A line single-phase grounding detection system

Abstract

The present invention discloses a line single-phase grounding detection system, comprising a grounding current signal wireless transmitter and an on-site detection device, wherein the grounding current signal wireless transmitter comprises a current transformer [1], a frequency modulation signal modulator [2], and a frequency modulation signal transmitter [3]; the on-site detection device comprises a metal grounding signal collection device, a signal receiver, and a signal strength display. The detection of the present invention does not require manual pole climbing, which brings a qualitative change to the single-phase grounding detection operation, helps to improve the fault handling speed of the distribution network system, and the effect of the present invention is more prominent at night or in bad weather.

Description

Technical Field

[0001] The invention relates to a line single-phase grounding detection system used in the field of power distribution line fault locating equipment. Background Art

[0002] The difficulty in finding the single-phase grounding fault point in the 10kV to 35kV power system has always been a major problem that plagues the operation of the distribution network. Whether it is arc suppression coil grounding or low-resistance grounding, there will be fault points that are difficult to find by conventional inspection methods, resulting in troublesome fault handling, frequent power transmission failures and other serious problems. With the increasing branching and cableization of distribution networks, various hidden faults, intermittent faults, high-resistance grounding faults, etc. have brought great inconvenience to the location and accident handling of single-phase grounding faults.

[0003] In response to this problem, some power companies have developed grounding search instruments based on the fifth harmonic method or signal injection principle. However, the existing grounding search equipment generally has inaccurate positioning accuracy and difficulty in high-resistance grounding, which greatly limits its promotion and use. Some more advanced fault indicators now also have grounding indication functions, but fault indicators cannot be installed densely. For lines with many cable outlet branches or long distances, their help in on-site search is still limited. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a line single-phase grounding detection system, which has the outstanding advantages of high degree of automation, no need for manual pole climbing, fast detection speed and safe operation process.

[0005] A technical solution to achieve the above object is: a line single-phase grounding detection system, including a portable grounding detector, a grounding current signal wireless transmitter and an on-site detection device;

[0006] The ground current signal wireless transmitting device comprises a current transformer [1], a frequency modulation signal modulator [2] and a frequency modulation signal transmitter [3], wherein the current transformer [1] is an open-end transformer, whose open end is clamped on the signal injection end of the portable ground detector, and whose secondary winding is connected to the signal input end of the frequency modulation signal modulator [2], and the signal output end of the frequency modulation signal modulator [2] is connected to the signal input end of the frequency modulation signal transmitter [3], and the transmitting antenna of the frequency modulation signal transmitter [3] is arranged outdoors;

[0007] The on-site detection device consists of a metal grounding signal collecting device, a signal receiver and a signal strength display. The metal grounding signal collecting device moves along the arrangement direction of the grounding current signal wireless transmitting device, collects the grounding signal and transmits it to the signal receiver. The signal strength display displays the signal strength to display the grounding signal strength.

[0008] Furthermore, the on-site detection device is an on-site detection vehicle, which includes two metal braided belt rollers [4], two water spray heads [5], a signal amplifier [7], a frequency modulation signal receiver [8], an adder [9] and a signal strength display

[10] . The two metal braided belt rollers [4] are respectively installed at the front and rear of the chassis of the on-site detection vehicle, the two water spray heads [5] are respectively installed on both sides of the two metal braided belt rollers [4], and wires are respectively led out between the two metal braided belt rollers [4] and connected to the signal input end of the signal amplifier [7]. The signal output end of the frequency modulation signal receiver [8] and the signal output end of the signal amplifier [7] are respectively connected to the signal input end of the adder [9], and the signal input end of the signal strength display

[10] is connected to the signal output end of the adder [9].

[0009] Furthermore, the on-site detection vehicle is provided with an ultraviolet corona imaging detector

[11] .

[0010] The beneficial effects of the present invention are:

[0011] The existing single-phase grounding location detection solutions all require manual pole climbing and the signal current measurement by wireless clamp meter to determine the range of the fault point. Due to the large number of line branches, sometimes it is necessary to manually climb the pole more than ten times to find the fault point, which is time-consuming, labor-intensive and unsafe. The detection of the present invention does not require manual pole climbing at all, which brings a qualitative change to the single-phase grounding detection operation. The present invention cleverly uses the vehicle-mounted detection roller to indirectly determine the range of the fault point by picking up the trace current signal on the road surface. The entire detection process is carried out on the vehicle, without the need for manual repeated pole climbing, and greatly improves the detection efficiency and safety. The present invention can complete many detections that cannot be completed in several hours within half an hour, thereby greatly improving the fault handling speed of the distribution network system. The effect of the present invention is more prominent at night or in severe weather. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a connection diagram of a ground current signal wireless transmitter of a line single-phase grounding detection system of the present invention;

[0013] Figure 2 A schematic diagram of an on-site detection vehicle of a line single-phase grounding detection system of the present invention;

[0014] Figure 3 The present invention is a schematic diagram of the connection of a signal system of a line single-phase grounding detection system. DETAILED DESCRIPTION

[0015] In order to better understand the technical solution of the present invention, the following is a detailed description through specific embodiments:

[0016] See also Figure 1 , is a connection diagram of a ground current signal wireless transmitter. The device includes a current transformer 1, an FM signal modulator 2, and an FM signal transmitter 3. The current transformer 1 is an open transformer, and its open clamp is clamped on the signal injection end of the portable ground detector. After a ground fault occurs, if it is a power outage detection, the detection personnel usually use a ground detector to inject a detection signal into the ground line, and then climb the pole at different positions to measure the signal current direction with a wireless clamp meter to find the fault point, but these operations require frequent pole climbing, low efficiency, and great safety hazards. The present invention connects its secondary winding to the signal input end of the FM signal modulator 2 through a transformer, and the signal output end of the FM signal modulator 2 is connected to the signal input end of the FM signal transmitter 3. The transmitting antenna of the FM signal transmitter 3 is set outdoors. This device can convert the signal current of the portable ground detector into a wireless FM signal, and transmit it to the outside for signal phase amplitude comparison during detection.

[0017] See also Figure 2 , Figure 3 , which is a structural diagram of the on-site detection vehicle. The on-site detection vehicle includes two metal braided belt rollers 4, two water spray heads 5, a signal amplifier 7, an FM signal receiver 8, an adder 9, and a signal strength display 10. The two metal braided belt rollers 4 are respectively installed at the front and rear of the chassis of the on-site detection vehicle, and the two water spray heads 5 are respectively installed on both sides of the two metal braided belt rollers 4. When a fault occurs, the grounding detection vehicle is driven to the area near the line where the grounding fault occurs. When the vehicle is driving, the metal braided belt roller can capture the weak grounding current on the ground. Considering that the conductivity of the road surface is poor when it is dry, spraying water through the water spray head can further improve the conductivity of the road surface and help pick up the grounding signal current. Wires are led out between the two metal braided belt rollers 4, respectively, and connected to the signal input end of the signal amplifier 7. The signal output end of the FM signal receiver 8 and the signal output end of the signal amplifier 7 are respectively connected to the signal input end of the adder 9. The signal input end of the signal strength display 10 is connected to the signal output end of the adder 9. The ground signal current picked up from the ground by the adder and the ground signal current transmitted by the received FM wave carrier are vector-added, and the phase and amplitude of the two signals can be compared. When the detection vehicle is close to the fault point area, the ground current signal strength of the ground is the largest. By comparing the current phase measured by the arc extinguishing coil transmitted by FM wireless transmission, the ground current can be determined. Then, by driving the detection vehicle in different directions, the specific ground fault point can be roughly located. In addition, the on-site detection vehicle is provided with an ultraviolet corona imaging detector 11, which can further help to find the fault point location.

[0018] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A line single-phase grounding detection system, comprising a portable grounding detector, a grounding current signal wireless transmitter and an on-site detection device, characterized in that: The ground current signal wireless transmitting device comprises a current transformer [1], a frequency modulation signal modulator [2] and a frequency modulation signal transmitter [3], wherein the current transformer [1] is an open-end transformer, whose open end is clamped on the signal injection end of the portable ground detector, and whose secondary winding is connected to the signal input end of the frequency modulation signal modulator [2], and the signal output end of the frequency modulation signal modulator [2] is connected to the signal input end of the frequency modulation signal transmitter [3], and the transmitting antenna of the frequency modulation signal transmitter [3] is arranged outdoors; The ground current signal wireless transmitting device can convert the signal current of the portable ground detector into a wireless frequency modulation signal, and transmit it to the outside for signal phase amplitude comparison during detection; The on-site detection device is composed of a metal grounding signal collection device, a signal receiver and a signal strength display. The metal grounding signal collection device moves along the arrangement direction of the grounding current signal wireless transmission device to collect the grounding signal and transmit it to the signal receiver. The signal strength display displays the signal strength to display the grounding signal strength. The on-site detection device is an on-site detection vehicle, which includes two metal braided belt rollers [4], two water spray heads [5], a signal amplifier [7], a frequency modulation signal receiver [8], an adder [9] and a signal strength display [10]. The two metal braided belt rollers [4] are respectively installed at the front and rear of the chassis of the on-site detection vehicle. Wires are respectively led out between the two metal braided belt rollers [4] and connected to the signal input end of the signal amplifier [7]. The signal output end of the frequency modulation signal receiver [8] and the signal output end of the signal amplifier [7] are respectively connected to the signal input end of the adder [9]. The signal input end of the signal strength display [10] is connected to the signal output end of the adder [9]. The grounding signal current picked up from the ground and the grounding signal current transmitted by the received FM wave carrier are vector-added by the adder to compare the phase and amplitude of the two signals. When the on-site detection vehicle is close to the fault area, the grounding current signal strength is the largest. The grounding current can be determined by comparing the current phase measured by the arc suppression coil transmitted by FM wireless transmission. The specific grounding fault point can be located by driving the on-site detection vehicle in different directions.

2. A line single-phase grounding detection system according to claim 1, characterized in that: The on-site detection vehicle is provided with an ultraviolet corona imaging detector [11].

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