voltage resistance detection before operation and partial discharge detection after operation, and the voltage resistance detection can determine whether or not the insulation resistance value of the cable is acceptable, and is a detection for determining whether or not the cable can be operated. The partial discharge detection is preventive detection, can find dangerous points which do not influence the operation of the cable temporarily in the cable, and needs to consider whether potential safety hazards exist under the action of long-term working voltage. Technical personnel in the field are used to perform voltage resistance detection before the operation of the cable, judge whether the cable is qualified, perform partial discharge detection after the operation of the cable, perform periodic inspection on the cable, and do not easily think that the voltage resistance detection and the partial discharge detection are performed at the same time.
In order to achieve a small and light-weight high-voltage dc power supply unit, a single voltage-doubling rectifying step-up should be used in principle. In fact, although the ripple and the voltage drop of the voltage doubling circuit can be reduced by increasing the output square wave frequency of the square wave inverter circuit, the output ripple and the voltage drop increase sharply with the increase of the voltage doubling grade, and the output voltage drops to zero to a certain extent.
The high-voltage direct-current power supply unit is small and light in weight in consideration of a transformer, under the same voltage, the size of a magnetic core of the transformer and the number of primary and secondary windings of the transformer are rapidly reduced along with the increase of square wave frequency, so that the volume and the weight are greatly reduced, but the equivalent parameters of transformer resistance and interlayer parasitic capacitance are correspondingly increased under the high-frequency condition, the generated charging and discharging current generates huge loss at an inverter side circuit switch and cannot work seriously, so that the primary and secondary side box ratio of the high-frequency transformer is not easy to be overlarge, and the high-voltage direct-current power supply unit outputs high-voltage direct current by adopting two-stage boosting.
In terms of converting a high-voltage direct-current power supply into an ultralow-frequency cosine square wave, the simplest method for conversion is inversion, but in the system, the inversion method is not applicable. On one hand, the reason is that the cable is a capacitive load, if an inversion mode is adopted, a large surge current can be generated during positive and negative polarity conversion, and huge impact can be caused on a switch tube, and on the other hand, the fact that the nature of cosine square waves can generate a smooth transition waveform during polarity conversion is considered, the waveform is similar to a commutation front edge wave of power frequency cosine waves, the wave width is kept between 2ms and 6ms, the difficulty of inversion control is high, and the realization is not easy. Therefore, the invention is realized by adopting the LC oscillation principle, and on one hand, the design can realize the energy recycling and reduce the input power; on the other hand, when the positive and negative polarities are switched, the waveform is smooth and excessive.
Compared with the prior art, the cable voltage-withstanding partial discharge synchronous detection device provided by the invention has the following beneficial effects:
1. the invention provides a cable voltage-withstanding partial discharge synchronous detection device which comprises a high-voltage direct-current power supply unit, a polarity conversion unit and an oscillation wave generation unit. The high-voltage direct current power supply unit converts alternating current into high-voltage direct current for the polarity conversion unit and the oscillation wave generation unit, the polarity conversion unit outputs ultra-low frequency cosine square waves for voltage withstanding detection of the cable, the oscillation wave generation unit generates damping oscillation, and the damped oscillation wave signals are obtained to perform partial discharge detection of the cable. During detection, the voltage of partial discharge detection can be increased, and the partial discharge phenomenon can be found more easily.
2. Compared with the conventional high-voltage direct-current power supply unit which often adopts a Buck circuit for direct-current chopping, the Buck-PFC circuit is adopted as the chopper circuit in the invention, so that the influence of voltage reduction caused by the use of the Buck circuit can be avoided. In a switching power supply, 220V alternating-current voltage is generally taken by a power grid side and then direct-current voltage is obtained through an uncontrollable rectifier bridge, but due to the nonlinear characteristic of a diode in the rectifier bridge and the clamping effect of a post-stage filter capacitor on the diode, current does not change along with the voltage in a direct-current chopper circuit, the waveform distortion of the current is serious, the harmonic current causes serious harmonic pollution to the power grid, the input power of the circuit is greatly reduced to about 0.65, and the efficiency of the system is greatly reduced. The Boost-PFC circuit can ensure that a post-stage circuit has enough input power, and the efficiency of the whole system is improved.
3. The invention provides a cable voltage-withstanding partial discharge synchronous detection device which comprises a feedback control module, wherein the feedback control module is connected with a voltage-multiplying rectification circuit through a voltage divider, the feedback control module comprises a voltage conditioning circuit and a voltage-stabilizing control chip, and the voltage-stabilizing control chip is in driving connection with a chopping voltage-regulating circuit. A feedback control module is introduced behind the voltage doubling rectifying circuit to form a large closed-loop control system. The open-loop control system has no inhibition effect on external disturbance and internal parameter change, and when the input quantity or load is changed, the working state and output voltage of the circuit system can be changed, so that the voltage required by the test cannot be ensured. The use of a closed loop control system ensures a stable output voltage even when the input and load changes.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings.
Fig. 1 is a block diagram of a cable voltage-withstanding partial discharge synchronous detection device provided by the present invention;
FIG. 2 is a circuit schematic of the chopper regulator circuit shown in FIG. 1;
FIG. 3 is a circuit schematic of the polarity conversion circuit shown in FIG. 1;
fig. 4 is a schematic circuit diagram of the oscillation wave generating unit shown in fig. 1.
In the figure, 10, a cable voltage-withstanding partial-discharge synchronous detection device, 100, a high-voltage direct-current power supply unit, 110, a voltage stabilizing module, 120, a boosting module, 121, a square wave inverter circuit, 1211, a constant-frequency inverter controller, 122, a high-frequency transformer, 123, a voltage-doubling rectifying circuit, 130, a feedback control module, 131, a voltage divider, 132, a voltage conditioning circuit, 133, a voltage stabilizing control chip, 200, a polarity conversion unit, 210, a polarity conversion circuit, 220, a current-voltage sampling circuit, 230, a digital timing controller, 300, an oscillation wave generation unit, 310, an oscillation wave generation circuit, 311, a current-limiting resistor, 312, a damping resistor, 313, an oscillation inductor, 314, a high-voltage switch, 315, a resistance-capacitance divider, 320 and a monitoring display unit.
Detailed Description
The present invention will be further described with reference to the following examples. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a block diagram of a cable voltage withstand partial discharge synchronization detection apparatus 10 according to the present invention. The invention provides a cable voltage-withstanding partial discharge synchronous detection device 10, which comprises a high-voltage direct-current power supply unit 100, a polarity conversion unit 200 and an oscillation wave generation unit 300. The high-voltage direct current power supply unit 100 converts alternating current into high-voltage direct current for the polarity conversion unit 200 and the oscillation wave generation unit 300 to use, the polarity conversion unit 200 outputs ultra-low frequency cosine square waves for voltage-withstanding detection of the cable, the oscillation wave generation unit 300 is used for generating damping oscillation, and the damped oscillation wave signals are obtained to perform partial discharge detection on the cable, so that voltage-withstanding and partial discharge detection can be performed synchronously, and the detection efficiency is improved. During detection, the voltage of partial discharge detection can be increased, and the partial discharge phenomenon can be found more easily.
In order to obtain stable high-voltage direct current and reduce the volume and weight of the high-voltage direct current power supply unit 100, in some preferred embodiments, the high-voltage direct current power supply unit 100 includes a voltage stabilizing module 110 and a voltage boosting module 120, where the voltage stabilizing module 110 is a chopper voltage regulating circuit connected to an alternating current power supply for outputting stable direct current; the boosting module 120 is connected with the chopping voltage regulating circuit, the boosting module 120 comprises a square wave inverter circuit 121, a high-frequency transformer 122 and a voltage doubling rectifying circuit 123, the square wave inverter circuit 121 is used for converting direct current into high-frequency square waves, the high-frequency transformer 122 is used for boosting the high-frequency square waves for the first time, and the voltage doubling rectifying circuit 123 is used for boosting the high-frequency square waves for the second time and rectifying the high-frequency square waves into high-voltage direct current. The stable high-voltage direct current is output by adopting a twice boosting mode on the premise of reducing the volume and the weight.
In some preferred embodiments, the chopper regulator circuit is a Boost-PFC circuit. Referring to fig. 2, fig. 2 is a circuit schematic diagram of the chopper regulator circuit shown in fig. 1. In the positive half cycle of the input voltage, when S is conducted, the power supply charges the inductor L; when S is off, the power supply and inductor charge C0 and power the load. In the negative half cycle of the input voltage, the working process is similar, but the rectifier bridge diodes are conducted differently. The Boost-PFC circuit is simple, the mature control method is high in reliability, high power factor correction can be still achieved under wide input voltage, the circuit adaptability is high, and the output voltage is high.
The high-voltage direct-current power supply unit 100 further comprises a feedback control module 130, the feedback control module 130 is connected with the voltage-multiplying rectification circuit 123 through a voltage divider 131, the feedback control module 130 comprises a voltage conditioning circuit 132 and a voltage-stabilizing control chip 133, and the voltage-stabilizing control chip 133 is in driving connection with the chopper voltage-regulating circuit. A feedback control module 130 is introduced behind the voltage doubling rectifying circuit 123, so that a large closed-loop control system is formed. The open-loop control system has no inhibition effect on external disturbance and internal parameter change, and when the input quantity or load is changed, the working state and output voltage of the circuit system can be changed, so that the voltage required by the test cannot be ensured. The use of a closed loop control system ensures a stable output voltage even when the input and load change, and in some embodiments the output voltage is in the range of 0 to 30 kV.
The square wave inverter circuit 121 further includes a constant frequency inverter controller 1211, the constant frequency inverter controller 1211 is configured to output an inverter control signal for driving the square wave inverter circuit 121 to perform constant frequency inversion, and the square wave inverter circuit 121 outputs a high frequency square wave after inverting the dc voltage in response to the inverter control signal. In some specific embodiments, the frequency of the high frequency square wave is between 30Hz and 300 Hz.
At present, the withstand voltage test of the cable has several modes such as power frequency withstand voltage, frequency conversion resonance withstand voltage, 0.1Hz ultralow frequency sine wave withstand voltage, 0.1Hz ultralow frequency cosine square wave withstand voltage and the like, wherein the power frequency withstand voltage test is mainly used for factory detection of the cable and is rarely used for field test of the cable; the frequency of the variable frequency resonance loop in the variable frequency resonance withstand voltage test depends on the L-C parameter of the loop, the capacitance corresponding to different cables is different in the field test, and in order to meet the test requirement, resonant reactors with different inductance values need to be selected, which is not favorable for the field test of the variable frequency resonance method; the 0.1Hz ultralow frequency sine wave withstand voltage test equipment and the 0.1Hz ultralow frequency cosine square wave withstand voltage test equipment are portable and are suitable for field tests.
Compared with 0.1Hz ultralow frequency sine wave voltage resistance, the 0.1Hz ultralow frequency cosine square wave has the advantages that the transition waveform of the cosine square wave during polarity conversion is similar to the waveform of the commutating front edge wave in a power frequency voltage resistance test, and has similar wave width, wherein the cosine square wave is 2-6ms, and the power frequency is 10 ms. In cosine square waves, the combination of this short dc component and the high frequency component of the switching process promotes a rapid and controlled development of the existing severe electrical tree in the insulation, which can expose this severe insulation defect in the cable by means of a flashover. But simultaneously, adopt 3U0 and 1 hour pressurization mode, can guarantee that only the most serious insulating defect position will be influenced, the position that is not serious will hardly be influenced, avoided withstand voltage test to cause huge damage to the cable. Therefore, the 0.1Hz ultralow frequency cosine square wave is adopted as the test wave in the invention.
In order to obtain the 0.1Hz ultralow frequency cosine square wave, the polarity conversion unit 200 comprises a polarity conversion circuit 210, a current and voltage sampling circuit 220 and a digital timing controller 230, wherein the polarity conversion circuit 210 is an LC oscillation circuit, the current and voltage sampling circuit 220 collects voltage and current information in the circuit and transmits the voltage and current information to the digital timing controller 230, and the digital timing controller 230 is in driving connection with the polarity conversion circuit 210 and is used for sending a pulse control signal to control the on-off of the circuit. The polarity conversion is realized by an LC oscillation principle, so that on one hand, the energy can be recycled, and the input power is reduced; on the other hand, when the positive and negative polarities are switched, the waveform is smooth and excessive.
The existing polarity conversion circuit 210 has energy loss in the polarity conversion process, which causes the inconsistency of positive and negative voltages after polarity conversion, increases the charge accumulation in the cable, causes hidden damage to the cable, and shortens the service life of the cable. In some preferred embodiments, the polarity conversion circuit 210 employs a reverse feeding type polarity conversion circuit 210, which can compensate for energy loss during polarity conversion, and effectively achieve the consistency of positive and negative voltages after polarity conversion. Referring to fig. 3, fig. 3 is a circuit schematic diagram of the polarity conversion circuit 210 shown in fig. 1, in which the capacitor charges the inductor first, and then the inductor charges the cable with negative polarity, thereby completing the polarity conversion. The inductor L1 can control the time of polarity conversion to be 2 ms-6 ms, and the auxiliary capacitor C1 can avoid the no-load phenomenon of the circuit at the moment of starting charging.
Referring to fig. 4, fig. 4 is a circuit diagram of the oscillatory wave generating unit 300 shown in fig. 1. The oscillatory wave generating unit 300 comprises an oscillatory wave generating circuit 310 and a monitoring display unit 320, wherein the oscillatory wave generating circuit 310 comprises a current limiting resistor 311, a damping resistor 312, an oscillatory inductor 312, a high-voltage switch 314 and a resistance-capacitance voltage divider 315, a cable is connected with the oscillatory wave generating circuit 310 to form an oscillatory loop to generate damping oscillation, the damped oscillatory wave signal is obtained to carry out partial discharge detection on the cable, and the monitoring display unit 320 is connected with the resistance-capacitance voltage divider 315. The working process of the system comprises the steps that firstly, a high-voltage direct-current power supply unit 100 is used for charging a test product Cx, the cable is a capacitive load and is equivalent to the test product Cx in a circuit, when a test voltage is reached, a switch of the high-voltage direct-current power supply unit 100 is closed, a high-voltage switch 314 is closed, at the moment, an oscillation loop formed by the test product Cx, an inductor L1 and a damping resistor 312 generates damping oscillation, an attenuated oscillation wave signal is obtained, and partial discharge detection is carried out on the cable.
The cable voltage-withstanding partial discharge synchronous detection device 10 provided by the invention comprises a high-voltage direct-current power supply unit 100, a polarity conversion unit 200 and an oscillation wave generation unit 300. The high-voltage direct current power supply unit 100 converts alternating current into high-voltage direct current for the polarity conversion unit 200 and the oscillation wave generation unit 300 to use, the polarity conversion unit 200 outputs ultra-low frequency cosine square waves for voltage-withstanding detection of the cable, the oscillation wave generation unit 300 is used for generating damping oscillation, and the damped oscillation wave signals are obtained to perform partial discharge detection on the cable, so that voltage-withstanding and partial discharge detection can be performed synchronously, and the detection efficiency is improved. During detection, the voltage of partial discharge detection can be increased, and the partial discharge phenomenon can be found more easily.
Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.
Claims (8)
1. The utility model provides a synchronous detection device is put in withstand voltage office of cable which characterized in that, detection device includes:
the high-voltage direct-current power supply unit is connected with an alternating-current power supply and converts alternating current into high-voltage direct current;
one end of the polarity conversion unit is connected with the high-voltage direct-current power supply unit and used for outputting an ultra-low-frequency cosine square wave as a withstand voltage test wave, and the other end of the polarity conversion unit is connected with the cable to carry out withstand voltage detection on the cable; and
and one end of the oscillation wave generating unit is connected with the high-voltage direct-current power supply unit, the other end of the oscillation wave generating unit is connected with the cable, and the oscillation wave generating unit and the cable form an oscillation loop to generate damping oscillation so as to detect partial discharge of the cable.
2. The cable withstand voltage partial discharge synchronous detection device according to claim 1, wherein the high voltage dc power supply unit comprises:
the voltage stabilizing module comprises a chopping voltage regulating circuit, is connected with the alternating current power supply and is used for outputting stable direct current; and
the boost module is connected with the chopping voltage regulating circuit and comprises a square wave inverter circuit, a high-frequency booster and a voltage-multiplying rectification circuit, the square wave inverter circuit is used for converting direct current into high-frequency square waves, the high-frequency transformer is used for boosting the high-frequency square waves for the first time, and the voltage-multiplying rectification circuit is used for boosting the high-frequency square waves for the second time and rectifying the high-frequency square waves into high-voltage direct current.
3. The cable voltage-withstanding partial discharge synchronous detection device according to claim 2, wherein the high-voltage direct-current power supply unit further comprises a feedback control module, the feedback control module is connected with the voltage-multiplying rectification circuit through a voltage divider, the feedback control module comprises a voltage conditioning circuit and a voltage-stabilizing control chip, and the voltage-stabilizing control chip is in driving connection with the chopping voltage-regulating circuit.
4. The cable voltage-withstanding partial discharge synchronous detection device according to claim 2, wherein the square-wave inverter circuit further comprises a constant-frequency inverter controller, the constant-frequency inverter controller is configured to output an inverter control signal for driving the square-wave inverter circuit to perform constant-frequency inversion, and the square-wave inverter circuit responds to the inverter control signal to invert a direct-current voltage and then outputs a high-frequency square wave.
5. The cable withstand voltage partial discharge synchronous detection device according to claim 2, wherein the chopper voltage regulation circuit is a Boost-PFC circuit.
6. The cable voltage-withstanding partial discharge synchronous detection device according to claim 1, wherein the polarity conversion unit comprises a polarity conversion circuit, a current-voltage sampling circuit and a digital timing controller, the polarity conversion circuit is an LC oscillation circuit, the current-voltage sampling circuit collects voltage and current information in the circuit and transmits the voltage and current information to the digital timing controller, and the digital timing controller is in driving connection with the polarity conversion circuit and is used for sending out a pulse control signal to control the on-off of the circuit.
7. The cable voltage-withstanding partial discharge synchronous detection device according to claim 6, wherein the polarity conversion circuit is a reverse feedable polarity conversion circuit.
8. The device according to claim 1, wherein the oscillatory wave generator comprises an oscillatory wave generator circuit and a monitor display unit, the oscillatory wave generator circuit comprises a current-limiting resistor, a damping resistor, an oscillatory inductor, a high-voltage switch and a RC voltage divider, the cable is connected to the oscillatory wave generator circuit to form an oscillatory circuit for damped oscillation, so as to obtain an attenuated oscillatory wave signal for performing the partial discharge detection of the cable, and the monitor display unit is connected to the RC voltage divider.
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| CN113311295A (en) * | 2021-01-11 | 2021-08-27 | 合肥开关厂有限公司 | Online cable alternating current withstand voltage test system |
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| CN113899993B (en) * | 2021-03-04 | 2024-03-26 | 哈尔滨理工大学 | Ultralow frequency cosine square wave withstand voltage test equipment and method for power cable |
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| CN113625143B (en) * | 2021-07-01 | 2024-02-06 | 深圳供电局有限公司 | Ultralow frequency cosine square wave generating device and driving method thereof |
| CN113433438A (en) * | 2021-08-23 | 2021-09-24 | 国家电网有限公司 | Method for generating cosine square waves and damping oscillation waves in cable test |
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Application publication date: 20201103 |