A high capacity pulse based cable weak click through control box

Abstract

The utility model relates to a cable weak point breakdown control box based on large capacity pulse, including box body, and the PCB board of built -in in the box body, has the breakdown circuit on the integrated PCB board, adjustable resistance is used for the adjustment of output current, overcurrent relay is used for overcurrent protection with alternating current contactor cooperation, the primary side of current transformer is connected in main circuit in series, the secondary side connects ammeter, is used for detecting the output current of adjustable resistance, and through ammeter direct -view display value, time relay is used for the delay control of discharge countdown with alternating current contactor cooperation. After using large capacity pulse to the cable weak point and carrying out breakdown, help to carry out the geographic positioning to the cable weak point through cable path appearance and cable fault pinpoint appearance, provide reliable information for the overhaul of cable, greatly improve the reliability of cable power collection line, reduce the loss and influence that wind power plant power collection line fault tripping brings, guarantee the continuous safe operation of wind power plant.

Description

Technical Field

[0001] This utility model relates to the field of cable testing technology, specifically to a cable weak point penetration control box based on high-capacity pulses. Background Technology

[0002] In the operation of wind farms, cable collector line tripping is an extremely common and significant type of accident. Once a tripping failure occurs, its impact is widespread, not only seriously threatening the safe and stable operation of the system, but also potentially causing irreversible damage to various equipment within the wind farm. Furthermore, it greatly reduces the reliability of power supply, bringing numerous negative impacts to the normal operation and economic benefits of the wind farm.

[0003] During long-term operation, the main insulation and cable joints of cable power distribution lines will inevitably age and may develop potential defects. These aging and defect problems can easily trigger fault discharges, affecting the safe operation of the cable power distribution lines.

[0004] Currently, the 35kV cables widely used in wind farms are laid directly underground. When these cables experience flashover faults or have weak insulation, the lack of effective geolocation technology makes it impossible to accurately pinpoint the exact location of the fault or defect. This directly hinders maintenance personnel from carrying out targeted repairs on defective cables, preventing the timely elimination of safety hazards in the cable collector lines and further exacerbating the operational risks of wind farms. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a cable weak point puncture control box based on high-capacity pulse, so as to overcome the shortcomings of the prior art.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: a cable weak point breakdown control box based on high-capacity pulse, including a box body and a PCB board built into the box body, the PCB board integrating a breakdown circuit; the breakdown circuit includes a power input terminal, a power output terminal, a time relay, an overcurrent relay, a current transformer, an AC contactor, and an adjustable resistor; The power input terminal is used to connect an AC220V power supply to power the device. The power output terminal is used to connect to the input terminal of the test transformer; Adjustable resistor, used to regulate output current. Overcurrent relays are used in conjunction with AC contactors for overcurrent protection. The primary side of the current transformer is connected in series with the main circuit, and the secondary side is connected to an ammeter to detect the output current of the adjustable resistor and display the value visually through the ammeter. A time relay is used in conjunction with an AC contactor for delay control of discharge countdown.

[0007] The beneficial effects of this invention are: after using a high-capacity pulse to break down the weak points of the cable, it helps to locate the weak points of the cable geographically using a cable path analyzer and a cable fault location analyzer, providing reliable information for cable maintenance, greatly improving the reliability of the cable collection line, reducing the losses and impacts caused by the fault tripping of the wind farm collection line, and ensuring the continuous and safe operation of the wind farm.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, it also includes circuit breakers, which are installed on the power input line.

[0010] Furthermore, the circuit breaker is a double-pole circuit breaker connected to both the neutral and live wires.

[0011] Furthermore, it also includes a protective grounding terminal, one end of which is connected to the enclosure and the other end is connected to the ground wire.

[0012] Furthermore, the control panel of the enclosure is equipped with a voltmeter and a measuring terminal block. The measuring end of the voltmeter is connected to the positive and negative terminals on the inside of the measuring terminal block.

[0013] Furthermore, a power lamp is connected in series between the power input terminals. Attached Figure Description

[0014] Figure 1 This is the electrical circuit schematic diagram of this utility model; Figure 2 This is a schematic diagram of the operation panel structure of this utility model; Figure 3 This is a physical image of the present invention; Figure 4 The curve showing the relationship between the cable fault point breakdown voltage and time according to this utility model; Figure 5 This is a flashover test diagram of this utility model. Detailed Implementation

[0015] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0016] like Figures 1-5As shown in Embodiment 1, a cable weak point breakdown control box based on high-capacity pulse includes a box body and a PCB board built into the box body. The PCB board integrates a breakdown circuit. The breakdown circuit includes a power input terminal, a power output terminal, a time relay, an overcurrent relay, a current transformer, an AC contactor, and an adjustable resistor. The power input terminal is used to connect an AC220V power supply to power the device. The power output terminal is used to connect to the input terminal of the test transformer; Adjustable resistor, used to regulate output current. Overcurrent relays are used in conjunction with AC contactors for overcurrent protection; for specific implementation details, please refer to [link / reference needed]. Figure 1 The signal input terminals of pins 6 and 8 of the overcurrent relay are connected to the secondary side of the current transformer, pins 2 and 7 are connected to the AC220V power supply, and normally closed contacts 1 and 3 are connected to the circuit. The primary side of the current transformer is connected in series with the main circuit, and the secondary side is connected to an ammeter to detect the output current of the adjustable resistor and display the value visually through the ammeter; in specific implementations, the specifications are 30A / 5A. A time relay is used in conjunction with an AC contactor for delay control during discharge countdown. For specific implementation details, see [link to implementation details]. Figure 1 The time relay's pins 1 and 2 are connected to an AC220V power supply, and the normally closed contacts of pins 7 and 8 are connected to the circuit. After using high-capacity pulses to break down weak points in the cable, it helps to locate the weak points in the cable using cable path analyzers and cable fault location analyzers, providing reliable information for cable maintenance, greatly improving the reliability of cable collector lines, reducing the losses and impacts caused by fault tripping of wind farm collector lines, and ensuring the continuous and safe operation of wind farms.

[0017] Example 2 is a further improvement based on Example 1, and its details are as follows: It also includes circuit breakers, which are installed on the power input line. They are used for leakage protection.

[0018] Example 3 is a further improvement based on Example 2, and its details are as follows: The circuit breaker is a double-pole circuit breaker connected to both the neutral and live wires. It can completely isolate the mains power input and prevent reverse current leakage from the neutral wire.

[0019] Example 4 is a further improvement based on Example 1, and its details are as follows: It also includes a protective grounding terminal, one end of which is connected to the enclosure, and the other end is connected to the ground wire. This improves the safety performance of the equipment.

[0020] Example 5 is a further improvement based on Example 1, and its details are as follows: The control panel of the enclosure is equipped with a voltmeter and measuring terminal blocks. The measuring terminals of the voltmeter are connected to the positive and negative terminals on the inside of the measuring terminal blocks. It can monitor the output voltage in real time as needed, and the display is intuitive and clear.

[0021] Example 6 is a further improvement based on Example 1, and its details are as follows: A power indicator light is connected in series between the power input terminals to indicate whether power is connected.

[0022] Specific implementation principle: Most cable lines are buried underground, making it difficult to locate faults in the event of a power outage. This is due to several factors: firstly, the age of the underground cable network and incomplete data due to mismanagement; and secondly, changes in the surface topography caused by wind farm reconstruction, further complicating the fault location process. Looking at cable fault detection methods, especially for open-circuit and high-resistance faults, high-energy signals are often used to break down the fault point. However, whether the fault point can be broken down, the extent of the breakdown, and the degree of breakdown remain unknown.

[0023] Common cable faults include open circuit, low resistance, high resistance, and flashover. Among these, high resistance and flashover are the most common and difficult to measure.

[0024] High-resistance faults. These are faults relative to low-resistance faults. The insulation resistance between cable phases or to ground is significantly lower than normal, exceeding 10⁻⁰, and the conductor continuity is good. This type of fault is called a high-resistance fault. Flashover fault. This type of fault often occurs in cable joints or terminations. The symptoms may vary. Sometimes it breaks down near the required test voltage and then recovers; sometimes it breaks down continuously at an unstable frequency, with intervals ranging from seconds to minutes. Sometimes the cable breaks down under a certain voltage, and the breakdown completely stops after the insulation recovers; this type of fault is usually called a closed-circuit fault.

[0025] For high-resistance faults and flashover faults, impulse-flashover testing is generally used: 1. The impulse flashover test applies an impulse voltage to the cable through a ball gap, causing the fault point to break down and discharge, generating a reflected voltage (or current). The instrument records this instantaneous state, and the location of the fault point is determined by waveform analysis. This is the main method for measuring high-resistance and flashover faults. Sampling methods include voltage sampling and current sampling, which can be further subdivided into high-end and low-end voltage sampling, inductance and resistance sampling, and beginning and end sampling. Low-end current sampling is highly practical due to its simple wiring, reliability, safety, and easily identifiable waveform. Increasing the ball gap and thus the voltage applied to the cable makes it easier for the fault point to break down. Cable faults are often caused by a doubled voltage due to the reflected voltage from the far end. For example, if the ball gap discharge impulse voltage is 10KV, the fault point on the cable can receive a voltage close to 20KV. Therefore, in actual testing, the impulse voltage value should ideally not exceed 50% to 70% of the specified cable leakage test voltage.

[0026] The energy supplied to the cable by the high-voltage equipment can be calculated using the following formula: W = C * U² / 2; The energy supplied to the cable by the high-voltage equipment is directly proportional to the energy storage capacity C and the square of the applied voltage. If the fault point does not break down or, although there is discharge, it is insufficient, no reflected echo from the fault point will be observed on the waveform. This can be addressed by increasing the energy storage capacity C or increasing the impulse voltage U to ensure sufficient discharge at the fault point. Increasing the pulse capacitor from 4uF to 8uF, without increasing the impulse voltage, is more conducive to the breakdown of the fault point. Due to the increased capacitance, the rated current of the control box is increased to 50A to ensure the charging speed of the capacitor.

[0027] Increasing the capacity of the energy storage capacitor increases the energy supplied to the cable by the high-voltage equipment, which in turn increases the duration of voltage on the cable, thus facilitating the breakdown of the fault point. Figure 5 A typical cable fault breakdown voltage versus time curve A is given, along with voltage versus time curves 1, 2, 3, and 4 for different capacitances C (ignoring the influence of far-end reflected voltage). Direct breakdown occurs when the latter intersects curve A. Under the same impulse voltage, curves 1 and 2 have larger capacitances and intersect with curve A, thus causing fault breakdown; while curves 3 and 4 correspond to smaller capacitances. Although the voltage on the cable is higher, it decays quickly and does not intersect with curve A, thus not causing fault breakdown. 4. During impulse flashover testing, the ball gap is repeatedly discharged. After burning the fault point for a period of time, the "cumulative effect" further damages the fault point, reducing the breakdown voltage and shortening the discharge delay.

[0028] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A cable weak point penetration control box based on high-capacity pulse, characterized in that, The device includes a housing and a PCB board built into the housing, the PCB board integrating a breakdown circuit; the breakdown circuit includes a power input terminal, a power output terminal, a time relay, an overcurrent relay, a current transformer, an AC contactor, and an adjustable resistor; The power input terminal is used to connect to an AC220V power supply to power the device; The power output terminal is used to connect to the input terminal of the test transformer; The adjustable resistor is used to adjust the output current; The overcurrent relay is used in conjunction with the AC contactor to provide overcurrent protection; The primary side of the current transformer is connected in series with the main circuit, and the secondary side is connected with an ammeter to detect the output current of the adjustable resistor and display the value visually through the ammeter. The time relay is used in conjunction with the AC contactor to perform delay control for the discharge countdown.

2. The cable weak point penetration control box based on high-capacity pulse according to claim 1, characterized in that, It also includes a circuit breaker, which is installed on the power input line.

3. A cable weak point penetration control box based on high-capacity pulse according to claim 2, characterized in that, The circuit breaker is a double-pole circuit breaker connected to the neutral and live wires.

4. A cable weak point penetration control box based on high-capacity pulse according to claim 1, characterized in that, It also includes a protective grounding terminal, one end of which is connected to the enclosure and the other end is connected to the ground wire.

5. A cable weak point penetration control box based on high-capacity pulse according to claim 1, characterized in that, The control panel of the enclosure is equipped with a voltmeter and a measuring terminal block. The measuring terminal of the voltmeter is connected to the positive and negative terminals on the inside of the measuring terminal block.

6. A cable weak point penetration control box based on high-capacity pulse according to claim 1, characterized in that, A power lamp is connected in series between the power input terminals.

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