CN112083293A - Partial discharge positioning device and method for ultra-long distribution cable - Google Patents
Partial discharge positioning device and method for ultra-long distribution cable Download PDFInfo
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- CN112083293A CN112083293A CN202011032655.9A CN202011032655A CN112083293A CN 112083293 A CN112083293 A CN 112083293A CN 202011032655 A CN202011032655 A CN 202011032655A CN 112083293 A CN112083293 A CN 112083293A
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/11—Locating faults in cables, transmission lines, or networks using pulse reflection methods
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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 relates to a partial discharge positioning device and a method of an ultra-long distribution cable, wherein the device comprises a pulse signal generator, an oscillating wave voltage generator and a signal receiving device which are arranged at the head end of the cable, and a plurality of capacitive sensors which are arranged on spaced cable joints; the capacitive sensor comprises a coupling unit, a signal acquisition module and a 4G module, wherein the coupling unit consists of a high-voltage coupling capacitor and an RLC coupling circuit, signals acquired by the signal acquisition module are transmitted to a signal receiving device through the 4G module, the high-voltage coupling capacitor is embedded between a cable joint grounding copper mesh and an outer semi-conducting layer, and an external connection wire of the high-voltage coupling capacitor is connected with the RLC coupling circuit in series. The device and the method effectively overcome the defects that the pulse echo is difficult to detect and the positioning is greatly influenced because the cable length is too long and the local discharge signal is seriously attenuated.
Description
Technical Field
The invention relates to the technical field of distribution cable state detection in a power system, in particular to a partial discharge positioning device and method for an ultra-long distribution cable.
Background
The power cable is mostly laid underground, does not occupy surface resources, is not easily influenced by severe weather such as strong wind, rainstorm, thunder, snow and the like, and has extremely low possibility of being damaged by machinery in the operation process, so that the power cable increasingly replaces the traditional overhead line and becomes an important component of the urban power transmission and distribution network. However, various faults may still occur in power cables during commissioning, mainly due to poor quality of the cable itself, damage during installation and insulation degradation during long term operation. The failures due to insulation degradation are often global and global. The cable itself can be aged due to the overlong operating life, and if the operating environment is severe, the insulation degradation speed can be accelerated. Because the inside trace moisture that is mingled with of cable in-process that wets, chain form moisture micropore can appear in the cable insulation inside, can produce the dendritic route and constantly grow in insulating inside along with the time lapse, and the holistic insulation resistance of cable is showing to be reduced during this period, and dielectric loss takes place obvious change. Finally, the water branches are converted into electric branches, which causes partial discharge and causes cable breakdown accidents. Partial discharge detection technology is an effective and commonly used means for field detection of power cables at present.
The oscillation wave partial discharge detection technology is a commonly used and mature partial discharge detection method at present, and is characterized in that a damping and attenuating sinusoidal voltage waveform is applied to a cable to excite defects in cable insulation, so that partial discharge is formed, partial discharge signals are received through a coupling unit, and the partial discharge position is positioned through a time domain pulse reflection method. However, in practical operation, due to the fact that the high-frequency partial discharge signal is seriously propagated and attenuated in the cable, the partial discharge pulse signal of the long cable is often difficult to complete transmission of two cable lengths, and the partial discharge pulse signal is submerged by noise.
Disclosure of Invention
The present invention is directed to solve the above problems and disadvantages and to provide a device and method for positioning partial discharge of an ultra-long distribution cable.
The technical scheme adopted by the invention for solving the technical problems is as follows: a partial discharge positioning device of an ultra-long distribution cable comprises a pulse signal generator, an oscillating wave voltage generator and a signal receiving device which are arranged at the head end of the cable, and a plurality of capacitive sensors which are arranged on spaced cable joints; the capacitive sensor comprises a coupling unit, a signal acquisition module and a 4G module, wherein the coupling unit consists of a high-voltage coupling capacitor and an RLC coupling circuit, signals acquired by the signal acquisition module are transmitted to a signal receiving device through the 4G module, the high-voltage coupling capacitor is embedded between a cable joint grounding copper mesh and an outer semi-conducting layer, and an external connection wire of the high-voltage coupling capacitor is connected with the RLC coupling circuit in series.
The partial discharge positioning device of the ultra-long distribution cable is further optimized as follows: and the head end and the tail end of the distribution cable are both provided with a coupling unit.
The partial discharge positioning device of the ultra-long distribution cable is further optimized as follows: the high-voltage coupling capacitor is embedded between a grounding copper net and an outer semi-conducting layer of the cable joint, and a signal receiving electrode of the high-voltage coupling capacitor is wound with the grounding copper net through an insulating tape.
The partial discharge positioning device of the ultra-long distribution cable is further optimized as follows: at least one cable joint of the distribution cable is embedded with a capacitive sensor every 1 km.
The partial discharge positioning device of the ultra-long distribution cable is further optimized as follows: the RLC coupling circuit comprises an inductor and a resistor which are connected in parallel.
The method for positioning the partial discharge by using the partial discharge positioning device of the ultra-long distribution cable comprises the following steps:
injecting a Gaussian pulse signal into a cable by adopting a pulse signal generator, and receiving the pulse signal by a signal acquisition module in each capacitive sensor to perform clock synchronization;
applying oscillatory wave voltage to the head end of the cable through an oscillatory wave voltage generator, and acquiring partial discharge information through a signal acquisition module by a capacitive sensor pre-embedded in a cable joint;
step (3), each capacitive sensor transmits the collected partial discharge information to a signal receiving device through a 4G module;
and (4) directly judging the position of the partial discharge between the two detection points according to the time difference of the signals received by the signal receiving device, and carrying out partial discharge positioning according to the time difference of the partial discharge information received by the two detection points.
The partial discharge positioning method for the ultra-long distribution cable is further optimized as follows: and (2) injecting Gaussian pulses with the pulse width of 100ns and the amplitude of 20V into the cable head end pulse signal generator in the step (1).
The invention has the following beneficial effects:
according to the device, the capacitive sensor is embedded in the cable, so that each cable joint can be used as a receiving point of partial discharge, the distance of partial discharge signals needing to be transmitted is greatly reduced, and the sensitivity of partial discharge detection is effectively improved; in addition, a coupling unit is added at the head end and the tail end of the cable, so that the influence of partial discharge attenuation in the cable on the partial discharge detection sensitivity is greatly reduced. The device and the method effectively overcome the defects that the pulse echo is difficult to detect and the positioning is greatly influenced because the cable length is too long and the local discharge signal is seriously attenuated.
The invention adopts Gaussian pulse which is similar to the partial discharge signal as injection pulse, so that the actual partial discharge pulse signal can be attached to the maximum extent, and the pulse signal strength can be adjusted to ensure that the last coupling unit can finish clock synchronization.
And thirdly, at least one cable joint is pre-buried in each 1km of cable, so that the upper limit of the length of the partial discharge detection of the cable can be effectively improved.
The invention no longer uses the time domain pulse reflection method for positioning, and each obtained partial discharge signal does not propagate too far in the cable, so the pulse width is shorter, and the dispersion effect has less influence on the partial discharge signal.
Drawings
FIG. 1 is a schematic diagram of Gaussian pulse signal injection in accordance with the present invention;
FIG. 2 is a schematic diagram of clock synchronization according to the present invention;
FIG. 3 is a schematic diagram of a pre-buried electrode of a cable joint according to the present invention;
FIG. 4 is a schematic view of the present invention when the oscillatory wave is pressurized;
FIG. 5 is a schematic illustration of partial discharge localization in accordance with the present invention;
fig. 6 is a schematic diagram of a two-terminal measurement of partial discharge localization in accordance with the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
Example 1
A partial discharge positioning device of an ultra-long distribution cable comprises a pulse signal generator, an oscillating wave voltage generator and a signal receiving device which are arranged at the head end of the cable, and a plurality of capacitive sensors which are arranged on spaced cable joints; the capacitive sensor comprises a coupling unit, a signal acquisition module and a 4G module, wherein the coupling unit consists of a high-voltage coupling capacitor and an RLC coupling circuit, signals acquired by the signal acquisition module are transmitted to a signal receiving device through the 4G module, the sampling rate of the signal acquisition module is more than or equal to 100MHz, the high-voltage coupling capacitor is embedded between a cable joint grounding copper net and an outer semi-conducting layer, and an external connection wire of the high-voltage coupling capacitor is connected with the RLC coupling circuit in series.
The head end and the tail end of the distribution cable are respectively provided with the coupling unit, so that the influence of the partial discharge attenuation in the cable on the partial discharge sensitivity is greatly reduced.
The high-voltage coupling capacitor is embedded between the grounding copper net and the outer semi-conducting layer of the cable joint, and the signal receiving electrode of the high-voltage coupling capacitor is wound with the grounding copper net through the insulating tape, so that the electrode is prevented from being directly short-circuited with the ground wire.
In order to ensure that partial discharge of a long cable is effectively received and reduce construction difficulty as much as possible, capacitive sensors are not embedded in each cable joint, but capacitive sensors are embedded in at least one cable joint of the distribution cable every 1 km.
The RLC coupling circuit comprises an inductor and a resistor which are connected in parallel. Stray capacitance is small and can be ignored, and the sensor has high sensitivity under high frequency and can effectively shield power frequency signals below 1 kHz.
A method for partial discharge detection using a device for improving the sensitivity of partial discharge detection of a distribution cable, the method comprising the steps of:
injecting a Gaussian pulse signal into a cable by adopting a pulse signal generator, and receiving the pulse signal by a signal acquisition module in each capacitive sensor to perform clock synchronization;
applying oscillatory wave voltage to the head end of the cable through an oscillatory wave voltage generator, and acquiring partial discharge information through a signal acquisition module by a capacitive sensor pre-embedded in a cable joint;
step (3), each capacitive sensor transmits the collected partial discharge information to a signal receiving device through a 4G module;
and (4) directly judging the position of the partial discharge between the two detection points according to the time difference of the signals received by the signal receiving device, and carrying out partial discharge positioning according to the time difference of the partial discharge information received by the two detection points.
And (2) injecting Gaussian pulses with the pulse width of 100ns and the amplitude of 20V into the cable head end pulse signal generator in the step (1). For the cable with longer length and serious aging, the pulse width is 100ns, the Gaussian pulse signal with the amplitude of 20V is difficult to transmit to the tail end, and the signal injection strength is increased until the partial discharge signal receiving device at the tail end can effectively receive the pulse signal transmitted by the head end.
In fig. 1, a pulse signal generator is used to inject a gaussian pulse signal with a pulse width of 100ns into a cable, and each signal acquisition module is used to receive the pulse signal for clock synchronization.
In fig. 2, the pulse times received by the individual capacitive sensors are clocked in synchronism with the calculated time differences for the individual sensor positions.
The clock synchronization satisfies the following formula
In the formula xnIs the position of the nth pre-buried capacitor, tnAnd v is the wave velocity of Gaussian pulse propagation.
In fig. 3, in the installation process of the cable joint, before the grounding copper mesh is installed, a high-voltage coupling capacitor is pre-buried on a cable semi-conducting layer at one end of the joint, an insulating tape is wound on the high-voltage coupling capacitor, and an insulating wire is led out to be connected with an external RLC coupling circuit.
In fig. 4, the oscillation wave voltage is applied to the head end, and the partial discharge information is detected at each point.
In fig. 5, since the partial discharge signal at each detection point can be detected, the partial discharge position can be directly determined by the time difference between which two detection points the partial discharge position is located, and then the partial discharge positioning is performed by the time difference between the partial discharge information received at the two detection points. The principle of partial discharge positioning is a double-end partial discharge measurement method, which is schematically shown in fig. 6, and when partial discharge occurs, the partial discharge is positionedThe electric signal is transmitted to two ends along the distribution cable with the length of L, the transmission speed is v, and the time when the sensor A and the sensor B detect the arrival time of the partial discharge signal is t1And t2Then the distance from the position of the partial discharge source to the sensor a is: (provided that both terminals A and B are guaranteed to be working simultaneously)
Wherein L is the distance between two adjacent coupling units, v is the propagation speed of partial discharge, and t1Time for partial discharge signal to pass to the first coupling unit at near end, t2The time for the partial discharge signal to propagate to the first coupling unit at the far end.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (7)
1. The utility model provides a partial discharge positioner of overlength distribution cable which characterized in that: the device comprises a pulse signal generator, an oscillating wave voltage generator and a signal receiving device which are arranged at the head end of a cable, and a plurality of capacitive sensors which are arranged on spaced cable joints; the capacitive sensor comprises a coupling unit, a signal acquisition module and a 4G module, wherein the coupling unit consists of a high-voltage coupling capacitor and an RLC coupling circuit, signals acquired by the signal acquisition module are transmitted to a signal receiving device through the 4G module, the high-voltage coupling capacitor is embedded between a cable joint grounding copper mesh and an outer semi-conducting layer, and an external connection wire of the high-voltage coupling capacitor is connected with the RLC coupling circuit in series.
2. The partial discharge locator for an ultra-long distribution cable according to claim 1, wherein: and the head end and the tail end of the distribution cable are both provided with a coupling unit.
3. The partial discharge locator for an ultra-long distribution cable according to claim 1, wherein: the high-voltage coupling capacitor is embedded between a grounding copper net and an outer semi-conducting layer of the cable joint, and a signal receiving electrode of the high-voltage coupling capacitor is wound with the grounding copper net through an insulating tape.
4. The partial discharge locator for an ultra-long distribution cable according to claim 1, wherein: at least one cable joint of the distribution cable is embedded with a capacitive sensor every 1 km.
5. The partial discharge locator for an ultra-long distribution cable according to claim 1, wherein: the RLC coupling circuit comprises an inductor and a resistor which are connected in parallel.
6. A method for partial discharge localization using the partial discharge localization apparatus for ultra-long distribution cables of claim 1, wherein: the method comprises the following steps:
injecting a Gaussian pulse signal into a cable by adopting a pulse signal generator, and receiving the pulse signal by a signal acquisition module in each capacitive sensor to perform clock synchronization;
applying oscillatory wave voltage to the head end of the cable through an oscillatory wave voltage generator, and acquiring partial discharge information through a signal acquisition module by a capacitive sensor pre-embedded in a cable joint;
step (3), each capacitive sensor transmits the collected partial discharge information to a signal receiving device through a 4G module;
and (4) directly judging the position of the partial discharge between the two detection points according to the time difference of the signals received by the signal receiving device, and carrying out partial discharge positioning according to the time difference of the partial discharge information received by the two detection points.
7. The method of claim 6, wherein the method comprises the steps of: and (2) injecting Gaussian pulses with the pulse width of 100ns and the amplitude of 20V into the cable head end pulse signal generator in the step (1).
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113791313A (en) * | 2021-08-03 | 2021-12-14 | 深圳供电局有限公司 | Partial discharge detection device and detection method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113791313A (en) * | 2021-08-03 | 2021-12-14 | 深圳供电局有限公司 | Partial discharge detection device and detection method thereof |
| CN113791313B (en) * | 2021-08-03 | 2023-08-25 | 深圳供电局有限公司 | Partial discharge detection device and detection method thereof |
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