Non-contact digital current sensor

Abstract

The invention discloses a non-contact digital current sensor which comprises a sensing unit, a notch unit, an amplifying / filtering unit, an output interface and a power supply unit. The sensing unit outputs detection signals in two paths, one path is sent to the trap unit, and the other path is sent to the amplification / filtering unit; the notch unit is communicated with the amplifying / filtering unit, the amplifying / filtering unit is communicated with the output interface, the output interface comprises a low-frequency channel and a high-frequency channel, and the power supply unit is used for providing electric energy. The non-contact digital current sensor has the advantages of being large in measuring range, wide in frequency band, small in size and convenient to deploy and maintain, can adapt to various application scenes, can provide power frequency signals and accurate fault traveling wave signals for fault positioning of a power system at the same time, and helps to confirm fault diagnosis of power equipment.

Description

Technical Field

[0001] The invention relates to the field of electric power sensors, and in particular to a non-contact digital current sensor. Background Art

[0002] Building a new power system with new energy as the main body is an important strategic measure to ensure the security of energy supply under the "dual carbon" strategy. The new power system has frequent impacts on power equipment such as overvoltage, overcurrent, DC bias magnetism, broadband oscillation, harmonic resonance, and stray current, and the safe and reliable operation of key power equipment will face major challenges. Comprehensive, observable, measurable, and controllable digital grid technology is an important means to achieve accurate assessment of equipment operating status, early warning of faults, and ensure the safe and stable operation of power equipment. Advanced sensors that can be widely deployed are the key to the construction of digital grids. Among them, current sensors are the most widely used. However, existing current sensors use contact measurement, which is inconvenient to install and deploy, has a narrow measurement band, a small range, a large size, and high power consumption. It is difficult to meet the needs of sensing the operating status of power equipment and fault diagnosis under the complex operating conditions of the new power system.

[0003] However, existing non-contact current sensors (such as patent document CN118409131A) often only support the output of power frequency signals and cannot obtain accurate fault traveling wave signals, making it difficult to provide effective assistance for fault location. Summary of the invention

[0004] The present invention provides a non-contact digital current sensor which can simultaneously output accurate power frequency signals and fault traveling wave signals and provide effective signal data for a fault location system, so as to solve the technical problems mentioned in the background technology.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: A non-contact digital current sensor comprises a sensing unit, a trap unit, an amplification / filtering unit, an output interface and a power supply unit; The sensing unit is used to detect the current and output a detection signal. The sensing unit outputs the detection signal in two ways, one way is sent to the trap unit, and the other way is sent to the amplification / filtering unit; The notch unit is connected to the amplification / filtering unit and is used to perform power frequency notch filtering of the high-frequency signal output channel on the received detection signal; The amplification / filtering unit is connected to the output interface and is used to receive the detection signal from the sensor unit and the trap unit and to amplify and filter the detection signal; The output interface includes a low-frequency channel and a high-frequency channel, the low-frequency channel is used to output the power frequency signal processed by the amplification / filtering unit, and the high-frequency channel is used to output the fault traveling wave signal processed by the amplification / filtering unit; The power supply unit is used to provide electric energy to the sensor unit, the trap unit, the primary amplification unit, the filtering unit and the secondary amplification unit.

[0006] As a further preferred embodiment of the above technical solution, the amplification / filtering unit includes a primary amplification unit, a filtering unit and a secondary amplification unit connected in sequence; The first-stage amplification unit is connected to the filtering unit and is used to receive the detection signal from the sensing unit and the trap unit and amplify the detection signal; The filtering unit is connected to the secondary amplification unit, and the filtering unit includes a low-pass filter and a high-pass filter; The secondary amplification unit is connected to the output interface and is used to amplify the detection signal processed by the filtering unit again.

[0007] As a further preferred embodiment of the above technical solution, the non-contact digital current sensor also includes a control unit, which is connected to the primary amplification unit and controls the opening or closing of the primary amplification unit according to the size of the detection signal received by the primary amplification unit.

[0008] As a further preferred embodiment of the above technical solution, the control unit is also connected to the secondary amplification unit, and controls the amplification factor of the secondary amplification unit according to the size of the detection signal received by the secondary amplification unit.

[0009] As a further preferred embodiment of the above technical solution, the filtering frequency of the low-pass filter is below 500 Hz, and the filtering frequency of the high-pass filter is above 500 Hz.

[0010] As a further preferred embodiment of the above technical solution, the sensing unit is a tunnel magnetoresistive sensor.

[0011] The present invention has the following beneficial effects: The non-contact digital current sensor of the present invention is easy to install and can be flexibly adapted to various application scenarios of high, medium and low voltages. The measurement frequency and amplitude range of the sensor can be adaptively adjusted according to the actual application situation to meet various application requirements including transient and steady-state waveform analysis of power systems and operation status evaluation. It has the advantages of a large measuring range and a wide bandwidth, and can provide accurate data for fault diagnosis of power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the structure of the non-contact digital current sensor of Example 1.

[0013] Figure 2 This is a schematic diagram of the use of the non-contact digital current sensor of Example 1.

[0014] Figure 3This is a schematic diagram of the filter unit composition of the contactless digital current sensor of Example 1. DETAILED DESCRIPTION

[0015] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0016] Embodiment 1: like Figure 1 As shown, the non-contact digital current sensor of this embodiment can measure a signal frequency range of 50-500kHz; an amplitude range of 1-1000A, and includes a sensing unit, a trap circuit, a primary amplifier circuit, a filter circuit, a secondary amplifier circuit, an output interface and a power supply unit, and a control unit.

[0017] The sensing unit is used to detect the current and output the detection signal. The sensing unit outputs the detection signal in two ways and can provide a low-frequency channel and a high-frequency channel at the same time. In the low-frequency channel, the sensing unit is directly connected to the first-level amplifier circuit to send the detection signal to the trap circuit; in the high-frequency channel, the sensing unit is connected to the first-level amplifier circuit through the trap circuit to send the detection signal to the first-level amplifier circuit.

[0018] The notch circuit is connected to the first-stage amplifier circuit and is used to perform power frequency notch on the high-frequency signal output channel of the received detection signal to ensure that there is no power frequency component in the signal of the high-frequency channel, thereby ensuring the accuracy of the fault traveling wave signal finally obtained.

[0019] The first-stage amplifying circuit is connected to the filtering circuit and is used for receiving the detection signal from the sensing unit and the trap circuit and amplifying the detection signal.

[0020] The filter circuit is connected to the secondary amplifier circuit, such as Figure 3 As shown, the filtering circuit includes a low-pass filter and a high-pass filter.

[0021] The secondary amplifier circuit is connected to the output interface and is used to amplify the detection signal processed by the filter circuit again.

[0022] The output interface includes a low-frequency channel and a high-frequency channel. The low-frequency channel is used to output the power frequency signal, and the high-frequency channel is used to output the fault traveling wave signal.

[0023] The power supply unit is used to provide electric energy to the sensing unit, the trap circuit, the primary amplifying circuit, the filtering circuit and the secondary amplifying circuit.

[0024] The control unit is connected to the primary amplifying circuit and the secondary amplifying circuit, and controls the opening or closing of the primary amplifying circuit according to the size of the detection signal received by the primary amplifying circuit to ensure the measuring range of the sensor. The control unit also controls the amplification factor of the secondary amplifying circuit according to the size of the detection signal received by the secondary amplifying circuit, and determines the amplification factor by controlling the 4-position dial switch, and can provide 4-position amplification factor selection.

[0025] When using, Figure 2 As shown ( Figure 2 In the figure, 1 is a high-voltage cable, 2 is a non-contact digital current sensor of this embodiment, 3 is a power line, and 4 is a signal line). The non-contact digital current sensor of this embodiment is deployed in parallel with the measured line, and the magnetic field of the measured line is measured non-contactly, so as to indirectly collect the current signal. The measurement distance can be flexibly adjusted according to the actual scenario, and can adapt to different application scenarios and perception requirements.

[0026] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

[0027] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A non-contact digital current sensor, characterized in that: It includes a sensing unit, a notch unit, an amplification / filtering unit, an output interface and a power supply unit; The sensing unit is used to detect the current and output a detection signal. The sensing unit outputs the detection signal in two ways, one way is sent to the trap unit, and the other way is sent to the amplification / filtering unit; The notch unit is connected to the amplification / filtering unit and is used to perform power frequency notch filtering of the high-frequency signal output channel on the received detection signal; The amplification / filtering unit is connected to the output interface and is used to receive the detection signal from the sensor unit and the trap unit and to amplify and filter the detection signal; The output interface includes a low-frequency channel and a high-frequency channel, the low-frequency channel is used to output the power frequency signal processed by the amplification / filtering unit, and the high-frequency channel is used to output the fault traveling wave signal processed by the amplification / filtering unit; The power supply unit is used to provide electric energy to the sensing unit, the trap unit and the amplification / filtering unit.

2. The non-contact digital current sensor according to claim 1, characterized in that: The amplification / filtering unit comprises a primary amplification unit, a filtering unit and a secondary amplification unit connected in sequence; The first-stage amplification unit is connected to the filtering unit and is used to receive the detection signal from the sensing unit and the trap unit and amplify the detection signal; The filtering unit is connected to the secondary amplification unit, and the filtering unit includes a low-pass filter and a high-pass filter; The secondary amplification unit is connected to the output interface and is used to amplify the detection signal processed by the filtering unit again.

3. The non-contact digital current sensor according to claim 2, characterized in that: It also includes a control unit, which is connected to the first-stage amplification unit and controls the first-stage amplification unit to be turned on or off according to the size of the detection signal received by the first-stage amplification unit.

4. The non-contact digital current sensor according to claim 3, characterized in that: The control unit is also connected to the secondary amplification unit, and controls the amplification factor of the secondary amplification unit according to the size of the detection signal received by the secondary amplification unit.

5. The non-contact digital current sensor according to claim 2, characterized in that: The filtering frequency of the low-pass filter is below 500 Hz, and the filtering frequency of the high-pass filter is above 500 Hz.

6. The non-contact digital current sensor according to any one of claims 1 to 5, characterized in that: The sensing unit is a tunnel magnetoresistance sensor.

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