CN109932616B - Method for judging and positioning one-phase-lack fault of 10kV distribution network - Google Patents
Method for judging and positioning one-phase-lack fault of 10kV distribution network Download PDFInfo
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Abstract
The invention discloses a method for judging and positioning a 10kV distribution network one-phase-lack fault, which comprises the following steps: step 1, adjusting the starting voltage of an electroscope to be higher than the voltage of a phase-lacking phase on the high-voltage side of a transformer; calling or measuring three-phase voltage values of the low-voltage side of the distribution line transformer on site through a remote information acquisition system, and when one phase voltage value is normal and the absolute value of the difference between the sum of the voltage values of the other two phases and the voltage value of the normal phase is less than 3V, judging that the fault type is that the transformer lacks one phase, and the transformer is on the load side of a phase-lacking point; and 2, detecting each phase voltage at the high-voltage side of the transformer in the step 1 by adopting the electroscope adjusted in the step 1, judging that one phase is a default phase when an acousto-optic indicating device of the electroscope does not act when only one phase is measured, narrowing the fault range to the phase of the transformer, and indicating that a default phase point is on the power supply side of a high-voltage access point of the transformer. The invention can determine the fault position without seeing the fault phenomenon.
Description
Technical Field
The invention relates to a method for judging and positioning a one-phase-lack fault of a 10kV distribution network, and belongs to the field of power fault analysis.
Background
When a 10kV distribution network lacks one phase, the motor cannot be started, and the reason of the phase lack is that, for example, a wire is broken, a switch is not closed in place, and the like. The general fault judgment method needs to see the fault phenomenon to determine the fault position, so that the inspection is directly free from directivity, and hidden faults cannot be found. This is the main drawback of the current fault determination method. The analysis processing for the fault firstly judges the type of the fault and secondly judges the position of the fault. For example, 16 minutes at 17 hours of 9 months, 7 days in 2018, clear, windless, and after no voltage in the low voltage of the 14# pole transformer in the east way of the eastern mountain in the lower line of the Renship of the Redwellings 942 people's station in Changan rush repair team reaches the site, the voltage value at the low voltage disconnecting link is measured as: the A phase 175V and the B phase are unstable at about 64V, and the C phase 239V. At the moment, the low-voltage three-phase disconnecting link is pulled open, the low-voltage B-phase voltage is still unstable, and the low-voltage fault is eliminated; taking down the low-voltage three-phase fusion tube, finding that the installation of the middle-phase fuse is not firm, and stably obtaining a voltage value of a low-voltage B-phase of 64V after the treatment, and eliminating the fault of the high-voltage fusion tube; respectively disconnecting A, B, C-phase fuses, measuring the voltage of three phases at a high-voltage outlet of the transformer by an electric appliance, and eliminating the high-voltage fuse fault; and considering that the transformer station insurance part has an over short circuit fault in the previous day, the transformer station insurance part is judged to be a transformer problem. And when the time is about 22 minutes, the replacement work of the transformer is finished in 00 minutes, the three-phase voltage value of the transformer is still abnormal, then the user can know that nearby high-voltage users report that one phase of low voltage is not electrified, and the phase of the transformer is not electrified when the Changan rush-repair office report is close to a transformer station, and when the user finds that the phase B jumper wire is blown at the position 5 cm below the strain clamp from the Qingyuan street to the Dong-shan road until the time is 23 hours, the insulation skin is not broken.
Why can the phase of wire break still be detected with electricity? Because a 10kV rod-shaped telescopic high-voltage electroscope which is commonly used belongs to a capacitive electroscope, the 10kV rod-shaped telescopic high-voltage electroscope detects whether high-voltage electrical equipment and lines are electrified or not by detecting current flowing through an electroscope in a stray capacitance to the ground. According to the provisions of the power industry standard DL740-2000 of the people's republic of China, the starting voltage of the high-voltage power supply is 0.1-0.45 times of rated voltage, namely the starting voltage is about 1 kV-4.5 kV. For example: the starting voltage of the existing 10kV electroscope is 2kV, and the electroscope can also give an alarm when one-phase electrified line is tested to be a 3kV line.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for judging and positioning a 10kV distribution network one-phase-lack fault, which can gradually reduce the possible range of fault points.
The invention adopts the following technical scheme:
a method for judging and positioning a 10kV distribution network one-phase-lack fault comprises the following steps:
step 1, adjusting the starting voltage of an electroscope to be higher than the voltage of a phase-lacking phase on the high-voltage side of a transformer;
calling or measuring three-phase voltage values of the low-voltage side of the distribution line transformer on site through a remote information acquisition system, and when one phase voltage value is normal and the absolute value of the difference between the sum of the voltage values of the other two phases and the voltage value of the normal phase is less than 3V, judging that the fault type is that the transformer lacks one phase, and the transformer is on the load side of a phase-lacking point;
and 2, detecting each phase voltage at the high-voltage side of the transformer in the step 1 by adopting the electroscope adjusted in the step 1, judging that one phase is a default phase when an acousto-optic indicating device of the electroscope does not act when only one phase is measured, narrowing the fault range to the phase of the transformer, and indicating that a default phase point is on the power supply side of a high-voltage access point of the transformer.
Further, the distribution line transformer is a Dyn11 type transformer.
Further, the normal range of the voltage value of the one-phase voltage in the step 1 is 198V to 235.4V.
Further, the device for detection in step 1 and step 2 is an electroscope.
Further, in the step 1, the starting voltage of the electroscope is adjusted to be higher than the voltage of the phase-lacking phase on the high-voltage side of the transformer, and the specific method is as follows: preparing a transformer with a certain phase lacking, continuously adjusting the sizes of voltage dividing resistors R1 and R2 connected with contact electrodes in an electroscope when the phase lacking is known, measuring the phase lacking of the high-voltage side of the transformer by adopting the adjusted electroscope until the electroscope is not started when the phase lacking is measured and the electroscope is started when the normal phase of the high-voltage side of the transformer is measured, wherein the voltage dividing resistors R1 and R2 are not adjusted at the moment, and the starting voltage of the electroscope is higher than the voltage of the phase lacking of the high-voltage side of the transformer, so that the adjustment is completed.
The invention has the following beneficial effects:
the invention can effectively overcome the defects of the prior art, and can determine the fault position without seeing the fault phenomenon. By the method, the range of possible fault points is gradually reduced by detecting twice, so that inspection is more directional, and hidden faults can be found.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic diagram of the detection principle for detecting the low-voltage side of a transformer.
Fig. 2 is a schematic diagram of the detection principle for detecting the high-voltage side of the transformer.
Fig. 3 is a schematic circuit diagram of an electroscope.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail and fully with reference to the accompanying drawings 1-3 and the following detailed description.
A method for judging and positioning a one-phase fault of a 10kV distribution network utilizes the relation of low-voltage three-phase voltage values of a common Dyn11 type transformer to judge the fault type, utilizes an improved 10kV high-voltage electroscope (hereinafter referred to as an electroscope) to judge the fault type and accurately position the fault, detects twice through the method, gradually reduces the possible range of fault points, enables inspection to have higher directivity, is favorable for discovering hidden faults, can effectively overcome the defects of the prior art, and can determine the fault position without seeing the fault phenomenon. The method specifically comprises the following steps:
step 1, adjusting the starting voltage of an electroscope to be higher than the voltage of a phase-lacking phase on the high-voltage side of a transformer;
calling or measuring three-phase voltage values of the low-voltage side of the distribution line transformer on site through a remote information acquisition system, and when one phase voltage value is normal and the absolute value of the difference between the sum of the voltage values of the other two phases and the voltage value of the normal phase is less than 3V, judging that the fault type is that the transformer lacks one phase, and the transformer is on the load side of a phase-lacking point; the principle is that when the transformer lacks one phase, the voltage of one phase of low voltage is normal, and the voltage value of the phase is equal to the sum of the voltage values of the other two phases.
Step 2, detecting each phase voltage of the high-voltage side of the transformer in the step 1 by adopting the electroscope adjusted in the step 1, judging that the phase is a default phase when an acousto-optic indicating device of the electroscope does not act when only one phase is measured, reducing a fault range to the phase of the transformer, and indicating that a default phase point is on the power supply side of a high-voltage access point of the transformer; the principle is that only the phase-missing phase voltage is lower than the normal rated voltage.
Further, the distribution line transformer is a Dyn11 type transformer.
Further, the normal range of the voltage value of the one-phase voltage in the step 1 is 198V to 235.4V.
Further, the device for detection in step 1 and step 2 is an electroscope.
Further, in the step 1, the starting voltage of the electroscope is adjusted to be higher than the voltage of the phase-lacking phase on the high-voltage side of the transformer, and the specific method is as follows: preparing a transformer with a certain phase lacking, continuously adjusting the sizes of voltage dividing resistors R1 and R2 connected with contact electrodes in an electroscope when the phase lacking is known, measuring the phase lacking of the high-voltage side of the transformer by adopting the adjusted electroscope until the electroscope is not started when the phase lacking is measured and the electroscope is started when the normal phase of the high-voltage side of the transformer is measured, wherein the voltage dividing resistors R1 and R2 are not adjusted at the moment, and the starting voltage of the electroscope is higher than the voltage of the phase lacking of the high-voltage side of the transformer, so that the adjustment is completed.
The reason why step 1 is established is discussed below, and as shown in fig. 1, a simplified diagram of three-phase high-low voltage windings of a Dyn11 type transformer is provided, assuming that the high-side a-phase is open-phase, and there is a phase loss at this time
And
in phase and easy to know
Then, according to the wiring group of the transformer and the transformation ratio of the transformer, the fact that the low-voltage side has
Namely Ua+Ub＝UcThereby, the correctness of step 1 can be proved.
The reason why step 2 is established is discussed below, because the high-voltage and low-voltage coils are coupled through the iron core, the voltage of the low-voltage side phase of the transformer is proportional to the voltage of the high-voltage side phase. In addition, under the condition of phase-B loss of a Dyn11 transformer, the measured data of the low-voltage phase a 175V, B, the phase 64V, c and the phase 239V and the Uac of 10kV show that:
get UAB＝7.32kV，UBC＝2.68kV
Again, since the voltage to ground of the high voltage side A, C is normally 5.77kV and the included angle is 120 °, fig. 2 can be obtained, and solving the triangle according to fig. 2 can obtain OB of 3.68kV <5.77 kV.
It can be seen that high-voltage side B is at a voltage lower than the rated voltage with respect to ground.
Similarly, the data of the low-voltage side when the high-voltage side A is out of phase are as follows: phase a 137.1V, b phase 235.2V, c phase 100.4V, the voltage of high-voltage side A relative to ground is 2.34 kV.
The voltage result obtained when the phase C of the high-voltage side is in phase loss is similar to that when the phase A is in phase loss due to the recurrent symmetry.
A10 kV rod-shaped telescopic high-voltage electroscope which is commonly used belongs to a capacitive electroscope and detects whether high-voltage electrical equipment and lines are electrified or not by detecting current flowing through an earth stray capacitor of the electroscope. According to the provisions of the power industry standard DL740-2000 of the people's republic of China, the starting voltage of the high-voltage power supply is 0.1-0.45 times of rated voltage, namely the starting voltage is about 1 kV-4.5 kV. However, the starting voltage of the existing electroscope is obviously lower, and the electroscope can still be started when measuring the phase-lacking phase, so that the phase-lacking phase and the normal phase cannot be distinguished. As shown in fig. 3, the resistor R1 and the resistor R2 connected to the contact electrode mainly perform voltage division, convert the collected capacitance current signal into a voltage signal, and then perform subsequent processing. Therefore, the voltage charged in the subsequent processing circuit can be increased by increasing R1 or decreasing R2, so that the starting voltage of the electroscope is increased. For example, a model electroscope is found for disassembly, and R1 ═ R2 ═ 330 kohms are measured. Continuously adjusting the value of the resistor R2 under the condition of the phase-B lacking phase and testing the phase-B (namely, the phase-lacking phase) and the phase-A (namely, the normal phase) on the high-voltage side, the following table can be obtained:
as can be seen from the above table, when 190 kOhm is less than or equal to R2 is less than or equal to 0.32 Mhm, the phase-deficient phase and the normal phase can be distinguished by the electroscope, and the median value of R2 is not 255 kOhm. The feasibility of step 2 can thus be demonstrated.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (5)
1. A method for judging and positioning a 10kV distribution network one-phase-lack fault is characterized by comprising the following steps:
step 1, adjusting the starting voltage of an electroscope to be higher than the voltage of a phase-lacking phase at the high-voltage side of a distribution line transformer;
calling or measuring three-phase voltage values of the low-voltage side of the distribution line transformer on site through a remote information acquisition system, and when one phase voltage value is normal and the absolute value of the difference between the sum of the voltage values of the other two phases and the voltage value of the normal phase is less than 3V, judging that the fault type is that the distribution line transformer lacks one phase, and the distribution line transformer is on the load side of a phase-lacking point;
and 2, detecting each phase voltage on the high-voltage side of the distribution line transformer in the step 1 by adopting the electroscope adjusted in the step 1, judging that one phase is a default phase when an acousto-optic indicating device of the electroscope does not act when only one phase is measured, narrowing the fault range to the phase of the distribution line transformer, and indicating that a default phase point is on the power supply side of a high-voltage access point of the distribution line transformer.
2. The method for judging and positioning the one-phase-lack fault of the 10kV distribution network according to claim 1, wherein the method comprises the following steps: the distribution line transformer is a Dyn11 type distribution line transformer.
3. The method for judging and positioning the one-phase-lack fault of the 10kV distribution network according to claim 2, wherein the method comprises the following steps: the normal range of the voltage value of the one-phase voltage in the step 1 is 198V-235.4V.
4. The method for judging and positioning the one-phase-lack fault of the 10kV distribution network according to claim 1, wherein the method comprises the following steps: the electroscope in the step 1 and the step 2 is a capacitance type electroscope.
5. The method for judging and positioning the one-phase-lack fault of the 10kV distribution network according to claim 1, wherein the method comprises the following steps: in the step 1, the starting voltage of the electroscope is adjusted to be higher than the voltage of the phase-lacking phase at the high-voltage side of the distribution line transformer, and the specific method comprises the following steps: preparing a distribution line transformer with a certain phase and a known phase loss, continuously adjusting the sizes of divider resistors R1 and R2 connected with contact electrodes in an electroscope, measuring the phase loss of the high-voltage side of the distribution line transformer by adopting the adjusted electroscope, starting the electroscope when the electroscope is not started and the normal phase of the high-voltage side of the distribution line transformer is measured until the phase loss is measured, wherein the divider resistors R1 and R2 are not adjusted at the moment, and the starting voltage of the electroscope is higher than the voltage of the phase loss of the high-voltage side of the distribution line transformer, so that the adjustment is completed.
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| CN110794226A (en) * | 2019-10-08 | 2020-02-14 | 云南电力技术有限责任公司 | Method and device for judging fused phase in three-phase three-column type distribution transformer |
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