CN111208391A - Line ground fault finder adopting alternating current and direct current signals and detection method - Google Patents

Abstract

The invention discloses a line ground fault finder adopting an alternating current-direct current signal, which comprises a box body, a support, a power supply module, a main board, a display module, a boosting device, a rectifying module, an insulation resistance testing module and a current detection device, wherein the power supply module is connected with the main board; the bracket is arranged inside the box body, and the power module, the mainboard, the booster device and the rectifier module are all arranged on the bracket; the mainboard is provided with a control module, a current detection module and a voltage detection module; the power supply module is electrically connected with the rectifying module through the boosting device; the display module, the current detection module, the voltage detection module and the power supply module are respectively and electrically connected with the control module; the current detection device comprises a current clamp and a receiver, and the receiver receives current data of the overhead line through a wireless signal receiving current clamp. Correspondingly, the invention also discloses a line ground fault detection method adopting the alternating current and direct current signals. The method is used for searching the single-phase earth fault, and can improve the searching efficiency.

Description

Line ground fault finder adopting alternating current and direct current signals and detection method

Technical Field

The invention relates to the technical field of single-phase earth fault detection of a power distribution network of a power system, in particular to a line earth fault finder adopting an alternating current signal and a direct current signal and a detection method.

Background

With the continuous increase of power consumption requirements, the 10kV power distribution network has longer and longer lines, more and more branch lines, more and more complex network structures and higher line fault rate, and becomes a core problem influencing the reliability of the power supply network. The single-phase earth fault is one of the most common phenomena in power transmission line faults, and particularly, the fault causes are difficult to judge in rural and mountain areas due to more factors such as tree barriers, insulator breakdown, single-phase line breakage, small animal harm, moisture, insulator failure, short circuit of a lightning arrester and the like.

At present, a point current line selection device can be used for searching a loop with a single-phase earth fault, and then the loop is searched by a worker in a line patrol mode, so that a large amount of manpower and material resources are wasted, and meanwhile, the economic loss is caused by long-time power failure.

Disclosure of Invention

The invention aims to provide a line ground fault finder and a detection method adopting an alternating current signal and a direct current signal, which are used for detecting a small-resistance ground fault and a high-resistance ground fault.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a line ground fault finder adopting an alternating current-direct current signal comprises a box body, a support, a power supply module, a main board, a display module, a boosting device, a rectifying module, an insulation resistance testing module and a current detection device; the bracket is arranged in the box body, and the power module, the mainboard, the booster device and the rectifier module are all arranged on the bracket; the mainboard is provided with a control module, a current detection module and a voltage detection module; the power supply module is electrically connected with the rectifying module through a boosting device; the display module, the current detection module, the voltage detection module and the power supply module are respectively and electrically connected with the control module; the current detection device comprises a current clamp and a receiver, wherein the receiver receives current data of the overhead line detected by the current clamp through a wireless signal.

Preferably, the power module comprises a storage battery and an inverter; the storage battery is electrically connected with the variable winding transformer through the inverter; the inverter is electrically connected with the control module.

Preferably, the boosting device comprises a variable winding transformer and a boosting transformer; the storage battery is electrically connected with the inverter, the variable winding transformer, the boosting transformer and the rectifying module in sequence.

Preferably, the top of the bracket is provided with a host panel; the display module is arranged on the host panel; the host panel is also provided with an alternating current test port, a direct current trial delivery port, a grounding port, a boosting knob, a test button, a reset button and an alternating current-direct current change-over switch.

Preferably, a box cover which is detachably mounted is arranged on the box body.

Preferably, the current detection device comprises an insulating rod, and the current clamp is mounted on the insulating rod.

The invention also provides a line ground fault detection method adopting the alternating current and direct current signals, which comprises the following steps:

s1: testing the insulation resistance of the overhead line, and if the insulation resistance reaches the standard, the line has no fault, and if the insulation resistance does not reach the standard, the step S2 is carried out;

s2: transmitting a pilot frequency high-voltage alternating current signal to the overhead line, judging a line ground fault point according to the measured voltage and current signals, and entering the step S3 when the recovery work of the fault point is completed;

s3: and (4) transmitting a direct current signal to the overhead line, judging whether the line has a fault according to the measured voltage and current signals, and returning to the step S1 if the line has the fault.

Preferably, step S2 includes:

s21: ensuring that the fault line has been powered off;

s22: wiring of a fault locator;

s23: turning on a power switch of a host, pressing a test button, adjusting a boosting button to boost, observing the voltage and current values of the host, automatically cutting off the output of the host when the current value exceeds 100mA, reducing the voltage to a zero value, stopping boosting when the current value reaches 100mA, and stopping boosting when the voltage value reaches the maximum value of 5kV if the current value does not reach 100 mA;

s24: using a current detection device to perform inspection along a fault line, when the current is detected in the line, indicating that a fault point is at the downstream of a measurement point, if no current exists, indicating that the fault point is at the upstream of the measurement point, and when the current value changes obviously, determining that the measurement point is the fault point;

s25: after the test is finished, a reset button is pressed, the boosting knob is restored to the zero position, the power line is disconnected, and the high-voltage output line and the grounding line are detached.

Preferably, step S24 includes:

s241: when the line has only one trunk line, firstly testing the midpoint of the trunk line, determining whether the fault point is upstream or downstream, if so, testing the midpoint of the upstream line, and gradually shortening the distance of the inspection line until the fault point is found;

s242: when there are more than two main lines in the line, the current at the branch of each main line is detected first, and the branch line with the larger current is the faulty line, and then the process returns to step S241.

Preferably, step S3 includes:

s31: ensuring that the line fault recovery work is completed;

s32: wiring of a fault locator;

s33: turning on a power switch of a host, pressing an alternating current-direct current switch, pressing a test button, adjusting a boosting knob, and observing a voltage value and a current value of the host at the same time, wherein if the direct current voltage is increased to 8kV, the current is far lower than 70mA, which indicates that the circuit has no fault, and if the direct current voltage is not increased to 8kV, the current is higher than 70mA, which indicates that the circuit has fault;

s34: after the test is finished, a reset button is pressed, the boosting knob is restored to the zero position, the alternating current and direct current change-over switch is restored to the alternating current position, the power line is disconnected, and the high-voltage output line and the grounding line are detached.

Compared with the prior art, the invention has the beneficial effects that:

the invention adopts the pilot frequency high-voltage alternating current signal which can be distinguished from a 50Hz power frequency signal, and can reduce the influence of the distributed capacitance of the circuit on the fault positioning test to the maximum extent; the output maximum current of the invention reaches 100mA, the fault current and the line distributed capacitance current can be distinguished, and the judgment accuracy is improved; the invention can also output direct current voltage signals and has a direct current trial transmission function; the invention can detect the low resistance ground fault and the high resistance ground fault.

Drawings

FIG. 1 is a diagram illustrating the operation of a host according to an embodiment of the present invention;

FIG. 2 is a diagram of a host panel according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating an internal structure of a host according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of an output waveform of the finder according to an embodiment of the present invention;

fig. 5 is a diagram illustrating the operation of the finder according to an embodiment of the present invention.

In the figure, 1-box; 2-a scaffold; 3-a power supply module; 4, a main board; 5-a host panel; 6-a booster device; 7-a rectifying module; 8-current detection means; 9-overhead lines; 11-box cover; 31-a storage battery; 32-an inverter; 41-a control module; 42-a current detection module; 43-a voltage detection module; 51-a display module; 52-ac test port; 53-dc trial port; 54-ground port; 55-a boost knob; 56-test button; 57-reset button; 58-AC/DC switch; 61-variable winding transformer; 62-a step-up transformer; 81-current clamp; 82-an insulating rod; 83-receiver.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

Referring to fig. 1 to 5, a line ground fault finder using ac/dc signals includes a box 1, a bracket 2, a power module 3, a main board 4, a display module 51, a voltage boosting device 6, a rectifying module 7, an insulation resistance testing module, and a current detecting device 8; the bracket 2 is arranged in the box body 1, and the power module 3, the mainboard 4, the booster device 6 and the rectifier module 7 are all arranged on the bracket 2; the mainboard 4 is provided with a control module 41, a current detection module 42 and a voltage detection module 43; the power module 3 is electrically connected with the rectifying module 7 through the boosting device 6; the display module 51, the current detection module 42, the voltage detection module 43 and the power supply module 3 are respectively electrically connected with the control module 41; the current detection device 8 includes a current clamp 81 and a receiver 83, and the receiver 83 receives the current data of the overhead line 9 by the current clamp 81 through a wireless signal.

In this embodiment, the power module 3 outputs a pilot frequency ac signal under the control of the control module 41, the pilot frequency ac signal outputs a pilot frequency high voltage ac signal through the voltage boosting device 6, the pilot frequency high voltage ac signal outputs a dc signal through the rectifying module 7, and the pilot frequency high voltage ac signal and the dc signal are switched and output as required, wherein the insulation resistance testing module is used to test the insulation resistance of the overhead line 9 to determine whether the line has a fault, and when the pilot frequency high voltage ac signal is output to the overhead line 9, the current detecting device 8 is used to perform inspection along the faulty line to detect the line ground fault, and when all detected line ground fault points are removed and recovered to normal, the dc signal is output to the overhead line 9 to check whether the line has a fault according to the voltage and current of the host, the current detecting module 42 and the voltage detecting module 43 are used to detect the current and voltage output by the host, the detected current and voltage values are displayed on the display module 51 through the control module 41, and when the current and voltage values are abnormal and exceed the maximum value of the output of the instrument, the instrument can automatically stop outputting and be automatically protected.

Preferably, the power module 3 includes a battery 31 and an inverter 32; the battery 31 is electrically connected to the variable winding transformer 61 through the inverter 32; the inverter 32 is electrically connected to the control module 41. In the design, the inverter 32 converts the direct current of the storage battery 31 into a pilot frequency alternating current signal, the output voltage is 220V/60Hz, the storage battery 31 is a lithium battery or a lead-acid battery, and the control module 41 is used for controlling the inverter 32 to output the pilot frequency alternating current signal.

Preferably, the booster device 6 includes a variable winding transformer 61 and a booster transformer 62; the battery 31 is electrically connected to the inverter 32, the variable winding transformer 61, the step-up transformer 62, and the rectifier module 7 in this order. In the design, after the pilot frequency alternating current signal is subjected to voltage regulation through a variable winding transformer 61, the voltage is boosted through a boosting transformer 62, a pilot frequency high-voltage alternating current signal is output, the output voltage is adjustable in the range of 0-5 kV, the frequency is 60Hz, the maximum value of the output current is 100mA, and an output voltage waveform diagram is shown in FIG. 4.

Preferably, the output dc voltage of the rectifier module 7 is 8kV at most and the output current is 70mA at most.

Preferably, the finder includes a low voltage transformer, an input end of the low voltage transformer is connected to the commercial power, and an output end of the low voltage transformer is electrically connected to the control module 41, the display module 51, the variable winding transformer 61, the step-up transformer 62, the rectifying module 7, the current detecting module 42, and the voltage detecting module 43, respectively. In this design, a low voltage transformer transforms the mains supply into a low voltage supply suitable for each device module.

Preferably, the bracket 2 is made of an aluminum alloy material.

As shown in fig. 2, a host panel 5 is arranged on the top of the bracket 2; the display module 51 is provided on the host panel 5; the host panel 5 is further provided with an ac test port 52, a dc test port 53, a ground port 54, a boost knob 55, a test button 56, a reset button 57, and an ac/dc switch 58.

In this embodiment, the display module 51 is used for displaying the voltage and current values of the host; the alternating current test port 52 is used for outputting a pilot frequency high-voltage alternating current signal; the dc pilot port 53 is used to output a dc signal; the ground port 54 is grounded with respect to the ac test port 52 or the dc test port 53, and functions as a protection circuit; the boost knob 55 is used for adjusting the amplitude of the pilot frequency high-voltage alternating-current signal output by the alternating-current test port 52 and the amplitude of the direct-current signal output by the direct-current trial sending port 53; the test button 56 is used for searching the instrument for testing; the reset button 57 is used for resetting the searching instrument; the ac/dc switch 58 is used for switching and outputting the pilot frequency high-voltage ac signal and the dc signal.

Preferably, the box body 1 is provided with a detachably mounted box cover 11. In this design, case lid 11 and box 1 are articulated, and the back is opened to case lid 11, then sees host computer panel 5, carries out the wiring through each port of host computer panel 5, then can test and operation such as reset.

Preferably, the current detection device 8 comprises an insulating rod 82, and the current clamp 81 is mounted on the insulating rod 82. In this design, use insulator spindle 82 to connect current tong 81, can be so that keep away from overhead line 9 when measuring current, guarantee operating personnel's personal safety to it is more convenient to operate.

Example 2

Referring to fig. 1 to 5, a method for detecting a line ground fault using ac/dc signals includes:

s1: and (4) testing the insulation resistance of the overhead line 9, and if the insulation resistance reaches the standard, the line has no fault, and if the insulation resistance does not reach the standard, the step S2 is carried out.

S2: and (4) transmitting the pilot frequency high-voltage alternating current signal to the overhead line 9, judging a line ground fault point according to the measured voltage and current signals, and entering the step S3 when the fault point recovery work is completed.

S21: ensuring that the faulty line has been blacked out, i.e. the substation stops supplying power to the overhead line 9;

s22: wiring of a fault locator: the wiring diagram is shown in fig. 5, the power module 3 is connected with a host through a power line, an output line of an alternating current test port 52 of the host is connected with a fault line, and a grounding port 54 is connected with a line ground line;

s23: turning on a power switch of the host, pressing a test button 56, adjusting a boosting button to boost, observing the voltage and current values of the host, automatically cutting off the output of the host when the current value exceeds 100mA, reducing the voltage to zero, stopping boosting when the current value reaches 100mA, and stopping boosting when the voltage value reaches the maximum value of 5kV if the current value does not reach 100 mA;

s24: inspecting along the fault line by using a current detection device 8, when the current is detected in the line, indicating that the fault point is at the downstream of the measurement point, if the current is not detected, indicating that the fault point is at the upstream of the measurement point, and when the current value is obviously changed, judging that the measurement point is the fault point;

s241: when the line has only one trunk line, firstly testing the midpoint of the trunk line, determining whether the fault point is upstream or downstream, if so, testing the midpoint of the upstream line, and gradually shortening the distance of the inspection line until the fault point is found;

s242: when there are more than two main lines in the line, the current at the branch of each main line is detected first, and the branch line with the larger current is the faulty line, and then the process returns to step S241.

As shown in fig. 5, the currents of the ab branch line and the ag branch line are detected first, if the current value of the ab branch line is larger and the current value of the ag branch line is smaller, the fault is at the downstream of the ab branch line, then the midpoint current of the abcd line is detected, the cd current is larger and the cf current is smaller, the fault is at the cd branch line, the midpoint current value of the cd branch line is detected again, and the fault point is found step by step.

S25: after the test is completed, the reset button 57 is pressed, the boost knob 55 is restored to the zero position, the power line is disconnected, and the high-voltage output line and the ground line are removed.

S3: a dc signal is supplied to the overhead line 9, whether or not there is a fault in the line is determined from the measured voltage and current signals, and if there is a fault, the process returns to step S1.

S31: ensuring that the line fault recovery work is completed;

s32: wiring of a fault locator: the power module 3 is connected with a host through a power line, the output line of a direct current test sending port 53 of the host is connected with a tested line, and a grounding port 54 is connected with a line ground wire;

s33: turning on a power switch of a host, pressing an alternating current-direct current changeover switch 58, pressing a test button 56, adjusting a boosting knob 55, observing a voltage value and a current value of the host, if the direct current voltage rises to 8kV and the current is far lower than 70mA, indicating that the circuit has no fault, and if the direct current voltage does not rise to 8kV and the current exceeds 70mA, indicating that the circuit has a fault;

s34: after the test is completed, the reset button 57 is pressed, the boost knob 55 is restored to the zero position, the alternating current/direct current changeover switch 58 is restored to the alternating current position, the power line is disconnected, and the high-voltage output line and the grounding line are removed.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.

Claims (10)

1. The utility model provides an adopt line ground fault finder of alternating current-direct current signal which characterized in that: the device comprises a box body, a bracket, a power supply module, a mainboard, a display module, a boosting device, a rectifying module, an insulation resistance testing module and a current detecting device; the bracket is arranged in the box body, and the power module, the mainboard, the booster device and the rectifier module are all arranged on the bracket; the mainboard is provided with a control module, a current detection module and a voltage detection module; the power supply module is electrically connected with the rectifying module through the boosting device; the display module, the current detection module, the voltage detection module and the power supply module are respectively and electrically connected with the control module; the current detection device comprises a current clamp and a receiver, wherein the receiver receives current data of the overhead line detected by the current clamp through a wireless signal.

2. The line ground fault finder using ac/dc signals according to claim 1, wherein: the power supply module comprises a storage battery and an inverter; the storage battery is electrically connected with the variable winding transformer through the inverter; the inverter is electrically connected with the control module.

3. The line ground fault finder using ac/dc signals according to claim 2, wherein: the boosting device comprises a variable winding transformer and a boosting transformer; the storage battery is electrically connected with the inverter, the variable winding transformer, the boosting transformer and the rectifying module in sequence.

4. The line ground fault finder using ac/dc signals according to claim 1, wherein: a host panel is arranged at the top of the bracket; the display module is arranged on the host panel; the host panel is also provided with an alternating current test port, a direct current trial delivery port, a grounding port, a boosting knob, a test button, a reset button and an alternating current-direct current change-over switch.

5. The line ground fault finder using ac/dc signals according to claim 4, wherein: the box body is provided with a box cover which is detachably arranged.

6. The line ground fault finder using ac/dc signals according to claim 1, wherein: the current detection device comprises an insulating rod, and the current clamp is installed on the insulating rod.

7. A line ground fault detection method adopting alternating current and direct current signals is characterized by comprising the following steps:

s1: testing the insulation resistance of the overhead line, and if the insulation resistance reaches the standard, the line has no fault, and if the insulation resistance does not reach the standard, the step S2 is carried out;

s2: transmitting a pilot frequency high-voltage alternating current signal to the overhead line, judging a line ground fault point according to the measured voltage and current signals, and entering the step S3 when the recovery work of the fault point is completed;

s3: and (4) transmitting a direct current signal to the overhead line, judging whether the line has a fault according to the measured voltage and current signals, and returning to the step S1 if the line has the fault.

8. The line ground fault detection method using ac/dc signals according to claim 7, wherein step S2 includes:

s21: ensuring that the fault line has been powered off;

s22: wiring of a fault locator;

s23: turning on a power switch of a host, pressing a test button, adjusting a boosting button to boost, observing the voltage and current values of the host, automatically cutting off the output of the host when the current value exceeds 100mA, reducing the voltage to a zero value, stopping boosting when the current value reaches 100mA, and stopping boosting when the voltage value reaches the maximum value of 5kV if the current value does not reach 100 mA;

s24: using a current detection device to perform inspection along a fault line, when the current is detected in the line, indicating that a fault point is at the downstream of a measurement point, if no current exists, indicating that the fault point is at the upstream of the measurement point, and when the current value changes obviously, determining that the measurement point is the fault point;

s25: after the test is finished, a reset button is pressed, the boosting knob is restored to the zero position, the power line is disconnected, and the high-voltage output line and the grounding line are detached.

9. The line ground fault detection method using ac/dc signals according to claim 8, wherein step S24 includes:

s241: when the line has only one trunk line, firstly testing the midpoint of the trunk line, determining whether the fault point is upstream or downstream, if so, testing the midpoint of the upstream line, and gradually shortening the distance of the inspection line until the fault point is found;

s242: when there are more than two main lines in the line, the current at the branch of each main line is detected first, and the branch line with the larger current is the faulty line, and then the process returns to step S241.

10. The line ground fault detection method using ac/dc signals according to claim 7, wherein step S3 includes:

s31: ensuring that the line fault recovery work is completed;

s32: wiring of a fault locator;

s33: turning on a power switch of a host, pressing an alternating current-direct current switch, pressing a test button, adjusting a boosting knob, and observing a voltage value and a current value of the host at the same time, wherein if the direct current voltage is increased to 8kV, the current is far lower than 70mA, which indicates that the circuit has no fault, and if the direct current voltage is not increased to 8kV, the current is higher than 70mA, which indicates that the circuit has fault;

s34: after the test is finished, a reset button is pressed, the boosting knob is restored to the zero position, the alternating current and direct current change-over switch is restored to the alternating current position, the power line is disconnected, and the high-voltage output line and the grounding line are detached.

Images