Movable handheld voltage waveform oscilloscope for judging disconnection of N600 neutral line

Abstract

The utility model relates to a movable handheld voltage waveform oscilloscope used for judging disconnection of an N600 neutral line. Comprising an easy-to-saturate miniature transformer used for accessing PT secondary terminal voltage analog signals, an analog-to-digital conversion chip used for converting the voltage analog signals into digital signals, a digital processor and a waveform display module used for displaying waveforms of the digital signals. The primary side of the easily-saturable small-sized transformer is connected with a PT secondary terminal, the secondary side of the easily-saturable small-sized transformer is connected with the input end of the analog-to-digital conversion chip, the output end of the analog-to-digital conversion chip is connected with the digital processor, and the digital processor is connected with the waveform display module. According to the invention, the voltage waveform of the PT secondary terminal can be conveniently checked, the situation that the field space is limited, the wiring is simple, the test result is quick and accurate, the device is convenient to carry and move is avoided, and the situation that equipment cannot be moved due to the crowded field space is avoided.

Description

Technical Field

[0001] The utility model relates to the field of electrical measurement tools, and particularly to a movable handheld voltage waveform oscilloscope for judging the disconnection of the neutral line of N600. Background Art

[0002] Nowadays, in power systems such as thermal power plants and substations, due to the increasing complexity of the primary part, a series of problems such as incorrect installation wiring of equipment and aging of wiring terminals have emerged, leading to misoperation and refusal to operate of in-station protection equipment, posing challenges to the safe and stable operation of the power system. In recent years, there have been many events such as disconnection and poor contact of N600 on the secondary side of PT, causing phase disorder and neutral point shift during the operation of the power system, resulting in incorrect measurement voltage, and in severe cases, misoperation and refusal to operate of protection equipment. During daily inspections, it is not convenient to view the waveform of N600 on the secondary side of PT by checking the wiring, so it is difficult to detect the hidden danger of disconnection of the neutral line of N600 on the secondary side of PT. Content of the Utility Model

[0003] In view of this, the purpose of the utility model is to provide a movable handheld voltage waveform oscilloscope for judging the disconnection of the neutral line of N600 to solve the problems in the prior art.

[0004] To achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A movable handheld voltage waveform oscilloscope for judging the disconnection of the neutral line of N600 of the utility model includes an easily saturable small transformer for accessing the voltage analog signal of the PT secondary terminal, an analog-to-digital conversion chip for converting the voltage analog signal into a digital signal, a digital processor, and a waveform display module for displaying the waveform of the digital signal;

[0006] The primary side of the easily saturable small transformer is connected to the PT secondary terminal, the secondary side of the easily saturable small transformer is connected to the input end of the analog-to-digital conversion chip, the output end of the analog-to-digital conversion chip is connected to the digital processor, and the digital processor is connected to the waveform display module.

[0007] In an embodiment of the present application, the easily saturable small transformer includes three sets of transformer coils. One end of the primary sides of the three sets of transformer coils are respectively connected to the three phase lines of the PT secondary terminal, and the other ends of the primary sides of the three sets of transformer coils are all connected to the neutral line of the PT secondary terminal; the secondary sides of the three sets of transformer coils are respectively connected to the three input ends of the analog-to-digital conversion chip.

[0008] In an embodiment of the present application, the digital processor is a single-chip microcomputer or a DSP digital processor.

[0009] In an embodiment of the present application, it further includes a communication module for sending digital signals to a remote host, and the communication module is connected to the digital processor.

[0010] In an embodiment of the present application, it further includes a battery unit and a power supply circuit. The battery unit is connected to the input end of the power supply circuit, and the output end of the power supply circuit is connected to the analog-to-digital conversion chip, the digital processor, and the waveform display module.

[0011] The beneficial effects of the present utility model are as follows: A portable hand-held voltage waveform oscilloscope for judging the disconnection of the neutral line of N600 of the present utility model includes an easily saturable small transformer for accessing the voltage analog signal of the PT secondary terminal, an analog-to-digital conversion chip for converting the voltage analog signal into a digital signal, a digital processor, and a waveform display module for displaying the waveform of the digital signal; the primary side of the easily saturable small transformer is connected to the PT secondary terminal, the secondary side of the easily saturable small transformer is connected to the input end of the analog-to-digital conversion chip, the output end of the analog-to-digital conversion chip is connected to the digital processor, and the digital processor is connected to the waveform display module. The present application can conveniently view the voltage waveform of the PT secondary terminal, avoiding the situation where it is restricted by the on-site space and the wiring is simple, the test result is fast and accurate, it is convenient to carry and move, and it avoids the situation where the equipment cannot be moved due to the crowded on-site space. Description of the Drawings

[0012] The following further describes the present utility model in conjunction with the drawings and embodiments:

[0013] Figure 1 It is a schematic structural diagram of a portable hand-held voltage waveform oscilloscope for judging the disconnection of the neutral line of N600 of the present utility model. Detailed Embodiments

[0014] The following specific examples illustrate the implementation manners of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0015] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Therefore, only the layers related to the present utility model are shown in the diagrams, rather than being drawn according to the number, shape, and size of the layers in actual implementation. The type, quantity, and ratio of each layer in actual implementation can be an arbitrary change, and the layer layout type may also be more complex.

[0016] In the following description, a large number of details are explored to provide a more thorough explanation of the embodiments of the present utility model. However, it is obvious to those skilled in the art that the embodiments of the present utility model can be implemented without these specific details.

[0017] As Figure 1 shown, this application includes an easily saturated small transformer for accessing the PT secondary terminal voltage analog signal, an analog-to-digital conversion chip for converting the voltage analog signal into a digital signal, a digital processor, and a waveform display module for displaying the waveform of the digital signal.

[0018] The primary side of the easily saturated small transformer is connected to the PT secondary terminal, the secondary side of the easily saturated small transformer is connected to the input terminal of the analog-to-digital conversion chip, the output terminal of the analog-to-digital conversion chip is connected to the digital processor, and the digital processor is connected to the waveform display module.

[0019] Specifically, the easily saturated small transformer includes three sets of transformer coils. One end of the primary sides of the three sets of transformer coils are respectively connected to the three phase lines of the PT secondary terminal, and the other ends of the primary sides of the three sets of transformer coils are all connected to the neutral line of the PT secondary terminal; the secondary sides of the three sets of transformer coils are respectively connected to the three input terminals of the analog-to-digital conversion chip.

[0020] The small transformer inside this application uses an easily saturated small transformer and has a self-produced 3U0 voltage that can reflect the third harmonic voltage with zero-sequence properties. When detecting the operating voltage loop, the magnetic flux density is relatively high, and it generally operates near the saturation magnetic density.

[0021] Once the primary operating voltage is slightly on the high side, it may enter the saturation region. Once the small transformer enters the saturation region, the sinusoidal exciting current cannot obtain a sinusoidal magnetic flux, and the magnetic flux waveform presents a clipped top shape. Therefore, a standard sinusoidal induced electromotive force cannot be induced on the secondary side, resulting in a large third harmonic component in the distortion of the secondary voltage waveform of the small transformer. At this time, if the primary winding of the small transformer is complete with the N600 neutral line of the PT, the third harmonic voltage component of each phase can form a third harmonic current. This current generates a third harmonic magnetic flux in the primary winding and is superimposed on the clipped top magnetic flux. Finally, a sinusoidal magnetic flux waveform is obtained, and the final secondary induced electromotive force of the small transformer is a sinusoidal wave.

[0022] If the primary winding of the small transformer is disconnected from the N600 neutral line, the third-harmonic current cannot flow through the primary winding and cannot be magnetized, which will cause the secondary voltage distortion and directly affect the reliability of the protection action. Therefore, the disconnection of the N600 neutral line can be identified through voltage waveform analysis. If the primary winding of the small transformer is disconnected from the N600 neutral line, the third-harmonic current cannot flow, and the third-harmonic magnetic flux cannot be generated. Only the magnetic flux generated by the sinusoidal exciting current in the primary winding exists in the iron core of the small transformer. At this time, if the magnetic circuit of the small transformer is not saturated, the magnetic flux is sinusoidal; if the magnetic circuit is slightly saturated, the magnetic flux will be clipped, and the secondary induced electromotive force will have a third-harmonic component, and the secondary phase voltage distortion will present a symmetric flat-top waveform or a spiky waveform, depending on the initial phase angle of the third harmonic.

[0023] Since the self-produced 3U0 voltage can reflect the third-harmonic voltage with zero-sequence properties, the integrity of the N600 neutral line can be identified according to the characteristics of the above-mentioned phase voltage and 3U0 voltage in the oscillogram. If the phase voltages of multiple PTs in the same power plant show different degrees of clipping (or spiking) and the 3U0 has a third-harmonic voltage during normal operation, it indicates that the disconnection may occur on the N600 bus of the PT. If only the voltage of individual equipment is abnormal, it means that the disconnection occurs on the branch of the N600 neutral line, and it may even occur within the device panel.

[0024] In an embodiment of the present application, the digital processor can be a single-chip microcomputer or a DSP digital processor.

[0025] In an embodiment of the present application, it further includes a communication module for sending digital signals to a remote host. The communication module is connected to the digital processor. The present application is fixedly installed on-site, and the waveform signal is received by the remote host to complete remote inspection.

[0026] In an embodiment of the present application, it further includes a battery unit and a power supply circuit. The battery unit is connected to the input end of the power supply circuit, and the output end of the power supply circuit is connected to the analog-to-digital conversion chip, the digital processor, and the waveform display module. Since the present application adopts a handheld and movable design, the battery unit and the power supply circuit are provided for power supply.

[0027] A portable hand-held voltage waveform oscilloscope for judging the disconnection of the neutral line of N600 according to the utility model comprises an easily saturated small transformer for accessing the voltage analog signal of the secondary terminal of the PT, an analog-to-digital conversion chip for converting the voltage analog signal into a digital signal, a digital processor, and a waveform display module for displaying the waveform of the digital signal; the primary side of the easily saturated small transformer is connected to the secondary terminal of the PT, the secondary side of the easily saturated small transformer is connected to the input end of the analog-to-digital conversion chip, the output end of the analog-to-digital conversion chip is connected to the digital processor, and the digital processor is connected to the waveform display module. This application can conveniently view the voltage waveform of the secondary terminal of the PT, avoiding the situation where the on-site space is limited and the wiring is simple. The test results are fast and accurate, easy to carry and move, and avoid the situation where the equipment cannot be moved due to overcrowded on-site space.

[0028] In the above embodiments, although the utility model has been described in conjunction with specific embodiments of the utility model, many substitutions, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art based on the foregoing description. The embodiments of the utility model are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims.

[0029] The above embodiments are only illustrative of the principles and effects of the utility model and are not intended to limit the utility model. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the utility model. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the utility model should still be covered by the claims of the utility model.

Claims

1. A portable handheld voltage waveform oscilloscope for judging whether the neutral line of N600 is broken, characterized in that: It includes an easily saturated small transformer for connecting to the PT secondary terminal voltage analog signal, an analog-to-digital conversion chip for converting the voltage analog signal into a digital signal, a digital processor, and a waveform display module for displaying the waveform of the digital signal; The primary side of the easily saturated small transformer is connected to the PT secondary terminal, the secondary side of the easily saturated small transformer is connected to the input end of the analog-to-digital conversion chip, the output end of the analog-to-digital conversion chip is connected to the digital processor, and the digital processor is connected to the waveform display module.

2. A portable handheld voltage waveform oscilloscope for determining whether the neutral line of N600 is broken according to claim 1, characterized in that: The easily saturated small transformer includes three groups of transformer coils, one end of the primary side of the three groups of transformer coils is respectively connected to the three phase lines of the PT secondary terminal, and the other end of the primary side of the three groups of transformer coils is connected to the neutral line of the PT secondary terminal; the secondary sides of the three groups of transformer coils are respectively connected to the three input terminals of the analog-to-digital conversion chip.

3. A portable handheld voltage waveform oscilloscope for determining whether the neutral line of N600 is broken according to claim 1, characterized in that: The digital processor is a single chip microcomputer or a DSP digital processor.

4. A portable handheld voltage waveform oscilloscope for determining whether the neutral line of N600 is broken according to claim 1, characterized in that: Also included is a communication module for sending digital signals to a remote host, wherein the communication module is connected to the digital processor.

5. A portable handheld voltage waveform oscilloscope for determining whether the neutral line of N600 is broken according to claim 1, characterized in that: It also includes a battery unit and a power supply circuit, wherein the battery unit is connected to the input end of the power supply circuit, and the output end of the power supply circuit is connected to the analog-to-digital conversion chip, the digital processor, and the waveform display module.

Images